I have a 1972 Camaro with a 350. It has a new manifold and carb, other than that it is stock. It has a miss that won't go away. I put the new carb and manifold on hoping that would take care of the problem. When I time it the mark will jump 2 to 4 degrees. The distributor has new points and everything is tightened down and secure. Could it be the timing chain has stretched or possibly a valve that is burnt? I have replaced all of the gaskets on the mainfold & carb. I would appreciate the help.

It could be as simple as the mechanical advance weights are sticking. The springs could be shot (too light), the weights could be warn out or things could just be dirty in the dist... Also your vacuum canister could be old and not functioning well. Other than cap, rotor and points the rest of the dist gets overlooked most of the time...

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...Dennis
'69 RS Convertible w/SS trim (http://www.camaroslimited.com/memberscars/den.htm)
'96 Z28SS #1679 of 2410 (http://www.camaroslimited.com/graphics/memcars/96ss.jpg)
"The Club" (http://camaroslimited.com)

Check the distributor for a worn bushing. Just pull the cap and rotor and move the dis. shaft back and forth. There should be very little play or it will cause your engine to do funny things like not run well, surg, backfire etc. Also if you have a dwell meter hook it up and see if the dwell varys alot while the car is running. I think it should be 32 degrees or somewhere near that. But it shouldnt vary more than 2 or 3 degrees at the most.

Alot of times when the timing mark is jumping around its a worn (too much slack) timing chain.

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Black 69 camaro

It can also be a plug wire misfire.

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Rick Dorion
69 RS Conv,355,M20,4.10's

If your timing is jumping around like that, although it could be a worn timing chain, it's more likely that it's your distributor. Worn bushings (as Dennis mentioned) can cause it, as can excessive up-down play in the shaft, which alters the drive gear phasing and affects the timing; the gap between the top of the drive gear and the bottom of the housing should be .002"-.007", and I've seen many that were up to .060", with the timing mark jumping all over the place. Remember that the bottom distributor shaft bushing gets engine oil, but the upper bushing doesn't - it's lubricated by special grease in a sealed well under the breaker plate, which probably dried up years ago, and the upper bushing is probably worn out. Weights could be sticking too, but that won't affect idle timing, as they haven't started to move out yet at idle.

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JohnZ
'69 Z28 Fathom Green

[This message has been edited by JohnZ (edited 08-20-2001).]

Thanks for all of your thoughts. This is a great web site. I hope to talk to all of you soon. Thanks again.....

It may be as simple as your distributor cap. I had the same problem and one of the terminals that the wire connects to was broke. Pull the cap off and check all of these, they're probably all good but it never hurts to check. I found out in my ASE class that it's best to start with the most obvious and simplest things first. This will usually find the problem and save money.