Head Gasket Bore Size Question
 

I'm going order me some Cometic gaskets soon for my 418 project motor. Previously, I have only used Fel-Pro 1011-1 and 1011-2 gaskets so I never had a choice of gasket bore size.

My question is whether I just order the size to match my machined bore or do I go larger for any particular reason. It seems like I would obviously order a 4.030 head gasket to go with my 4.030 bore, but I just want to make sure that there would be no reason to buy bigger.

Here is the gasket I'm looking to order:

http://www.cometic.com/da_viewimage.aspx?da=215

Buy it just a little larger for the room to "squish" a little and to make sure both surfaces are clamping on it...

Getting it too big can leave a gap between the surfaces for crap to get in and pit/corrode the deck surfaces.

btw: FelPro makes a MLS gasket I think #1133... It's getting real good reviews in the racing circles.

I thought that their bore sizes would be rated at the "compressed" state.... I know that all gasket thickness measurements normally are. :shrug:

Cometic's next size larger is a 4.080.


:hmm:

All of mine were sized at 4.100

I had aksed the question on Cometic's web site and I already got a response from them:

:nice:

I USE THE 4.200, This actually moves the fire ring away from the heat a little, have never had any adverse affects because of it, And also have never blown a gasket, (been supercharged since 1995) I do use a fel-pro gasket ( cant remember part # but its 51 thousant thick compressed If you want the number i can find it, these gaskets are expensive though around 80 bucks apiece)have never liked the cometic, Although a lot of my customers have requested the cometic and i have used them without a complaint.Hope this helps. EDIT: found gasket # and specs.Part # 1046, Gasket Bore 4.200, Comp volume 11.7 cc, .051 thick, Pre flattened steel wire ring,

Brian, go with the 4.060 bore, that is what I used all the time when the bore was .040 on the block. If they don't have it, next will be the 4.080, .040 thicknes. Here is a trick that I use so it will not leak thru any of the water holes or oil return. Get some Copper seal gasket, the liquid one, at Car Quest or O'Reilly. Then, in between the layers were there is a water jaket or oil return lay some of the gasket seal, then go to the block, at the top of the lifter galley lay down from on end to the other, front to back a bitt of the seal, then every hole on the block put a bit on top of them. The go to the head, and do the same thing, only were the head matches the lifter valley and every water hole and stud or bolt holes. None on the fire ring of the head or the block. Another thing keep an eye on the rivets at the front and rear, some of them will not clear the block or the head, if that hapens you can take the rivet off. Any questions call me.

Edgar