Car back firing bad

[mtuck]

I was wondering if you all had any ideas on how to fix the back firing on my car. I have a 67' Camaro with a 355 in it. The car will start up and idols fine, but when i give it gas it back fires through the carb. I had tried adjusting the timing from 6° all the way to 14° timing. But it still back fires all the time. When I do get it going the car is very sluggish, like I am losing a lot of HP.

Please let me know if you have any ideas.

Thank
Matthew

[TPI Monte SS]

Sounds like it could be a cam with one (or more) flat lobes on it. They usually pop back through the intake when it goes bad.

[rocketman]

Do you have a holley carb,might have blown the power valve.

[mtuck]

I do have a Holley 750. How would I check the carb?

[kamaroman68]

What about valve lash. The holley problem can be solved by putting new PV's in and adding a backfire retrofit kit. Chris

[Madspeed]

How bout we start with the basics?
#1 Is your firing order correct? SBC BBC? +18436572
Driver side 1357 pas side 2468
Clockwise dist rotation
Good now we have that established lets move on
#2 run a Compression test first. Find a low cylynder?
If you have a leakdown tester use it to determen weather you have deective valve sealling, if thats not it then take the valve cover off that side. have the engine cranked over while watching that cyl's valves, Does one of them not move much? or at all?
Then you need to start tearing it down and looking at the valvetrain IE lifters and cam lobe
If none of this is the problem then repost and Ill give you more to check

Edit: let me share this one too check the timing chain. you can do this by taking of the dist cap and putting a brakerbar with a sokett on the crank and moving the balancer forwards and backwards while you watch the rotor on the dist if you can move the crank a lot before the rotor turns then your timing chain is stretched beyond specs and your cam timing is WAY retarted