I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Just started doing this a few months back, I don’t drive it much. But I now have to turn it off in gear (auto) so it wont run on (warm)

Also if I’m off the gas decelerating for a bit it will pop back thru carb after initially after giving it gas….runs great other than that.

Thoughts from those who know more than me…

Timing ?

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Timing would be my first guess....

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Advance or retard ?

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

My initial thought that it was too far retarded, but I've experienced run-on far more with too far advanced. How's it start (cold)?

Also, have you confirmed that the distributor isn't 180-degrees out?

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Starts good cold with a few pumps. Giving to much gas while cold will also cause backfire thru carb.

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Backfire is from being lean and retarded.

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Thanks,
… to much going on, i have to wait a bit before getting into it

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Usual suspect for after run is too much idle. Often due to vacuum leak or bad timing.

Make sure the distributor hold down bolt/nut hasn't backed off. If that gets loose, timing can change.

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

First suspect on a vehicle that's been sitting OR doesn't get driven much would be sticking advance mechanism in the distributor. Easy fix.

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Thanks

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

What the other guys said about timing. A little more timing will bring your idle speed up, so you can back off on the idle speed screws, closing the throttle.


Also try premium.
It resists knock and preignition.

As a last resort you can install an idle speed solenoid. It bumps up the throttle position when the key is on for a stronger idle, and it closes the throttle a bit when the key is off, giving less of a chance to run on or "diesel."

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Also, if you have combustion chamber deposits that can build up over time, you can clean them up with a bottle of Techron Concentrate (sold by my employer) used at the right dosage. One bottle ounce per gallon of tank, 20oz for a 20gal tank. Drive normally. Stop and go driving is fine. You don't need to blast it out with WOT runs.

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

My theory is, don't mess with your timing if you're getting run-on after turning the ignition off.
Once you turn off the key, your distributor is not producing spark, so playing with the timing does nothing.
Usually too high an idle is what causes run-on.

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Thanks again y’all, the Coolmino has been sitting in the shop waiting on me to get off my arse and work on it. I really need to pull the engine and fix/check some leaks out, find some quality headers, put an electric fan on and finally work on the interior since I bought a donor SS 73 to pull from.

https://i.postimg.cc/g2nry1kx/IMG-3564.jpg

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

I like it! Rg

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Very cool truck! Is it on a Blazer chassis? I've always loved these car on a 4x4 truck frame conversions.

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Not a frame swap, lots of custom fabrication from back in the early 90’s. Running gear from a 69,70 or 71 as much as I can tell.

https://i.postimg.cc/TYpWbGSn/IMG-4267.jpg

Re: I have a 383 stroker engine in my ElCoolmino, getting run on and backfire …
 

Even cooler.