I had an issue with timing gear..........anyhow got it back together, dwell was at 15 degrees before removal, now, same distributor, dwell is 29 degrees.......how did that happen?

Thanks in advance, Frank

 

Did you take the distributor cap off? Did you bump the points at all? Rubbing block wear will change the dwell, but not that fast. What exactly did you change to repair your timing gear issue? More info will help with replies. Year of car, engine size, and of course we always like pictures.

 

Who set your dwell at 15? Its actually supposed to be 30. It may have changed because your points mounting screw is loose. Also in case you don't know the dwell needs to be set before doing your timing.

 

To clarify:
It's a 1970 350 with a GM HEI and no vacuum advance.
I put the distributor in 2 years ago and set the initial timing at 15 degrees at idle, it ran great until my timing gear problem a month ago.
Removed the distributor to do the repairs, after the repair work was done, put the distributor back in and now it takes setting the advance at 29-30 degrees for it to run smooth.
I cannot understand how that happened.

 

That is not dwell, that is timing advance. There is no dwell adjustment for an HEI. If its not running correctly you need to start trouble shooting. Did you install the cam and crank sprocket correctly? Do you have full battery voltage at the batt terminal on the HEI, remove the tach if its hooked up. Are you getting good spark at the plugs. Is your firing order correct? Are all the wires seated on the cap and spark plugs? Is the carb adjusted right?

 

When you put the distributor back in you probably just rotated it an additional 14 degrees advanced by accident since there is no way to assure you have the distributor in exactly the same spot as before. Also if you replaced your timing chain and didn't get the cam/crank timing marks correct that will throw of your ignition timing.
First just reset your ignition timing and see how it runs.

 

Yes, I mislabeled this question........I meant timing only, we went through everything and now think we may be off a tooth on the timing gear, so off comes the front end to verify if it is correct or not. Going from 15 degrees advanced before the problem to 29=30 advanced now doesn't make sense. We will verify.
Thanks for all the help, bummer.

 

Let us know the results!

 

What was the issue with your timing gear?

 

Before tearing of the front cover check to make sure it isn't the distributor that is installed one or two teeth out. Other than the ignition timing being too advanced why do you think the cam is out of time?

 

If your timing chain and gears(sprockets) were worn badly enough, replacing them may have moved the timing that far forward without adjusting the distributor setting. I don't know how you would be able to tell if that is the situation without taking at least some of the engine apart. You either verify the gear alignment by taking the cover off or you use a degree wheel and check the valve timing against the crank position. If you aren't going to degree the cam in, the easiest way is to check the gear alignment.

 

Ok.......decided to start from scratch.
Checked harmonic balancer using piston stop method, keyway slot was elongated, TDC was off by 5*........got a new balancer.
Decided to check timing gear, which was new, to see if it was installed correctly, doing that today.
Should have the answer this weekend.

Timing gear marks lined up perfect........putting back together to see if balancer was the problem.

Ok, put it back together with new balancer and timing gear was checked for correct lineup, started it and it was still at 30* for it to start and run decent. I told my friend I'm pulling the distributor to take it to a guy to put on a Sun machine. So we pulled the distributor, took a close look at and my friend said the reluctor had a wiggle to it, I had another HEI distributor and it had no wiggle to the reluctor, so we switched everything to the other one, started it and it ran perfect, idles great and starts quick with the key only all at 15*, finally done.
How the reluctor malfunctioned when timing gear problem happened is still confusing to me.

 

 

No one would have thought of that as the issue. Glad you have it fixed.

 

Thanks, the distributor expert wants to inspect the bad distributor, says this is highly unusual.
See him Monday.