Head Gasket ?

[boostmaster]

Hey guys have a head gasket question I have an 85 T Type that comes with steel shim head gaskets. I just removed the heads to have a valve job and i was told that they resurfaced the head .020. Being that it's a hot air I don't want to raise my compression anymore so I purchased a fel pro 9441pt for an intercooled car and man are they thick. Will these work to put me back where I was or will these lower my compression.

 

[VictoryTrans]

Well, some guys with 86-87 cars use the steel shims have a stronger gasket and they have to double them up to be close to the same compression as before. So as I take it, 2 steel shim gaskets are pretty close to one 86-87 composite gasket in thickness. Im not exactly sure how thick either gasket is, but I'm guessing it should be pretty close to the same with the .020 resurfacing.

Well I tried
HTH, Good luck

 

[FJM568]

First off, what block do you have??? Is this still the original block or the later 109 block??? If you still have the original block, then the stock thickness 86/7 should bring you back to the right compression...or very, very close...

 

[Lee Thompson]

gasket

84-85 steel shim head gasket--.018 thick compressed.
In 86 Gm dropped the deck height and used a composition gasket--.060 thick compressed.
Do the math.
I have found you can go .020 without having a problem with intake bolts lining up. Good luck

 

[VictoryTrans]

Re: gasket

Originally posted by Lee Thompson
84-85 steel shim head gasket--.018 thick compressed.
In 86 Gm dropped the deck height and used a composition gasket--.060 thick compressed.

So your saying you have to stack approx. 4 steel shims to equal 1 composite gasket??? Hmmm.... That doesn't seem right to me

But maybe so

 

[boostmaster]

Head gasket

If the stock steel shim gasket is .018 and the later composite gaskets are .060 and I had my heads shaved .020.
.060-.018-.020=.022 which would mean that I possibly raised my deck height .022 /. Again how would this affect my compression ratio. I don,t want to lower it any, but if I put in the steels I need to know if I would run the risk of raising it too much, which I don't want to do on a hot air car.

 

[Nick Micale]

Re: Head gasket

Originally posted by boostmaster
If the stock steel shim gasket is .018 and the later composite gaskets are .060 and I had my heads shaved .020.
.060-.018-.020=.022 which would mean that I possibly raised my deck height .022 /. Again how would this affect my compression ratio. I don,t want to lower it any, but if I put in the steels I need to know if I would run the risk of raising it too much, which I don't want to do on a hot air car.

First, taking 0.020 off when just surfacing a head is LOTS? We usually are about 0.005 or less, and the most ever at 0.010?

Do what Lee said, the math shows if you use 2 steel gaskets, the compression will be about stock.

On an '87 block, 2 steels in place if the stock gasket will raise the compression about one half a point to 8.5 to 1.

 

[6SENSE]

Interesting. I used some GM '87 head gaskets on my '84 a few years back. So I guess my compression ratio is quite a bit lower than stock, huh? Plus my block is .030 over, so that would bring it down more, right?
What would this mean as far as performance? Would this be a good thing and mean that I should be able to run more boost, or was it a mistake?

 

[Lee Thompson]

gasket

If the shop took .020 off your heads ( a bunch ), I would bet it/s a shop that does mostly Chevy or Fords
You could use Felpro 1000---.040 compressed.

 

[Nick Micale]

Originally posted by 6SENSE
...... So I guess my compression ratio is quite a bit lower than stock, huh? Plus my block is .030 over, so that would bring it down more, right? .......................

No, an overbore will increase compression ratio, although it will be a minor amount.

 

[FJM568]

The deck height on the 84/5 blocks are about .020 taller than the later 86/7 109 blocks...If they machined your heads .020, then just using the 86/7 composite head gaskets would bring the compression back to where you started...