I have converted my ignition on my 1986 Dodge D150 225 cu in, automatic transmission, factory A/C, power brakes, power steering pickup to the GM HEI recommended here in this forum. I have disconnected both electrical connections to the ESC computer in the left inner fender area. The truck runs fine with the new ignition. I do continue to have a slight rough idle that probably is not related to the new HEI ignition as I had the problem before the HEI conversion as well. I set spark plugs to .045 gap and ignition timing to about 8 degrees BTDC. I do not have any pinging.

I am going to do the Super Six conversion (2BBL carb, 2 BBL intake manifold, choke control, accelerator cable and associated OEM parts.) I have a A904 transmission and not a A727 as I previously thought. The A904 is a lockup transmission for top gear. I have a few questions:

1. Can I remove the Electronic Control unit on the firewall?

2. Can I remove the Vacuum Amplifier and all the connections to it? Would this effect the heating and A/C controls or some other important system?

3. How will the A904 transmission lockup work without the ESC computer?

4. If I remove the EGR is there any downside? (I have the EGR block-off plate.)

5. Are there any other parts that I could remove that are not required anymore?

viewtopic.php?f=20&t=8525 Lock up will not work with out computer. This can be made to work, brake switch vacuum and pressure switches etc. For now leave alone. Get manual.

Not sure on the trucks, but my diplomat was lean burn, and had the hydraulic lockup trans, not the electric. Converting from lean burn to HEI had no effect on lockup. Verify by seeing if you have a second electrical connection (other then the neutral safety switch) on the trans.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 225 nitrous
64 Valiant Signet
64 Valiant 4dr 170

Yes, you can remove the ESC unit. If your torque converter lockup is, in fact, electric (definitely the case in '87, I don't recall if electric or hydraulic in '86 -- the giveaway is presence or absence of a single wire running to the transmission near the left rear corner of the trans pan. If wire, electric. No wire, hydraulic. If hydraulic, go ahead and remove the ESC box; the lockup will still work. If electric, you will need to put in a torque converter lockup control circuit as described here (disregard "727" and "518" -- this exact technique and these exact parts are what you need).

The vacuum amplifier (hockey puck) is part of the EGR system. If you disable the EGR, you can remove the vacuum amplifier. However, you may want to keep the EGR system operational, perhaps with the updated/improved EGR valve, depending on your distributor advance curves and other factors. Does this truck still have a catalytic converter on it?

Make sure your thermostatic air cleaner is intact and working. Charcoal can, too. See here and here.

About your HEI swap, rough idle, etc: read and follow instructions in this (long but worthwhile) thread. And talk to DusterIdiot on here about a custom-curved distributor to maximize your truck's driveability, performance, and economy.

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一期一会
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Thanks for the reply! I am using the truck to pull my 6,000 lb boat and tandem axle trailer with surge disk brakes on all wheels. I am changing exhaust to complete 2 1/4” exhaust system with Flowmaster performance rear cat and muffler. Also adding deep transmission pan and trans cooler in front of A/C condenser. Also adding Super Six setup. Also changing diff to 3.73 ratio. If I do nothing about trans lockup will this setup be enough to pull boat? Will trans overheat? I will not be towing long distances at high speed.

And yes, I do have the electric lockup on my 1986 Dodge D150 A904 transmission. There is a blue wire going to a switch on the back of the transmission above the pan. I recently had the torque converter replaced with a new lockup converter (due to missing teeth on the ring gear.)

I understand that the A904 transmission lockup is sort of an overdrive for highway speed operation that results in lower RPM and better gas mileage. (Even when I had the ESC computer installed, I never noticed a drop in RPM at highway speeds due to the lockup engaging. I do have a small tachometer on the dash. 70 MPH occurs at about 3,000 RPM with the 3.21 ratio differential.)

I have read a lot of posts on this forum and others about the A904 lockup function and there appears to be numerous conflicting opinions about how the lockup works. I believe not having a functional lockup switch will simply cause higher RPM at highway speed and thus more heat in the transmission. Any additional wear on the transmission clutches would be due to the extra heat generated is my assumption. Therefore, an additional high capacity transmission cooler and deep transmission pan (2 additional qts of ATF) should take care of this problem. In any event, I will not be towing the boat at high highway speeds very frequently. Therefore, I don't see a need to have the lockup working.

I am mainly concerned that the truck will be able to pull the rig up the launch ramp and up hills along the way to the launch ramp. I can pull the rig on the level now with no problem.