Ignition Advance - Engine, Vacuum and Centrifugal Distributor Advance

As an addendum to the excellent John Washburn article on Ignition Advance and Vacuum Advance, I compiled Ignition Advance information for the 1963 & 1964 Cadillacs specifically and included in our March 2014 1963/64 Cadillac Chapter Newsletter. I have saved that "Tech Tip" as a separate standalone PDF document which you can see by clicking on
 
Ignition Advance

I have also copied it in here:

We have periodically discussed ignition timing and vacuum advance and the idea that vacuum advance at high engine vacuum (low rpm and cruising), and the mechanical centrifugal advance (at higher RPM and wide open throttle) all play into setting the engines "total advance".

Understanding the basics of max vacuum and centrifugal advance, total advance, manifold vs ported vacuum, and how it all works to make your engine run smoothly and efficiently is a complex topic, but have to say that John Washburn's 2 parts look at this subject in the January and February 2014 Issues of the Self Starter provides an excellent summary.

In Part 1 in the January 2014 Self Starter, he covers vacuum advance includes the part # for the 1956 to 1963, and 1965 to 1966 Vacuum Advance (part # 111 6168 in groups 2.410) but skips over the 1964 one year only vacuum advance (part # 111 6237).

In Part 2 in the February 2014 Self Starter he covers all 3 elements of engine advance including engine timing, vacuum advance and centrifugal/mechanical advance and how they affect performance. Both Part 1 and Part 2 include charts and stats and illustrations up through 1962 which is applicable to our cars since the 1963 distributor and advance where used for previous years.

A quick look at the Shop manuals reveals the difference in vacuum advances from 63 to 64:

For 1963 the shop manual indicates:
Vacuum Advance: Start 8" - 10", Full 13.25" - 15.25", Max Vacuum advance 11.25 degrees
Centrifugal Advance: Start 0 to 1.5 degree advance at 400 rpm, Max 7 to 9 degrees at 2000rpm
Timing advance 5 Degrees BTDC

For 1964 the shop manual indicates:
Vacuum Advance: Start 5 - 7", Full 20", Max Vacuum Advance 10.75 degrees.
Centrifugal Advance: Start 0 to 1 degree advance at 400 rpm, Max 8 to 10 degrees at 2000rpm
Timing advance 5 Degrees BTDC

In 1965, Cadillac went back to the same distributor and vacuum advance used in 1963.

In summary:

--> FIRST: The vacuum advance at high vacuum conditions (low rpm and cruising speeds) provides a LOT of advance. That's 10.75 to 11.25 degrees advance if you have sufficient manifold vacuum, and your vacuum advance is in good working order. If in doubt have your distributor checked on a Sun Distributor machine using the specs on the previous page and replace and rebuild if needed.

--> SECOND: The 1964 requires a full 20" of vacuum to hit its max advance, so if you drive at a high altitude (as referenced in Mr. Washburn’s article) or have other issues causing low engine vacuum and do not reach the 20" of vacuum, you will never reach the max vacuum advance. The article references adjustment using alternate parts to compensate for the lack of obtaining maximum advance at high altitudes.

--> THIRD: You can compensate for defective vacuum advance by physically changing the engine timing setting; however, you will be adversely affecting performance somewhere else as you alter the total engine vacuum. Mr. Washburn references the fact that at cruising speeds your engine is running lean and does not need a lot of horsepower.

--> FOURTH AND FINALLY: Read the excellent article by John Washburn on vacuum advance in the January and February 2014 Self Starter

--> Also. Check out a good description of ported vs manifold vacuum for those running aftermarket carbs, by a GM tech by Clicking Here.

Views: 2091

Comment

You need to be a member of 63/64 Cadillac Website to add comments!

Join 63/64 Cadillac Website

Comment by Jason Edge on June 21, 2018 at 5:34pm

That's fantastic regarding the local and original vacuum advance find. Glad the info was useful! 

Comment by M123 on June 21, 2018 at 4:04pm

Love this section with all the amazing information. Did actually order one 111 6237 from a Cadillac part specialist here in Sweden today, was not free but just the feeling that I will have the right part is overwhelming. =)

Comment by Jason Edge on April 5, 2016 at 3:36pm

Click on the Help page link and scroll down to Pertronix.

