Need help ordering pistons
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Need help ordering pistons
OK, so I'm doing a small block to big block engine conversion on my '79 Vette. The block is a standard bore 402 (4.125) which is a 30 over 396.
I've had the block checked , cleaned, new cam bearings and frost plugs are also done. I have a forged 396/427 crank (internally balanced) and I have a good set of rods. The original pistons from this engine were not bad at all but I'm thinkin if I'm this far into this I should replace pistons as well.
As an added note I've also bought a new set of Edelbrock Performer RPM heads. They have a 110 cc chamber.
Here is where my concern is: I do street drive this car about 5000 kms per summer and since I'll be running pump fuel I'd like to keep the compression in the 9:1 range, or at least under 9.5:1.
This is the link to the set of pistons I'm considering.
http://www.jegs.com/cgi-bin/ncommerc...21&prmenbr=361
I just wonder if I'm on the right track here.
Thanks as always
Indynut
I've had the block checked , cleaned, new cam bearings and frost plugs are also done. I have a forged 396/427 crank (internally balanced) and I have a good set of rods. The original pistons from this engine were not bad at all but I'm thinkin if I'm this far into this I should replace pistons as well.
As an added note I've also bought a new set of Edelbrock Performer RPM heads. They have a 110 cc chamber.
Here is where my concern is: I do street drive this car about 5000 kms per summer and since I'll be running pump fuel I'd like to keep the compression in the 9:1 range, or at least under 9.5:1.
This is the link to the set of pistons I'm considering.
http://www.jegs.com/cgi-bin/ncommerc...21&prmenbr=361
I just wonder if I'm on the right track here.
Thanks as always
Indynut
Last edited by Indynut; Mar 20, 2005 at 12:30 PM.
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From: NC,USA
Did you have the block bored, or was it bored before you went in?
Normally the way you order pistons is one part number with the "Oversize" after the part number...
I'd give jegs a call! (I dont know much about big blocks... so I'm not gonna touch "Flat tops vs domed...")
Normally the way you order pistons is one part number with the "Oversize" after the part number...
I'd give jegs a call! (I dont know much about big blocks... so I'm not gonna touch "Flat tops vs domed...")
Thread Starter
Pro
Joined: Oct 2000
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Its a factory 1972 402 cubic inch. The block has been honed and measured and it did not require boring at all. The 402 was actually a 30 over 396, so that would be the piston I'd be ordering. The originals were not flat tops, they did have a small dome on them, and some valve relief.
Last edited by Indynut; Mar 20, 2005 at 07:50 PM.
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From: The Top of Utah
But they were under much larger cc heads. Unless you're planning to add a blower, I would think you could add another point of compression with those aluminum heads, But if that is what you want, those pistons ought to be fine.
RACE ON!!!
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Thread Starter
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Joined: Oct 2000
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So you think I could get away with more compression and still run on pump gas. Am I following you right?
What size chambers would those old 1972 402 heads?
What size chambers would those old 1972 402 heads?
Last edited by Indynut; Mar 20, 2005 at 07:53 PM.
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From: The Top of Utah
My guess would be about 116 ccs, but that doesn't really matter because you know what the new heads are. You can measure the old heads, if you really care. I'm thinking 10.0 to 10.5:1 with aluminum heads and a tight quench, should work well.
RACE ON!!!
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