Thread: Engine Question
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Old 04/21/2005, 07:27 AM   #4
coloradoHCS
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Location: Conifer, Colorado
Joined: Aug 04
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Re:Engine Question

Case12, vibration at the engine could be a number of things both internal and external. Here are my thoughts:
1)Eliminate the plugs and wires. If the plug is tan it is a good indication that it is firing properly.

2.Timing chain and or valve timing could be the cause. Check to see that the valves are closing on the compression stroke. Pull the spark plug and plug the hole with your finger. Jog the starter and the compression should push your finger away at TDC of the compression stroke.

3)If timing is dead on and the pressure is not there during the compression stroke look for a flat cam or valve adjustment/failure. These may cause vibration.

4)Sometimes the rubber ring within the harmonic balancer will have spun. This will throw the balance of the engine out, especially at higher RPM. Visually inspect your balancer for cracking or separation. This is a common cause of high vibration in engines when all is correct internally.

5)Does your car have an auto or a manual tranny. If is is manual sometimes a bad flywheel can cause vibration. I think this possibility is remote but worth considering.

6)I can see no reason why the heads should be causing this problem. How long have they been on the car? If they are a new install and this did not occur prior to their installation then obviously they are "suspect one" but I doubt it.

Case, I would start at the balacer inspection first, then the timing to see if it is electrical (timing, plugs, points if present, etc) then look at internal mechanical (valves, cam, crank-ugh!, or flywheel). I hope this helps, Mark.
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