[kukamojo]

Given the following specs from the motor I just built, what would the recommended advance at idle (including vac) be and what would the best 'all in' advance be, and at what RPM?

Currently it is 12 degrees at 800 rpm with no vacuum hooked up. At 3000 rpm with vac, all in, it is reading 50 degrees. Is this too much?

Here is what the build included:

#416 casting 305 heads: 1.84 intake, 1.5 exhaust, 58cc chamber
Edelbrock 1406 Carb (600 CFM)
Edelbrock RPM Performer 2101 Intake
Summit Racing Cam SUM-1103
HEI distributor, 45 gap.


Cam specs:
Intake Duration at 050 inch Lift 214
Exhaust Duration at 050 inch Lift 224
Duration at 050 inch Lift 214 int./224 exh.
Advertised Intake Duration 272
Advertised Exhaust Duration 282
Advertised Duration 272 int./282 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.442 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.465 in.
Valve Lift with Factory Rocker Arm Ratio 0.442 int./0.465 exh.
Lobe Separation (degrees) 112

As built, I calculated the static compression ratio to be 10.5:1 with a dynamic compression ratio of 9.33:1.
These numbers may not be 100% accurate, but they should be pretty close. If th online calculator I used is correct.


So far it is running great on 93 octane pump gas.

I am loving the end result. I do not have any specs yet on actual horsepower or torque, but the seat of the pants results are enough to get 2 thumbs up in my book. It is a huge difference. The edelbrock is a piece of cake to get setup.

[1930u]

38 at 2500-3000 is a good rule of thumb...

[kc8oye]

run as much timing as you can.. when it starts to ping, that's 'too much' back it off a couple of degrees and run with it. every engine is different.. every engine wants something different.

[kukamojo]

Originally Posted by kc8oye

run as much timing as you can.. when it starts to ping, that's 'too much' back it off a couple of degrees and run with it. every engine is different.. every engine wants something different.

Good advice. I am finding that to be very true.

[jimfulco]

Originally Posted by kukamojo

Currently it is 12 degrees at 800 rpm with no vacuum hooked up. At 3000 rpm with vac, all in, it is reading 50 degrees. Is this too much?

Depends on how much of that 50* is via vacuum. Like 1930u mentioned, ~38* is typical with vacuum disconnected, with an additional 10-15* added at part-throttle by the vacuum can.