3400/3500 head gaskets

[asylummotorsports]

I wish, however I dont have time to wait for the Cometic gaskets.

It has been suggested the 3400 3.75" GM gaskets will work on the 3500 3.70" bore.

(And they can be bought individually, not a whole damn $200 set!) GM is SOOO Anal!

Now they are .060" and I would have some room to play with.

Ben, how much do you take off the Ported heads?

Can I cut another .010" with a .060" gasket on a 3500?

The numbers I have suggest so, but then I'm old and feeble.


Let the flaming begin!

[SappySE107]

Depends on how much needs to be taken off, or if the customer wants them cut a certain amount. I wouldn't take another .010 off. What are you trying to accomplish?

[asylummotorsports]

Well I would like to get to the .050" gasket thickness to achieve the .040" quench, and on the tighter 3400 gaskets it might be a tighter compression situation.

I could be all wet on this and be mathematically whacko, but does this make any sense?

The 3500 piston only come .010" out of the block as opposed to the 3400 .020"

So it would make sense, and is in line with Cometics numbers that a .050" gasket is the one to use on a 3500.

That can't be had, but does cutting .010" off the head accomplish that?

Or do I just need another beer?

[3400-95-Modified]

You need another beer... .010 off the head only makes your CC smaller... and raises your compression, the area between the top most part of the piston and the cylinder head will still be a distance of .050 also stock GM 3500 gaskets are .060 too IIRC.

Now if you decked the block .010 that would accomplish what you want. The 3500 pistons would then stick out .020 like the 3400.

[asylummotorsports]

Well I'm not decking the block, but I am seriously considering the 3400 GM head gaskets with the 3.75 bore.

And I still might take a bit off the heads. It appears there is still .010" to play with.

[95Grand-Am]

If you deck the block have them square it, It will make both deck heights the same. I had eight thousandths cut on one side and two on the other to give me a 8.810" deck height on my engine.

[ForcedFirebird]

The only thing you would gain by using 3400 instead of 3500 gakets is the eeny-tiny bit of raise in compression by the .050" decrease in HG bore. They are the same thickness, and Jon is right, you need to just get another beer haha.

[3400-95-Modified]

Yes but he's hoping to not have to buy the whole 3500 top end set for $200 since he already has all the other gaskets.

I only spent $28 for each head gasket for the 3400, and they are something like $36 list so even those two would be a much cheaper solution than $200 for the whole top if he doesn't need it.

But at the same time he dropped close to $2000 for the rest of the engine parts... What's another $200 and then ending up with a spare LIMG and upper intake set