When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Thanks a lot Erik and everyone.
I ordered an 82 distributor, and will experiment with how the actuator arm moves with vacuum and boost on the advance port. I see where my TB port has been capped for the retard line, so I can add that back in if needed. I've got a feeling that open to air at the distributor retard fitting might be OK, but we'll see. BTW I'm also going to see how the 84 distributor without the retard line behaves with boost applied. I would not be surprised that it is probably vented and would behave the same as the 82 with its retard fitting open. Again, we'll see.
There is always something,
Dave
Perhaps the answer is less advance than Andrew O. was running in his Coke race car ....
Maybe so. I thought his car was NA. Also don't know what he was running. I guess I should just run less than makes my engine blow up. Good to know.
But seriously: I have an old school car that is boosted. I would like to have decent performance at both low speeds and higher speeds. Dialing off several degrees of timing across the board makes it run lazy except under full throttle. Erik's idea allows me to dial off those same degrees under boost, but leave my timing advanced down low where a lot of day to day driving occurs.
Thanks for the sympathy,
Dave
Hi guys,
I got my 82 distributor in the mail today. It looks OK.
Both advance and retard functions work with the Mityvac. Better still, when I put 6PSI of pressure on the boost line, the mechanism moves to the full vacuum retard position.
I might not get around to install until next week. Anything I can lube while I have the distributor out?
Also, I found Hacker's old post on this subject from 2006:
Just so you guys know what I'm looking for, I hope this will allow a little more timing advance when running without boost, and still retard timing during boost. Again, I don't have electronics to control this so I hope to depend on pressure diaphragms to get it done.
Thanks,
Dave
Last edited by j.kenzie@sbcglobal.net; 05-08-2019 at 12:40 PM.
Well, I swapped distributors, and set mechanical timing (without vacuum or retard connected). I verified that 7 PSI of pressure in the vacuum port of the distributor gives 4-5 degrees of retard. Now I am waiting on a vacuum check valve for the retard line, so I can check vacuum advance function.
Thanks,
Dave
Hi guys,
Well this morning I verified my throttle body ports for my distributor. Looks like I had two connections interchanged at the back of the TB so my vacuum behavior was initially incorrect. With them corrected I get proper vacuum readings on the advance and retard lines on idle and part throttle. I connected the distributor vacuum lines in the stock 82 configuration and set up my timing to the low end of the 82 specs (82 distributor), and I verified that 7PSI positive pressure on the advance line retards the timing 6-8 degrees at 3000 RPM. This gives pretty much stock 84 timing specs (idle and 3000 RPM) with boost retard.
On a test drive the car feels very strong off idle and through the throttle range. I can hit 5-7 PSI oost for short periods and that feels strong too.
For right now, I think I have achieved what I was after. Enough timing at the low end to be peppy, and some retard protection at the top end.
The only problem I ran into was the recommended check valve on the retard vacuum line. I could not make it work and did not use it. When in place, it would not release the vacuum pressure on the retard line and thus maintained full retard at all times. I thought about leaving it dangle off the distributor retard port, but I'm afraid it will interfere with vacuum advance. Maybe Hacker can give details of how it's installed.
I plan to drive it a while as it is currently.
Thanks to all,
Dave
07-27-2017, 11:27 AM
