1931 Chevrolet Distributor Advance Curve Technical

 NOTE:  See data and chart at bottom of this page.

---------- Original message ----------
From: The Gilson Family
Date: Fri, Jan 22, 2010 at 5:32 PM
Subject: 1931 Chevrolet
To: bill@barkerville.net

Bill, I thought you might like to share this information on the site.  I take an antique auto restoration class through a local community college and I decided to bring one of my freshly re-built 1931 Chevrolet distributors in for a test.  We used a Sun Distributor machine to evaluate the advance curve. The results are attached.

Knowing the maximum advance of your distributor and the RPM that it peaks at is relevant to fine tuning your car for better performance.  You never want your total advance to go over 36 degrees. Therefore, if you set your timing at 18 deg BTC (flywheel) and you add 12 deg Advance max from your distributor, your total maximum advance would be 30 degrees.

This particular distributor peaks at 1200 distributor rpm, or 2400 engine rpm.

Just for kicks, I tested an un-restored 1931 Chevrolet distributor that was not taken apart, cleaned and re-lubricated what-so-ever.  The results showed that the maximum advance was only 7 degrees at 1150 distributor rpm.  We turned up the speed to 1500 rpm and it did not change the 7 deg. max.

Just like anything else, if you want it to work properly, make sure each part works properly.

P.S. I hope this information is useful.


Jim G.
Distrubutor RPM Deg.  Advance
200 0
250 0
300 0
350 0
400 1
450 2
500 2
550 4
600 4.5
650 5
700 6
750 6.5
800 7
850 7.5
900 8
950 8
1000 10
1150 11
1200 12
1250 12
1300 12
  November 2012 - I have recently found this information about the "automatic" advance on the 1929-31 distributors:
Excerp: "...at speeds below 22 miles per hour, the automatic distributor advance feature does not function and the only variation in firing is obtained by the spark control button on the instrument panel. At speeds 22 miles per hour or more, centrifugal force begins to throw both weights out until at a maximum speed, they reach full advance..."
--Bill B