I know if you go too small with the diameter, the gasket protrudes into the chamber and causes problems. But I really don't know what kind of problems could happen if you go too big with the gasket bore...

I'm putting a set of heads on a 355 set up for a high boost street application and really want to try the SCE ICS Titan head gaskets... the only bore diameter that I can find readily available for the LT1 is 4.200". For a cylinder bore of 4.030", is a head gasket bore of 4.200" too big?

 

yes

 

Edit... Summit just called me back with SCE on the line... SCE only makes a ICS Titan head gasket in the 4.200" diameter. They said that diameter is designed to seal the full range of bores for LT1 (4.000 on up).


What kind of problems would a 4.200" gasket on a 4.030" bore cause with a standard gasket? Any idea why they say there's no problem with the ICS Titan gaskets?

It doesn't make a lot of sense to me, but I want something that seals excellent for high boost, so I'll give it a try.

 

Try the cometic head gaskets. If your block and heads have a very fine finish, these should seal perfectly. Do a search here.

 

That wasn't the point of the thread... I know about the different head gaskets on the market and I wanted to try the SCE ICS Titans for several reasons (one being that MLS gaskets have a problem with boost seeping between the layers of steel at high boost levels). What I wanted to get out of this thread was information about the gasket bore diameter...

I still wonder why your typical gasket manufacturers say .020"-.030" bigger than the bore diameter and why too big would be bad.

But now that the SCE guys say that 4.200" is fine with a 4.030" cylinder with their gaskets (and having no problems with 20psi of boost), I guess the point of thread is now moot...

 

It is also important to match the gasket bore diameter to the cylinder head...because the chamber is not on centerline with the cylinder, it's widest point is sometimes wider than the bore and you can have a gasket that fits the block fine, but will over-hang the chamber. You are just fine using a 4.200" gasket. Make sure to spray those with copper coat.

 

Sorry, just thought I'd let you know since they have a 4.040 bore gasket. I don't know if you want boost getting up under the head that far.

 

good info... I'll make sure to put the gaskets on the heads with dowel pins to see how they fit. SCE said they don't need the spray, but I already have a can of it and plan to use it anyway.

No big deal... I was just trying to keep the thread on track to get the info I wanted.

 

I have seen them leak if the spray is not used, I talked to SCE about it and they said there was absolutely no harm in using the copper coat - they like to market it as a gasket that does not need sealer though due to the rubber beads.