Hello everyone. First, I've been coming on this forum for a few years mostly researching different engine combos and would like to thank everyone for contributing, especially the regulars.
Now to my question: ive been dreaming up a turbo dx build for years and have gathered some of the key pieces, but realize i probably wont get to that for awhile. now i'm thinking about just upgrading my current combo:

Currently:
461, trws, torker, holley 750, jm22/25 cam, home ported c heads with harland sharps,main studs with straps,9.75 actual compression,1 7/8 headers 3" full exhaust, 3.70 gears in a 81 cutlass street strip car.

Possible new combo of stuff i mostly already have::
I got a package deal a long time ago with an excellent condition rotating assembly with 60 over arias pistons, reconditioned stock toronado rods with spit hole and arp bolts, came with stock balancer and nodular balanced crank. ( i might ditch the stock rods in favor of some scats if budget allows).Also picked up some used edelbrock heads that were extensively ported with stock valve sizes. I will have these flow tested at some point. the problem is the previous owner had these heads milled and I cc'd them to 66-67 ccs. Using the summit compression calculator i come up with 12.47:1 with these parts:
(4.185 bore 4.25 stroke 3 cc valve refs, .020 deck clearance?, .040 gasket).
this is a street strip car which I drive to the track about 1 to 1.5 hours dpending, and want to run 93 octane gas. Using a .098 cometic gasket, it brings it down to 10.92:1 or .080 gasket, 11.36:1.

So two questions really
1) ive read a lot of posts about optimizing quench at around .035 to .040. Obviously using the thicker gaskets will give a huge quench. I'm looking for real world examples on an OLDS engine of reducing compression. for example "i have a xxx hp big block with xxxx compession and used a thicker gasket to lower compession , resulting in xx quench and the engine perfomed great or had detonation, etc"
my suspicion on a open chamber head like the olds it wont really matter. Also, are the thicker gaskets more prone to failure? mls or copper better?
2) what is the maximum compression i could safely run with the edelbrock heads? and hopefully some real world examples. I've seen some posts where people say to keep it around 10.5: and others running 11.25:1? I'm aware about dynamic compression and will obviously go with a different cam to lower this. also might consider detuning slightly for street use and running water/ meth at the track

Alright, that was more than two questions so thanks again!

 

Considering selling those Edelbrock heads to someone with a SB or maybe consider E85. I think you are asking for trouble having pistons .100" in the hole with high compression.

 

Squish is something that happens when you step on a slug. 😁

Quench on the other hand is the result of the area (sq/in) between the piston and head (usually the deck). What this does simply put is, it causes the mixture to more thoroughly mix. This allows for better combustion. A side effect is you can run less timing with the same amount of power. The amount of quench needed depends on a few things. The most important is chamber and piston configuration. On an Oldsmobile engine due to the chamber shape and most pistons being flat or dished combined with the low intake port quench is not overly important. You can get away with less. If I recall right (brain a bit fuzzy) their is one particular turbo SBO that uses a .060 copper gasket no issues. However in the case above it sounds like you are trying to band aid the combination due to your piston situation. IT WONT WORK. Get the correct pistons, you will save yourself alot of grief and money.

 

Quench causes swirl as well, which promotes a more even burn.
However swirl can also be induced by intake port design as well as the design of the piston top.
But it’s not an absolute for max performance. There are a lot of engines out there that have little quench yet run quite well, ie the Dodge Hemi both early and late, is a good example.

 

Thanks to everyone for replies. I'm leaning toward not doing this particular combo right now. E85 not available here. I'll be holding on to these heads for future build. Still would like to hear from people about heir experience with maximum acceptable compression on a pump gas engine.
Just talked to a friend of mine yesterday who i hadn't heard from in a long time. Hes got a strong running pump gas 496 built by Trovato awhile back. This motor is at 10.7:1 which Bill specified as about max at that time for his particular combo. So this is a good starting point. Anyone else running much higher?