Suggestions on initial timing for BN1

[mjobrien]

Wanted to see where folks with 100’s are setting initial at idle timing? I know there was a lot of discussion but would like to poll the audience per say. I’m using the Petronix ignition and while the book suggests 6 deg BTDC Advanced Distributor suggested 12 to 14 Deg BTDC.

I’m looking for that mix of advance and power that will keep the dreaded Knock away, gas is always a variable so I’m using the highest Octane and wondering if an Octane Booster would be in order.

Aanyone using an Octane Booster?

Suggestions on initial timing?

Thanks,
Michael.

 

[johnea]

I think i depends largely on the camshaft. On a stock cam, 6 deg BTDC is ok, a fast road cam might need 10-12 deg. Definately more important is that the total timing (initial + distr. advance) does not exeed 36 deg.

 

[RonMacPherson]

Have you altered your compression ratio from stock? In other words what is it? Have you changed the cam?

If stock compression then you may be wasting money by putting in high octane gas when regular will suffice.

My suggestion, use a vacuum gauge for initial timing. This also helps to compensate for worn, slipped dampers, etc.

hook up the vacuum gauge to manifold vacuum, set your timing where the vacuum gauge reads highest at idle speed, compensating your idle speed to keep it at the proper rpm when you alter your timing. Then back off the timing 4 inches. ie. if you get a reading of 22 inches of vacuum retard the distributor to 18 inches.

That is my initial advice for idle timing. After you have that set then you can compare timing marks on your damper. If they are correct then with an advance reading timing light verify that your timing advance does not go over 34 degrees btd at 2000 rpm and higher.


For performance purposes you would be setting your timing light with a cyl temp gauge and multigas air fuel monitor.

 

[mjobrien]

All stock... so I'll try some of the above suggestions and see how it goes....


Thanks,
Michael.