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Discussion Starter #1
I have a 396 thats been bored .030 and has a domed pistons in it that has L2242 .030 stamped in the top of the piston. The short block has been all rebuilt, new bearings, rings, freeze plugs, the whole nine yards. Looking up the piston number I find they are the 396/375 horse pistons. My problem is with finding a set of heads that will work with those domed pistons. I have a set of casting #215, closed chamber oval port heads available to me for a good price. But I cant find out anywhere whether I can run those heads on this short block with those pistons. Will the compression ratio be too high? I want to run pump gas seeing that the car will be just a nice 1970 Nova SS street car.

Should I look for a pair of open chamber heads? If so, I've read where the pistons may interfere with the combustion chamber? I am on a very tight budget and cannot afford to do this twice. I really can't afford to tear the engine back down and replace or have the pistons machined. Am I screwed or is the proper head out there? If so, what casting number should I be shopping for?

Thanks in advance!
 

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i'd look for a set of heads that came on a 390 hp 427 , they were semi open of my memory is correct , they'd help scrub off some compression , i think they're a 109 cc head , compared to a 96 cc closed chamber
 

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I run LS6 open chamber steel heads with my 402, they reduce the compression enough for good pump gas. I like the way they work on my engine, it pulls real hard, all the way to the top of it's rpm range.
 

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Discussion Starter #4
LS6 Open chamber heads

Thanks for the info guys. Do you know what the casting numbers for the LS6 heads is? Did you have to rework the combustion chambers at all or just bolt them up?

Thanks!
 

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It would help to know what cam was put in the engine or what cam you plan on using. The cam is going to effect how much compression you can run with "pump" gas.
 

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Discussion Starter #6
cam choice

Well, I was planning on running a Hyd. Roller set up in it. Nothing to radical or anything. Thinking something that would mimic the L78 cam or a slight bit bigger. This car will be a street car. It will be a college graduation gift for my 20 y.o. daughter. Using the trim tag we are trying to bring the car back as close as we can from it's racing days. It only has 31k on it but the original engine and trans are long gone.

Any help I get is great and I appreciate all of it.


1970 Nova SS, big block car, Fathom blue, black bucket seat interior, auto, disc brakes, 12 bolt and two bright trim options.
 

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To me, the #215's would be the ideal combo on that shortblock but not for a 20 yr. old girl and a daily driver. I'm guessing the comp. ratio would be in the 10.5 to 11:1 range.
 

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Discussion Starter #8
Cam choice

Here are the cam specs for the cam I picked out.

Comp Cams Hyd Roller

adv dur .291 .311

@ .050 .235 .249

lift .558 .542


The car will not be her daily driver, She will do the cruise night hang out at the beach at night thing with it. The kid can drive, I'm not too worried about that really.
 

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I ran the Speed Pro 2287 pistons in my 408 with the 781 casting open chamber heads. They were still high at like 10.5-1 compression, but my pistons had a much bigger dome. Since they were closed chamber pistons with an open chamber head, I had to open the side of the chamber a little to clear the dome sides. It is not a difficult job to do. I used the 8180 pt2 gasket as a template and laid out the chamber sides to the gasket. This engine with a Lunati 40209 cam, .574/.588 249/[email protected] made 501hp at 6800 rpm on 93 octane gas.
 
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