chevy 350 help!!

GMCmademe

GMCmademe

Well-Known Member
Joined
Sep 23, 2009
Location
concord nc
i have a 1992 350 engine that i changed into carbureted on it and at an idle it does fine. but when i give it gas it pops and has a mild back fire. whats wrong is it a burnt valve or the carb. not adjusted right?
 
timing issues.
 
Or the carb not adjusted right most of the time popping back means it ain't getting enough gas if timing is set right.
 
ok the timing is set at 0 and it will idle at 1000 rpms but still it pops sometimes while in idle idk what to do ne more
 
GMCmademe said:
ok the timing is set at 0 and it will idle at 1000 rpms but still it pops sometimes while in idle idk what to do ne more
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still got timing issues. if you changed it to carb and non computer controlled distributor in it, timing should be somewhere near 8-12 advanced. the reason the sticker on that truck says 0 degrees is bc the computer adds in whatever timing it is programed to.
 
Yes set base a bit more... That and also make sure the vacuum advance is hooked to ported vac. (above the base plate w/ no vac. signal at idle.. )
 
ok i got the timing set on 8 and idles fine around 1000 and poping and backfire stoped at idle and when u give it gas slowly it does fine but when punch the gas it will once then when the rpms go back to 1000 and punch it again it will backfire again
 
i took the tbi off bc all i had was what was on the engine no wirers or ne thing and no its a quadrajunk
 
get rid of the quadrajunk and get you a holley or edelbrock.. your prob is more than likely in your carb or timing..my bet is your carb...been there too many times....
 
I had this problem, and I unhooked the vacuum advance and plugged the line. It is a combination of your timing and fuel. Sounds like you need to advance it even more. I had mine raked wayy out, prob 15-18 degrees all the way up. If there is a backfire, lean it out a bit on the top. Quadrajets are hard to set up, I really liked it though. It sounds like it could be just flooding at idle, and not burning all the gas causing the backfire. Or you could get the mighty vac, and hook it up and set it all up with it. Its like a carb tuning device I like to use.
 
x2 I have a quadrajet runnin on my 350 and I know I have it advanced more than 8-10 degrees. Im prolley more up in the 18-22 range
 
yeah its going to be my big toy truck thats y i dont want to get a diff carb. but still it will crank and run for about 2sec. now the truck i put the engine into didnt have anything the the eingne bay like the canister and stuff like that i dont have to pass emmisions so what do i need and not need? and can some one like draw a pic of where all the vacuum lines go and send it to me? have just been playin around with the line trying to find what goes where it aint workin out to well lol
 
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