Compression ratio ?
#1
Registered
Thread Starter
Join Date: Feb 2003
Location: bluffton sc
Posts: 1,517
Likes: 0
Received 0 Likes
on
0 Posts
Compression ratio ?
TORE APART 502 MOTORS,everything is in good shape ,trying to settle on compression ratio.stock pistons Je700 with slight dome.buying new merlins port &polished gasket matchedand would like to run crane 139741 cam.with 119cc heads whats the compression ratio with these pistons?Are these 4cc domes?oso member gave me breakdown but im aliitle lost with regard to decking block.If Iwant to make 575 hp with this cam optimum comp ratio 9.5?If compression ratio is at 8.5 this cam would be no good?
#3
Registered
Join Date: Nov 2000
Location: Sevierville,TN
Posts: 131
Likes: 0
Received 0 Likes
on
0 Posts
#4
Registered
Assuming the block is zero decked and you are going to use a head gasket with no more than .039 compressed thickness, and the heads are surfaced just enough to make sure they are perfect, you will be approaching 9 to 1 but no more!
I run a similar setup and the cam is borderline too much!!
I was thinking of going to 110cc Edelbrock aluminum "marine" rectangular port heads!
I would be interested in any feed back from anyone who has tried these heads.
I run a similar setup and the cam is borderline too much!!
I was thinking of going to 110cc Edelbrock aluminum "marine" rectangular port heads!
I would be interested in any feed back from anyone who has tried these heads.
#5
Registered
Thread Starter
Join Date: Feb 2003
Location: bluffton sc
Posts: 1,517
Likes: 0
Received 0 Likes
on
0 Posts
compression ratio
Mcollinstn,what do you think about 741 cam and 9.1 cr
do I buy pistons or buy 111cc heads to bump up to 9.5 cr?following your advice on past reply,I would make approx 540hp with stock ported heads and 8.75 cr.Now that Im buying new heads,what would you estimate increase in hp and torque?Obviously the motor should not have to work as hard to make power,but interested in feedback .If small gains I might just save the $3,000.
do I buy pistons or buy 111cc heads to bump up to 9.5 cr?following your advice on past reply,I would make approx 540hp with stock ported heads and 8.75 cr.Now that Im buying new heads,what would you estimate increase in hp and torque?Obviously the motor should not have to work as hard to make power,but interested in feedback .If small gains I might just save the $3,000.
#7
Registered
Join Date: Nov 2000
Location: Sevierville,TN
Posts: 131
Likes: 0
Received 0 Likes
on
0 Posts
Please check my math but
You can mill the heads to increase compression but the intake may have to be milled also.
0 Deck , .039 gasket, 118cc open chamber head milled .035 (equals -6.8cc), 1cc dome you get around 9.64 to 1
.005 deck = 9.54 to 1
You can mill the heads to increase compression but the intake may have to be milled also.
0 Deck , .039 gasket, 118cc open chamber head milled .035 (equals -6.8cc), 1cc dome you get around 9.64 to 1
.005 deck = 9.54 to 1
Last edited by RickR; 01-18-2004 at 05:00 PM.
#8
Platinum Member
Platinum Member
RickR
0/.039/118-6.8/1 on 4.470x4.00 = 9.39:1
.005 deck = 9.30:1
JE shows the BBC flattop at "minus 3cc".
They also list a "minus 4cc" piston, but don't show it in a standard bore size. The next dome for a std bore 502 is 13cc.
0/.039/118-6.8/1 on 4.470x4.00 = 9.39:1
.005 deck = 9.30:1
JE shows the BBC flattop at "minus 3cc".
They also list a "minus 4cc" piston, but don't show it in a standard bore size. The next dome for a std bore 502 is 13cc.