Ant
Well-Known Member
106 PSI compression!!!
Ok I won't say it but I couldn't find any other refurbished LA distributors in stock from Classic Industries or Year One. I still have the previous distributor that I can give another go.If you have a lean-burn distributor or a junker that you can lock everything out of, try that and see if it stabilizes.
I second checking the damper ring, and also....where did you get your parts? (don't say O'rielly or Autozone or Advance, please). I've had new distributors from AZ that had locked out advance cans and missing advance weights and all sorts of screwery.
Today after work I'm planning to put the old distributor on and see what happens. I recall I only replaced it because the advance canister leaked and I couldn't source just the canister, and could only find a distributor from AutoZone in stock. Every test I ran on the new distributor has been fine though. I've had the varying spark problem for a while and can't recall if I had it before the new distributor.Interested to see what the fix for this is.
That's what it seems like.I may just need to have the engine rebuilt.
What about wear in the distributor shaft bushings. With the cap and rotor off try wiggling the shaft to the front and rear and left and right. It should only have .002" clearance. Hardly enough to feel. If the bushings are worn, the shaft can flop around causing timing to jump around.I've had for a while a problem with varying spark timing and it's been getting worse, varying about 3-4 deg each rotation. Now the engine runs pretty poorly at idle and does not get better with RPMs.
I've put on a new distributor, cap and rotor included, and just checked point gap again, setting it to .018.
I put on a new coil and new wires.
I thought I had diagnosed a timing chain with weak stretch, as it had all around low compression (106-122 psi) and varying spark timing. I read of a way to test chain stretch without removing the cover by counter rotating engine twice stopping at TDC, then rotating the engine until the distributor rotor moves and measure the degrees it took. Supposedly 7 is ideal, 10 is limit of acceptable, and I measured 12 degrees. So I then did a timing chain replacement and the engine is not running better. I've not checked compression or timing chain stretch since however.
What else could be the culprit?