Engine

Cylinder heads, compression math & valvetrain

Still oval-port aluminum heads, but with two corrections. First, the AFR 3610 (265 cc, 109 cc, hydraulic roller package, about $2,640-$2,770 per pair, currently out of stock at Clay Smith) has 0.375" raised exhaust ports, so confirm header fit before ordering. The Edelbrock 60455 (standard-location ports) is the…

Research note on sourcing: summitracing.com, jegs.com, dartheads.com, compcams.com and several forums blocked page fetches (HTTP 403). Prices below come from vendor pages I could fetch (Clay Smith Cams, 90racing, shafiroff, the tre.dev.webshopmanager mirror, Edelbrock's own PDF) or from search-result snippets of the blocked sites. All were seen on 2026-10-12, but a snippet does not tell me when the vendor last updated its price, so treat every price as "seen 2026-10-12, confirm at checkout". Anything I could not confirm says "price not confirmed". Piston dome/dish volumes and the factory '77 chamber volume are NOT confirmed anywhere I could read, so the compression math is built so you can plug in your own measured numbers.

The pick

Good
Edelbrock 60455 or 60435 pair, about $2,080 (Jegs sale) to $2,570 (CompCams), plus Proform 778-66913K rollers ($262), Fel-Pro 1017-1 gaskets (about $135-$162 per pair) and ARP bolts ($120-$143). Roughly $3,100-$3,400 before pistons, pushrods and valve covers.
Better
AFR 3610 pair, about $2,640-$2,770, plus COMP 249-1620-16 rockers ($531), ARP 135-3703 ($120-$143), Fel-Pro gaskets (about $135-$162), custom pushrods (price not confirmed) and tall valve covers (Proform VC240, $362). Roughly $3,800-$4,300 before custom forged pistons (price not confirmed). The Trick Flow PowerOval 280 pair, about $2,790-$3,300, is the alternative at this tier.
Best
AFR 290/300 (3640/3650/3670), Dart Pro 1 or Brodix Race-Rite pair, about $3,300-$3,830 (AFR 3650 solid-roller about $3,700-$3,780 per pair, with the per-pair status needing checkout confirmation), plus Harland Sharp SH2001 rockers ($507), pushrods, studs and gaskets. Roughly $4,800-$5,500 before pistons (price not confirmed). All of these have raised exhaust ports, so header selection comes first.

Path A (full performance build, 489 ci, forged rotating assembly; matches section 90 Recipe 2): Edelbrock Performer RPM 60455 (110 cc, hydraulic-roller springs) with COMP Ultra-Pro Magnum 1.7 rockers. Reasons: (1) standard exhaust-port location, so the C10 header and steering-box problems of raised-port heads are removed (gate in the AFR row below); (2) Edelbrock rates the head 1,500-6,500 rpm and tested it on a 454 at 9.5:1 for 540 hp with its RPM package (source 3), enough head for roughly 450-500 hp at 5,500-6,000 rpm on 489 ci; (3) at 9.2-9.3:1 the 110 cc chamber needs a net piston volume of only about +0.9 to -0.6 cc (table above), i.e. an ordinary forged flat top, no dome; (4) it is name-brand, serviceable and widely stocked. Price about $2,080 (Jegs sale) to $2,570 (CompCams) per pair; sold each. Alternate (460 ci only): AFR 3610 (265 cc, 109 cc, hydraulic roller package). AFR rates the 265 oval "up to 468 cubic inches at or below 6,200 rpm" (source 6), so it is NOT matched to the 489, and its exhaust ports are RAISED 0.375" (ordinary OEM-pattern headers, including the Hedman 69170/69176 family, may not fit; ask AFR and the header maker in writing). On a 460 at 9.2-9.5:1 it needs about -5 to -9 cc of net dome (table). The 3610 was out of stock at Clay Smith when checked. The Edelbrock is the lower-risk and $500-$1,000 cheaper choice either way.

Piston recipe for the 489 (Path A): 4.280" bore forged flat top, compression height 1.540" on the 9.800" deck / 6.135" rod / 4.250" stroke (zero-deck), set so the piston sits 0.004" below the deck, Fel-Pro 1017-1 at 0.039" (quench 0.043"), net piston volume about +0.9 to -0.6 cc for 9.2-9.3:1 with 110 cc heads (a stock-style valve-relief flat top at +4 cc gives 9.0:1; zero relief gives 9.26:1). The Scat 942-1-42452 kit's actual piston type, compression height and relief cc are NOT confirmed (section 90 U1; JEGS describes a flat top with a single valve relief and quotes 9.4:1 at 112 cc, which the arithmetic cannot reproduce). So 9.26:1 and 9.0:1 are design numbers; the real number comes from CC-ing the kit piston and the chosen heads and measuring piston-to-deck with the kit assembled. If the shop finds the kit lands above 9.5:1, use a thicker (about 0.045") gasket or a +4 to +6 cc relief; if below 9.0:1, a thinner gasket or a deck skim. Target (section 90, adopted here): static 9.2-9.3:1, DCR 8.4-8.6, cam closing the intake at 41-45 degrees ABDC. The earlier draft of this section recommended about 9.8:1 (9.6-10.0) with a 240-250 degree cam on a 460; that was withdrawn because a 240-250 cam closes the intake 48-55 degrees ABDC, which is a poor idle/converter/A-C match for this truck, and 9.8:1 at the 489's IVC 41-44 would be DCR 9.0 or more.

If the owner goes to a 496-504 stroker (4.375" stroke) instead of the 489: the AFR 290 oval (3640/3650 family) is the better head (rated up to 509 ci at or below 6,500 rpm, source 9), and the dome requirement drops to about -12 to -14 cc. But AFR's 290 and 300 ovals have exhaust ports raised 0.375", so ordinary C10 headers may not fit; those heads need headers designed for raised ports (header section dependency). The 265 is rated only to 468 ci, so do not put it on a 489 or a 496. (A 496-504 is outside the project spec: the 489 is the maximum the two-bolt block, the 4L80E converter and the 93-octane target are sized for.)

Path B (freshen stock bottom end plus bolt-on top end, about 400-450 hp): Edelbrock Performer RPM 60435 (100 cc, hydraulic-roller springs) with COMP Ultra-Pro Magnum or Proform rollers. Reasons: the 100 cc chamber is the only way to get a stock-style flat-top piston up to roughly 9.0-9.5:1 with aluminum heads (my math above: 9.2-9.5 at 0.004" deck with 0 to +4 cc relief on 4.280", versus 7.9-8.8 for the 110 cc head); the head is about $1,040 (Jegs sale, 60455) to $1,285 each versus AFR 3610's roughly $1,320-$1,385 each; Edelbrock's own test used this head with 9.5:1 and a mild hydraulic roller on pump gas for 540 hp (source 3), though "pump gas" there is not specified as 93 octane and that 540 was a full RPM-package number; and the head bolts on to Mark IV with ordinary headers. Do not use stock-spec 0.025" deck-down pistons: have the block decked so quench lands near 0.043". If the original dished/relieved pistons are reused, expect only 7.9-8.5:1 and the aluminum heads buy almost nothing, so new flat-tops are worth it.

