1967 Timing marks

[Bill K.]

This is the timing plate on my early 67 427 - 400 HP original motor. First time I've ever seen and A & R vs Before and After. Want to confirm A = Before and that the timing index marks are 2 degrees each. Car seems to idle fine 3-4 marks above the 0 (6-8 degrees BTDC) on the plate. I know the book says 4 degrees. Gets rough the closer I go to 0. I still have to check the overall timing after I confirm what I'm looking at.

Thanks,

Bill

[Joe R.]

Re: 1967 Timing marks

Bill,

I think A means Advanced and R means Retarded relative to TDC on number 1.

Joe

[Larry M.]

Re: 1967 Timing marks

Bill,

I think A means Advanced and R means Retarded relative to TDC on number 1.

Joe

I agree.

Larry

[Duke W.]

Re: 1967 Timing marks

This is the timing plate on my early 67 427 - 400 HP original motor. First time I've ever seen and A & R vs Before and After. Want to confirm A = Before and that the timing index marks are 2 degrees each. Car seems to idle fine 3-4 marks above the 0 (6-8 degrees BTDC) on the plate. I know the book says 4 degrees. Gets rough the closer I go to 0. I still have to check the overall timing after I confirm what I'm looking at.

Thanks,

Bill

As stated A is advance and R is retard. Based on the moderate valve overlap of the OE cam, optimum total idle advance is mid to high 20s, which is achieved with the sum of initial and full vacuum advance. That's why as you retard the timing idle quality degrades.

I believe total centrifugal is 30, but it's very lazy... not all in until around 5000 (check your CSM and AMA specs), so a lighter set of centrifugal springs to bring it in quicker should improve low and mid-range performance, and fuel economy as long as it doesn't detonate.

Given that best top end power is achieved with total WOT advance in the range of 36-40, initial timing should be in the 6-10 range.

The OE spark advance map including recommended initial timing is very conservative.

Duke

[Bill K.]

Re: 1967 Timing marks

Thanks ... confirmed my thoughts. Now to check the total advance at higher RPM !