There are “GM” HEI distributors for Ford v8’s, I’ve seen them used for Chryslers and a number of other things, good solid simple system. I think Delco-Remy may still have been a separate entity back then but I wouldn’t swear it. It remains popular though. I’ve replaced more than a few of those modules and pickups, lot fewer coils.
I sure wouldn’t put one anywhere hotter than it already was. Most of the Bosch ignition modules of that era were mounted to a heatsink bolted to the firewall or inner fender, likely for good reason.
And the Lucas AB14-style amplifier (there are a number of sub-variations) was used on a variety of British cars. Jaguar called it “Lucas CEI”; not sure about the others. But it, too, was actually a perfectly good system. No worse than any other, if nothing else. It got the job done.
For the 455 Buick bored out their 430 engine which was introduced in '67.
The 425 was the last of Buick’s previous generation of V8s, the revered “nailhead”. Last year for that engine family was '66.
Great cars, great engines!
Cheers
DD
Another hot soak test. As Aristides said, heat paste didn’t help. But i still feel i did a better job this time.
Spraying water on ignition box did not help idle, and ignition box was only 185F, so not crazy hot.
What instantly smoothed out idle, and of course raised rpm, was disconnecting vacuum line to B bank FPR (while plugging intake manifold port)
So I’m back to fuel!? Seems like Jaguar knew what they were doing. But my fuel rail sensor doesn’t cut vacuum during these hot starts. Rail not hot enough. But i remember us talking a few years back about ethanol gas vaporizing at much lower temps.
So i think what i am gonna try is a switch to cut vacuum to B bank FPR, hooked up to my 45 second start timer. Hopefully cold starts won’t be too high rpm or rich. Will test that in the morning.
I’ll need a vacuum switch that is normally open. 12V to close it. Any options?
Looks like the Lucas AB14 is a GM module in a box to me.
It was probably a good idea all in all but the putting it in a box to hide it makes me chuckle.
Since I’m wrong about the gm module, and back to fuel again, I’ll end here. We talked this to death a few years ago. Happy spring!
There is the three way solenoid valve that kills the vacuum advance via the 45 sec timer, maybe you can use that?
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Google “Vacuum solenoid 12 volt normally open” and you have lots of options.
But be careful. Some are switches that use vacuum to open/close and electrical circuit.
Others are switches that use 12 volts to open/close a vacuum circuit…which is of course what you want.
Cheers
DD
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I’ve discovered many newer cars use a vent valve for the charcoal canister (ours is always open). They tend to be normally open. They close the vent when doing a vacuum test on the evap system. So hopefully several to choose from.
Thanks for the advice!
Side note, discovered why my heat soak idle suddenly got worse. I swapped in the wrong gm vacuum advance modulator!
Was supposed to provide 8 inHg to vacuum advance at idle, it was only providing 5 inHg. So less advanced timing. (Cold or no heat soak, idled fine)
This hasn’t solved the heat soak idle, it just seems to idle better with heat soak at a more advanced timing at idle.
If you’re still running the oem brown modulator, that provides 10inHg, giving roughly a good 16 BTDC at idle. And this is what the ecu expects, since our Lucas ecus cannot measure timing values, correct?
Right.
The ECU has no idea what’s going on with ignition timing.
Other than the “trigger” signal from the ignition amp to the ECU the ignition system and the fuel injection system to not talk to each other.
Cheers
DD
I managed to get my heat soak idle better by making sure vacuum advance had the right vacuum from regulator to achieve around 16 BTDC at idle, and i lowered my ecu idle fuel mixture a few clicks leaner. Now it idles around 500rpm until things cool down.
A less advanced idle and a richer fuel setting last week caused it to barely hold 300rpm, and stalled a few times.
This doesn’t cure the heat soak issue, just treats it a little.
Question:
Don’t you have the Extra Air Valve hooked to the 45 sec timer?
When my 45 sec timer went defunct I replaced it with a adjustable positive trigger delay relay. It might be your answer to boost idle until things cool down.
I remember you had gone to great lengths to adjust your Fuel Base Map, now you went leaner?
Yes, the idle is still boosted for 45 seconds.
My ECU Fuel Base Map is still on the rich side. I gave up trying to adjust it by voltmeter, and dialed in by idle improvement at open loop idle.
I’m at +6 rich. Was previously at +10. Probably too rich.
I’ve simply discovered with these old Lucas V12s, get the basics exactly to spec (spark plug gap, timing, TPS, throttle gap, etc). And then tinker with what can be adjusted (RPM idle and ECU Fuel Base Map) until it runs best in all conditions.
FWIW, I adjusted RPM idle to give me the smoothest best idle while in gear once warmed up. That roughly translates to 750-800rpm in Park, which can change depending on so many things it seems. Trying to dial in a perfect idle in Park is not the way to do it, I found out. In closed loop, my idle seems very consistent.
What I was trying to say is that you could put a relay with a longer delay to help the heat soaked idle.
I have discovered that a vacuum gauge is very useful to set things up.
Setting the base fuel map correct voltage with a voltmeter coincides with the highest vacuum on closed loop.
I also set timing that way, find the highest vacuum setting and then retract a bit.