What the owner should expect: Path A (489, 9.2-9.3:1, 110 cc oval heads, 230/230 hydraulic roller) is estimated at about 450-500 hp (about 480 expected) / 520-560 lb-ft (section 84 C4 reaches the same range independently by torque-curve reasoning). Anchors, all published: the Chevrolet Performance ZZ454/440 (454 ci, 110 cc aluminum ovals, 9.6:1, a very mild 211/230 cam) makes 469 hp / 519 lb-ft (source 20); scaling its torque by displacement (489/454 = 1.077) gives about 559 lb-ft at the same efficiency, and Edelbrock's own RPM-head test made 540 hp on a 454 at 9.5:1 (source 3). Taking roughly half a point of compression away and adding a 4.250" stroke points to the high-440s to 500 hp neighborhood, and the torque near 520-560 lb-ft. The owner's 500-520 hp at 5,500-6,000 rpm goal is at or above the top of that range and is NOT validated for this exact parts list: there is no dyno or engine-simulation result for it in this research. Treat 500 hp as the optimistic end and 520 as a stretch; an engine-simulation run (Engine Analyzer, Dyno2000 or the cam maker's) with the real cam card and head flow data is the way to close it before parts are ordered. Path B lands near 400-450 hp. These are estimates.

Why it matters

The heads are the biggest lever in the whole engine, and on a '77 Mark IV 454 they are also where the original engine is weakest. The factory 454 of this era was an 8.25:1 low-compression emissions motor with big iron oval-port heads and flat-top valve-notch pistons. Forum and NCRS posters put the later 454s at roughly 110 to 118 cc chambers (a '70 454 was about 96-100 cc and the '74 about 110-113 cc), so compression fell by about 2 points mostly because of the chamber and a lower piston (source 28). The owner originally wanted 10.3-10.5:1 on 93 octane with a 5,500-6,000 rpm powerband. That target does not survive the dynamic-compression math for a truck cam (see DCR section). Project-wide design target after the integration pass (section 90): 9.2-9.3:1 static on the 489, a 230-236 degree hydraulic roller closing the intake at 41-45 degrees ABDC, DCR 8.4-8.6, 9.5:1 absolute ceiling. Compression at that level is only realistic with aluminum heads (they shed heat and tolerate roughly a point more static compression than iron), a tight quench (about 0.035-0.045"), and a cam whose intake valve closes late enough to keep dynamic compression sane (see the DCR section). Compression and cam have to be chosen together, and the cam also sets manifold vacuum for the power brakes, so this section hands real constraints to the cam/trans/brake sections.

Port choice: for a 454/460 that will live under 6,000-6,200 rpm, oval-port heads are the right tool. Edelbrock rates its oval RPM head 1,500-6,500 rpm (source 3). AFR rates its 265 oval for "street, street/strip and towing, up to 468 ci, at or below 6,200 rpm" (source 6), and its 290 oval for up to 509 ci at or below 6,500 rpm (source 9). The ChevyHardcore comparison says go rectangle only if the engine will spend most of its time above 6,500 rpm (source 2). A rectangle port (AFR 305/325, Dart 310/325 and up) gives up low-end velocity and torque for flow this truck will never use. It is also harder on drivability with a mild idle lope and a converter that must work at 2,000-3,000 rpm. Rectangle ports also force a different intake manifold and different head-bolt/valve-cover/header situations.

Square-body specifics: this is a heavy half-ton that will be driven on the interstate at 65-70 mph. Torque at 2,500-4,500 rpm matters more than a peak number. The Performer RPM-class oval head's marketed strength is exactly that, "flow numbers traditionally associated with rectangular port heads but with the smaller runner size and velocity of an oval port" (source 3). Clearance also matters more than on a Chevelle: the C10 has a power-brake booster and a tight firewall, and aluminum-head builds with roller rockers require taller valve covers (source 3 itself says taller covers are usually needed), so valve cover fit against the booster must be checked before buying (see Fitment).

Options

Head candidates (all are oval/"early style" Mark IV compatible unless noted)

