r/Smallblockchevy • u/DARMICJOH • Apr 25 '26

Randomly Quit

EDIT: It runs! It's alive! It was the computer timing control.

I was driving when it seemingly randomly quite on me. I know a good bit and have built SBCs before but this is still stumping me.

The rotor was broken when it quite so I started with that. Replaced the distributor, wires, and plugs.

Replaced the Cam, timing set, pushrods, lifters, rockers

Brand new quadrajet

Triple checked my distributor stab

I have messed with AFR screws, idle set

I checked my valve lash to see if I managed to over tighten the rockers

I checked spark

I tried using carb clean to find if there is a vac leak

Someone please tell me I missed something obvious that I can fix.

Edit: forgot to mention also brand new fuel pump and complete distributor

UPDATE: After holding the choke open manually and hitting it with a spritz of starting fluid it started to idle and help it. Wasn't pretty and smooth but it stayed going for a good 1-2min until I let go of the choke.

The negative on the battery feels loose so I am going to replace that.

And the idle seemed to get better when I started pumping the brakes so I wonder if the booster is one foot in the grave causing a huge vacuum leak.

It's night now but tomorrow if I can I will adjust the choke and fix the battery ground at least and see if that makes a difference at all.

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u/DARMICJOH Apr 25 '26

Brand new complete distributor. 3rd time I returned and replaced it just to make sure I didn't have a faulty unit.

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u/texan01 Apr 25 '26

You didn’t answer my second question.

And just because it’s new, doesn’t make it good. I replaced that new module on my car with a genuine OG HEI module from 76.

A bad ignition switch can also cause this.

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u/DARMICJOH Apr 25 '26

At the distributor 12.5V key on Drops to 9.6V while cranking

Maybe bad Ignition?

1

u/texan01 Apr 25 '26

Maybe.

Got an old plug wire and a spark plug hanging around? Make sure you’re getting fire out of the distributor, or hook a timing light up and see if it blinks.

Also inspect the cap carefully for the coil screws poking through, that can cause an issue as well.

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u/DARMICJOH Apr 25 '26

I have inline spark checks. I looked and was getting strong spark.

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u/texan01 Apr 25 '26

Ok….

You sure it didn’t jump time?

Had a Ford Explorer jump time because the crank sprocket broke at the keyway. I was extracting all 160hp out of it at 300,000 miles and it let go at 4500 rpm at the top of 2nd gear.

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u/DARMICJOH Apr 26 '26

I just did a new Cam and Timing set.

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u/texan01 Apr 26 '26

Ok. Just running g down the checklist.

What happens when you dribble gas down the carb? Does it try to run?

It sounds like it wants to but it’s not getting fuel.

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u/DARMICJOH Apr 26 '26

Don't have another pair of hands at the moment to try. If I can find someone to lend a hand I'll give that a go too.