lewtot184
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Are you using an early piston with a late head?
Reuse shim head gasket?
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mala
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What exactly is near zero? I measure my factory/stock piston and they are .030 in the hole.
mala
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No! Factory piston and stock 906 casting. All 906 heads I have cc the chamber of is 86-88 cc.
lewtot184
Well-Known Member
Zero is where the piston is even with the block deck. I think you have 67 or earlier pistons, not the 68 or later that would match up the 88cc head. 67 or earlier used an as cast 80cc closed chamber head with a shorter pin height, or your measurements aren't accurate.
Daves69
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There's this for reference..........
From the Chrysler 1968 link.....
From the Chrysler 1968 link.....
mala
Well-Known Member
Yes I know exactly what piston to zero deck means, but You said NEAR zero so I wondered were the piston in your -68 engine was in relative to deck hight?
Dodge Bros
Well-Known Member
.030” below the deck sound correct to me for 1970. Seems like I recall the 70 383 and 440s were about .030” to .040”shorter than the 68 and 69.
Our 383 is set up with pistons that are .004” from zero deck, and has the heads milled .070” to 72cc. It is just barely over 10. Not many factory 383s were close very to 10:1 like it was advertised, actual was closer to 9:1.
It was not a great idea, but we have reused the steel shim gaskets in a pinch, with tons of copper coat head gasket sealer spray on both sides. That second time the crush to about .016” to 018”. Not a lot of room for things to be off.
Our 383 is set up with pistons that are .004” from zero deck, and has the heads milled .070” to 72cc. It is just barely over 10. Not many factory 383s were close very to 10:1 like it was advertised, actual was closer to 9:1.
It was not a great idea, but we have reused the steel shim gaskets in a pinch, with tons of copper coat head gasket sealer spray on both sides. That second time the crush to about .016” to 018”. Not a lot of room for things to be off.
mala
Well-Known Member
You're on the right track, and since you measured what you got, you know what you got.
Blueprint #s are simply something to aspire to, but not applicable to what's in your hands.
Daves69
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I looked up the specs that Mopar gave NHRA on 68/69 383 4 Brl.
Deck................021. ABOVE BLOCK
Gasket.............020 THICKNESS
Head................79.5 CCs
Of course, these are minimums if everything is perfect and that
is how we blueprint these engines.
Deck................021. ABOVE BLOCK
Gasket.............020 THICKNESS
Head................79.5 CCs
Of course, these are minimums if everything is perfect and that
is how we blueprint these engines.
lewtot184
Well-Known Member
This chart shows the 68 383 piston .021 above the deck, not below, for a blue printed engine. Mine was right at zero for a non-blueprinted engine. I you guys are off base on this.
You have a head sealing problem. Steel shim head gaskets are great on a new block and new heads. But that's not the case here. The Fel-Pro is what I would be using. And I know the instructions say dry but I would spray them with Copper Coat.
Daves69
Well-Known Member
??
As in?
Daves69
Well-Known Member
The stock factory stuff is never even close to the minimm/maximum spec. Years ago NHRA records were lost. They asked the company's for specs. Lets just say the specs furnished by Chrysler were creative.
Doug
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Even back when I was racing in the 60's, Larry
Shepherd at Mopar gave NHRA "Optimized) Specs if everything
was at the perfect low tolerance.
The shipping weights were even worse. Since you could
not add or lower weight to make a Class, Larry calculated
the bottom weight for each class and put a Mopar exactly on
it! Often car models that were with a few pounds were list
a couple hundred different.
GM did some interesting things as will such as rating stock
camshafts at 360 Degree duration when the might have beed 230
@ .050
Shepherd at Mopar gave NHRA "Optimized) Specs if everything
was at the perfect low tolerance.
The shipping weights were even worse. Since you could
not add or lower weight to make a Class, Larry calculated
the bottom weight for each class and put a Mopar exactly on
it! Often car models that were with a few pounds were list
a couple hundred different.
GM did some interesting things as will such as rating stock
camshafts at 360 Degree duration when the might have beed 230
@ .050
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Specs are always provided by the manufacturer. Who else would have them?
BSB67
Well-Known Member
The OP has a 1970.
BSB67
Well-Known Member
Can you- yes
Have other done it with success - yes
Should you? In my opinion, no. Especially in light of your problem, a leaking head gasket.
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