thebufenator

iTrader: (2)

I need some help choosing a head gasket now for my 383.

4.03 bore
3.75 stroke
56cc chambers
5cc dish pistons

non-decked block, I know I should have had the block zero decked now,
but owell.

I have heard the average to be about -.025 in the hole.
The heads have also been milled .002, I assume that means I take .002
off of the quench....

The gasket set I have now are they .029 Impala set.
Using those I will have about 11.87:1 compression with a ptv ~.052

using the Mr Gasket .026, I will have 11.97:1 with a ptv of ~.049

Neither of those have the best ptv really.

Now, I heard I can use SBC gaskets, but I will have to open some of the holes.....is this possible?

If it is, I can use either an SCE or Felpro .015 gasket.
That would give me 12.35:1 with a ptv of ~ .038


Will this work?????

I really like the last idea....but not sure if it will work.
I have not yet picked a cam yet.....but its a daily driver, and I like to get on the gas I dont want to spin past 6500rpm though.

thoughts?

jasonisdn

iTrader: (1)

cometic will make custom thickness gaskets

thebufenator

iTrader: (2)

I heard cometic didn't go thinner then .027..... and if my deck is around the average of .025, then I need something smaller

dhdenney

iTrader: (53)

What head has 56cc chambers?

jasonisdn

iTrader: (1)

i just know they offer custom thickness. i never called to see how thin they will go. i don't think the .027 is a custom gasket. they claim any thickness. http://www.cometic.com/custom.aspx

94 guy

iTrader: (125)

i have a brand new set of cometic's 4.040 bore and .040 thick $110.00 shipped.

dhdenney

iTrader: (53)

That's way thicker than he was considering.

Lonnies Performance

iTrader: (16)

1. SBC gaskets can be made to work on the LT1 with some modification, but I recommend buying the correct gaskets instead. Some brands may not seal properly near the holes at the top corners.

2. Cutting the heads will not alter the quench, only the compression. Only the block & gasket will change quench.

3. I would not sweat the gasket thickness too much. Use the thinnest LT1 gasket readily available & be happy, or get the block shaved.

4. Very thin gaskets may not give the best seal either. The thinner they are, the less they are able to conform & seal.

4. The PTV is what I assume to be piston to valve. You need to check it at the piston valve relief, and only in direct relation to the cam timing. If claying the piston top & getting this small reading, you will have problems. Measuring the valve to block deck clearance is useless for determining operating conditions.

thebufenator

iTrader: (2)

Thank you, that was a big help!

I will be measuring how far in the hole my pistons are tommorrow now that I am home for the weekend and can take a look at the block...

dhdenney

iTrader: (53)

Seriously, what head has 56cc chambers? Are these custom chambers?

thebufenator

iTrader: (2)

LE2 heads that I am getting used.

dhdenney

iTrader: (53)

I didn't know Lloyd opened up chambers on his heads unless this was a custom request.

thebufenator

iTrader: (2)

I really dont know, thats what the guy said that I bought them from.

I might double check it though

dhdenney

iTrader: (53)

Yeah that's why I ask that question. Perhaps he is mistaken and your calculations are now all wrong! Stock is 54cc I think so they shouldn't be any more than that. I believe a simple call or e-mail to Lloyd might tell you more. He might say something like "I have never opened up combustion chambers!" Then you'll know. He might even tell you exactly how much they are milled if any.