If I'm not sure whether my heads are decked (the compression ration might be 1/2 point higher)...will that cause any problems when chip tuning my computer? Do I need to know for sure how much they were shaved to tune?

 

Not really... At most it will make your timing table need to change a bit for optimum performance, but odds are that it won't change much...

 

My friend has AL l98 heads that was milled to hel and back. Even had to shave the intake to line up. My guestimate is aprox 12.0:1 compression. He only uses 92 octane pump gas. The end of last year it ran 122mph (1/4mi). Have been tuning his car for over a year. He shaved the heads 3 times or more since we met. The car started out with 38*, it loved 38-39*. Even in hot weather. Now, the car will detonate with anything more than aprox 33* total timing. This is all WOT stuff. I raise the advance up until it "pings" and then back it off some. *That's not something for the noob to try!!!* Better have a good sense of detonation when pushing the limits.


On the other hand, idle and part throttle will like more timing. For example, idle might like 20-30* of timing...Keep that in mind. There is tweeking to be done, even with a 1/2 point increase.

 

Don't get me wrong, I'd still tune it...