Skip to main content

How Much Vacuum Advance for our Cars?

I have been working on ignition timing and can find ample information about timing values for mechanical advance.  For example, 16 degrees initial and 36 total advance, all in by 3000 rpm.  Similar information for vacuum advance is a little scarce for the 351C motor.  There is ample information about vacuum advance for the Small Block Chevy but not for our cars.  Any insight you have is appreciated.

I am concurrently working on two cars.  One has a Duraspark distributor and the other has an electronic distributor.  The Duraspark is currently adding 15 degrees vacuum advance at idle.  I used an allen wrench to adjust the pod to that value.  With the timing light I can see the vacuum advance fall off when I blip the throttle.

Here are the settings for the electronic distributor.  The vacuum advance setting of 8 degrees is their default and I left it there while working through this.

A473BFE7-B51F-4286-9647-7693EA8318CF

The table below shows the relationship between vacuum and kPa.

page4image2665445360
Here is the generated table.
C20E742E-65BD-498B-B1C2-F13536C0110A_1_102_o

Attachments

Images (3)
  • A473BFE7-B51F-4286-9647-7693EA8318CF
  • blobid0
  • C20E742E-65BD-498B-B1C2-F13536C0110A_1_102_o
Original Post
×
×
×
×