Holley Carb Tuning Problems --- Help

[CdnCutlass]

You could switch your pistons to Speed-Pro H615CP's to increase compression or if you like your KB's use Part# KB147. Both will bring you up to around 10:1, easily runable on pump gas with aluminum heads. Don't forget to get it re-balanced afterwards, unless you get a piston that is within a few grams of your current set.

Do you think it would have detonation issues going with higher compression than 10:1? Say 10.5 or 11:1?

 

[crotchss]

On pump gas? Definitely will have issues with the short duration figures and 11:1. You may be able to get by at 10.5:1 and 91 octane, but that's all dependent on chamber efficiency, quench, etc. If it were me I would run 10:1 and be able to run 91 for sure or 89. Running 10:1 or 10.5:1, you won't be able to feel a difference between the two.

 

[CdnCutlass]

Update:

I pulled the motor and confirmed that it had the wrong pistons from the get go, the machine shop I dealt with installed the KB 126 pistons, giving me only about 9:1 compression when I had asked for 10:1.

The Patriot heads have several valves that don't seal properly.

And finally the camshaft is scrap. After breaking it in by the book, having the right valve springs, and always running the ZDDP additive in addition to high zinc Valvoline VR1 oil several lobes are heavily worn. The intake lobe on the #8 cylinder is completely gone.