HELP! 305 poping throught carb HELP!
 

Ive got a 85 monte carlo with with a 305 and comp controlledQJet the issue i am having is that at high rpms and under wotit bogs a little and pops throught the carb. it has ac accell coil and accell super stock wires and a cherry bomb witch conects where cat used to be.with about 3 feet of exhaust hooked on

i have so many placesi havestarted
-ignition
-checked plugs all look good less than 2 monthes old
-checked wires all on good less than 2 monthes old
- checked rotor looked good

carb
- well aint much to adjust since the pos is comp controlled
- thought it might be becuase of rear flaps not opening adjusted and no change
- made sure all electrical conections were good
-checked vacumes to carb all goood

vacume line
- was up and down them no cracks breaks or leaks
- just replace cracked weather worn and brokenabout 2 monthes ago

so things i might have missed let me know
also other ideas i think it may be are

bad cam
bad valve
bad valve spring

let me know any help would be great right now

RE: HELP! 305 poping throught carb HELP!
 

How many miles does the engine/carb have on it??

RE: HELP! 305 poping throught carb HELP!
 

94xxx so could be 94 194 or above but the way it drives and handles and since im in minnesota and was origionall a texas car im going with 194sorry no idea if it's been rebuilt or replaced in the past

RE: HELP! 305 poping throught carb HELP!
 

Backfiring thru the carb indicates the intake valve(s) aren't completely shut during combustion for whatever reason.
I doubt a wiped cam is the problem.
A bad intake valve or weak valve springs is possible too. They could be bouncing under high RPM's.
Stretched timing chain is a good possibility too since it gets worst under heavy pressure.
I'd check things out with a timing light first. Then do a compression test.
If you suspect slop in the timing chain test by putting a socket on the bottom pully and see if your getting any movement on the crankshaft that isn't immediatelymoving the camshaft.

RE: HELP! 305 poping throught carb HELP!
 

k question with the botom line there what is the best way to tell if i have moovement on the crank and not imediatly at the cam with out tearing down the front of the motor

RE: HELP! 305 poping throught carb HELP!
 

Had this issue with an 81 Chev P/U w/305. Pull the passenger side valve cover and look at the valves on the front 2 cylinders and make sure they are opening and closing. The problem with mine was worn cam lobe, which was common on the 305. It was a wornexhaust lobe so the exhaust valve didn't open and there was still pressure left when the intake opened causing the pop. Pop wasn't noticeable until opening the throttle a bit. I think you'll find your problem there. If not the pass side then try the drivers side.

Bud-Where in MN are you?

RE: HELP! 305 poping throught carb HELP!
 

igh south burbs right next to wsp

Conclusion tore up cam lobe... motor and trany are out and waiting on money

1. Timing
2. Timing chain /gear worn out

Just got a hold of an 87 cutlass with a 350 in it. Set top dead center timing and tried to start it. Keeps popping through the carb no matter how u move the timing.

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