383 Stumble / slight spit through carb off idle (no consistency when it happens)

[69RR383]

First off, sorry for the long post, but glad to be a new member!
I've looked around for information about off Idle stumble or spit through the carb on the forum, there are a few that come close to what I'm experiencing, but not quite. I have a 4 speed, 383 with 440 heads, mild cam. The issue I have is a slight cough or spit, if you want to call it that, on acceleration that does not happen consistently. It could be in 1st gear accelerating, 3rd gear accelerating, or cruising in 4th gear. I had an Edlebrock 1406 that gave me nothing but fits! Changed to a Holley 4160C and what a difference in performance, but the problem still exists. I had a new distributor (MSD 8388), new wires, and new plugs installed hoping it would take care of this problem, for they needed to be replaced badly. Timing is spot on, Vacuum is strong at 18. I’m at a loss and the only thing I can think of is a wiring problem, for the harness is not the original from what I can tell. Plus, whoever owned it before me has a lot of non-factory splicing’s. Any thought or suggestions would be appreciated.

 

[RAINMANYEH]

Since you've changed carbs a couple of times..... Clogged fuel filter? Fuel pump going out?

 

[69RR383]

New pump and filter. also checked the line and flow...all good.

 

[Ranger]

If you still had the Edelbrock, I might have an idea or two, but I know nothing about the Hollys.

I assume you have ruled out a burnt valve or a jumped tooth on the timing chain?

 

[RAINMANYEH]

It may be a gremlin in the spliced together wiring... IMO, the only sure fire way to kill it is to rewire the bird.

 

[69RR383]

Yes, had the engine pulled and checked out. All good.

 

[69RR383]

What is the best wiring kits to purchase?

 

[quikbird]

Any of the top four, Ron Francis, painless, auto wire, haywire will do a good job. Problem is Chrysler as well as ford have not turned loose of the tooling for the connectors. You will need to save the connectors in your current harness to reuse. It is a real pain of a job but most will get rid of one of the biggest problem with stock system which is the bulkhead connector. As well as be a whole lot safer.

 

[droptop]

Sounds like a timing issue to me. You say the timing is "spot on". What is it set at and what is the total advance? I have seen the harmonic balancer spin inside of itself and cause timing issues that you are experiencing.

 

[69RR383]

Thanks droptop, I will look into that and get back to you.

 

[69hemibeep]

If you find the timing is not an issue do a dry and a wet compression test to check the valves and overall condition of the engine

 

[siouxindian]

check your valve springs

 

[Coyote]

If you find the timing is not an issue do a dry and a wet compression test to check the valves and overall condition of the engine

Bingo! I'll bet that finds it.