Tier Brand & model Part # Price (vendor, seen 2026-10-12) Link Notes
Good Edelbrock Performer RPM oval, hydraulic-roller springs, 110 cc 60455 (polished 604515) $1,284.50 each at CompCams (search snippet, 2026-10-12); $1,039.98 each at Jegs (on sale from $1,223.50, search snippet, 2026-10-12); $1,785 at Lordco (Canadian retailer, outlier). Heads are sold EACH, so a pair is about $2,080 (Jegs sale) to $2,570 (CompCams). The older Mancini page ($1,108-$1,180) mixes in 84 cc heads and is not a reliable price for this part compcams.com Complete head. 2.19"/1.88" stainless valves, 11/32" stems, 7/16" studs, 3/8" guide plates, Edelbrock Sure-Seat springs 175 lb seat at 1.975" installed (hyd roller), 0.700" max lift, 1.54" spring OD. Intake port about 290 cc (per Eagle Auto Parts listing summary; Edelbrock's own sheet gives no port cc). Edelbrock claims 540 hp at 9.5:1 on a 454 on pump gas with its RPM package (source 3). Not legal on pollution-controlled vehicles; no EGR. Project pick for the 489 (sections 90/92): standard exhaust-port location (no raised-port header risk), 110 cc chamber gives 9.0-9.3:1 with a flat-top valve-relief or zero-relief piston at a 0.004" deck (table below). Exhaust port shape is described as square in vendor listings (search summaries, not a fetched page); Hedman HH626-V is the matching 1-3/4" mid-length family (see Fitment #2).
Good (compression-friendly) Edelbrock Performer RPM oval, hydraulic-roller springs, 100 cc 60435 $1,251.50 each at CompCams (search snippet, 2026-10-12; page itself returns 403 to my fetch). Pair about $2,503 compcams.com Identical to 60455 except 100 cc chambers (source 3). This is the key head for Path B because the smaller chamber buys about 1 point of compression. CompCams' listing text says "9.2:1 compression with flat-top pistons", which agrees with my 9.2-9.5 math below. Edelbrock calls the chamber "semi-open ... rolled over" (angle-milled), so it is not a closed-chamber head.
Better (460 ci only; alternate, not the 489 pick) AFR 265 Magnum oval, partial CNC, hydraulic-roller assembled AFR 3610 $2,638.77 pair (Clay Smith Cams, page fetched 2026-10-12, listed OUT OF STOCK); $2,768.00 pair (CJ Pony Parts, search snippet; page fetch 403); the tre mirror lists the solid-roller version (3620) at $2,686.00 (it labels that "each", which looks like a template default; AFR sells pairs); bare 265 pair $2,270 (tre mirror) claysmithcams.com 265 cc intake / 132 cc exhaust runner, 109 cc chamber (112 cc with full CNC chambers), 354 cfm intake and 260 cfm exhaust at 0.650", valves 2.190"/1.880", 24 degree intake / 15 degree exhaust angles, A356 aluminum, spring pocket 1.725" OD. EXHAUST PORTS ARE RAISED 0.375" over stock location (the Clay Smith 3610 page, the tre 265 pages and AFR's own text all say so; the original draft wrongly implied the 265 was standard-location). AFR says this "rarely affects header or chassis fitment" and requires 1" longer head bolts in the four lower exhaust-side holes (ARP 135-3703 Mark IV kit is the one the vendor names), but square-body builders do report raised-port heads moving the header flange up and out, so verify header fit (see Fitment #2). Hydraulic roller spring: the 3610 page I could fetch does not state it; the AFR 3640 hydraulic package is 1.550" OD dual with damper, 170 lb on seat / 430 lb open, and the "473 lb at 0.600"" figure belongs to the 300 listing, so confirm the 3610 spring with AFR before choosing a cam. AFR specifies 0.120" wall pushrods and warns some domed pistons need clearancing "in the piston, not the head".
Better (more flow) AFR 290 Magnum oval, fully CNC, assembled AFR 3640 (hydraulic-roller package varies; 3650 is solid-roller) 3650 solid-roller: $3,700.04 at Clay Smith (page fetched; out of stock; the page's quantity field says "Each", which is probably a template default) vs $3,780.00 "per pair" at the tre mirror; treat about $3,700-$3,780 per PAIR as likely and confirm at checkout. 3640 hydraulic-roller: US price not confirmed (only AUD/NZD listings found, e.g. A$7,418.95 at enginemaster) claysmithcams.com 290 cc intake / 135 cc exhaust, 112 cc chamber, 375 cfm at 0.700", 2.250"/1.880" valves (enginemaster listing for 3640), rated up to 509 ci at or below 6,500 rpm. Exhaust ports are raised 0.375" over stock, which can interfere with ordinary headers. Choose this only for the 496-class engine.
Better (comfortable street) AFR 300 oval, CNC ported, hydraulic-roller springs AFR 3670 (per tre listing) $3,830.00 (tre mirror) tre.dev.webshopmanager.com 112 cc chambers, 2.300"/1.880" valves, dual springs 175 lb on seat, 473 lb at 0.600", maximum RPM 6,500-6,700. "The Ultimate Street Weapon". Raised exhaust ports (0.375") and needs 1" longer head bolts on four lower exhaust-side holes.
Better (value alternative, added in verification) Trick Flow PowerOval 280, aluminum, assembled, 113 cc TFS-41310001-M13 (hydraulic roller, OPGI); TFS-41310002-M13 (chromoly retainers, 0.700" lift, tre) $1,395.99 each (OPGI, search snippet); $1,549.99-$1,649.99 each for titanium-retainer / 0.700"-0.850" versions; tre page shows $1,599.99 for TFS-41310002-M13; bare casting $999.99 (tre-mirror search snippet; prices disagree across mirrors, confirm). Pair about $2,790-$3,300 tre.dev.webshopmanager.com CORRECTS the original claim that no Trick Flow oval BBC head exists. 280 cc intake / 129 cc exhaust runner, 113 cc heart-shaped chamber, 2.190"/1.880" valves, dual springs, exhaust ports RAISED 0.300" (same header caveat as AFR). Trick Flow also sells a "580 HP PowerOval 113cc top-end kit" (TFS-K413-580-560, $5,063.99, tre mirror) with heads, hydraulic roller cam/lifters/pushrods/1.7 rockers, gaskets and timing set; its 580 hp claim assumes a 468 ci short block with domed pistons and 10.25:1, an Edelbrock manifold and an 850 cfm carb (not included). The 113 cc chamber costs about 4 cc more dome than AFR's 109 cc.
Alt (flat-tappet, added in verification) Edelbrock Performer RPM oval for hydraulic FLAT-TAPPET cams, 110 cc / 100 cc 60459 (110 cc) / 60439 (100 cc) $1,295.50 each (60459) and $1,214.50 each (60439) (search snippets, 2026-10-12) compcams.com Same head with 135 lb flat-tappet springs (per the Edelbrock sheet). Worth mentioning because a flat-tappet hydraulic cam avoids the roller-lifter retrofit in a Mark IV block, but zinc/ZDDP and lobe-wear risk is a real long-term cost on a truck that is supposed to last to 2042, so the roller package stays the recommendation.
Best Dart Pro 1 oval, 275 cc port, 121 cc chamber (110 cc also exists) 19000010M (marine coated) and sibling SKUs; 110 cc chamber SKU is 19900010 $1,640.36 each uncoated / $1,834.51 coated, per search snippet of dartheads.com (assembled vs. bare unclear) dartheads.com Dart's own Pro 1 oval, A356, 24 degree. Fetch blocked, so valve size and spring spec not confirmed. The 121 cc chamber is large for an oval street engine and forces a large dome. Pair is roughly $3,280 if per-head pricing holds.
Best (alt) Brodix Race-Rite oval port, 270 cc, 119 cc chamber, hydraulic roller assembled 2061000SSCC $1,661.99 each (Summit snippet) summitracing.com 2.250"/1.880" valves, hydraulic roller. Pair about $3,324. Brodix BB-2 Plus (312 cc port, 119 cc) was snippet-listed at $1,129.99 each but is closer to a rectangle-style big-port head and too big.
Skip Speedmaster (and similar Chinese-made) aluminum BBC heads PCE281.2031 (119 cc) etc. Price not confirmed jegs.com Not recommended for a head that must last 15+ years. Owner reviews describe bad Heli-Coil installs, thin castings, soft aluminum, and debris from grinding left in ports (source 24). Some posters buy them bare for a valve job, but at that point a name-brand head is a similar total price.

Trick Flow: the original draft said no current Trick Flow oval-port BBC aluminum head could be confirmed. That was wrong: the PowerOval 280 (113 cc, 280 cc intake, 0.300" raised exhaust) is a current product and is added to the table above. Trick Flow's PowerPort 320/365 BBC heads are rectangle-style and too big for this truck.

Also considered: rebuilding the stock cast-iron oval heads is the cheapest baseline (machine-shop price not confirmed), but iron heads force roughly one point less compression on 93 octane, (iron heads shed heat poorly), and they weigh noticeably more over the front axle, so they are not recommended given the compression goal. Dart Iron Eagle iron ovals exist (only AUD prices found) and are the iron fallback if the owner wants to keep a cast-iron look.

