brushmor

I just finished a month long project on my new to me 1985 corvette. I replaced the intake manifold gasket, injectors, and other stuff that was in the way as preventive maintenance like hoses, belt, plugs, wires, rotor, and distributor cap. There were no issues until I went to check the timing. The weird thing was that it was way advanced off the scale, maybe at least 10 degrees! Yes, I unplugged the EST wire before I checked (I know it was the correct wire because the check engine light came on). So I cranked the distributor counter clockwise until it was 6 degrees BTC. But the problem was that it ran horribly and would not even idle and just stall. So I put it back to my initial markings I made before I pulled the distributor and everything was fine. So with this timing like this it starts right up, idles, and runs great.

Any ideas what's going on? I don't really think the mark is wrong because the rotor seemed to be at #1 when I pulled the cap.

Hot Rod Roy

I'd be suspicious of the harmonic damper. The rubber bond between the hub and the outer ring may be broken, which will throw off the timing marks.

brushmor

Is there an easy way to tell if the harmonic damper slipped?

Good news is that doesn't seem like an expensive part. Bad news is that it does not look like it would be easy to get a puller in there!

John A. Marker

I would check the damper as suggested above.

Next double check to see that your pickup for your timing light is on wire #1.

brushmor

Yup, I was on the #1 wire. That was one of the first things I checked.

Cliff Harris

You can check the balancer by using a straight edge on one of the spokes. Also, they tend to walk into the timing chain cover, so look for that.

What the straight edge test looks like:

brushmor

It does look lit could be rubbing on the time chain cover. That might also explain the faint metal on metal scrapping I hear on occasion at idle coming from the crank.

Thanks all for the help.