Head Gaskets for 440

[Chatt69chgr]

Do they make any sizes besides .020 steel shim and .039 composition?  I thought I heard that Cometic had a whole series of thicknesses but I didn't see them on their website.  Didn't find much of anything on Summit either. 

Also---------how many thousands can you mill off the cast iron heads on a 452 head without weakening them or causing trouble? 

[chargerbr549]

I have been doing some research on this lately for my 440 and so far here is what I have found from different sources so this will give you an idea of what is available, I have heard cometic has a .027 composition gasket and then they have several different bore sized gaskets but they keep it at .040 thick to keep a nice quench on a zero deck motor but varying your compression ratio's and then felpro has their normal .039 gasket that displaces 9.9 cc's and then a .051 gasket that displaces 13.7 cc's that's just some of what I have found out yet. I think some of the cometic gaskets are fairly spendy so be prepared.

Kevin

[firefighter3931]

I think some of the cometic gaskets are fairly spendy so be prepared.

Kevin

Yep, and the deck/head surfaces need special machining or it will leak. 

Chatt ; what are you trying to achieve ? Reduced compression ?



Ron

[Chatt69chgr]

I've been playing around with the Keith Black Website Calculators to choose a piston for my 440 project.  I have not had my two blocks sonic tested yet so I don't know what bore I am going to have to go with.  But ignoring that, my idea was to build a zero deck motor and use my 452's for now and have the capability of upgrading to something like the 440 Source 84cc closed chamber heads later.  Discussions with folks at Keith Black indicated that I should keep the static compression ratio to less than 9.5 to one for 91 Octane pump gas for the iron heads----they actually felt that maybe half way between 9.0:1 and  9.5:1 would be better.  I have read that you need 1 point more on CR when running Aluminum heads to make everything equal due to greater heat loss of the aluminum.  Of course, I would want the zero deck so that when I added the aluminum heads, I would have the proper quench distance.  I also called Engle with questions about how to apply the Keith Black Calculator for dynamic compression to their K56 cam.  They said that I wouldn't be able t bleed off that much compression to make any difference in a motor turning less than 6000 rpm so I would be better off just worrying about the static CR.  And they said that I should stick with 9:1 or not much more than that for 91 octane pump gas.  Also, the Keith Black folks said that the dish piston would perform better than the flat top since it promotes swirl.  So I was looking to see if there was a combination that would let me build a zero deck motor now using the 452 heads and achieve a 9.4:1 CR and then add 84cc closed chamber heads later and bump this up to 10.4:1.  Factors that could be varied after pistons were purchased and installed would be the volume of the combustion chamber by milling the heads and choice of the head gasket.  I forgot to mention that the operating rpm should be in the approx 1500-6000 range and that it will be used with a manual transmission and that I don't plan to do any racing----just some spirited, but legal, street driving (also, I'am using a CH4B intake with stock exhaust manifolds and will probably retain the stock valve sizes).  I've already determined that to build the zero deck configuration the block will have to be milled approximately 15 thousands as most of the offered pistons have a compression height of 2.065 to 2.067. 

It's a pretty tough little problem and I don't have it figured out yet.  I am starting to come to the conclusion that I may have to just build another motor later if I want to do one with 84cc closed chamber heads.

I'am not real keen about having to do special machining required for head/deck surfaces that was mentioned.

Those are some of the considerations that I have been looking at. 

Using a KB836 40 over piston (2.067 compression height) with 12cc dish, 88cc 452 heads, .039 head gasket, and milling the block to yield zero deck height yields a 9.361 Compression Ratio.  That looks like about what the folks at Keith Black and Engle were shooting for.  But you can't pop on a 84cc closed chamber head with this setup and get the extra point of CR desired to make things equal (aluminum vs iron).  For that matter, what is the actual depth in thousands to the quench surface for something like a Eddy 84cc closed chamber head?  Is the quench surface flush?  I don't know.  If it is, then the thickness of the head gasket will determine the quench distance and you really don't want to have it closer than about 40 thousands or you might get head bumping by the pistons which would be catostropic to your engine. 

A final note.  I saw an earlier post where someone used this piston with a Comp Cams xe274 cam.  Their piston was not zero deck height I don't think.  In fact, I think it was sitting about 15 thousands in the hole.  They did mill their 452 heads down to 85cc.  A quick look at the Comp Cams catalog seems to say that this was a little too much cam for this setup.  It indicated something like a 262 or a 268 would be best.  But they said the motor ran real good on 91 octane.  Does that mean you can go a little further in duration than the catalogs say?

Sorry for all the rambling. 

[firefighter3931]

Chatt,

to answer a few questions;

(1) on any closed chamber head....the quench surface is flush (closed) so the head gasket becomes the effective quench didstance.
(2) Use a flattop piston with a 4-5 cc valve relief area and zero deck it for the future build
(3) use the .051 felpro gasket with your open chamber heads
(4) CC the heads and if need be open the chambers up to 92cc for a 9.4:1 static compression ratio. The last set of 452's i had cc'd right at 92

* this will get you going while you wait for the better (Aluminum) closed chamber heads. Then all you have to do is drop a .040 head gasket on with the 84cc closed chamber alum heads and you'll be good to go. 

It just takes a little planning and forethought. 



Ron

[Chatt69chgr]

Hey Ron-----thanks for looking over my configuration.  I now recall that the 88cc for the 452's was just a guesstimate.  They could actually vary up to 92cc.  I had not thought of increasing the chamber volume a little if necessary.  I reran the calculator using the 92cc chamber volume and a .051 head gasket, 4cc flat tops, 0 deck, with a 40 over and it gives a 9.438 CR.  Changing the chamber volume to 84cc with a .039 head gasket gives 10.388.  That looks like a winning combination.  I appreciate the assistance.

[Musicman]

Well, that was a good read... another satisfied costomer 

[firefighter3931]

Hey Ron-----thanks for looking over my configuration.  I now recall that the 88cc for the 452's was just a guesstimate.  They could actually vary up to 92cc.  I had not thought of increasing the chamber volume a little if necessary.  I reran the calculator using the 92cc chamber volume and a .051 head gasket, 4cc flat tops, 0 deck, with a 40 over and it gives a 9.438 CR.  Changing the chamber volume to 84cc with a .039 head gasket gives 10.388.  That looks like a winning combination.  I appreciate the assistance.

You're welcome. 

Another thought ; should you want more than 10.38:1 static comp with the next stage of the build (alum heads) you can simply mill .010-.020 off the surface to achieve your desired target ratio. 

FYI :
10 thou = 2cc
20 thou = 4cc
* for 84cc alum head casting


Ron