Comment by michael k accardi on April 5, 2016 at 1:19pm

is there a electronic ignition conversion so i no longer have to worry about points? I have always liked  h.e.i style ignitions/ distributors for simplicity and performance.   ty michael. 

Comment by Tony and Ginny 429 on March 31, 2014 at 10:37am
Wondering if Cadillac thought that they would need the additional intake manifold increase to a vacuum of 20, to make up for all the vacuum systems that are vacuum controlled by the Comfort control heat and AC in the 1964 cars ?
Just seems odd that they went back to the 63 spec's in 65
Don't you wonder what the thinking was behind that change ?

Photos

  • Add Photos
  • View All

Forum

Current 1963/64 Cadillac Listings on eBay

Started by Jason Edge in For Sale. Last reply by Jason Edge 18 hours ago. 1 Reply

To see all 1963/64 Cadillacs Listed on eBay in the USA…Continue

Tags: ebay

Classic Cadillac Parts For Sale - Misc Items

Started by Jason Edge in For Sale. Last reply by Jason Edge 18 hours ago. 274 Replies

I have posted a few Misc items over on my Classic Cadillac Parts Facebook page at…Continue

Tags: classic cadillac parts, classiccadillacparts

You Know You Are Into Some Serious Car Doctor When You Have to Get the Ice Out!

Started by Jason Edge in 1963/64 Cadillac Specific Discussion. Last reply by Tony and Ginny 429 on Saturday. 17 Replies

You know you are into some serious car doctoring when you have to get the ice packs out. More to come on my 64 Coupe de Ville resuscitation in the next 1963/64 Cadillac Chapter Newsletter!  Mades…Continue

Unknown part, maybe the last one?

Started by Matti Roth in Restoration Discussion. Last reply by Jason Edge on Friday. 1 Reply

Hithanks to great help from chapter members I am getting my 64 Deville ready, slowly but surely.There is only one part still unclear, or actually three bolts and nuts. They are clearly different from…Continue

Blog Posts

1963 series 62 convertible transmission issue

Posted by Matthew VanDeWater on June 22, 2021 at 3:03pm 1 Comment

Hello I've been restoring a 63 for way to many years. Down to almost done, but have issue with trans linkage, when column in park shift rod 2 inches short. everything original. been trying to find picture of manual rod hooked up from under car to see position of linkage. was wondering if anybody has access for pictures. I wanted to see if my manual linkage is bent  wrong out of the trans if somebody dropped the trans or something. Doesn't make sense why it doesn't work. Thanks for any input…

Continue

New vehicle in the club

Posted by Patrick Westphal on June 17, 2021 at 4:00pm 1 Comment

I was successful in getting a vehicle from the New York contact I talked about at the last club meeting. I am still trying to figure out how to post a picture of the vehicle that is tied with this comment so if you see a random picture of a black convertible in a yard, that's me haha.  …

Continue

Torque converter grab when idling in Drive

Posted by Cliff Johnston on June 14, 2021 at 8:47pm 2 Comments

Hi Everyone, been quite a while since i have been on here.

I have had an issue with the idle on my 64 Coupe Deville ever since i have had it.

With the Idle set high enough that it is smooth, but still a nice idle, the RPM seems only slightly too high for the stall of the Torque Converter. And therefore it tends to sit there and grab and lunge a bit. So until now, i have been putting the car in Neutral at the lights to stop this happening.

I've had the car dyno tuned and…

Continue

Can you help? Driveshaft Question....

Posted by Chris on May 30, 2021 at 8:55am 1 Comment

Hello!

Newbie to the group here - we have already found tons of invaluable information on the board, so thanks! We are restoring a 1963 Series 62 Convertible. We are wondering if anyone knows of a source to buy the propellor yoke flange (that bolts to the pinion flange) for the driveshaft? One of our ears partially broke off. Not sure if we can buy just the yoke flange as an aftermarket part, or if it has to be rebuilt by a welder/fab guy? Maybe a salvage yard for a source? Again, any…

Continue

Videos

  • Add Videos
  • View All

© 2021   Created by Jason Edge.   Powered by

Badges  |  Report an Issue  |  Terms of Service