Ignition Timing

Hey all!

New here, so I thougnht I would start off with a real stumper (for me at least). I have a 68 Dart 440 that I drag race. I set the timing at 35 degrees total. I made two passes and the timing was 25 degrees total. The distributor is not moving and it is not the harmonic balancer, as I have replaced it. I am at wits end. This has happend the last 3 times out. I set the timing make a pass and it changes. :banghead: :banghead: Need help fast.
Any suggestions?

Thanks for the help!

Jeff

are you using a mechanical distributor? if so you might want to change the springs inside the distributor to a stiffer spring.

are you using a mechanical distributor? if so you might want to change the springs inside the distributor to a stiffer spring.
This is the right track; I bet the weights are sticking, or the little pivot points that the advance weights ride on are worn. Stiffer springs would change the advance curve, so IMO its not the best solution, unless the existing springs are obviously stretched or missing.

I think you need to rebuild the distributor advance mechanism, or at least take it apart and polish all the friction points for the weights with extremely fine sandpaper. Even a bit of rust/dirt can cause excessive friction and allow the weiths to hang-up and not return fully.
It would also help to find a shop with a distributor machine, these things spin the distributor and plot an advance curve, allowing some fine tuning and making sure its working properly.