Valvetrain parts

Tier Item Part # Price (vendor, seen 2026-10-12) Link Notes
Good Proform roller rocker kit, 1.7, 7/16" stud 778-66913K $261.98 jegs.com Budget aluminum roller. OK on mild lift.
Better COMP Cams Ultra-Pro Magnum, 1.7, 7/16" stud, chromoly 249-1620-16 (CC1620-16) $530.95 for 16 jegs.com 8650 chromoly, rated to about 850 lb spring pressure. Stock-looking and stays in adjustment. Sold also as 1620-8 (8 pieces, $242.95).
Best Harland Sharp heavy-duty aluminum roller rockers, 1.7, 7/16" stud 851-SH2001 (SH2001) $506.99 jegs.com Rated over 1,000 lb spring pressure. Needs tall valve covers.
Alt Crower Enduro stainless rockers 258-73605-16 Price not confirmed jegs.com Listed on Jegs. I could not confirm ratio or price.
Alt Scorpion Race Series aluminum rollers, 1.7, 7/16" SCP1014 Price not confirmed eagleautoparts.com.au Fine alternative. Listing is an Australian retailer.
Required Pushrods, hardened, 3/8", 0.120" wall, custom length custom (measure) Price not confirmed (custom sets are typically sold by Manley/Trend/Crower/Comp; I did not retrieve a price) (none; the fidanza.com link in the original draft returned 404 and was removed) Edelbrock retrofit pushrods were reported in 7.800" and 8.800" lengths (original draft, link now dead), but intake and exhaust are different lengths on a BBC and the right length must be measured with a checking pushrod after the heads, cam and lifters are installed. AFR specifies 0.120" wall.
Included Springs, retainers, locks, studs, guide plates on the head n/a Edelbrock complete heads include 7/16" studs, 3/8" guide plates, and Sure-Seat roller springs (replacement hydraulic-roller spring # 5823; flat-tappet # 5745). AFR hydraulic-roller packages include the dual springs above.
Required Head gasket, Mark IV 454, 4.540" bore, 0.039" compressed Fel-Pro 1017-1 $66.99 each at CJ Pony Parts (MSRP $76.99), $74.49 FindItParts, $81.03 SDParts (search snippets, 2026-10-12). Sold EACH, so a pair is about $135-$162 sdparts.com Recommended by Edelbrock for Mark IV 454. For Mark V 454 use 1037. Edelbrock gasket #7302 is the alternative. A thinner MLS gasket (about 0.027-0.030) would let the quench be set without milling the block, but I did not retrieve a Cometic/other MLS thickness list, so thicknesses are unconfirmed.
Required Head bolts/studs Edelbrock 8551 kit (lengthened bolts) for Edelbrock heads; ARP 135-3703 12-point Mark IV kit (the kit AFR's vendor listings name for the 1"-longer-bolt AFR ovals) 8551 price not confirmed; ARP 135-3703 about $119.99-$143.01 (search snippets, 2026-10-12) (Edelbrock PDF, source 3; summitracing.com) Edelbrock heads need 4 lengthened bolts per head (positions 15, 8, 2, 7); Edelbrock ships them. Use hardened washers. Edelbrock also lists head gasket set #7363 for 454-and-smaller Mark IV.

Compression math (the real deliverable)

Formulas: static CR = (swept + clearance) / clearance, where clearance volume = chamber cc + gasket cc + deck-clearance cc + piston net cc. Swept volume per cylinder = pi/4 x bore^2 x stroke x 16.387. Gasket volume = pi/4 x gasket bore^2 x compressed thickness x 16.387 (Fel-Pro 1017-1: bore 4.540", 0.039"). Deck clearance = the amount the piston top sits below the block deck. Quench = deck clearance + compressed gasket thickness. Net piston cc is plus for a dish or relief and minus for a dome (a dome with valve reliefs is the net of both).

Inputs used (assumptions are marked):

  • 454 + 0.030 over: 4.280" bore x 4.000" stroke = 460.4 ci. Swept per cylinder = 943.06 cc.
  • Stock 4.250" bore x 4.000": 929.88 cc. 4.280" x 4.375" (504 ci): 1031.5 cc. 4.250" x 4.375" (496 ci): 1017.1 cc.
  • Gasket 4.540" x 0.039" = 10.35 cc. Deck clearance 0.004" on 4.280" bore = 0.94 cc (0.005" = 1.18 cc; 0.010" = 2.36 cc; the original draft said 1.89 cc for 0.004", a typo - the tables below already used 0.94 cc and were re-checked).
  • Quench 0.039 + 0.004 = 0.043". Hits the 0.035-0.045" target.
  • Mark IV 454 deck height is 9.800" (corrected in the 2026-10-12 integration pass; this section previously said 10.200" and was wrong). Sources: enginelabs.com ?p=8443 (the Hardcore Horsepower 460, built on a Chevrolet Performance 454 block: "9.800-inch deck height", 6.385" Scat rods, 1.395" compression-height pistons), chevydiy.com's big-block guide ("Standard big-block deck height is 9.800 inches ... tall-deck blocks measure 10.200 inches"), swapmeetconnect's Mark IV casting guide (short deck 9.800" for 396/402/427/454 passenger cars) and a corvetteforum thread (the 10.200" tall deck was a heavy-duty/medium-duty truck block, not a production Mark IV 454). The gmsquarebody thread (source 1) is ambiguous because it calls the 10.2" block the "tall deck truck block"; that refers to the medium-duty 366/427 casting. Still measure the actual block. Stock rod 6.135", so the compression height of a zero-deck piston is 9.800 - (stroke / 2) - 6.135 = 1.665" for the 4.000" stroke, 1.540" for the 4.250" stroke (489 ci), 1.478" for 4.375" (my arithmetic). Cross-check: the Hardcore Horsepower 460 used 6.385" rods and a 1.395" CH piston: 9.800 - 2.000 - 6.385 = 1.415", i.e. the piston sits about 0.020" down the bore, which agrees with the 9.800" deck. A custom piston must be ordered to the actual CH for the rod you choose.

