High compression head torque

[Marshall57]

Hi Folks,
I just put a high compression head on a Model A and was wondering if the torque required was to be higher than 55 lbs. of torque? Grade 8 hardware is recommended and that got me thinking that the extra strong hardware was used because the head needed more torque than its less compression brothers. Any comments would be helpful, because there doesn't seem to be much on this that I can find. Thanks in advance.

[Glenn C.]

With both of my cars, I stayed with the 55lbs, as a person still has to be concerned with the integrity of the threads in the block. Still check them again after you have run the engine up to temperature, and let it cool back down

[Mikeinnj]

A recent call to Snyders told me not to go higher than 55 foot pounds on the head studs as the threads in the block may deform and pull up.

[Glenn C.]

I have also found that the replacement studs do not "bottom out" in the threaded holes in the block. If you do bottom the stud out, the stud is not long enough to use the correct thickness of nut, and still provide 1 1/2 thread exposure above the nut. A small amount less is still acceptable.

[Marshall57]

Thank you guys, that is exactly what I found but was wondering if I had it right.

[wensum]

Sponsored Links (Register now to hide all advertisements)

When I found the high tensile studs too short for the Winfield head, I had a new set made locally.
As only metric stock is available, they had to be machined down from larger diameter material.
Interestingly they fitted more accurately in the block threads and were more perpendicular enabling the head to slide on effortlessly.
I have torqued them to 65ft.lbs and now after 4000 miles there have been no problems.
With the block bored to 100thou oversize I was concerned at how little meat there was between bores and felt the extra torque justified?
Keith

[Bruce Adams]

I was told to torque my HD head to 65 Lb-ft by my engine rebuilder, Antique Engines in Skokie, IL, by Rich the owner. I have 10,000 miles on it. I did have a head gasket fail at 7000 miles which I replaced with the BEST 573 gasket and all is well.

[Y-Blockhead]

Originally Posted by Bruce Adams

... I replaced with the BEST 573 gasket and all is well.

Did you use the 573C (Copper) or the 573G (Graphtite)? I only ask because most recommend Copper head gaskets but I've had good luck with the Graphtite head gaskets on Y-Blocks.

[Bruce Adams]

Originally Posted by Y-Blockhead

Did you use the 573C (Copper) or the 573G (Graphtite)? I only ask because most recommend Copper head gaskets but I've had good luck with the Graphtite head gaskets on Y-Blocks.

It was a composite, and clearly not copper, so I guess it is Graphite based upon your statement. It is gray in color.

[Mike V. Florida]

60 to 65 ft.-lbs was recommended with the Brumfield HC heads

[H. L. Chauvin]

A. In my opinion, head surface flatness and block surface flatness are more important than types of head bolts, types of head gaskets, different head gaskets sealers, and extra applied torque which in excess, can over-stress center bolt(s) areas of blocks.

B. Just one (1) recent experience:

C. Installed my Original High Compression Police Head with:

1. New standard head bolts as opposed to a higher grade; and,
2. Torqued incrementally to 55 ft-lbs as opposed to 65 ft-lbs.; and
3. Used the new silicone head gasket as opposed to the recommended copper one; and,
4. Provided Permatex No. 2 non-hardening gasket sealer on both sides of the silicone head gasket as opposed to the recommended no gasket sealer.
5. No leaks in over six (6) years.

But as always, Model A owner opinions vary ... so one should do what he/she thinks is best.

[Mike V. Florida]

Originally Posted by H. L. Chauvin

A. In my opinion, head surface flatness and block surface flatness are more important than types of head bolts, types of head gaskets, different head gaskets sealers, and extra applied torque which in excess, can over-stress center bolt(s) areas of blocks.

Some more from the maker of the Brumfield head,

" ...the block and the head combined should be flat at .0035 maximum, i.e., no more than .002 on the block and about .001 on the head (flat less than .001 is best on the head as well as flat less than a .001 on the block if possible). Please check the block and head (after re-surface) to make sure everything is in range. Otherwise, depending on how far you put the pedal to the floor, service life may be less."

[PC/SR]

I "compromised" at 60 lbs, with a Best composite gasket and copper coat spray on both sides, ARP bolts which I like because they are straight and the head goes on easy.