ruger311

just checkin my builders work wondering if someone has a calculator or can calculate my compression ratio for my 347

heres the JE piston specs

Part # Cubic Inches Bore Stroke Rod length Block Height Compression Distance Head Cubic Centimeters DomeVolume GramWeight
56cc 60cc 64cc
compression ratio
170848 347 4.030 3.400 5.400 8.200 1.100 9.1 8.8 8.5 -22.0 415


i am running RHS 200s with 64cc combustion chamber, i belive the felpro metal head gaskets are like .041", and i think the block deck is like 0.012 or something like that

he said 9.2:1 but im gettin like 8.5 or 8.68

5IVE.OH

How far down is the piston @ TDC? I used the following specs:
64cc chamber
Head gasket bore 4.002
Head gasket thickness 0.041
Piston Down from TDC 0.012
Volume above piston @ 1.10
I got 10.5:1

r.barn

.012 in the hole deck height is not good. should always shoot for 0 deck on performance engine.
you can run into problems with too big of a quench area


C/R with:
4.03 bore
3.4 stroke
4.10 head gasket bore
.041 compressed thickness
64cc heads
22cc dish pistons
.012 deck clearance

= 8.29

you dont need that big of a dish unless you're shooting
for high psi boost.

ruger311

come to think of it he did say 0 deck hight

r.barn

you sure about that 22cc dish?

you're JE pistons specs are confusing.

ruger311

yeah they are a 22 dish

http://www.jepistons.com/cat/je/auto/ford/302_inv.shtml

part number 170848

ruger311

im getting 8.5:1

http://www.csgnetwork.com/compcalc.html

ruger311

going to the dyno tomorrow to figure out why my headers are glowing red/orange either lean or rich and maybe burn a chip, just though i would like to figure it out for sure,, and yes going to boost the hell outta it

r.barn

I used same calculator and came up with about 8.5 c/r

4.03 over bore
3.4 stroke
4.10 head gasket bore
.041 compressed
64cc head
22cc dish piston
0 deck

that calculator does work too.

r.barn

If your exhaust is too hot you are running lean, end of story

what size injectors you running on a 347? need 36#'s