Well, I don't own a 1st gen, but do I have an '84-85 GSL-SE motor in my '74 REPU. When I first got the truck the disty was off one tooth and the leading spark was almost 40 degrees out of timing, okay, now that's fixed. Now I'm trying to get the trailing timing right, something is wrong.

Adjusting the vacuum unit does nothing at all. No movement on the pulley timing marks whatsoever. Me being curious, I removed the vacuum unit screws completely and pulled the unit as far as it would stretch and only then would it begin to advance the trailing timing. Only problem is, I need to go the other way and it's not letting me at all.

Anyone ever have this problem personally, or have an understanding of what's happening here?

Thanks in advance.

 

So you're using the stock SE dizzy, yeah? Take the cap off and look inside at the mechanism. It's pretty simple. There are two arms with springs. One rotates the leading pickups, and one the trailing, I think they're even labled. Get a vacuum pump and hook it up to the trailing vacuum clam and apply a bit of vacuum, that should pull the trailing arm inside the dizzy.

The screws are there to adjust the physical position of the arm in its resting state. Loosen them and move the vacuum clam in and out and it should pull the arm as well. If that doesn't work, perhaps the arm is off or broken.

Another thing to test is shine a light at the trailing mark on the pulley and rev the engine a bit. If the mark moves, then at least your vacuum advance is working and the issue with the dizzy mechanism itself.

Not a very good explaination, but once you play around with it, you'll see how it works and I'll make sense.

 

Vacuum advance has been capped, since the Dellorto gives me no proper venturi vacuum nipple to advance off of.

I removed the disty cap and metal cover to make sure the arm was still connected and it was, which I expected. Although I didn't see any springs.

I'll figure the rest of this out tomorrow, my co-worker had a good idea, apply a Mitty-Vac to the nipple and see if that sucks the trailing timing to the general are where I need it to be, then fine tune with the adjustments. This makes sense to me because without vacuum the unit can't retard. I'm keeping my fingers crossed...

 

How did you correct the leading timing that was off?

Common thing that happens when timing is off is that the lower pulley is incorrectly installed when either replacing a water pump (no need to remove that pulley) or it is not put back correctly in a engine swap. You would have to verify that it is only correctly. Their is a thread in the archives on how to verify this.

 

Pulled the entire distributor out of the motor, rotated the gear by one tooth in whatever direction it needed.

I really don't think this is the case since the running condition, also, doesn't the e-shaft have a key on the front and rear that prevent you from installing pulleys or flywheels any other way than the right way? It runs great with the leading timing being on the money, it could just run...better.

 

The hub that goes into the front of the engine has a key way but the pulleys just bolt on and you can put them on incorrectly. Verify that when the timing mark is lined up with the yellow mark that the distributor rotor is facing toward L1 with the arrow on the rotor. If it is not then the pulley is on wrong or the distributor is in wrong.

This is not like a "chevy" where you rotate it a tooth to put it in correctly. :-)

 

Damn, I'm hardly a Chevy guy haha. Although I think they are the lesser of the big three evils.

Anyways, I'm definitely going to try that before I move any further.

Thanks doc.