Used to have the timing at 8 degrees BTDC, and when motor was running around 200 degrees I could hear knock between shifts. I bumped the timing down to 6 and can't audibly hear it, but when I hooked up Diacom, it counted 81 spark knocks within 3 full throttle runs...car is running on edge of stoich and rich under full throttle...what would you suggest, turning timing down again...car has correct TPS voltage and runs great.

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1989 Camaro IROC-Z
TPI ZZ4
Superram intake
Crane AFPR
Hooker Competition Headers
March Power and Amp pulleys
Moser 9" rearend with 3.70 gears and Detroit Locker differential

 

are you using the best fuel you can find? if so i think i'd back the timing down a little.

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ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

i'd say cool it down. backing off the timing is one way of going about it, but cooling it down more would really help. you shouldn't be making it work that hard at 200 degrees. finding a way to cool down the intake charge would help too. also, was it lean?? what were the o2 readings?

 

According to my Air/Fuel ratio gauge and the Diacom software, the car is running rich at full throttle. About how rich I don't know...but the gauge is like on the border of stoich and rich...I didn't look on the software to see how many milivolts it was putting out. I tried having the motor cool, temp was around 175 degrees and still did it. I am getting some 103 unleaded gas to see what happens then. A friend of mine thinks that it could be valve train noise, which might be because it does have a LITTLE noisy valve train. couldn't be a bent pushrod or nothing though, because the motor hasn't ever been overrevved but once, and it only went up to about 6600...redlines at 5800. I doubt it is the valve train though. I might just need a better custom chip burned...I have a crappy Hypertech custom one. Thanks for both of your inputs.

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1989 Camaro IROC-Z
TPI ZZ4
Superram intake
Crane AFPR
Hooker Competition Headers
March Power and Amp pulleys
Moser 9" rearend with 3.70 gears and Detroit Locker differential

 

I have some bad news for you, the stock GM heads especially with TPI do not like a lot of spark advance.

I have used all types of T-stats, burnt tons of eproms with a variety of spark advances, changed various sensors and I have always found a little knock (inaudible) occuring at virutally all spark advance settings INCLUDING when I backed the spark advance to the point of being ridiculous.

You are not the first to discover this (with a scan tool), nor will you be the last. The bottom line is, stock GM heads (even a ZZ4) just does not like a lot of spark advance and prone to knock. Forget the magazine articles about running 36-38* of spark advance. You will HEAR detonation way before that. Some head/intake combos just don't like a lot of spark advance.

Find a combo of spark/mixture that gives you the best performance with the LEAST amount of knock. But, be prepared to find knock occurring at all, but the most ridiculously low settings.

FYI, I find my best performance around 28-30* (net after deducting knock retard). I found the best way is to set my total advance around 28-30* and "cap" my max knock retard and have a "fast" recovery rate.

 

Well, I'm in the market for some heads here soon anyways...I would like some AFR's, and I want an aluminum head. What would any of you suggest with my combo(zz4, supperram intake, fixing to put on a 58mm throttle body and the superram upper plenum and runners.)?

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1989 Camaro IROC-Z
TPI ZZ4
Superram intake
Crane AFPR
Hooker Competition Headers
March Power and Amp pulleys
Moser 9" rearend with 3.70 gears and Detroit Locker differential

 

AFRs are good. Remember, that aluminum don't need a lot of spark advance.

In fact, rather than try and run the highest possible spark advance you can; you are better off to run the lowest spark advance you can and get the best performance.

If your car runs just as fast at 28* as it does at 32*; use 28* spark advance. Your motor will last longer.

Again, forget those magazine articles; do what YOUR engine wants.

 

Just how do you go about setting spark advance? All I know how to do is set base timing. I think when I looked at the Diacom on a full run it once reached 40* advanced. Knock Sensor was pulling anywhere from 15* to 4* out.
One more thing: With the Diacom software, on the diagnostics mode(assuming you have this software)do you use the tpi cable or the 82 & up cable? I can't get my car to link with the tpi cable in diagnostics mode but it works perfect in ALDL mode. 82 & up cable links up in diagnostics mode, but rate transfer is really slow acting compared to the ALDL mode.

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1989 Camaro IROC-Z
TPI ZZ4
Superram intake
Crane AFPR
Hooker Competition Headers
March Power and Amp pulleys
Moser 9" rearend with 3.70 gears and Detroit Locker differential

 

I do have Diacom but I have an SD car, so the ECM works differently. SD TPI actually has a "Normal" mode where the scan tool does not "interact" with the ECM as ALDL mode. It is the prefer to use Diacom on SD cars.

Using ALDL, the scan tool has some "overriding" factors which prohibit the ECM from working exactly as if no scan tool was connected to it.

But, as for your Knock Sensor issue, I don't beleive that running in ALDL Mode would affect it. You SHOULD be able to get quick capture rates in ALDL.

Diagnostic mode is another thing again. I personally have never found a reason to use Diagnostic Mode. I was under the impression that if your car did not have the "Normal" mode option, then you should use ALDL Mode.