head bolts grade

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tinner12
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head bolts grade

Post by tinner12 » Sat May 27, 2023 6:48 pm

I had my engine rebuilt and after machineing my head bolts are a 16 th to long . Im going to 2 1/2 " bolts. Do they need to be grade 5 or 8


Topic author
tinner12
Posts: 55
Joined: Sat Sep 11, 2021 8:31 am
First Name: Vernon
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Location: newport wa

Re: head bolts grade

Post by tinner12 » Sat May 27, 2023 6:56 pm

Found my answer in the search part of the forum


Art M
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Re: head bolts grade

Post by Art M » Sat May 27, 2023 7:49 pm

Just grind 1/16 inch off the end of the standard bolts. As often suggested on this forum, check the the bolt lenght by setting the head on the block without a head gasket and the bolt head must contact the cylinder head rather than bottoming out. Install each bolt in the location that the the check was made. Bolt hole depth varies from hole to hole. Failure to do this could result I. Bottoming out the bolt and cause a lot of trouble.

Art Mirtes


jiminbartow
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Re: head bolts grade

Post by jiminbartow » Sat May 27, 2023 10:16 pm

When grinding the end off a bolt, it can damage the threads on the end of the bolt so you will not be able to get it started into the hole, so, before grinding the bolt down, screw on a nut. After grinding off what you need to, bevel around the end of the bolt then remove the nut, which will open up the threads on the end that were flattened and damaged by the grinder.


frontyboy
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Re: head bolts grade

Post by frontyboy » Sat May 27, 2023 11:13 pm

Another issue that will give you a false depth gage reading is the base of the head bolt hole collects hard packed carbon. I use a small bore brush cut the end off chuck it up in my drill, flood the hole with brake clean and clean the hole. You will be amazed how much crude you will get out.

just sayin'

frontyboy

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George Mills
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Re: head bolts grade

Post by George Mills » Mon May 29, 2023 9:06 am

Not sure what you found doing the other research...

The FORD OEM bolts were actually grade 2/3. You can't buy that grade anymore so 5 works.

The FORD design only has 2/3 of the threads needed to conform to Torque tables of today, (but everyone seems to ignore that.)

The design torque is closer to 35# -38# seating (but everyone seems to ignore that too.).

Using an Aluminum head changes everything.

DO take a dental pick and clean all the way down each tap as every thread actually counts...work with a 7/16-14 Bottom tap if you can as your 'chisel' . (At the time of the T design they were not yet aware...once there has been run in and out a few times you can't really rely on the top lead thread anymore in the stretch scenarios. Thread failure is actually a pancake failure where each thread lets go from top to bottom.)

I know, nobody asked :roll: its been a while since a reminder discussion...sorry.

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RajoRacer
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Re: head bolts grade

Post by RajoRacer » Mon May 29, 2023 11:19 am

Anyone who replaces a head or head gasket should have one of these in their toolbox -
Attachments
head bolt clean-out tap.jpg

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