Tuning & drivability

#A. EFI tuning plan (Terminator X Max Stealth 4150 + HyperSpark)

A1. Setup and verification checklist (do these before the first start)

A2. Base map and self-learn procedure

Holley markets Terminator X as having fuel-map self-learning; Engine Labs' dyno comparison on a Terminator 4500 needed 2 pulls versus about 15 for a carburetor to reach the same numbers (350 ci LS test, not a big block). That supports "self-learn gets close fast", not "self-learn finishes the job". The workflow below follows the 10-step order HP Academy publishes (ECU configuration, trigger, base tables, base timing/fuel pressure, first start, idle, steady-state fuel, steady-state ignition, full power, road confirmation).

1. Enter the engine: 489 ci, injector size from the kit, 8 cylinders, firing order 1-8-4-3-6-5-7-2 (standard Chevy big block), rev limit 6,200 (see A5).
2. Load the nearest Holley base map for a big-block 4150 and set idle target 850-900 rpm warm, in park/neutral (start value; see part C for in-gear idle).
3. First start: use the prime function; confirm fuel pressure before cranking; keep the throttle shut. Check for fuel leaks at the 58.5 psi rail with the engine off.
4. Warm up to 180 F coolant (thermostat per section 14). Set idle timing and idle fuel by logs, then enable fuel self-learn only after the engine is hot and the wideband is warm.
5. Drive 40-60 miles of mixed use in light-load conditions (not boulevard cruising only) so the learn table fills across the load axis. Review the learned corrections; write them into the base fuel table and then turn learn off or limit its authority to about +/-10%. Leaving unlimited learn on hides sensor and fuel-delivery faults.
6. Steady-state ignition, then WOT pulls, in that order (below).

A3. Wideband placement and sensor

• Sensor: Holley says all Terminator X systems use a Bosch LSU 4.9 wideband (search summary of Holley/dealer listings). Replacement Holley part number 554-155 per the EFI System Pro listing. Do not run a leaded fuel or silicone-based sealants near it.
• Location: guidance in section 15 stands (collector, or 1-10 inches past it so all cylinders mix; 10 to 2 o'clock, never bottom; roughly 18 inches of straight pipe after it for a Sniper 2). I could not retrieve the Holley page that states this, so it carries the section 15 confidence level.
• One bung is enough to run the system. A second bung, on the other bank, lets the owner see bank-to-bank mixture differences on the 489's cylinder-5-and-6 side; this is optional and needs a second wideband controller for logging (price not confirmed).
• The sensor should be fitted after the H-pipe/crossover choice in section 15 so the pipe geometry is final. Cross-bank balance changes with an H-pipe or X-pipe.

A4. Target numbers (starting points, not Holley data)

Engine Masters/Engine Labs published results on comparable big blocks show tuned engines reach best torque near 12.5-13 on gasoline, but I did not retrieve a source giving Holley-specific targets. Treat the table as a place to start and verify with torque/logging, not as a standard.

A5. Knock detection: what Holley supports

Because the compression is deliberately modest (DCR 8.4-8.6) and the plan is not to chase peak power, I recommend no knock sensor dependence. Treat the conservative table as the knock strategy.

A6. Rev limiter, fans, A/C

• Rev limit 6,200 rpm for the roller/hydraulic valvetrain (Edelbrock rates the 60455 head and 7561 manifold to 6,500; COMP rates the Magnum 232 to 6,200). Use a soft limit with fuel cut, set at 6,200; owner's 5,500-6,000 powerband target is below it. Section 90 notes the Sanden 508 compressor is rated to 6,000 rpm sustained, so use a pulley ratio that keeps it under that at redline.
• Fans: use the Terminator X Max fan outputs (per section 90) with on/off near 195/185 F and on whenever A/C is requested. Add a separate timer relay if after-run is wanted, because the ECU is not powered when the key is off.
• A/C: wire the compressor clutch request into the ECU's A/C input so idle air or idle timing goes up before the clutch pulls in (see D). The Sniper-family settings list an "AC Kick" entry under IAC Rampdown according to a forum summary; check whether the same menu exists in the Terminator X software.

