Holley sniper

[Sweet5ltr]

I have tried to make sense of your post for a few minutes now. You are throwing out a ton of good info here. Are you saying that his dynamic compression ratio is too high for his setup. Therefore he needs to lower his compression? Yes - IMHO. That is why he is required to run a fuel additive and run conservative timing, but both aren't enough to actually fix the issue. Hughes engines should have known better than to advise him to run this camshaft with 10.5:1 static & cast iron heads. This would be an excellent combo with 9.5:1 static compression.

If static CR doesn't mean jack then how do you go about figuring out if you components work together on the dynamics CR side? I am planning out a 440 right now and haven't yet considered dynamic cr. Just static at 10.5 for pump gas. Google - dynamic compression ratio calculator. If you're running a modern aluminum head & chamber, 10.5:1 static isn't out of the question, as a general rule, you can get away with anywhere between 8.5-9:1 dynamic in most situations on 93-octane. With factory iron heads, 8.5:1 dynamic is probably out of the question on pump fuel. We don't have the luxury of an ECU pulling ignition timing and altering injector pulse width, every time it senses knock. So, in most cases, it's better to be conservative.

 

[Sweet5ltr]

I guess my problem was kind of missed here, the car runs fine, but I think it ran a little stronger with the 750 eddy that was on it at least to 5000 rpm. I know the 750 was to small, and the sniper throttle position sensor is not calibrated correctly, only show 78% at wide open, that could be a big part of my problem. Holley being reallt slow at getting back to me. email them 2 time already

Russ, you just stated the car was pinging terribly under WOT. Idle and cruise won't make a difference as the engine is under very little load, I would hate for you to lose an engine due to detonation (#1 cause of failure) trying to tune a problem that can't be solved with a laptop or firmware update; but it's your car and your money. Custom cylinder head gaskets are less than $200. That's a drop in the bucket when it comes to these cars. Don't take my word for it. Ask around if your dynamic compression ratio is realistic on pump fuel with iron heads.