The Ford Barn

Init1 · 02-24-2014, 06:59 PM

Hey flathead experts...

I have run into a problem with my fresh 50 Merc. 2 exhaust valves just very slightly kissed the head . No damage but what is the minimum thickness for cast iron heads and where and how do you measure it?
My heads have been milled flat at least once and probably more over the last 65 years.
Also who makes the thickest head gaskets. I have been using BEST
graphite.

Thanks for the help...

Straightpipes · 02-24-2014, 07:48 PM

Rather than go to all the trouble and expense of thick gaskets I'd just find another set of heads. Then I would measure the valve and piston to head clearance before assembly.

Neal · 02-24-2014, 09:16 PM

I get it so the valves and pistons don't touch without a gasket. There are other ways to fix the problem that may not be accepted these days. One is doubling up on the gaskets. There are also head gasket shims or spacers or whatever they are called made. I have not done either of these fixes but have heard of them being done.

If you are dealing with stock heads, they are not that hard to find replacements.

Neal

flatjack9 · 02-24-2014, 10:15 PM

If they are stock cast iron heads, you should be able to find some different ones pretty cheap. If you were closer to Wisconsin, I'd give you a pair.

Karl Wolf · 02-25-2014, 12:02 AM

Quote:

Originally Posted by Init1

Hey flathead experts...

I have run into a problem with my fresh 50 Merc. 2 exhaust valves just very slightly kissed the head . No damage but what is the minimum thickness for cast iron heads and where and how do you measure it?
My heads have been milled flat at least once and probably more over the last 65 years.
Also who makes the thickest head gaskets. I have been using BEST
graphite.

Thanks for the help...

I took router and a die grinder to mine. For clearance, I put the heads on the block loose on a couple of studs... Made it so that the valves no longer pushed the heads up... When you add a gasket, that's your clearance...

I didn't have to take a lot out, and I must have cut up an old head to find that I had plenty to work with.

Karl

Russ/40 · 02-25-2014, 12:24 AM

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The simplest and most sensible solution is to use a die grinder and just cut the eyebrow area at the topmost of the combustion chamber. It won't take much if you have minimal contact and no damage with engine rotation now. If that is the only contact problem you have, you can't take enough off to be a problem. The concept others mentioned ( no contact with no gasket ) is the way to go.

Init1 · 02-25-2014, 12:10 PM

Thanks for the reply. Grinding is what I will do. This is not a racing engine and it won't matter at all.

Vergil · 02-25-2014, 04:35 PM

If you look close you can see where the valve will contact the head first ... (the far side of the valve)

Init1 · 02-25-2014, 07:13 PM

Thats is exactly where the exhaust valves for cylinders 4 and 8 slightly touched.
I think I will use copper gaskets that are thicker than the graphite. Graphites run about .0050 thick after crush and copper are about .0062 after crush.
Looking for another set of Mercury heads now that have not been shaved as much as the ones I used. Thanks for the photo.

Init1 · 02-25-2014, 07:19 PM

Thanks for your reply. I am looking now locally for a pair of 49-53 Merc heads. Like to stay with Mercuries since my engine has a 1/4" Merc crank motor.
I might be interested in your offer if I can't find anything suitable.

Walt Dupont--Me. · 02-25-2014, 07:43 PM

Quote:

Originally Posted by Init1

Thanks for your reply. I am looking now locally for a pair of 49-53 Merc heads. Like to stay with Mercuries since my engine has a 1/4" Merc crank motor.
I might be interested in your offer if I can't find anything suitable.

Seeing that you are going to look for an other set of heads, I'd look for a set of EAB heads, 52-53 Ford. They have smaller combustion chambers =more power. That don't stand much milling or you'll have the same problem. If your lucky enough to find a set that hasn't been milled they will stand .010 mill, probably more. I probably have 1/2 doz. Merc heads in my storage barn, I never use them. Your welcome to a set if you were here. Walt

Ross F-1 · 02-25-2014, 09:17 PM

Quote:

Originally Posted by Walt Dupont--Me.

