[Big Earl]

Gentleman, Its been awhile since I last posted but with the warm weather just around the corner a lads interests shift towards octane and burning rubber.

I've got this 468 with this monster cam ( Crane #131541) solid lifers with .580 radius dome pistons with rectangle opem chamber heads was told 12.5:1 compression. Bought it in the fall of 2009 ex drag car.

Tuned on it all last summer thinking that I was going to get it more streetable. Well I have made some gains, but it's just to much of a headache to deal with, octane boost 4 mpg's setting valves stuff like that. Soooo.... I was thinking of using thicker head gasket to try and releave some compression. I'm going to change the cam as well.

So may Q's is how thick of a head gasket will I have to go to get this thing around 10:1 and also any help in picking a street cam would help. Was thinking about the Comp Cam # XR288HR.

Thanks in advance Guys,

 

[tonkas69]

Need to know the following to give a good answer.


1. How much dome/type you have? not sure if this is what you ment by .580 = @47/48 cc's

2. How far DITH the piston are?

3. How many CC are the heads?

 

[Big Earl]

The pistons are TRW #L2307F30
And as far as the heads they're Merlin World Pro rectangle port, open chamber, cast dart heads with 219 intake, 188 exhaust Manley Race Flow Valves. Thats about all the info. I have on the heads and pistons as I didn't build it, but was lucky enough to have contacted the engine builder and thats a few years back.

 

[Big Earl]

I found some more info. about the heads. If there is an engine builder out there that might be able to help me that would be great.

Again it's a 454 bored out either 30 over are 60 over not real sure. Merlin World pro heads rectangle ports open chamber# I-043 no letter. Did some resereach and found out 2.19 intake 1.88 exhuast with 199cc with 345cc runners. Pistons are TRW L2307F with .580 dome radiuis, I've got conflicting onfo. as to if the bore is 30 or 60 over. Was told that it's 12.5:1? With the info. provided in this post could someone confirm this. Also in an atempt to reduce the compression how thick of a head gasket should I go to achieve a 10:1 or a 10.5:1 compression.

 

[Tom Mobley]

you can't change it that much with a thicker gasket. even if you did or stacked gaskets or something like that the quench area would be so big it might ping just as bad as before.

you probably need to bite the bullet and start thinking about different pistons. be a good time to lose the gorilla cam too. think along lines of 9.5:1 CR and a cam with 230 - 240 duration. A roller cam, not a flat tappet. roller hydraulic is fine.

 

[Tom Mobley]

you need to buy yourself an inexpensive dial caliper so you can measure things like the bore and the valve sizes. $25 will do it.

 

[Big Earl]

Thanks Tom was hoping someone like you would chime in.

The engine runs fine it's just too much. As far as I can tell it's not pinging, but some guys I've talked to some that say running pump gas (octane 94 with a an additive)with that compression that it's detonating you just can't hear it? No doubt about losing that cam as well. I was hoping for a budget sensitive option like thicker head gaskets.

With the info. that I posted can you tell me if 12.5:1 is correct either which a 30 or a 60 over? Sorry for being a pain but I'd like to get some sort of a handle on this before I open it up.

Again Tom, thanks for you input.

Big Earl