Problem setting timing

[wondermelon]

I just tried setting the timing on my 4-AFE. Before starting this the timing was around 0 degrees BTDC. I set it to 10 degrees, readjusted the idle down to around 800, and shut it off. I pulled the jumper from the diagnostic connector and restarted the engine. Now the timing jumps around between 5 and 15, and when it jumps to the high end I get some after fires. Haven't taken it out for a drive yet.

May not be related but I think the exhaust manifold has a crack on the backside that I can't see.

[patcal]

Are you sure you have the jumper on the right connector? What about being warmed up before trying this? I drive the car or run it until the fan comes on and then goes off before I check the timing. There is a small possibility that your crank pulley outer ring has come loose from the inner part. Should be easy to check. Hope that help s a little.

[wondermelon]

thanks for the reply pat.

i had the jumper wire set up correctly and the car was very warmed up.

I have fixed the after fires by tightening up the manifold to flex pipe nuts as they had become quite loose (again). I guess i'll have to put some locktite on those bolts later. This also smoothed out the idle. The leak was causing a rich situation.

Interestingly the timing still jumps around between 5 and 15 degrees, though it seems less erratic now. With the diagnostic connector bridged the timing is dead on 10 degrees with no variation. Is this normal?

Also, I can't believe I didn't want to spend the money on a timing light. The car has SO MUCH MORE POWER! 0 degrees BTDC is no way to roll!

[patcal]

Actually that is correct. According to the FSM Page IG-16 with the connector jumped the timing should be 10 BTDC. With the jumper off the timing will range between 5-15 BTDC at idle. You seem to have it set right.