Net piston cc needed for target static CR (gasket 0.039", deck 0.004"). Negative = dome net of reliefs:

Engine Chamber cc 10.0:1 10.3:1 10.4:1 10.5:1
460 ci (4.280 x 4.000) 100 (Edelbrock 60435) -6.5 -9.9 -11.0 -12.0
460 ci 109 (AFR 265) -15.5 -18.9 -20.0 -21.0
460 ci 110 (Edelbrock 60455) -16.5 -19.9 -21.0 -22.0
460 ci 112 (AFR 290/300) -18.5 -21.9 -23.0 -24.0
460 ci 119 (Brodix) -25.5 -28.9 -30.0 -31.0
460 ci 121 (Dart Pro 1) -27.5 -30.9 -32.0 -33.0
496 ci (4.250 x 4.375) 109 -7.3 -10.9 -12.1 -13.2
496 ci 112 -10.3 -13.9 -15.1 -16.2
496 ci 119 -17.3 -20.9 -22.1 -23.2
504 ci (4.280 x 4.375) 112 -8.7 -12.4 -13.6 -14.7

Net piston cc for the project engine, the 489 (4.280 x 4.250, 489.2 ci, swept 1,002.0 cc), added in the integration pass (same gasket 10.35 cc and 0.004" deck 0.94 cc; positive = relief or dish, negative = dome net of reliefs):

Chamber cc 9.0:1 9.2:1 9.3:1 9.5:1 9.8:1 10.0:1
100 (Edelbrock 60435) +14.0 +10.9 +9.4 +6.6 +2.6 0.0
109 (AFR 265 3610) +5.0 +1.9 +0.4 -2.4 -6.4 -9.0
110 (Edelbrock 60455, project pick) +4.0 +0.9 -0.6 -3.4 -7.4 -10.0
112 (AFR 290/300, full-CNC 3610) +2.0 -1.1 -2.6 -5.4 -9.4 -12.0
118 -4.0 -7.1 -8.6 -11.4 -15.4 -18.0

The same table for the 460 at the lower, safer targets: 110 cc head needs -3.4 cc at 9.0:1, -6.3 at 9.2:1, -7.7 at 9.3:1 and -10.3 at 9.5:1 (109 cc: -2.4, -5.3, -6.7, -9.3). Reading the 489 table: with the 110 cc Edelbrock head a zero-relief flat top lands at 9.26:1 and a flat top with a +4 cc valve relief at 9.0:1, so the 489 reaches the safe window with an ordinary forged flat-top and no dome. The 10.3-10.5:1 columns above are kept only as a record of why the original target was dropped.

Reading this: on a 460 with a 109-110 cc oval head you need a net dome around -19 to -21 cc for 10.3-10.5:1. That is a real dome (a forged piston with a moderate dome and valve reliefs), which is doable but at the upper end of what keeps flame travel good. A 119-121 cc head would need -29 to -33 cc, which is a bad piston for a street engine, so large-chamber heads and 460 ci do not mix at this compression. A 496/504-class stroker is far friendlier: -11 to -14 cc with 109-112 cc heads. Sanity check against a published engine: the Chevrolet Performance ZZ454/440 is 4.250 x 4.000, 110 cc aluminum oval heads, 9.6:1 (source 20). My model says that needs about -13 cc net piston, which is a believable forged-dome-with-reliefs number, so the model is reasonable (I could not confirm the piston's actual dome cc).

Cross-check of the factory engine (to estimate what a stock '77 piston can do): the NCRS thread (source 28) says a '74 454 used flat-top valve-relief pistons with 110 cc heads for about 8.25:1. Working backwards at 4.250" x 4.000", total clearance volume = 929.88 / 7.25 = 128.3 cc, so piston + gasket + deck = about 18 cc with a 110 cc chamber (about 15 cc if the chamber were 113 cc, about 10 cc if 118 cc). I do not have the '77's chamber cc, so the stock-piston net volume is bracketed rather than known. Measure it.

Path B results (stock-style flat-top valve-relief pistons, aluminum heads, Fel-Pro 1017-1 0.039", assumed piston net +0 to +12 cc):

Bore Chamber Piston net cc Deck clearance Quench Static CR
4.250 110 +8 0.025" (typical stock, not zero-decked) 0.064" 7.93
4.250 110 +8 0.004" 0.043" 8.19
4.250 109 +4 0.004" 0.043" 8.48
4.280 110 0 0.004" 0.043" 8.78
4.280 110 +8 0.004" 0.043" 8.29
4.250 100 0 0.004" 0.043" 9.36
4.280 100 0 0.004" 0.043" 9.47
4.280 100 +4 0.004" 0.043" 9.18
4.280 100 +8 0.004" 0.043" 8.91
4.280 100 +4 0.025" 0.064" 8.84

Takeaway: dropping 110 cc aluminum heads onto stock-style low-compression pistons gives only 7.9-8.8:1, no better than the factory. To reach the Path B goal (about 9 to 9.5:1 on 93 octane, which is Edelbrock's own tested 9.5:1 / 540 hp point) you need all three: the 100 cc head (60435), zero-decked block so quench is about 0.043" rather than 0.064", and flat-top or near-flat pistons with small valve reliefs (+0 to +4 cc). A stock block with the original 0.025" deck-down piston position will not be tight enough (0.064" quench), and gmt400 and cliffshighperformance posters warn detonation is common between roughly 0.050 and 0.100" quench (source 12).

Dynamic compression (DCR) vs. cam IVC. Aluminum heads let you run roughly one point more static compression, but what actually knocks is dynamic compression. Forum guidance for aluminum heads on pump gas is a DCR of about 8.0-8.5, with 8.24 "fine with aluminum heads and tight quench" (sources 26, 27). I computed DCR for a 4.280 x 4.000 engine (the 489 is tabulated below) with a 6.135" rod; the number is highly sensitive to intake valve closing (IVC) in degrees after bottom dead center (ABDC, at 0.050" lift):

Static CR IVC 38 deg IVC 45 IVC 50 IVC 55 IVC 60 IVC 65
10.0:1 9.33 9.05 8.83 8.58 8.31 8.02
10.3:1 9.60 9.32 9.09 8.84 8.56 8.25
10.5:1 9.79 9.50 9.26 9.00 8.72 8.41

IVC at 0.050" is (intake centerline ATDC + duration at 0.050" / 2) - 180. I re-derived the table above and it is correct. A mild COMP Xtreme Energy 224/230 hydraulic roller (cam 11-423-8; COMP lists 224/230 at 0.050", 110 LSA, 106 intake centerline, 0.510"/0.510" lift, source 21) closes at 106 + 112 - 180 = 38 degrees ABDC at 0.050" (COMP's own "intake close 64 ABDC" is the ADVERTISED 276-degree number - do not confuse the two; DCR guidance is quoted at 0.050"), which would put a 10.3:1 engine at a DCR near 9.6, too much for 93 octane.

