Topic: compression-ratio
in Forum: C3 Engines
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Other factors involved,,cam,rockers ect,but just as a rule of thumb, Id say about 9.0 to 1,,just a educated guess,,If I were going to do that though, Id step up the cam from stock, also you have to make sure stock intake will mate up to new heads,,good luck, rd
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Assuming you have 8.5:1 ratio now, you might get around 9:1. The head gasket thickness will play a part, also, as will valve size.
Joel Adams
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thanks thats what i wanted to know.
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Who...ME? 
I'm doing pretty well, I suppose. Good to see you back on the forum, Jack & Marcia!!
I'm doing pretty well, I suppose. Good to see you back on the forum, Jack & Marcia!!
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Same here...any job is a good job these days...
Sounds like you are getting the Vette ready to go! Good Luck with it, and keep us up to date on how it's coming along.
Sounds like you are getting the Vette ready to go! Good Luck with it, and keep us up to date on how it's coming along.
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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New Albany, OH - USA
Joined: 8/17/2010
Posts: 173
Vette(s): 1980 Coupe /
Snowcrest White /
L48, 350 /
Comp Cam /
Edelbrock Heads /
Cyclone Intake /
Holley Carb /
Holley Fuel Pump /
Patriot Headers /
Dual Exhaust /
Magnaflow Mufflers /
1964 Coupe /
Riverside Red /
L76, 327, 365hp
I have an L-48, 350 engine and I just put in a Comp Cam hydraulic roller cam, (210/220 and 112-degrees); a set of aluminum Edelbrock E-Street heads (2.02/1.60; 64-cc); a Holley Street Avenger 770-cfm carb; Patriot tight-tuck headers; 2 1/2-inch aluminum dual exhaust and Magnaflow mufflers. My CR now measures 9.7:1. The stock engine was rated at 8.5:1.
Chuck
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Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1031
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
79 L48 engines had 8.2:1 ratio with 73 cc heads. The only thing that affects compression ratio in this example is the volume of the chamber with the valves closed. With dished pistons, your new ratio will be about 9.2:1. That is enough to support a little more cam, but I wouldn't go wild with long duration: maybe a 262 advertised degree cam with upper 400 lift.
Larry
Larry
in Forum: C3 Engines
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