Seeing that you are going to look for an other set of heads, I'd look for a set of EAB heads, 52-53 Ford. They have smaller combustion chambers =more power. That don't stand much milling or you'll have the same problem. If your lucky enough to find a set that hasn't been milled they will stand .010 mill, probably more. I probably have 1/2 doz. Merc heads in my storage barn, I never use them. Your welcome to a set if you were here. Walt

I have EAB heads on my Ford engine, and with a stock cam I measured over .150" between the valves and the head. If the heads have been shaved, it wasn't much. Not sure why you are saying they won't stand much milling? On mine the pistons would be hitting first.

hardtimes · 02-25-2014, 10:14 PM

Quote:

Originally Posted by Init1

Thats is exactly where the exhaust valves for cylinders 4 and 8 slightly touched.
I think I will use copper gaskets that are thicker than the graphite. Graphites run about .0050 thick after crush and copper are about .0062 after crush.
Looking for another set of Mercury heads now that have not been shaved as much as the ones I used. Thanks for the photo.

You can call BEST and they will tell you compressed thickness of gasket that you get from them. They told me ,recently, that copper gasket I bought , compressed to .053.

Ol' Ron · 02-26-2014, 11:29 AM

My 280 has EAB heads milled .040" they hit the pistons on the outer diameter of the cyl bore. I clearances this with a die grinder. Didn't take much. Had no trouble with the valves. Using a copper gasket I have .045 around the outer dia of the cyl. CR is alittle over 8:1

Init1 · 02-26-2014, 11:36 AM

I have read that graphite composite head gaskets compress to .0050 and copper head gaskets from Best compress to .0062. Copper may solve my problem but I will continue to look for a set of usuable heads.
I am also running a 3/4 cam with slightly higher lift so that compounds the problem.
Typically a stock cast iron head un- cut would have plenty of clearance.
Do you have any suggestions on how to spot usuable heads at swap meets? The Portland swap meet is in a month and there be plenty of them there.

Init1 · 02-26-2014, 11:42 AM

Hello Ol' Ron... My engine is 276 CI with a 3/4 cam. That is probably why I have a clearance issue. I should be able to find iron heads with more clearance than the ones I used. And I will add some clearance just to be sure. I would like to use Mercury heads just because the engine is a Merc.

Init1 · 02-26-2014, 11:48 AM

I think stock cast iron heads un- milled can be cut up to .0040 with out clearance issues if you are running a stock cam. A higher lift cam could cause a problem especially if the heads have been milled several times in their life. I think that is the problem with the heads I used.

Ross F-1 · 02-26-2014, 12:05 PM

Init1, you're off by a zero; graphite composites are about .050" compressed, you can cut most stock heads about .040" without worry.

Here's a thread with pictures of how to gauge how much the heads have been milled:
http://flatheadsrus.com/viewtopic.ph...t=3538&p=22813

Here are the missing pictures, first one is of a head with a small shave, the second of one that has been shaved pretty far. The milling machine starts cutting into the thermostat housing beyond maybe .030".

Init1 · 02-26-2014, 12:21 PM

Thank you Ross F-1. The Pics say it all. I will look at heads with a healthy ridge below the thermostat housing.

rotorwrench · 02-26-2014, 01:36 PM

Ross F-1 hit the nail for checking all of the 8BA family of heads. This is the only way to tell how much a head has been shaved. If it goes all the way down to the thermostat housing, it has had a lot of meat cut off and can end up unusable for any application. The head deck parting surface should stand near .040" proud of the thermostat housing on most heads at the OEM spec (never been shaved before).

02-24-2014, 06:59 PM	#1
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	49-53 minimum cast iron head thickness?? Hey flathead experts... I have run into a problem with my fresh 50 Merc. 2 exhaust valves just very slightly kissed the head . No damage but what is the minimum thickness for cast iron heads and where and how do you measure it? My heads have been milled flat at least once and probably more over the last 65 years. Also who makes the thickest head gaskets. I have been using BEST graphite. Thanks for the help...

02-24-2014, 07:48 PM	#2
Straightpipes Senior Member Join Date: May 2010 Location: Ballston Spa, NY Posts: 789	Re: 49-53 minimum cast iron head thickness?? Rather than go to all the trouble and expense of thick gaskets I'd just find another set of heads. Then I would measure the valve and piston to head clearance before assembly.

02-24-2014, 09:16 PM	#3
Neal Senior Member Join Date: May 2010 Location: North Dakota Posts: 129	Re: 49-53 minimum cast iron head thickness?? I get it so the valves and pistons don't touch without a gasket. There are other ways to fix the problem that may not be accepted these days. One is doubling up on the gaskets. There are also head gasket shims or spacers or whatever they are called made. I have not done either of these fixes but have heard of them being done. If you are dealing with stock heads, they are not that hard to find replacements. Neal

02-24-2014, 10:15 PM	#4
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: 49-53 minimum cast iron head thickness?? If they are stock cast iron heads, you should be able to find some different ones pretty cheap. If you were closer to Wisconsin, I'd give you a pair.

