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Old 11-12-2015, 12:20 PM   #1
John Stone
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Question Tapered Head

Took an engine apart the other day. Head looked clean and checked flat. Still had machining marks. Set it aside and after cleaning it up and painting yesterday noticed the counterbore was not consistent. Difference from the front to the back averages .035".

My take is that it should be replaced. Milling it to the point that everything is even will remove almost all the counterbore.

What do you guys think?
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Old 11-12-2015, 12:31 PM   #2
MikeK
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Default Re: Tapered Head

Stock head? You always wanted that new Snyder's 5.5 or 6.0 head. Now's the time.
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Old 11-12-2015, 01:09 PM   #3
bbrocksr
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Default Re: Tapered Head

Quote:
Originally Posted by John Stone View Post
Took an engine apart the other day. Head looked clean and checked flat. Still had machining marks. Set it aside and after cleaning it up and painting yesterday noticed the counterbore was not consistent. Difference from the front to the back averages .035".

My take is that it should be replaced. Milling it to the point that everything is even will remove almost all the counterbore.

What do you guys think?
I had the same situation. I had the head ground and apparently it moved in his setup and turned out with about .050 difference front to back.
I then took it to a good machinist and he set it up carefully to get it level and started milling at the high end until he just barely cleaned the low end. as a result we saved the head and only removed .001-.002 at the low end.

You should measure your piston protrusion and mill the head accordingly.
I've got an engine with no protrusion and I milled it to remove the counterbore entirely, work fine.

It all depends on your protrusion or lack of.

Original pistons protruded some aftermarkets didn't.
Bill
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Old 11-12-2015, 01:40 PM   #4
hardtimes
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Default Re: Tapered Head

Quote:
Originally Posted by John Stone View Post
Took an engine apart the other day. Head looked clean and checked flat. Still had machining marks. Set it aside and after cleaning it up and painting yesterday noticed the counterbore was not consistent. Difference from the front to the back averages .035".

My take is that it should be replaced. Milling it to the point that everything is even will remove almost all the counterbore.

What do you guys think?
Picture ? 'looked clean/checked flat'...
There is an 'idea'/process for taper milling (expensive) a head to achieve wanted combustion chamber performance (quench). Haven't seen this with a stock setup engine, but would work to improve c/r and wanted quench improvement shape. Maybe this is what you have here ? Be aware of your piston 'popup' , or not, setup before considering this idea/process.
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Old 11-12-2015, 02:22 PM   #5
Charlie Stephens
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Default Re: Tapered Head

I would either go with another stock head or a high compression head. The price on original heads is low due to the availability of high compression heads.

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Old 11-12-2015, 02:26 PM   #6
John Stone
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Just checked my stash and have one more uncracked stock head. Will just change it out.
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