I purchased ARAP bin part number 16134193 from a GM dealer. And as far as I know it is for the 89 Vette with aluminum heads. Now I am running it on an '89 L98 with stock iron heads with some success. But I have a question: What are the differences in the spark tables for the aluminum and iron heads? In a post made my Grumpy he states:

The AL heads make for quite a different animal, for timing (when using non oem cams). Also, can run alot less timing at WOT, and if you smooth out the chambers really make a difference.

Now since the ARAP for the Vette is running less timing at WOT what is happening?

 

I'm positive this was covered in the last week or 2, but the spark advance in the ARAP chip is quite a bit higher than the normal '89 350 chip for an F-body. They have more timing in most of the s.a. table from what I recall, definitely too much for iron heads and aftermarket aluminum heads. You could reduce your base timing a few degrees if you start encountering spark knock, or change the s.a. table itself.

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Greg Westphal
'87 IROC 305TPI/A4

 

I did a compare using tunerCat between a 1990 camaro 350 bin and a 1990 Vette(alum head) bin. Vette bin has a good bit more timing, up to 10 degrees more at 50kPa 2000 - 3000rpm. 6-7 degrees more at 75 kPa, 1000-3200rpm. At WOT, 100kPA it had between 2 and 3 deg more advance depending on rpm. The vette program gave me lots of part throttle mid rpm pinging, I took out about 10 deg. My motor is a 383 TPI w/ edel heads, 9.6:1 and NO EGR which makes a big difference at part throttle.

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Dave Zelinka

 

I've looked at the spark table, too, and I think I'll have major detonation problems with that. I would like to look at stock '89 Camaro and Vette bins for comparison, if they're available. Are they on DIY-EFI? If so, what are they called? Where else might I get them?

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'87 IROC 5.7l TPI - original owner!

[This message has been edited by P J Moran (edited April 25, 2001).]