I changed distributors in my engine. Once I got my engine fired up I tried timing it. when I went to plug the vacuum line onto the advance, the engine slowed down. Unplug it and engine speeds up. I also notice that the engine doesn't change speed as you adjust the distributor advance or retard. Throw some ideas at me.

 

Just so everybody is on the same page, what distributor? Aftermarket, rebuilt Autolite, ?

Have you verified TDC is accurate and distributor stabbed in correctly.

 

Aftermarket unit that was in that rebuilt junk 312 I bought last year. Brand new with a pertronix in it. My old unit was about 6yrs old and ran in this engine before rebuild. I changed them cause of a pinging issue, so I thought this distributor might have a different curve. I guess it has no curve!

 

Distributors for Y-blocks in good condition are getting harder to find. Maybe you know this already, beware the "rebuilt" or remanufactured distributors listed by some of the parts houses. Since they ran out of cores some are taking SBF distributors and slapping a gear on it. They will run but the length dimensions are incorrect and it doesn't engage with the oil pump rod correctly. If you keep an eye on epay sometimes NOS or service replacements show up. If you see one, grab it. Worn out distributors don't run right and can't be made to run right, not without a real rebuild with new shaft, bushing, weights, etc anyway.

 

I guess I will re-install the previous distributor. I've just never seen the reaction that it increases speed when vacuum is removed. It's always slowed down from what I remember.

 

That sounds right, the engine usually stalls?