Thread: Small Block 400 Timing Question??

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My engine will run smoothly until i get on it a little then it will backfire through the carb...i messed with the timing but no matter where i set it at it still did the same....just wondering if its the timing chain??

Could be timing, could be carburetor, could be ignition. Any one of these things could cause a backfire thru the carb. You could check the chain by removing the distributor cap and, if you can, grab the fan and turn it back and forth while watching the ignition rotor. There should be a little play, but not much. How much depends on how worn the chain is. If you have a clutch fan, then you'll have to put a socket on the balancer hub bolt and turn it that way. That's the way I do it. Another way is to just change it, it's probably time anyway.

Put a timing light on it. Does the timing bounce all around - or hold steady. A loose timing chain will cause "spark scatter."

You are running lean. Richen it up!

If your timing checks out OK, could be something as simple as a vacuum leak. I would check out the carb 1st................

Its a quadrajet carb....i heard those carbs are junk anyway.