A7. 4L80E shift firmness, line pressure and lockup (Terminator X Max trans control)

I could not retrieve Holley's transmission-control documentation, so the numbers below are derived, not Holley's. The derivation uses section 90's 3.70 axle, a 27.87 inch tire, and the 0.75 fourth gear: 33.5 rpm per mph in fourth, so 45 mph is about 1,500 rpm, 55 mph about 1,840, 65 mph about 2,175, and 70 mph about 2,345 rpm.

Cruise note: at 70 mph the engine turns about 2,345 rpm in locked fourth, and the lockup threshold above keeps the torque converter from interfering with the comfortable 65-70 mph interstate cruise.

#B. Carbureted plan (Phase 1 Quadrajet, later Edelbrock AVS2 800 with DUI)

B1. Quadrajet baseline (Phase 1)

The original Rochester Quadrajet on a 1977 454 is calibrated for an 8.25:1 emissions engine. After a new cam and different compression it will be rich at idle and lean at cruise. Baseline steps:

1. Rebuild with a quality kit; check float level and the secondary air door/tension.
2. Set fuel pressure to 5.5-6.5 psi (practice for a Q-jet; the regulator is the owner's choice).
3. Set idle: warm, in gear, adjust mixture screws for maximum vacuum, then lean 1/8 turn.
4. Use a wideband in the exhaust, read 14.0-14.7 at idle and 14.5-15.2 at light cruise, 12.3-12.8 WOT.
5. Tune primary metering rods and the secondary hanger by logging; a Q-jet has a very tunable rod range. Specific jet and rod numbers for this exact carburetor were not retrieved; look up the carburetor's casting number and use a Q-jet reference chart from the owner's preferred vendor.

B2. AVS2 800 (later), starting points

Guidance for the mean lope: on a 489 with 8-11 inHg idle vacuum, 4 and 5 inHg springs are the likely region. Measure vacuum with the transmission in Drive first.

B3. DUI curve (CH33771) and vacuum

#C. Idle, driveability, and "lope vs manners"

C1. Expected idle quality for the specified cam on the 489

Section 03/90's cam (230/230 @0.050, 110 LSA, about 106 ICL) is a mild-to-moderate street roller. Published and anecdotal data points:

• Clay Smith's HR-294-0-CSR (235/235, 110 LSA, max 6,000 rpm) is stated by the maker to make "12 inches of vacuum at 1000 rpm" and to be power-brake compatible, but it is written for a 502-509 with AFR heads (section 03).
• The Yenko.net report cited in section 03 shows a 242/248 on 110 LSA / 106 ICL made only about 5 inHg in gear at elevation. Kansas City is near 800-1,000 ft, so vacuum should be better than that.
• My estimate for the specified cam on the 489 with an Air-Gap: 9-12 inHg in park, 8-10 in gear at 850 rpm. A mild lope, audible mostly when the exhaust is open. This is an estimate, not a measurement.

C2. Is a tighter LSA now viable?

Hydroboost removes the booster as a limit. Remaining effects of a tighter LSA at the same duration:

Notes: (1) DCR depends on where the intake valve closes. Narrowing the LSA by moving only the exhaust lobe does not change DCR. If you narrow it by advancing the whole cam to hold the same exhaust event, intake closing moves earlier, which raises DCR toward the 8.7-9.0 knock region; avoid that on 93. (2) Narrow LSA at constant duration increases overlap, which on a big block adds reversion and exhaust smell at idle, and widens the dyno-measured torque band at the cost of cold-start and low-speed manners. (3) EFI can compensate for idle quality much better than a carburetor can, per section 03 and the Engine Labs test above, which is why the choice is easier on Recipe 2 than Recipe 1.

C3. Owner choice table

Recommendation: keep the 230/230 on 110 LSA. If the owner wants more lope, narrow to 108 with the same intake closing and let the EFI do the idle work; do not go below 108 on a truck that Walter will drive in 2042.

