[MIKEWITH THE 81'S]

HOW MUCH OF A DIFFERENCE DOES IT MAKE
IF I USE A EXTRA THICK GASKET THEN HOW MUCH WILL IT DROP MY COMPRESSION RATIO.

 

[onovakind67]

If You Just Use A Thick Gasket You Will Lower The Compression Less Than If You Use An Extra Thick One. A Super Thick One Will Lower It Even More, But If You Really Want To Lower The Compression Use A Super Duper Thick One. Depending On The Quench Situation In Your Combustion Chamber You May Actually Raise The Possibility Of Detonation By Using A Thicker Gasket To Lower The Compression Ratio.

 

[MIKEWITH THE 81'S]

Well I am looking into this just incase i use a set of vortecs on a 406 flat top piston . if the head gasket is not enough i think i will probably fly cut 2 of the valve releifs.

 

[MIKEWITH THE 81'S]

i really dont want over 10/1 with the setup i was thinking about running

 

[novaderrik]

2 valve relief flat tops with .015" head gaskets will put you at around 10:1 with Vortecs on a 350, so probably 10.5:1 or so in a 406- and with what some would consider a perfect .035 quench, which will make the chamber really efficient with less timing- which helps out with holding off detonation.

 

[MIKEWITH THE 81'S]

I've heard of engine builders using like a 4.200 gasket on a 4.155 bore to lower compression will that work?? does any one know what i would be looking at with a 4.200 gasket on the same setup

 

[onovakind67]

You're easily over 11:1 with a 64cc head and most any gasket that will fit a 400. With a typical -7cc piston, .040" quench and a 64cc head you're right at 11.4:1. Add .025" for deck clearance and you're down to 10.75:1 but you're flirting with detonation due to the loss of quench effect.