340 Head gasket

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MLS Gaskets is the closest modern day gasket for the steel shim Orig. Cometic Makes a .28 and a .40 for the LA Engines
 
I bored my 340 .020 over, KB pistons, Eddy 60179 Heads with the Felpro .039 Compressed head gaskets. Cranking compression 165 ish. I'd have to check my notes. I'm just wondering how mush compression would bump to with the .028 gasket.
 
Summit has a nice calculator when you look a pistons. You need to know
Bore
Stroke
Dome CC’d + or -
zero deck?
Chamber cc’s
 
Kendog 170 said:
I bored my 340 .020 over, KB pistons, Eddy 60179 Heads with the Felpro .039 Compressed head gaskets. Cranking compression 165 ish. I'd have to check my notes. I'm just wondering how mush compression would bump to with the .028 gasket.
Click to expand...
Bump it to just about right :)
iam 169 cranking comp power timed on 94 no problems
 
furrystump said:
Summit has a nice calculator when you look a pistons. You need to know
Bore
Stroke
Dome CC’d + or -
zero deck?
Chamber cc’s
Click to expand...
Current calculation says 9.66:1 with .039.with 028 gasket 9.92:1
Was hoping to achieve the original 10.50:1 when I did motor but inexperience and maybe mis-calculation on my part leaves me hoping 9.92:1 will bump me up a bit more.

Compression Calculator​

Get accurate compression without the guesswork!

Get your engine's optimal compression ratio and total displacement in no time flat! Just complete your engine setup, click calculate, and you’re on your way to maximum performance.

Bore: (diameter) in. mm
Stroke: in. mm
Cylinder Head Volume: cc in.
Effective Dome Volume:
Use (-) for Dome and (+) for Dish.		 cc in.
Deck Clearance: in. mm
Compressed Gasket Thickness: in. mm
Number of Cylinders: 4 6 8 10 12
Compression Ratio :9.66 : 1
Total Displacement (in.3) :171.41
Total Displacement cc's :2810

With .028 gasket

Compression Calculator​

Get accurate compression without the guesswork!

Get your engine's optimal compression ratio and total displacement in no time flat! Just complete your engine setup, click calculate, and you’re on your way to maximum performance.

Bore: (diameter) in. mm
Stroke: in. mm
Cylinder Head Volume: cc in.
Effective Dome Volume:
Use (-) for Dome and (+) for Dish.		 cc in.
Deck Clearance: in. mm
Compressed Gasket Thickness: in. mm
Number of Cylinders: 4 6 8 10 12
Compression Ratio :9.92 : 1
Total Displacement (in.3) :171.41
Total Displacement cc's :2810
 
Kendog 170 said:
I bored my 340 .020 over, KB pistons, Eddy 60179 Heads with the Felpro .039 Compressed head gaskets. Cranking compression 165 ish. I'd have to check my notes. I'm just wondering how mush compression would bump to with the .028 gasket.
Click to expand...
You'll get about 1.8 psi for each degree of Cam advance. and/or
same 1.8psi per an increase of 1/10 of a compression point.
Swapping from 039s to 028s at same 4.18 bore is worth about 3/10s compression ratio, and 7psi.
A custom 020 gasket with a 4.07 hole, will get you 4.5cc, less than the 039s, increasing the compression ratio of a 10/1 engine to 10.55, and the pressure jumps from 166 to 177, a gain of 11psi.
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With alloy heads, long rods and short stroke, I bet you could run near 200 psi and still on 87E10.
I mean, with the closed chamber eddies, I ran 195 with a 360 on 87E10.
Since 2004 tho, I've been at 185 or so on same 87E10.
she's got well over 100,000miles on 87E10. and went 93 in the Eighth on that swill.
I run the 039FelPros, with the pistons up ~.007 for a Q around .032. I have run the Q down to 028 without contact.
 
I think you’re running into “trying to get back to 10.5” it probably never was 10.5, higher that other LA’s? Yes, true 10.5 probably not. The deck heights are usually higher than spec. How far in the hole are your pistons. I would lean towards the cometics. Probably overkill, but the lack of a 5th head bolt needs all the help it can get. As long as the surface finish is to the spec. I just search for a conversion for RA to sandpaper grit. To give me an idea of how smooth it needs to be. It isn’t THAT smooth.
 
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If your running a KB pistons they should be above the deck, by at least .012 maybe more. i would think anything less .040 is a little to tight.
 
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