ProComp/Speedmaster aluminum heads

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All the research I did and the best I can find out the 596 heads had anywhere from a 68 to 72 CC average. 70 CC is about what I believe them to be.
And of course those are open chamber. I used a 1008 Fel Pro .039. my open chamber heads were gasket matched in countersunk just it's managed to make sure the Pistons had plenty of room. Now of course I'm going to the closed chamber heads and considering using the suggested 8553 Fel Pro.053. hoping that that will get me extra .030 Clarence that I believe you're supposed to have piston to head?..
I was wondering because I haven't used them before if closed heads have any kind of different performance characteristics than open chamber besides compression?
 
j par said:
I was wondering because I haven't used them before if closed heads have any kind of different performance characteristics than open chamber besides compression?
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yes, the don't flow as good as open chamber heads.
 
Jpar, refresh my memory, what pistons do you have? Are they positive deck height?
 
Ok 318, so if closed chamber don’t flow as well, then how come every head for the last 30 plus years are closed chamber? Except a couple Resto type heads. Kim
 
oldkimmer said:
Ok 318, so if closed chamber don’t flow as well, then how come every head for the last 30 plus years are closed chamber? Except a couple Resto type heads. Kim
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Ok. Compression, quench, emissions, will be an improvement. But FLOW itself will suffer a little with a closed chamber head vs open chamber.
 
oldkimmer said:
318, And u know this how? Kim
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I guess my answer won't be acceptable, but I know it because I know it. Shrouding around the valves is never an enhancement to flow. I do not have a chart or graph to show you.
 
Well, I’m just curious as then why the switch to closed chambers as most ppl say they will take flow over compression every time. I hear ya on knowing things, cause there is things I know that someone else doesn’t know or comprehend. Kim
 
oldkimmer said:
Well, I’m just curious as then why the switch to closed chambers as most ppl say they will take flow over compression every time. I hear ya on knowing things, cause there is things I know that someone else doesn’t know or comprehend. Kim
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well, I think most people that "switch" to closed chamber heads do so by buying after market heads, as J par did. Their new purchase usually will flow much better in the ports, and the bowls, which is huge. Also, they'll see a bump in compression, and usually quench, giving them another bump in power. So, they gain performance and are happy. But the performance they gained isn't due to power gained in the head chamber design.
 
Mopar Sam said:
Jpar, refresh my memory, what pistons do you have? Are they positive deck height?
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I have the icon forged flat top pistons with valve reliefs...
.010 above deck...
probably actually zero deck if they wouldn't have shaved .010 off the top of my block....
 
j par said:
I have the icon forged flat top pistons with valve reliefs...
.010 above deck...
probably actually zero deck if they wouldn't have shaved .010 off the top of my block..
..
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Cometic mls .045 gasket should provide the desired .035 quench
 
fishmens67 said:
Cometic mls .045 gasket should provide the desired .035 quench
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Actually I'm on the fence right now because what I really wanted out of the heads was some better heat dissipation. And stop having to run a little bit of race gas in my tank too get the engine to shut off. If I went kemetic I was thinking 60 or 80 thousandths....
 
j par said:
Like I was saying last night, I'm not sure where they're getting the material to take off? When I felt them they felt very Hollow and then the sound when I tap down on them or anything there was definitely a very Hollow feeling...
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Cheap aluminum with impurities. I’ll bet they ever are funky to grind on.
 
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