Head gaskets and quench

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peeeot
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Head gaskets and quench

Post #1 by peeeot » Wed Nov 14, 2018 9:12 pm

Elsewhere, it has been mentioned that 0.035-0.050 is a desireable target for quench, and that the current head gasket offerings are currently at least 0.025” thicker than the originals. Fel-pro publishes its MLS gasket thickness at more than 0.050”, and I just measured one I took off of a rebuilt 223 and got 0.060” with my calipers.

If the head gasket is 0.050-0.060” thick, doesn’t that make it the limit as to what quench can be attained? If so, since it is possible to buy an NOS steel beaded head gasket, is there any objection to using the old technology to maintain quench and compression? Seems like a head gasket that requires sealant wouldn’t be as reliable as the modern stuff...

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bubba22349
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Re: Head gaskets and quench

Post #2 by bubba22349 » Thu Nov 15, 2018 8:51 am

peeeot wrote:Elsewhere, it has been mentioned that 0.035-0.050 is a desireable target for quench, and that the current head gasket offerings are currently at least 0.025” thicker than the originals. Fel-pro publishes its MLS gasket thickness at more than 0.050”, and I just measured one I took off of a rebuilt 223 and got 0.060” with my calipers.

If the head gasket is 0.050-0.060” thick, doesn’t that make it the limit as to what quench can be attained? If so, since it is possible to buy an NOS steel beaded head gasket, is there any objection to using the old technology to maintain quench and compression? Seems like a head gasket that requires sealant wouldn’t be as reliable as the modern stuff...


Yes the ideal quench distance is .035 to .050, but no the limit of the quench can still be changed some even if the new head gaskets are.050 to .060 thick, the Victor head gasket is one of the thinnest at about .045. Still changing the quench distance (i.e. The distance from top of pistion to block deck plus the head gasket thickness) is as simple as decking the block enough to attain your goal. This would bring the pistion tops up above the deck the needed amount to offset the extra of the head gasket thickness. Other ways to change this amount is to increase the crankshafts stroke slightly during the regrinding prosscess (offset grinding) to gain a small amount of extra stroke. Beyond that you could used slightly longer Connecting Rods by custom bushing their small end during the rebuilding process to make make them a little longer and most important of all so that they are all equal length. Lastly you could use a set of custom Pistons or some off the shelf Pistons from a different application. Good luck :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

peeeot
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Re: Head gaskets and quench

Post #3 by peeeot » Thu Nov 15, 2018 9:20 pm

I didn’t realize it was possible to let the pistons go past zero deck! Good to know.

Do you think using an NOS head gasket would produce a reliable seal for a mildly warmed street car?

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Re: Head gaskets and quench

Post #4 by Max_Effort » Thu Nov 15, 2018 9:40 pm

peeeot wrote:I didn’t realize it was possible to let the pistons go past zero deck! Good to know.

Do you think using an NOS head gasket would produce a reliable seal for a mildly warmed street car?


It’s not unusual to have the pistons protrude above the deck on some engines.

I don’t see any problem with an NOS gasket, unless it was damaged or obviously deteriorating in some way.

What is the NOS gasket made from? Composition (fiber and metal) or steel shim?

Another option is Cometic gaskets. If they already have the pattern in MLS, they can make it in different thicknesses by the amount of layers.

If they don’t have it in MLS, Cometic will make you a custom composition head gasket for around $100. I think the thinnest composition will be around .030” compressed.

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Re: Head gaskets and quench

Post #5 by peeeot » Fri Nov 16, 2018 4:32 am

The NOS gasket is a beaded steel shim. Here is an example: https://www.ebay.com/itm/NOS-1954-1964- ... SwQt9bp5eE The shop manual says to apply a layer of sealer to it at installation.

If the OEM gasket can be expected to work reliably for 50,000 miles or more than I would prefer to use it—very inexpensive and surely the thinnest option. But I will take a look at cometic. It’s nice to know there are more options than fel-pro and victor!

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Re: Head gaskets and quench

Post #6 by Max_Effort » Fri Nov 16, 2018 6:48 am

peeeot wrote:The NOS gasket is a beaded steel shim.


Steel shim is the the thinnest least expensive option. It doesn't "go bad" in storage unless bent or rusted.

I use them on some SBC for the same reason, increasing compresssion and adjusting quench distance.

As long as your gasket surfaces, the head and block deck are smooth, straight and flat, a beaded steel shim is fine. The sealer is to prevent fluid seepage. Old school is loctite aviation gasket sealant. I've also used copper coat gasket spray and hylomar.

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bubba22349
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Re: Head gaskets and quench

Post #7 by bubba22349 » Fri Nov 16, 2018 8:03 am

X2 yes if the steel shim gasket is available I'd use it! Most times have used the spray copper coat on them in a pinch though have even used some Aluminun spray paint on them too. Good luck :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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B RON CO
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Re: Head gaskets and quench

Post #8 by B RON CO » Sun Nov 18, 2018 2:40 pm

Hi, if you use the steel shim gasket many guys paint them, as mentioned.
You also need to re torque them after you run the engine. Good luck
B RON CO. Still workin' on it!

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