Road racing head question

[Roadracer350]

Ok weird question. I am going to try and find a decent road race cam from Comp or Crane. My question is about the compression. I don't want to run a supercharger or turbo. So with that being said has anyone bumped the compression with the head gaskets? In bikes if we want a little more power with compression we will take the stock 3 layer head gasket and pull a layer off. On a 1000cc you can bump it from say 11:1 up to 12:5-13:1 by pulling a layer off the head gasket and setting the valves a little tight to trick the motor into thinking it has a higher lift cam than it really does. Is this feasible on the 4.6 3 valve?

 

[Marc s]

Going from a .037 compressed gasket to a .025 compressed gasket will raise the compression roughly a 1/2 a point.

 

[Sinner]

Marc, I've never seen a gasket thickness listed, but I've never really paid attention lol. Do you know where to find those gaskets and what's stock?

 

[Full_Tilt]

Its a pretty good way to raise compression IMO because of the added quench. Only if you have the clearance obviously.
You could always clay it if youre worried about it.

Do people ever agressively mill the heads on the mod motors? Ive seen in pics that the 3 valves and coyotes seem to have some amount of quench pad area in the chamber, but it would be pretty cool if they could be made a bit bigger while adding some compression.

 

[Roadracer350]

Not sure about our Mod Motors but the bikes it just depends on how much compression you want. On the bikes you can do the head gasket trick and bump it a little or you can skim the head by .030", 2 layer head gasket, degree in the cams and set them at the bottom close to tight and end up with somthing like 16:1 but you have to use good fuel like MR9. Im not really sure what the compression is in a 4.6 actually. If its like say 10:1 I wouldnt mind bumping it up to say 12:1.

 

[kevinatfms]

3v compression ratio is 9.8:1 IIRC.

 

[Marc s]

Marc, I've never seen a gasket thickness listed, but I've never really paid attention lol. Do you know where to find those gaskets and what's stock?

The FRPP gasket is .037 compressed. Cometic lists .030 in stock for the Mod motor. If I remember correctly, Cometic will make any thickness down to .022 for the Mod motor. However, in a zero decked engine, .022 qwench is really close between the piston and the head.

 

[Roadracer350]

Ok so in theroy you could go with a .022" gasket and as long as the squish and valve strech areas would be good it would work. May end up having to mill the area where the piston comes close to the head tho...