CORRECTION (verification pass): the draft's "240-250 degree cam closes 60-65 ABDC" is wrong. IVC at 0.050" for realistic street roller cams: 232/108 ICL = 44; 240/108 = 48; 244/108 = 50; 250/110 = 55; you need roughly 260 degrees at 0.050" on a 110 centerline just to reach 60. A 260+ cam is not a 65-70 mph interstate truck cam (poor idle vacuum for the power brakes, a loose converter, teen-driver manners). So 10.3-10.5:1 static does NOT fit this build on 93 octane without EFI knock control. The maximum static compression that holds a given DCR (4.280 x 4.000, 6.135 rod, my calculation):

IVC at 0.050" Static for DCR 8.25 Static for DCR 8.50 Static for DCR 8.75
38 (mild 224 cam) 8.84 9.11 9.38
46 (about 236/108) 9.15 9.43 9.71
50 (about 244/108) 9.33 9.62 9.91
54 (about 248/110) 9.55 9.84 10.14
58 9.79 10.09 10.40
62 10.07 10.38 10.69

Confidence note on the DCR ceiling: it is a community rule of thumb, not an engine-builder standard. The sources found are forum threads (forabodiesonly: 8.0-8.75 for aluminum heads with tight quench, source 27; NCRS and gbodyforum threads: 8.0 iron / 8.5 aluminum), plus a search summary of an Engine Labs article ("Discussing Compression Ratio And Pump Gas Compatibility", enginelabs.com ?p=267751; page returns 410 to fetch) that gives the conventional street guidance as 9.0-9.5:1 static for pump gas, and the published Edelbrock test (540 hp at 9.5:1 static with the RPM package on a 454; source 3). I could not retrieve a Wallace Racing, Engine Masters or engine-builder page that states a DCR limit (wallaceracing.com fails TLS). The project target of 9.2-9.3:1 static (DCR 8.4-8.6) sits inside the 9.0-9.5 static guidance and at the aluminum-head DCR rule; it carries no extra margin beyond that, so keep the knock-retard ignition table and plan for 91-octane tolerance only through timing, not compression. Counter-evidence that the 8.5 rule is conservative: Chevrolet Performance sells the carbureted ZZ454/440 at 9.6:1 with a 211/230 cam (its intake centerline is not published in what I retrieved; if it is near 106-108, IVC is about 31-34 at 0.050", which this method rates well above DCR 9) for pump gas, but that is a factory-calibrated, conservative-timing package and not a hot-summer, A/C-loaded, heavy half-ton. Practical conclusion for THIS truck: design for 9.2-9.3:1 static on the 489 with a 230-236 degree hydraulic roller (intake closing 41-45 ABDC, DCR 8.4-8.6); 9.5:1 is the absolute ceiling for this cam family; go above that only with a later-closing cam (worse for idle and converter) or EFI knock control and a dyno tune.

DCR for the 489 (4.280 x 4.250, 6.135 rod; same model as above, reproduces the section 90 values):

Static CR IVC 38 IVC 41 IVC 44 IVC 46 IVC 50 IVC 55
9.0:1 8.42 8.32 8.22 8.14 7.99 7.77
9.2:1 8.60 8.50 8.40 8.32 8.16 7.94
9.3:1 8.70 8.60 8.49 8.41 8.25 8.02
9.5:1 8.88 8.78 8.67 8.59 8.42 8.19
9.8:1 9.16 9.05 8.94 8.86 8.68 8.45

Maximum static for a given DCR on the 489: DCR 8.50 allows 9.20 (IVC 41), 9.31 (IVC 44), 9.40 (IVC 46), 9.59 (IVC 50); DCR 8.75 allows 9.47 / 9.59 / 9.68 / 9.88.

Fitment & gotchas

  1. Valve covers and the power-brake booster. Edelbrock says roller rockers usually require taller valve covers (source 3). On a C10 the booster sits close to the left cover. A forum thread (corvetteactioncenter, search result only) asks whether the tall cover can even be removed with the booster installed; I found no definitive answer, so treat this as an open fitment risk. Candidate covers: Proform VC240 tall slant-edge polished, $361.95 at CJ Pony Parts (search snippet 2026-10-12; the draft described it as having recessed corners, which I could not confirm - Proform's VC243 chrome is the one listed as "recessed"), Holley Track Series tall covers (3.75" tall, HL241278), or Speedmaster's C10-specific BBC cover (CJ Pony Parts 131400201). Check clearance with the engine in the truck before final paint. Test-fit with the engine in the truck.
  2. Spark plug / header clearance. Edelbrock says use 14 mm x 3/4" gasketed plugs and, if headers crowd the plug, Champion RC12YC (about 0.230" shorter) (source 3). Hedman mid-length 1-3/4" headers for 2WD C10 396-502 exist (CJ Pony Parts HH626-V; Hedman part 69170 uncoated / 69176 HTC, advertised for 1967-87 trucks with 396/454 or aftermarket big blocks and, per a search summary of the CJ listing, for "factory profile heads" with a square exhaust port) (source 30). Edelbrock's RPM exhaust port is described as square in vendor listings (search summaries of the Edelbrock/CompCams/eagleautoparts pages) and takes any OEM-pattern header per Edelbrock; the HH626-V (square port) is therefore the matching Hedman family. All port-shape statements rest on search summaries, not fetched pages: confirm by holding a flange gasket against the port before ordering. ALL the AFR ovals (265, 290, 300) and the Trick Flow PowerOval (0.300") have raised exhaust ports, so ordinary OEM-pattern headers may not fit without a flange/collector check; AFR itself says fitment is rarely affected, but square-body builders report otherwise (a gmsquarebody "Header hell" thread lists AFR, GM, Edelbrock and Blueprint raised-port clearance problems with control arms and steering).
  3. Head bolts. Edelbrock heads have four taller bolt bosses and ship lengthened bolts; the AFR 265, 290 and 300 ovals need 1" longer bolts in the four lower exhaust-side holes (ARP 135-3703 or AFR #6306 per the vendor listing). Both need hardened washers on aluminum. Check for blind holes on any non-standard block.
  4. No EGR, no emissions. Edelbrock RPM heads have no exhaust crossover and are "not legal for sale or use on pollution-controlled motor vehicles" (source 3). The AFR heads also have no EGR. Missouri's emissions program (Gateway Vehicle Inspection Program, gatewayvip.mo.gov) covers only St. Louis city and St. Louis, Jefferson and St. Charles counties; Sugar Creek (Jackson County) is outside it, and other sources say pre-1996 gasoline vehicles are exempt anyway. A Missouri-registered 1977 truck should therefore not need a smog test; I did not check Kansas, which does not matter unless the truck is registered there.
  5. Hydraulic roller lifters in a '77 Mark IV block. The factory block is flat-tappet; retrofit roller lifters and link bars are needed (cam section), and pushrods must be measured after assembly. Stock pushrods are too short or too thin for these heads.
  6. Pushrod guide plates and alignment. Edelbrock notes a visual check of rocker-to-valve alignment, loosening guide plates if needed and re-torquing studs to 45 ft-lb (source 3).
  7. Torque specs and gasket. Edelbrock: short bolts 65 ft-lb, long bolts 75 ft-lb in three steps, re-torque after first heat cycle; use Fel-Pro 1017-1 (Mark IV 454) not 1037 (Mark V).
  8. Spring pocket and installed height. Edelbrock springs are set for 1.975" installed height with 175 lb seat pressure and 0.700" max lift, so the cam lift limit is about 0.700" at the valve (that is 0.411" lobe lift at 1.7 ratio). AFR hydraulic-roller springs are about 170 lb seat / 430 lb open for the 3640 package (473 lb at 0.600" is the 300 listing); the 3610 spring spec was not on the page I could fetch, so keep valve lift at or below about 0.600" until AFR confirms.
  9. Chinese heads. See the Speedmaster row; I would not use them.
  10. Block checks. Machine shop should verify deck height, bore and deck squareness; one 454 rebuild thread had 0.020-0.035" piston-to-piston deck variation from a sloppy surface job (source 12). Zero-deck the block for Path A and B.

