Has anybody else noticed a difference is the knock retard reporting. It reads tenths (.1) now for one, but normally when I get a count I see quite a few degrees retard (7-9). Now I get a string of .7-2.2 before it goes back to 0. I could actually hear the knock on the 2-3 shift about the time I saw the count on the scan. In the past, when audible knock was present I've seen much more retard. This was my first chip, and with the ARAP I expected to see some knock, but normally I wouldn't be overly concerned with 1-2 degrees. Anybody else?

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'87 Formula WS6 - ZZ4 Crate TPI, Scroggin-Dickey ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel base, ported plenum, Edelbrock 58mm TB, Crane Fireball ignition, SLP cold air, SLP 1 5/8 headers, !cat, Summit exhaust cutout, Walbro 255, Koni yellows, Hotchkis panhard & LCA's, 9 bolt w/3.27's.

 

I introduced a divisor of 10 to the reported retard values. Is this correct? Folks had suggested it was. Perhaps someone could verify/clarify on this. The numbers I was reporting previously were believed to be exaggerated.

 

I wonder if audible knock is an indication that you should be seeing maximum retard, depending on what's in your chip's table. Maybe others can share what retard values they see when using the ARAP tables. Anyhow, knock is knock, so I'm going to be tuning and burning today with a goal of no knock.

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'87 Formula WS6 - ZZ4 Crate TPI, Scroggin-Dickey ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel base, ported plenum, Edelbrock 58mm TB, Crane Fireball ignition, SLP cold air, SLP 1 5/8 headers, !cat, Summit exhaust cutout, Walbro 255, Koni yellows, Hotchkis panhard & LCA's, 9 bolt w/3.27's.

 

Craig,

I was looking at this reference:
http://www.geocities.com/MotorCity/S.../prog_101.html

According to Bruce, the correct divisor is:
Knock retard N x (45/256) 0-45 degrees
or, about 5.7 rather than 10

HTH

Jim
Red '86 4+3

 

I don't think that audible knock means that you should be seeing max retard. It may happen that way because of loud exhaust and what not drowning out the knock, but really any knock incidences could be audible so you may or may not be at max retard when you hear it.

I ran the ARAP timing tables unchanged in my GTA which is ~10:1 with aluminum heads and I rarely heard any knock. When the spark tables were still untouched, I would hear some knock while on 92 octane at part throttle + heavy load conditions and I would record retard as well. When I would run 100 octane (unleaded), I saw no knock incidences at all. At WOT and heavier loads I never recorded any knock counts with the latest version of Craigs software with 92 or 100 octane with the ARAP spark settings at heavier loads and WOT untouched(I have backed off some of the light load/low rpm timing since that is where I was getting most of the knock when it did occurr).

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club