383 backfires on passenger header at big end
 

after a quick rev with rpm dropping I have a back fire in passenger header I has never done this before timing is good. Could a valve be out of adjustment I have poly locks and a stud girdle

check the valves
 

the popping maybe a cracked valve spring , or unseated valve. carefull I would lookin to it before racing again. pull the valve covers and check things out JMO

Check your header bolts/gaskets, a exhaust leak will cause one to backfire.

it could be many things a broke or weak valve spring is what i would check for first if it was running fine before. Also do a leak down on the cylinders to make sure the rings and valves are sealing. That will tell you real quick were the cause is

Valve Spings X3

I agree with Charlie. Check for header leak. Gets a large shot of fuel when the throttle is closed and when it sucks air past the flange it will ignite in the header. Mine will do it if I don't keep an eye on the bolts.

Curtis

you Guys nailed it loose header bolt thanks to everyone that replied

Man, isn't that awesome when it is something that simple??? If it were ME, I would have a spun bearing, wiped cam w/ several busted polly locks & a cracked head... plus a dog peeing on the front wheel too.

It was a simple fix I had a lot of bad thoughts too thats what is great about the forums there is so much knowledge out there and people willing to give advice

Amen. Great folks here. I have learned a bunch from many of them over the years... stick around... something else will happen. LOL Welcome.