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383sbc HP and ideas

2K views 5 replies 4 participants last post by  ericnova72 
#1 ·
I found out that I have a 383 in my 79 Camaro. I was wondering what type of horse power I would be making and if I switched from 76cc to 64cc heads would do. The engine is a 1970s 350 bored 30 over with flat toped pistons. Forged rods and a 400 crank with a push on harmonic balancer. It has a .015" head gasket and old after market over the counter 882 heads with new valve job and springs. Has a summit racing 1103 cam. Holley 600cfm, edelbrock eps intake, hei, 30w race oil with a 4.3 high torque starter. Connected to a 4 speed close ratio Saginaw with 11" clutch and hurst shifter with posi and 4.11s. Thanks
 
#2 ·
Cam Style:Hydraulic flat tappet

Basic Operating RPM Range:1,600-5,200

Intake Duration at 050 inch Lift:214

Exhaust Duration at 050 inch Lift:224

Duration at 050 inch Lift:214 int./224 exh.

Advertised Intake Duration:288

Advertised Exhaust Duration:298

Advertised Duration:288 int./298 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.444 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.466 in.

Valve Lift with Factory Rocker Arm Ratio:0.444 int./0.466 exh.

Lobe Separation (degrees):112

Computer-Controlled Compatible:No

Lifters Included:Yes

Lifter Style:Hydraulic flat tappet
 
#3 ·
You're pushing the compression limits right now for pump gas, especially with iron heads. If your pistons are .025 in the hole, with 76 cc heads you're close to 10.29:1. If the block has been zero decked you're at 10.90, too much for the pump.

If you reduced the heads to 64 cc you'd be at 11.8:1 and 12.67:1 respectively. Strictly race gas territory, even with aluminum heads. A thicker gasket would bring you down around .9 with a .041 gasket.

Also, if you're zero decked your quench area is too tight, .015 with your current head gasket.
 
#6 ·
68NovaSS, I'm not getting anywhere near that high of compression ratio figures with 76cc heads(882's), the .015" x 4.100" gasket, and assuming standard .020"-ish deck height 6cc eyebrow flat-top piston(nothing was said about block decking)...only about 9.7-1 comp right now. (something not right on your calculator maybe, like valve relief volume???)

I would guess 330 or so HP right now, the 882's really suck.

It would jump to 11-1 with a 64cc head, would be pump gas safe if head was aluminum.

79CamaroMatt,
Cam, intake, carb change to 220+/230°+ @ .050" and .500"+ lift, Performer RPM intake and 750 carb and a 195-200cc+ intake runner 64 cc chamber aluminum head and you'll pick up an easy 100 hp.
 
#5 ·
I'd stick with the 76cc heads. If you want a better flowing head afr makes a 75cc head. I'd imagine you have the 64cc heads on the shelf doing nothing though, right. If the pistons are .025 in the hole which I doubt they are being a stroker engine. They're probably more like .017 or so then your pushing pump gas and need to be running good fuel with a good tune.

Do you think the engine lacks power or you just want more?
 
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