How it touches other systems

  • Camshaft: compression and IVC are locked together (DCR table above). Per the DCR tables, a 230-236 degree-at-0.050" roller closing at 41-45 ABDC supports 9.2-9.3:1 static on the 489 at DCR about 8.4-8.6; a 240-250 degree cam (IVC 48-55) would allow 9.6-10.0:1 but is the wrong cam for this truck, and 10.3:1 would need IVC about 63. Pick the cam first, then set static compression from the table (section 90 resolution).
  • Brakes (vacuum power booster): a hydraulic roller of this size with a rough idle may leave about 9-13" Hg at idle in gear. That is marginal for a vacuum booster; the project uses hydroboost (section 12/90), so cam vacuum no longer constrains the grind.
  • Transmission/converter: a cam like this wants an actual converter flash of about 2,300-2,600 rpm (section 90 resolution; catalog labels run lower than the real flash on a 500 lb-ft engine), which affects all three transmission options in the transmission section.
  • Intake/carb: oval-port heads pair with Edelbrock Performer RPM 7161 (square-bore) / 7164 (spread-bore) intakes (source 3), or any manifold matching Fel-Pro 1212 gaskets. The Edelbrock Torker II 2-O (5061) is the lower option if the hood is tight. The carb/EFI section must pick an oval-port manifold.
  • Exhaust: AFR 290/300 raised ports change header selection (see Fitment). Edelbrock is standard location. CORRECTION: the AFR 265 is ALSO raised 0.375" (Clay Smith 3610 page and tre 265 pages), as is the Trick Flow PowerOval (0.300"). Header selection must be settled before the heads are bought.
  • Rear gear/tires: the target powerband tops out around 5,500-6,000 rpm, which means a cam and head package that makes peak power at about 5,500 and keeps pulling to 6,000; gear choice must keep 70 mph near 2,500-3,000 rpm.
  • Cooling/fans: aluminum heads on an iron block need coolant with proper aluminum-compatible chemistry and the dissimilar-metal expansion reminder (use composite gasket as specified). The radiator/cooling section covers coolant.
  • Fuel: 93 octane only. The calculated DCR limit is why E85 is irrelevant here; ECU/EFI section may want a knock-retard-capable system if the owner ends at the upper end of compression (Holley Sniper/Terminator X).
  • Budget: heads are about $2,100-$3,800 per pair (Edelbrock Jegs-sale low to AFR 290/300 high; Trick Flow PowerOval $2,790-$3,300 per pair); valvetrain (rockers, pushrods, bolts, gaskets) adds about $800-$1,200. Custom pistons are separate; price not confirmed.

Check on the truck

  1. Which block is it? Read the casting number at the rear of the block and measure deck height (should be 9.800" for a production Mark IV 454, truck or car; 10.200" would mean a tall-deck medium-duty block). Measure bore wear to decide .030 over versus .040.
  2. What are the actual chamber volumes of the cast-iron heads on it (head casting number, then CC them)? That sets how much of the stock compression loss was heads versus pistons.
  3. What do the stock pistons measure out at (dish/relief cc, height below deck)? A 15-minute check in the shop sets the real Path B compression instead of my bracketed estimate.
  4. Which path: the 489 (4.280" x 4.250", project spec) or a 460 (4.280" x 4.000")? The 489 uses the Edelbrock 60455; a 460 could use the AFR 265 (raised ports, header gate).
  5. Is exhaust-port location a problem for the headers you intend to run (raised-port AFR versus stock location)?
  6. (Answered in verification: Jackson County MO is outside Missouri's St. Louis-only emissions program. Confirm only the annual safety inspection rules.)
  7. Will you accept a power-brake solution that does not rely on idle vacuum (reservoir, electric pump, hydroboost)? That decides how big the cam can be, which decides how much static compression the 93 octane can take.
  8. Will the owner accept 9.2-9.3:1 static (DCR 8.4-8.6) with a 230-236 degree cam? Insisting on 10.3-10.5:1 needs a 260+ cam or EFI knock control.

Fact-check notes

Adversarial fact-check run 2026-10-12. Fetched pages: Clay Smith 3610 and 3650, tre mirror 265/290/300 listings, 90racing, shafiroff, Mancini, enginemaster 3640, Edelbrock ED60435 installation PDF (downloaded and read in full), chevyhardcore, enginelabs 8443, gmsquarebody x2, gmt400, forabodiesonly x2, Scorpion/Eagle, Gateway VIP. Blocked with HTTP 403 (verified only through search snippets): Jegs, Summit, CompCams, CJ Pony Parts, Dart, Speedway, Chevrolet.com, NCRS.

Dead or wrong links: fidanza.com pushrod page (404), enginelabs ?p=274863 (410) - removed. sdparts Fel-Pro page loads but shows unrelated products on fetch; the part itself is confirmed by other vendors.

Integration-pass changes (2026-10-12): deck height corrected to 9.800" and compression-height arithmetic redone; 489 net-piston and DCR tables added; Path A recommendation changed from the 460/AFR 3610 at 9.8:1 to the 489/Edelbrock 60455 at 9.2-9.3:1 to match section 90; AFR 3610 relabelled as a 460-only alternate (rated to 468 ci, raised ports); DCR ceiling labelled as a rule of thumb; power estimate anchored and its limits stated; header port-shape statements labelled as search-summary level.

