Reuse shim head gasket?

[lewtot184]

Are you using an early piston with a late head?

 

[mala]

Where are you getting. 030" deck height. I know my 68 road runner was near zero.

What exactly is near zero? I measure my factory/stock piston and they are .030 in the hole.

 

[mala]

Are you using an early piston with a late head?

No! Factory piston and stock 906 casting. All 906 heads I have cc the chamber of is 86-88 cc.

 

[lewtot184]

What exactly is near zero? I measure my factory/stock piston and they are .030 in the hole.

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]

There's this for reference..........

NHRARacer.com - NHRA Engine Blueprint Specifications

From the Chrysler 1968 link.....

 

[mala]

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.

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]

.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.

 

[mala]

There's this for reference..........

http://[URL]https://www.nhraracer.com/content/general.asp?articleid=46634&zoneid=132

[/URL]


From the Chrysler 1968 link.....
View attachment 1686081

Thank you, Interesting here is much info.

 

[RemCharger]

A 383 engine is not a high compression in 1970. If I calculate correct so is has it 8.9:1 with steel head gasket and 8.55:1 with a .039 gasket.

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]

Thank you, Interesting here is much info.

FWIW, It's also in the DC Racing and MP Engine manuals............

 

[GTX JOHN]

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.

 

[lewtot184]

There's this for reference..........

NHRARacer.com - NHRA Engine Blueprint Specifications

From the Chrysler 1968 link.....
View attachment 1686081

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.

 

[rickseeman]

Now to the problem, its leak oil betwen head and block in the rear ( cyl 8) I was thinking to pull of the heads and mill them. The run time is just a cuple of minutes, can I reuse the shim/steel head gasket?

Thanks!

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]

........I you guys are off base on this.

??
As in?

 

[Daves69]

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.

Lol, the 383 was all over the place......

 

[dvw]

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

 

[GTX JOHN]

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

 

[Photon440]

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

Specs are always provided by the manufacturer. Who else would have them?

 

[BSB67]

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.

The OP has a 1970.

 

[BSB67]

Now to the problem, its leak oil betwen head and block in the rear ( cyl 8) I was thinking to pull of the heads and mill them. The run time is just a cuple of minutes, can I reuse the shim/steel head gasket?

Thanks!

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.