'67 390 GT advance timing

[anthem75]

Hello all,

So I just bought a new advance timing capable timing light for my freshly rebuilt 390. I am not a mechanic, but I am not without basic capability and engine understanding. I have never set advance timing before and am looking for procedural advice and specs to guide me. Initial timing for my engine is listed as 12 BTDC. My distributor is a very base model Autoline D404. Mild cam (270 grind); 60 over (yes, 60 over…); original Ford-Holley 600 CFM carb and Pertronix ignition with an RCCI pedapter.

Hope someone can help…

Thanks!

[ddurden]

I’ve got a 67 GT 390. Someone in the past had pot a mark at 8 degrees on my engine. And and sure enough at about 500 rpm that is where it seems to idle the best and creates good vacuum. I also have a pentronix ignition system. Don’t know anything about advance timing…always thought that was something automatic taking place inside distributor.

[anthem75]

I’ve got a 67 GT 390. Someone in the past had pot a mark at 8 degrees on my engine. And and sure enough at about 500 rpm that is where it seems to idle the best and creates good vacuum. I also have a pentronix ignition system. Don’t know anything about advance timing…always thought that was something automatic taking place inside distributor.

Thanks for the response. Advance (or total) timing, and initial timing are very different. I’m surprised that you have good vacuum at 8* BTDC. Have you measured it with a vacuum gauge?

[ddurden]

Gonna fiddle with carb tomorrow. Will try to take vacuum reading and post. Always ready to learn something…thanks

[Royce]

To set initial timing:

1. Disconnect and plug distributor vacuum.
2. Start the engine
3. Using a timing light check and / or adjust the advance to achieve 12 degrees at idle. On that engine, stock idle speed should be about 600 RPM in neutral or park with headlights on.

[anthem75]

To set initial timing:

1. Disconnect and plug distributor vacuum.
2. Start the engine
3. Using a timing light check and / or adjust the advance to achieve 12 degrees at idle. On that engine, stock idle speed should be about 600 RPM in neutral or park with headlights on.

I appreciate this Royce. The initial timing is already set. Am looking for tips from those more experienced than I at setting the total timing.

[Royce]

Total timing with modern gas / everything stock needs to be maybe 35 degrees with everything hooked up / 3000 RPM.

This will likely move the initial timing back to 6 degrees.

To fix the discrepancy for best performance will require limiting either centrifugal or vacuum advance in the distributor.

To set initial timing:

1. Disconnect and plug distributor vacuum.
2. Start the engine
3. Using a timing light check and / or adjust the advance to achieve 12 degrees at idle. On that engine, stock idle speed should be about 600 RPM in neutral or park with headlights on.

I appreciate this Royce. The initial timing is already set. Am looking for tips from those more experienced than I at setting the total timing.

[tinman]

A quick google search I found some info on setting/changing total advance:
http://www.bob2000.com/dist.htm
https://www.fordmuscle.com/archives/2000/03/timing/

Like Royce said with 35 degrees total advance initial may be 6 degrees. To get back to 12 initial/35 total you would have to change the advance slots.

Mike