Changes made in the earlier verification pass:

  1. AFR 265 exhaust ports are raised 0.375" (draft implied standard location). Header section dependency, fitment note, recommendation gate and interactions bullet all fixed.
  2. Compression target revised. The draft's "240-250 degree cam gives 60-65 ABDC IVC" was wrong (IVC at 0.050" = intake centerline + duration/2 - 180; a 244/108 cam is IVC 50, and 60 needs about 260 degrees). 10.3-10.5:1 therefore does not fit a 65-70 mph truck on 93 octane; recommendation changed to about 9.8:1 (9.6-10.0), dome about -13 cc, with a max-static-for-DCR table added. The draft DCR table itself re-computed correctly. The 10.3-10.5:1 option is kept only for EFI with knock control.
  3. Trick Flow PowerOval 280 added (draft said no Trick Flow oval BBC head exists). Also the Trick Flow 580 hp top-end kit and Edelbrock flat-tappet heads 60459/60439.
  4. Prices updated with dates: Edelbrock 60455 (CompCams $1,284.50, Jegs sale $1,039.98), 60435 ($1,251.50, was "not confirmed"), Fel-Pro 1017-1 ($66.99-$81.03 each, was "not confirmed"), ARP 135-3703 ($119.99-$143.01), Proform VC240 ($361.95). Confirmed unchanged: AFR 3610 $2,638.77 (Clay Smith, out of stock), 3650 $3,700.04, tre 3620 $2,686, tre 300 $3,830 (now with part number AFR 3670), 90racing AFR 2001 $4,510, Dart Pro 1 345 $3,495, COMP 1620-16 $530.95, Harland Sharp SH2001 $506.99, Proform 778-66913K $261.98 (these last four via search snippets).
  5. AFR 3650 "each" vs "per pair" ambiguity flagged. AFR 3610 hydraulic-roller spring spec not on the fetched page (the 473 lb at 0.600" figure belongs to the 300 listing); corrected.
  6. Arithmetic typo fixed: 0.004" deck on a 4.280" bore is 0.94 cc, not 1.89 cc (tables were already right). All static-CR tables (Path A and Path B) were re-computed and match.
  7. Proform VC240 is not described as "recessed" by the vendor; the booster-clearance claim was softened to an open risk.
  8. Missouri emissions answered: St. Louis-area program only.

Verified true: Edelbrock 60455/60435 specs, 100 vs 110 cc, 1,500-6,500 rpm, 540 hp at 9.5:1, stock-location exhaust ("any header designed for OEM heads"), Fel-Pro 1017-1 for Mark IV 454, Fel-Pro 1212/1411 gaskets, 7161/7164 manifolds; ZZ454/440 (469 hp, 519 lb-ft, 9.6:1, 110 cc, 211/230); AFR 3610 flow and chamber specs; XE 224/230 IVC (38 at 0.050"); 1977 truck 454 at 8.25:1; CORRECTED (integration pass): Mark IV 454 deck is 9.800", not 10.200" (enginelabs ?p=8443, chevydiy, swapmeetconnect and corvetteforum; the original verification note here had the gmsquarebody thread backwards).

Still unconfirmed: Dart Pro 1 oval prices (blocked, snippet only) and whether its exhaust ports are raised; custom piston prices; pushrod prices; Crower and Scorpion rocker prices; the exact 1977 stock chamber cc (aftermarket piston listings suggest about 118 cc with 8.2:1, versus 110-113 cc in the NCRS thread).

Sources 38

  1. gmsquarebody.com (Mark IV 454 specs thread; deck height, valve sizes, domed-piston compression discussion)
  2. chevyhardcore.com (oval vs rectangular port comparison, rpm guidance, casting numbers)
  3. totalperformance.net.au (Edelbrock Performer RPM BBC installation instructions: part numbers, chamber cc, valves, springs, gaskets, torque, 540 hp at 9.5:1)
  4. shafiroff.com (Dart Pro 1 345 specs and $3,495 pair)
  5. cjponyparts.com (AFR 3610, $2,768 in search snippet; page fetch blocked)
  6. claysmithcams.com (AFR 3610 specs, $2,638.77)
  7. tre.dev.webshopmanager.com (AFR 265 listing, 3620, $2,686, valve sizes)
  8. tre.dev.webshopmanager.com (AFR 300 oval, $3,830)
  9. claysmithcams.com (AFR 3650/290 specs, $3,700.04)
  10. 90racing.com (AFR 2001 335 cc rectangle, $4,510, for rectangle-port comparison)
  11. enginelabs.com (Hardcore Horsepower 460: 115 cc heads, 22 cc dome, 9.0:1, 551 hp on 87 octane, 1.395" CH)
  12. gmt400.com (454 rebuild: piston-to-deck variation, quench warning)
  13. compcams.com (Edelbrock 60455, $1,284.50; fetch blocked, from search results)
  14. jegs.com (COMP rockers, $530.95; search result)
  15. jegs.com (Harland Sharp SH2001, $506.99)
  16. sdparts.com (Fel-Pro 1017-1: 4.540" bore, 0.039")
  17. enginemaster.com.au (AFR 3640 specs)
  18. jegs.com (Brodix BB-2 Plus, search result)
  19. summitracing.com (Brodix Race-Rite 270 oval, 119 cc, $1,661.99; search result)
  20. chevrolet.com (ZZ454/440: 9.6:1, 110 cc aluminum oval, 469 hp; search result)
  21. compcams.com (Xtreme Energy 224/230 hyd roller; search result)
  22. manciniracing.com (Edelbrock BBC head price range)
  23. speedwaymotors.com (Edelbrock 60455, search result)
  24. jegs.com and forabodiesonly.com (Speedmaster quality reports, search results)
  25. (both links in the original draft are dead: fidanza.com returned 404 and enginelabs ?p=274863 returned 410; removed)
  26. forabodiesonly.com (quench 0.035-0.045"; search result)
  27. forabodiesonly.com (DCR 8.0-8.5 on pump gas; search result)
  28. forums.ncrs.org (NCRS: 1970 vs 1974 454 chambers and compression; search result, fetch blocked)
  29. dartheads.com (Dart Pro 1 oval, $1,640.36 / $1,834.51, search result; fetch blocked)
  30. cjponyparts.com and cjponyparts.com (C10 BBC headers and tall valve covers; search results)
  31. jegs.com (Proform rocker kit, $261.98)
  32. jegs.com and eagleautoparts.com.au (Crower and Scorpion rockers, listings only)
  33. enginemaster.com.au (Speed Pro piston page; turned out to be a 4.155" bore piston and was NOT used)
  34. tre.dev.webshopmanager.com and tre.dev.webshopmanager.com (Trick Flow PowerOval 280 head and top-end kit; fetched 2026-10-12). Note tre.dev.webshopmanager.com is a vendor dev/mirror domain; the prices on it can differ from the vendor's live site.
  35. gatewayvip.mo.gov (Missouri Gateway Vehicle Inspection Program: St. Louis area only; fetched 2026-10-12)
  36. jegs.com (ZZ454/440: 469 hp, 519 lb-ft, 9.6:1, 110 cc aluminum ovals, 211/230 cam; search result)
  37. claysmithcams.com (ARP 135-3703; search result)
  38. gmsquarebody.com ("Header hell": raised-port heads and C10 header fit; fetched 2026-10-12)