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Old 09-23-2020, 01:04 PM   #1
Smooth_One
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Default Cylinder head machining advice.

Hey all, towards the winter time I am going to pull the head off my A and probably mill it as minimal as I can just to get it flat for a new gasket. I pulled the center not loose with the clamp that holds the armored cable to it to replace the cable and the stud came out with it unfortunately. I ignorantly thought I would just put it back in and tighten it to spec but as soon as I walked away from the car for about an hour coolant was coming up through the stud threads around the nut. And then I ran the car for a few minutes and had some coolant in the oil so I drained it immediately and put fresh stuff in it.
So after all that reading if you made it this far… My question is I don’t know if my head has ever been machine before but I will measure it before I do any machining.
What is the minimum thickness I can get away with on the head before I have to clearance the valves?
And in your opinion what should be done to the actual top of the block surface before reinstalling the new gasket besides rigorously cleaning the surface?
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Last edited by Smooth_One; 09-23-2020 at 01:09 PM.
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Old 09-23-2020, 06:49 PM   #2
Chuck Sea/Tac
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Default Re: Cylinder head machining advice.

That stud hole may have rusted through into the water jacket, so you need a thread sealer like permatex. There’s not much you can do to the deck without a disassembly and machine shop. Usually the deck gets off around the corners in the water jacket area, but usually seals fine. .002” is the acceptable unevenness allowed. You can take almost all the combustion chamber off on the head. The problem is, has the block been decked? I’d worry about the pistons hitting the head, before the valves. You can do a test fit with a used gasket and clay or tinfoil balls to find any interference.
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Old 09-23-2020, 10:04 PM   #3
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Default Re: Cylinder head machining advice.

Quote:
Originally Posted by Chuck Sea/Tac View Post
That stud hole may have rusted through into the water jacket, so you need a thread sealer like permatex. Theres not much you can do to the deck without a disassembly and machine shop. Usually the deck gets off around the corners in the water jacket area, but usually seals fine. .002 is the acceptable unevenness allowed. You can take almost all the combustion chamber off on the head. The problem is, has the block been decked? Id worry about the pistons hitting the head, before the valves. You can do a test fit with a used gasket and clay or tinfoil balls to find any interference.
I have heard of using clay. Ill try and get a hold of a local club too.
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Old 09-24-2020, 12:46 PM   #4
rotorwrench
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Default Re: Cylinder head machining advice.

Clay or aluminum foil rolled into small loose balls can be used for a clearance check. Unless a person knows the history of the head, it's a good idea check it pretty well before putting it on the head mill table.
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Old 09-25-2020, 07:47 AM   #5
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Default Re: Cylinder head machining advice.

safest way is check without head gasket and use the foil balls, if you have clearance then you can rest assured with head gasket you are good to go. As told to me by an old flathead racer. I am running a Super Winfield with no fly cut, and this proved to be a safe method with a Best 509 gasket. Got lucky on my .60 over motor.. had less than stock piston pop up.
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Old 09-25-2020, 07:45 PM   #6
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Default Re: Cylinder head machining advice.

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Surfacing the head is usually less than .006-.008. Will not have much or any affect on setting valve lash. If there are problems with valve to head, it will be because some clown surfaced the snot out of the head to up the compression. if not the valves on most blocks are sunk deep, if so once again you have loads of clearance.Lash is the distance between lifter and but of the stem. not interference valve to head. Part 2. use a shop straight edge and check with a feeler gage. Most of this would be relatively free if the block was in the back of a Pick up at the machine shop.

Last edited by 100IH; 09-25-2020 at 07:53 PM.
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Old 09-26-2020, 02:03 PM   #7
1931 flamingo
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Default Re: Cylinder head machining advice.

After going thru all the trouble of removing the head and finding a shop that can cut it I'd "spring" for a new hi-comp head if you've got some spare change. JMO
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Old 09-26-2020, 08:30 PM   #8
Purdy Swoft
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Default Re: Cylinder head machining advice.

A higher compression head will give the most improvement in torque and power that can be felt than any other mod that I have tried .. I really didn't feel as much improvement in shaving an original head . All of the higher compression heads have improved combustion chamber shape . A heart shaped combustion chamber is good .
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