Pontiac Street Performance
Home | Profile | Register | Active Topics | Members | Search | FAQ
Username:
Password:
Save Password

 All Forums
 Pontiac Performance
 Ignition Tech
 Point distributor
 New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 30 Aug 2012 :  8:46:54 PM  Show Profile  Reply with Quote
How much mechanical advance could i expect out of the stock point type GM distributor? Are there some mods that should be preformed? Thanks, B&P


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 31 Aug 2012 10:32:36 AM

bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 31 Aug 2012 :  6:39:12 PM  Show Profile  Reply with Quote
I got 30 degrees with the stock on off my 74 FBird.

The one thing I did find with mine is that the bushing that goes over the limiting pin was gone and I had too much mechanical advance.

I found a thin piece of vacuum hose(I actually believe it was WW Fluid hose) that fit over the pin that worked out great.

And I ended up using one heavy spring and one medium spring to control the rate of advance.
Go to Top of Page

clintww
Cochise

USA
582 Posts

Posted - 18 Sep 2012 :  9:58:50 PM  Show Profile  Reply with Quote
The Motors book should list the advance. Buy a spring/bushing kit from Summit or Ames. I welded mine up to limit total even with a bushing. Im at 12int and 32 total. If you use a machinist ruler and measure the original gap you get a degree to thousands ratio. I don't remember the exact measurement, but say a degree would equal .010 of an inch. You can get very close to your goal on the first try.
Go to Top of Page

bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 19 Sep 2012 :  06:44:30 AM  Show Profile  Reply with Quote
quote:
I got 30 degrees with the stock on off my 74 FBird.


Turns out I can't add or subtract. I went back and looked at my notes.
Mine actually advances 21 degrees mechanically.
Go to Top of Page

Bill Boyle
Horse Feathers (Charter Member)

USA
4793 Posts

Posted - 31 Jan 2014 :  09:21:38 AM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
I spotted this old thread and thought it would be one to update with a recent experience.

A fellow enthusiast sent me his points distributor out of his 70 GTO. I ran a test on it and recorded the curve. I was amazed overall of the good condition of the piece but the stock curve was slow. In fact it never plateaued. The unit was run above 6000 rpm but the springs allowed it to slowly climb all the way to that rpm. This was the first distributor that I've run across that did that. The amount of mechanical climbed to 30 degrees.

The dwell was lowered from 31 to 30.3 and the combination of new springs altered the curve so that it was all in at 3000. The mechanical was stopped at about 24 total degrees. The unit will use manifold vacuum and was set up that way.

When the owner gets this back into his engine, he will really see a performance difference, I'll bet on it. An adjustable vac can was included as well to work with the mechanical curve and to keep it all down and right for his street performance.

FYI, this distributor spun smoothly past 6000 with no misfiring. Point distributors are still practical on our cars that see limited use. That's my read.

Bill

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
Go to Top of Page

67drake
Sitting Duck

Azerbaijan
1501 Posts

Posted - 31 Jan 2014 :  11:01:07 AM  Show Profile  Reply with Quote
I had my original points distributor rebuilt a few years back also. I noticed it was putting way too much mechanical advance in at higher RPM. The weights' stop was apparently worn out. I think it was adding 8-10 degrees too much advance at higher RPM.
Another thing I RARELY read about concerning points distributors is running a higher weight points set. I run a 32 oz. set in my GTO. I believe factory was around 22 oz. The higher the oz. rating the "stiffer" it is,and less likely to bounce at higher RPM. I've had my 400 over 6000RPM a few times,and shift around 5800 or so at the track,no points bounce.


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires

Edited by - 67drake on 31 Jan 2014 11:03:31 AM
Go to Top of Page
  Previous Topic Topic Next Topic  
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
Pontiac Street Performance © 2006-2017 Go To Top Of Page
This page was generated in 0.39 seconds. This Site Sponsored By:
Powered By: Snitz Forums 2000 Version 3.4.05