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Old 09-24-2019, 02:15 PM   #1
Ford-A-baquet
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Default piston hit the head

Hello, I restore a ford a baquet from uruguay. I suspect engine block
and cylinder head was skimmed much to increase the compression.
The engine builder now skimmed only the necessary minimal
thickness and warned me to pay attention when assemble the engine.
Now after crank, connecting rod and piston fitting I`m smarter.
When Piston is top dead, the head is laying on the piston.
Between head and block there is a gap now of about 1,3 mm (0,0512).
The compound head gasket A-6051-M (snyders) give me a compensable
thickness of 2,3 mm (0,09055) but not torqued. Any experience out
there how thick is the gasket if everything is squashed and
torqued down a while (twice).Any proposals, how much I should trim
down the piston head. Thanks in advance
Rik
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Old 09-24-2019, 02:30 PM   #2
62pan
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Default Re: piston hit the head

I understand that you should have .040 squish area between head and piston. If you are able to remove some from the piston that is best. I had the same problem but it was my choice to run double head gaskets. It has been five years with no problems.
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Old 09-24-2019, 02:42 PM   #3
Purdy Swoft
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Default Re: piston hit the head

I believe that the Fel Pro copper clad gaskets compress to a thickness of seventy thousands . The pistons usually rise around thirty three thousands above deck height . After checking piston rise , this may show if the thicker copper clad gasket will solve the problem rather than tearing the engine down to trim down the pistons . I use the Fel Pro 7013 C copper clad head gasket on all of my model A's . The 7013 C head gasket is also a big bore head gasket .
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Old 09-24-2019, 05:58 PM   #4
PC/SR
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Default Re: piston hit the head

The BEST composition gaskets compress to about .050. Any idea how much the head was "SKIMMED?" You might compare the height of your head from bottom to top of bolt holes to a known stock head.
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Old 09-24-2019, 06:12 PM   #5
mike657894
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Default Re: piston hit the head

What kind of head do you have? If its a cut down stock one you may want to get a new 5.5 head and see if that has a better clearance.
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Old 09-30-2019, 02:21 PM   #6
Ford-A-baquet
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Default Re: piston hit the head

Thanks for tips and advice. Removed about 0,025 from the piston.
The engine was still on the bench.
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Old 10-01-2019, 07:02 AM   #7
chap52
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Default Re: piston hit the head

Foil check the clearances.
With the head removed take small balls of aluminum foil (or modeling clay) and place them in several places on top of each cylinder. I dip the foil balls in wheel bearing grease to hold them in place. put head gasket on, put on head (no nuts) without tightening it down. Now slowly turn the hand crank through a complete revolution. Lift off the head and using a micrometer or calipers measure the thickness of any squished foil.
On the old V8 flatheads we have used a grinder to deepen head recesses and/or run double head gaskets as suggested. Never a problem. Chap
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Old 10-01-2019, 10:55 AM   #8
Jim Brierley
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Default Re: piston hit the head

Stock-type pistons are not very thick, so be careful how much you remove. I've run 2 gaskets with no troubles.
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Old 10-01-2019, 12:48 PM   #9
Purdy Swoft
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Default Re: piston hit the head

Removing stock from the pistons effect balance if the pistons are not all the same weight . I would try another method or pick another block . adding extra head gaskets plays hell with the compression !!!
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Old 10-01-2019, 12:52 PM   #10
Y-Blockhead
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Default Re: piston hit the head

On Ford Y-Blocks, on the corner of each end of each head (exhaust side) there is a machined 'block' that measures 1". Anything less than 1" you can tell how much the head was machined.

Is there any such 'telltale' on a Model A head?
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