02-25-2014, 12:24 AM	#6
Russ/40 Senior Member Join Date: May 2010 Location: Santee, California Posts: 3,505	Re: 49-53 minimum cast iron head thickness?? Sponsored Links (Register now to hide all advertisements) The simplest and most sensible solution is to use a die grinder and just cut the eyebrow area at the topmost of the combustion chamber. It won't take much if you have minimal contact and no damage with engine rotation now. If that is the only contact problem you have, you can't take enough off to be a problem. The concept others mentioned ( no contact with no gasket ) is the way to go.

02-25-2014, 12:10 PM	#7
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	Re: 49-53 minimum cast iron head thickness?? Thanks for the reply. Grinding is what I will do. This is not a racing engine and it won't matter at all.

02-25-2014, 04:35 PM	#8
Vergil Senior Member Join Date: May 2010 Location: Tehachapi, CA Posts: 361	Re: 49-53 minimum cast iron head thickness?? If you look close you can see where the valve will contact the head first ... (the far side of the valve) __________________ Bigger fonts to aid in reading

02-25-2014, 07:13 PM	#9
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	Re: 49-53 minimum cast iron head thickness?? Thats is exactly where the exhaust valves for cylinders 4 and 8 slightly touched. I think I will use copper gaskets that are thicker than the graphite. Graphites run about .0050 thick after crush and copper are about .0062 after crush. Looking for another set of Mercury heads now that have not been shaved as much as the ones I used. Thanks for the photo.

02-25-2014, 07:19 PM	#10
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	Re: 49-53 minimum cast iron head thickness?? Thanks for your reply. I am looking now locally for a pair of 49-53 Merc heads. Like to stay with Mercuries since my engine has a 1/4" Merc crank motor. I might be interested in your offer if I can't find anything suitable.

02-26-2014, 11:29 AM	#14
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,859	Re: 49-53 minimum cast iron head thickness?? My 280 has EAB heads milled .040" they hit the pistons on the outer diameter of the cyl bore. I clearances this with a die grinder. Didn't take much. Had no trouble with the valves. Using a copper gasket I have .045 around the outer dia of the cyl. CR is alittle over 8:1

02-26-2014, 11:36 AM	#15
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	Re: 49-53 minimum cast iron head thickness?? I have read that graphite composite head gaskets compress to .0050 and copper head gaskets from Best compress to .0062. Copper may solve my problem but I will continue to look for a set of usuable heads. I am also running a 3/4 cam with slightly higher lift so that compounds the problem. Typically a stock cast iron head un- cut would have plenty of clearance. Do you have any suggestions on how to spot usuable heads at swap meets? The Portland swap meet is in a month and there be plenty of them there.

02-26-2014, 11:42 AM	#16
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	Re: 49-53 minimum cast iron head thickness?? Hello Ol' Ron... My engine is 276 CI with a 3/4 cam. That is probably why I have a clearance issue. I should be able to find iron heads with more clearance than the ones I used. And I will add some clearance just to be sure. I would like to use Mercury heads just because the engine is a Merc.

02-26-2014, 11:48 AM	#17
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	Re: 49-53 minimum cast iron head thickness?? I think stock cast iron heads un- milled can be cut up to .0040 with out clearance issues if you are running a stock cam. A higher lift cam could cause a problem especially if the heads have been milled several times in their life. I think that is the problem with the heads I used.

02-26-2014, 12:21 PM	#19
Init1 Senior Member Join Date: May 2010 Location: Oregon City, Oregon Posts: 208	Re: 49-53 minimum cast iron head thickness?? Thank you Ross F-1. The Pics say it all. I will look at heads with a healthy ridge below the thermostat housing.

02-26-2014, 01:36 PM	#20
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,426	Re: 49-53 minimum cast iron head thickness?? Ross F-1 hit the nail for checking all of the 8BA family of heads. This is the only way to tell how much a head has been shaved. If it goes all the way down to the thermostat housing, it has had a lot of meat cut off and can end up unusable for any application. The head deck parting surface should stand near .040" proud of the thermostat housing on most heads at the OEM spec (never been shaved before).