86 chevy won't turn off

When I turn off the key on my 86 chevy half ton it sort of sputters a few times like the engine keeps running. It has a 305 V8 and a four barrel carb. It didn't do this until the day after I rebuilt the carb. Someone told me that this is caused by too high of compression but I'm guessing that the engine easily has over 100,000 miles and I can't imagine that this is the case.

sounds like it is dieseling, I'm not to good with carbs, so I won't be of much help.

Yes, it does sound like dieselling. Check your timing and check your carb settings. The cause is usually high carbon in the cylinder will keep heat and will ignite fuel that is being drawn into the engine as it shuts down.

Rochester Quadrajet 4bbl. carb's are one of the most difficult carbs to rebuild. Lots of little adjustments that are critcal important, but the instruction's that come with the rebuild kit are less than accurate. I don't question your skill, but I would be suspect of the carburerator. Is it a Quadrajet 4MV? There's like 79 parts (58 which are moving parts) on this units.

i used to rebuild these carbs before and i find there really sensitive to even a spec of dirt. the way i use do it, with the least amount of headaches, is dissassemle everything, soak in cleaners for a couple of days, rinse with water, dry with compressed air and then assemble in clean work room. like skipr was saying 58 moving parts and only way to be sure is that eveything is very clean. i'm not saying that you didn't do this but i this is something people didn't do and would bring to me to fix. use some carb cleaner on the throttle blade area, could be some carbon built up around there.

Thanks for the replies guys. I rebuilt it the way you explained, AKWE-gt, my dad helped me out and he is good with cars. The thing I don't understand is that it did run really good for probably 150 miles the day I rebuilt the carb. those miles were mainly off road and in some mud but the truck still ran good untill I let it sit overnight. Then it started having the problems i mentioned. When I get some time I will try to check all the adjustments.