Hi everyone. I got a distributer (HEI) from the junkyard for my 86 Camaro IROC Z. when I took off the cap I noticed that it was missing some metal pieces that sit under the rotor on the shaft. I compared it to my brother in laws distributor and I saw that his has the metal pieces that sort a look like a Ying Yang. Are these pieces necessary? What are theyre funtion? Can I slap a new rotor on without the pieces installed?

 

These metal pieces (on the left) are centrifugal advance. The distributor on the right has a a vacuum advance. Two different systems to accomplish the same thing: advance the engine timing. One advances it with engine speed (RPM), the other does so with engine load (intake plenum pressure).

Hope this helps.
Lou

 

ok. Im not going to have the vacuum advance connected because im running a TPI system. So Im going to buy a new distributer. See if I buy a new one, it would look like the one on the right but with out the vacuum deal. So what your saying is that I can run my IROC Z without the vacuum plunger and without the fancy little plates in the left picture right?

 

If you're running a TPI system, I would recommend to get the correct distributor with the right pickup coil and right ignition module. Unless you like modifying old boxes to work with computer control.
You should have NO mechanical or vacuum advance on your distributor if the ECM is controlling the spark, you will blow a hole in a piston on your first test drive.

Hope this helps.
Lou

 

Nice. Thanks bro. now that I know that I need nothing else, Ima gonna start to tune the timing. thanks man.

 

BigBadLou, So is this the way I should go for my TPI System?
All I got to do is slap on the rotor and Im good to go Right?

 

Well, as long as these connectors work with your engine harness and the ignition module can interface with the ECM, you should be good.

I'm hoping somebody with a HEI distributor knowledge will chime in and correct me if I'm wrong.

Lou

 

your good with that one just make sure that you have the engine set at TDC when you stab the new distributor or your in for a big problem with miss firing... If you have it set at TDC and you stab it and it still is missing after tuning. Reset the engine at TDC and restab the distributor after rotating it 180 degrees... that should fix whatever probs you will have... I run a Vacuum advanced distrib on my 82 with the "ying Yang" pieces modded to give better pick up off the line.. you can accomplish the same thing with the performance chip... Hope this helps you out

 

tight. Thanks for the info fellas. And yup. I got a hyperchip in my ECM. wish me luck.

 

The distributor in your photo looks like it doesn't have a drive gear.