C4. Horsepower sanity check

Section 90 originally stated 480-520 hp / 520-560 lb-ft (now revised to 450-500 hp, same torque) for the 489 at 9.2:1 with a dual-plane Air-Gap and a 230-class cam, with no source. Evidence I could find:

My engineering judgment: a 489 at 9.2-9.3:1 with an oval-port head and a dual-plane manifold limited to 6,500 rpm, and a 230 cam, should make about 540-570 lb-ft near 3,800-4,200 rpm, and the torque curve falls after that. At 5,500 rpm a torque value near 470-490 lb-ft gives about 495-510 hp, but dual-plane and head flow cut it, so a realistic dyno figure is 450-500 hp at the crank, with 480 as a fair expectation. The 480-520 hp figure is optimistic at the top; the torque range is plausible. A chassis dyno will read about 15-18% below that through a 4L80E. This is a reasoned estimate, not a sourced one. A simulation (Engine Masters or a commercial program) would sharpen it; I did not run one.

#D. Heat, hot restart, A/C idle

D1. How it fails. Big-block Chevys in a closed square-body engine bay under a hood at 100 F ambient heat soak: after shutdown the coolant, intake, headers and starter keep heating, fuel in the rail or float bowl boils, and the engine cranks without firing. Field reports of Holley EFI hot-restart trouble point to: external pump above tank level and near headers, tank not venting, low pressure that drops while cranking, voltage drop in power wires, and a mis-scaled coolant sensor. Those are forum and tech summaries (low confidence) but consistent with standard practice.

D2. Mitigations and options

D3. A/C idle-up and compressor load. Section 17 estimates the compressor takes about 200 rpm off idle. Plan: ECU A/C input to raise idle 100-150 rpm and add 2-4 deg of idle timing before the clutch engages; fans on with A/C; verify the idle does not dip below 700 rpm at clutch engagement. For the carb, a fast-idle bump solenoid on the throttle is required.

#E. Fuel logistics: 93 octane and ethanol

E1. Availability. Sugar Creek to Overland Park via I-35 / I-435, and the Osceola route (MO-13 / US-50 / US-71), are all in the Kansas City sphere where Casey's and QuikTrip are common brands. Casey's lists a "93 Octane" product on its fuel page (search result) and says it is its highest octane. QuikTrip sells premium widely in KC, and a QT's grade menu depends on the store. I could not confirm which specific stations on this route sell 93 versus 91. Fuel finder tools (GasBuddy, station apps) show grade per station; the owner should check the route before relying on it. Midwest premium is often 91 at some brands, 93 at others. Not confirmed.

E2. Ethanol content. E10 is the typical blend for regular and premium in Missouri and Kansas; ethanol-free (E0) and E15 are sold at a minority of stores. Casey's markets ethanol-free 87 and 91 (not 93) and E15 at some Kansas stores. QuikTrip's E0 availability varies by store. A premium E10 at 93 AKI is therefore the normal and the likely fuel.

E3. Effects of E10 on the truck.

E4. Storage stabilizer. A reputable ethanol-compatible stabilizer (STA-BIL / Sea Foam class; product and dosing not verified) is fine. For storage over about 3 months: fill tank to near full, add stabilizer, run the engine for 10 minutes so treated fuel reaches the rail or bowl, and for a carb consider draining the bowl. For the EFI truck, hold pressure by closing the pump relay and keep a battery tender on. Try to burn the tank down every 3-4 months.

E5. "If only 91 is available" fallback. The static compression and cam were chosen so that 91 still runs; the decisive number is DCR 8.4-8.6, which section 02 puts inside the forum rule of thumb for aluminum heads on pump gas (8.0-8.75; a community rule, not an engine-builder standard - see the confidence note in section 02). Plan: (1) keep a second EFI ignition table "91" with 2 deg less total timing and 2% richer WOT; the Terminator X can hold multiple tune files, so Walter can load it from the tune log; (2) for the carb, curve springs and total timing 2 deg lower (32-34 total); (3) never add 87; (4) listen on the first hot WOT pull after a fill; (5) do not drive WOT with 87. Rule-of-thumb "about 1 deg of timing per octane point" is low-confidence folklore.

#F. Tuning services in KC

Recommendation: self-tune the base map and the first 100 miles, then pay for one dyno session (WOT timing and fuel verification, 2-3 hours) at the best shop that accepts Holley; ask KC Maxx first. For the carb path, tune on the street with the wideband; no one local was confirmed for carburetor dyno tuning. Ask the shop what files they can load and whether they will tune the Terminator X Max trans-control tables as well.