unstable timing mark

[rockinw]

I have a 383 crate motor. When trying to set the timing the mark will not stay steady. The mark on the balancer jumps about 4*- 6*. Any idea's what might be the cause?

[BadBowtie]

1) Radical cam?

2) New timing set?

 

both of those might cause something like that...

[rockinw]

The cam in the GMPP HT 383 crate motor is not very radical. The motor has about 1300 miles on it now. I have been trying to get it to run right. After putting in 10* of intital advance and changing the intake gasket from the stock GM to a Felpro, the motor is waking up. I was going to give it another 2*- 4* but now the mark is unsteady.

[frdfandc]

If the mark is moving 4-6* then you have a bad balancer. A friend of mine had the same problem on his mustang. A quick swap of balancers fixed the problem.

[n8huntsman]

Thats what i was thinking too. There is rubber between the outer and inner shell on the balancer. When this gets old the 2 pieces slip. Then you no longer get a accurate timing mark.

[rockinw]

Balancer is new and has about 1700 miles on it. I know that does not mean much though, new parts fail all the time........