Hey guys, I have a 1985 Corvette with a Miniram, 58mm Throttle Body, Hedman Longtube 1 5/8" Headers, flat tappet zz409 cam, AFR 195s, 3.75s, and a lot of other small modifications.

Anyway, my Miniram is coming back tomorrow from being ported, and I am going to have to tune the timing tables for the addition of the new heads.

How do I do this? Can anyone link me to a guide to tuning this or explain it?

Also, when someone says they are running lets say 34* of total timing, what do they mean in regards to EST?

I also have an 870 ECU that I'm using right now, if that makes any difference.

I can tune all the other areas pretty decently but I'd like to understand how to go about tuning the timing.

Thanks very much!

 

Total timing is usually the spark advance (SA) at WOT. At 34* a timing light will show it on the damper at 34* BTDC.

Other areas of the SA table will be higher then the 34* of total timing. This is the light load and cruise areas.

Other areas are going to be lower then 34*, such as idle and low speed, high load areas.

IIRC, AFR publishes the total timing value for there various heads. That is a good place to start.

It also helps to try various timing tables. Such as the f-body LT1 spark advance tables, and the y-body ARAP table. See which ones work the best.

RBob.