Engine: 454 superhighrise edelbrock intake, BRAND NEW holly 650 double pumper, 544 lift lunatti cam, msd6a ignition and mallory performance coil.

After i turn the key off the engine keeps running for a bit then stops, then sounds like it turns backwards and blows smoke out of the carb. Also backfires when driving and when u punch the gas. The whole entire set up on the car is NEW. Less that an hour total run time. The water temp is also high, got up to 220 and 235 when i shut the engine off. What could cause this? timing? carb?


thanks Thanks for all the replies! Got new info
I think the timing may be the issue I timed the car to 4 degrees and whenever I revved the engine, no advance.... The line on the harmonic bale cer did not move at all. So I checked my distributor and saw there was no vacuum advance! it's Mallory performance distributor. What next? Should I just go buy a distr. With vacuum advance?? I also unhooked the power wire to the electric fan, and it still dieseled..... Maybe feedback from my msd or Mallory ignition box??

*UPDATE*

Ok I think I figured it out. My timing is off and my positive battery cable to the starter is melted and touching the engine block!! Haha. So what do I time my mechanical Mallory distributor to? 454 big block with 544 lift cam. THANKS!!
Gage

 

I read somewhere that the MSD could cause your "run on" i have the same 6a but its not hooked up yet...

 

I have an electric radiator fan hooked to a switch. If I leave the fan on and turn off the ignition, the fan back-feeds power, the MSD picks it up, and the engine keeps running for a couple of seconds, then does a diesel run on. Turning the fan off first stops that from happening. Make sure you don't have any electrical motors running when you shut down, and double check your timing. Running hot like that, and getting run-on, can mean the timing might be retarded.

 

+1 with the timing, never used msd but my truck did the same thing until i fixed the timing.

 

yeah sounds like a timing issue to me. that would be a good place to start

 

I also have had the run on problem with a 454 in my 86 monte ss and when i put the timing light on it and fixed it it no longer had the problem so i would start there like everybody else says.

 

+a couple more on timing. I am all too aware of the run on due to electric fans back feeding. If you have an electric fan it can happen. When I was younger I had a habit of using a jumper wire to fix fan relay problems on my DD. The fan would come on with the key and everytime would cause it to diesel. But the drivability problems sound like timing. Nothin worse than trying to look cool and your car is still spittin and sputtering and your two feet from it.

 

I forgot to turn the fan off only ONCE, after parking it at a cruise night gathering. Hmmmmm, was that my car?

 

Mine was on a DD Ford Escort GT, couldn't look cool anyway. Had a Corsica that did it too.

 

Timing and temperature can both cause the dieseling issue. Or timing can also cause the temp issue, so it may all be realted to timing.
Next time you get ready to shut it off, loosen the distributor a bit and have someone shut the key off. As it continues to diesel, try advancing the distributor a tiny bit and see if it stops. Then restart it and see if it starts correctly. If it does lock it down and drive it to see if the problem is gone.