Is Quench Required?

Kern Dog said
That was the Lunati cam I have in the engine right now.

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At first, it was August 2013. I had degreed in at their recommended spec and anything past 1/2 throttle.... it knocked.
I tried 91 octane, 100 octane, 104 and 110 leaded. All of this was with no more than 31 degrees of total timing. The 110 was the only fuel that allowed full throttle running without any knocking at all and son of a *****....it was a monster. 3.91 gears and a 3000 stall converter and this dude felt incredibly fast. This made me want to keep the cam and find some way to make it work. December 2013 I pulled the heads for porting and the .075 head gaskets. It lost a bit of torque so in March 2014 I advanced the cam 4 degrees. March 2015 I swapped in the MP '528 and that was in the engine until June 2022 when it lost several lobes within a very short time.

That cam has a super late intake closing. After plugging that info in a caluculator, I'm getting at DCR of 6.8 at a SCR of 10.17. Was that when you swapped to 0.075" gaskets? Advancing it 4* would bring the DCR up to 7.1. And with the 0.528" cam I get a DCR of 7.65. Sorry, just trying to keep all of that info straight so I can make use of the information.

I think my issue is the cam I plan on running has an intake closing at 67*, so it doesn't bleed off as much compression.

Newbomb Turk said
Absolutely. You still need to get your timing curve in shape and keep the engine no hotter than 180.

But you are always less detonation prone with a tight quench and more compression.

My compression ratio is 12.2x:1 and my effective compression ratio is 9.2:1 and it will run on pump gas and not detonate.

Thank you. I appreciate the feedback. I'm hoping I don't end up having to replace the pistons with the Autotec version with the 4.1cc larger dish and re-balance the assembly. If that's the case, I'd rather do it now with it apart. Do you think 8.24 DCR will be an issue (in terms of detonation) with 91 octane and 0.039" quench? At this point, it's well beyond my expertise.

I'd hate to think it will only work with a perfect tune on a cool day under a specific set of circumstances. I'd rather have soom wiggle room for error (bad batch of gas, engine gets hot - I am in Sacramento CA after all, etc.). Obviously **** happens, so I'd like to have at least some wiggle room.

Jim Kueneman said
Have you calculated the cranking cylinder pressures with that compression and cam?

Jim

With which scenario?