The Ford Barn

50Trucking · 03-07-2024, 09:18 AM

My main bolts are square and I can’t get 90 lbs of torque before the edges of the bolt head shear off with a 16 point socket.

oldspert · 03-07-2024, 10:05 AM

Quote:

Originally Posted by 50Trucking

My main bolts are square and I can’t get 90 lbs of torque before the edges of the bolt head shear off with a 16 point socket.

Buy a 9/16 square point socket.

Bruce of MN · 03-07-2024, 10:47 AM

I can’t remember, can you get a crowfoot wrench on it?

Flathead · 03-07-2024, 11:10 AM

The original bolts were a snug fit in the block. You would tighten up the nut, after positioning the cotter pin hole in the bolt for best installation. This snugness is what centers the main cap on the block, there are no dowel pins or other methods to keep the cap in position. The popular grade 8 bolts are looser in the block and do not center the cap. Just something to think about.

Bob Bidonde · 03-07-2024, 01:22 PM

Torque of a structural joint should be to 75% of the bolt / stud yield strength. This reduces the alternating stress range (varying tension) induced by the reciprocating parts in the engine. Reducing the alternating stress range significantly improves the joints fatigue life.

There should be nothing in the joint that compresses before the bolt / stud reaches its maximum loading. If there is, the joint looses its preload and the strength and fatigue life of the joint is threatened.
I strongly suggest that the original joint design should not be altered by the addition of any none stock parts.
Oil leakage from the exposed nuts is rare in my experience, but can be easily sealed by coating the nuts with an epoxy paint like POR15.

nkaminar · 03-07-2024, 06:24 PM

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On my Burtz block I used some O rings that had a small (thin) cross section. They were completely compressed into the hole so that the fastening was metal to metal.

All steel has very much the same coefficient of elasticity up to the yield point. It is 30,000,000 psi. The grade 8 bolts have a higher yield point than grade 5 or lesser grade.

Dan McEachern · 03-09-2024, 01:37 AM

Are you guys really pulling main bolts to 100 ft-lbs ???????????

Flathead · 03-09-2024, 03:28 PM

No.

Gene F · 03-09-2024, 03:39 PM

What Bob said goes for me too. I have a center pressurized main in my engine, and the microscopic amount of oil that may get past the shank of the bolt is insignificant. In fact, I have never even noticed such a thing on my car. I used to fix things (and equipment) for a living. We used to say tinkeridus has ruined a lot of equipment.

Just put the engine together, do a good job, and go on. No magic washers needed.

03-07-2024, 09:18 AM	#21
50Trucking Junior Member Join Date: Sep 2020 Location: St Augustine Fl Posts: 20	Re: Main bearing bolts My main bolts are square and I can’t get 90 lbs of torque before the edges of the bolt head shear off with a 16 point socket.

03-07-2024, 10:47 AM	#23
Bruce of MN Senior Member Join Date: May 2010 Location: VA Posts: 1,410	Re: Main bearing bolts I can’t remember, can you get a crowfoot wrench on it?

03-07-2024, 11:10 AM	#24
Flathead Senior Member Join Date: May 2010 Location: Southern Maine Posts: 1,499	Re: Main bearing bolts The original bolts were a snug fit in the block. You would tighten up the nut, after positioning the cotter pin hole in the bolt for best installation. This snugness is what centers the main cap on the block, there are no dowel pins or other methods to keep the cap in position. The popular grade 8 bolts are looser in the block and do not center the cap. Just something to think about.

03-07-2024, 01:22 PM	#25
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,472	Re: Main bearing bolts Torque of a structural joint should be to 75% of the bolt / stud yield strength. This reduces the alternating stress range (varying tension) induced by the reciprocating parts in the engine. Reducing the alternating stress range significantly improves the joints fatigue life. There should be nothing in the joint that compresses before the bolt / stud reaches its maximum loading. If there is, the joint looses its preload and the strength and fatigue life of the joint is threatened. I strongly suggest that the original joint design should not be altered by the addition of any none stock parts. Oil leakage from the exposed nuts is rare in my experience, but can be easily sealed by coating the nuts with an epoxy paint like POR15. __________________ Bob Bidonde Last edited by Bob Bidonde; 03-08-2024 at 10:03 AM.

03-07-2024, 06:24 PM	#26
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,899	Re: Main bearing bolts Sponsored Links (Register now to hide all advertisements) On my Burtz block I used some O rings that had a small (thin) cross section. They were completely compressed into the hole so that the fastening was metal to metal. All steel has very much the same coefficient of elasticity up to the yield point. It is 30,000,000 psi. The grade 8 bolts have a higher yield point than grade 5 or lesser grade. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

03-09-2024, 01:37 AM	#27
Dan McEachern Senior Member Join Date: Aug 2010 Location: SF Bay Area Posts: 193	Re: Main bearing bolts Are you guys really pulling main bolts to 100 ft-lbs ???????????

03-09-2024, 03:28 PM	#28
Flathead Senior Member Join Date: May 2010 Location: Southern Maine Posts: 1,499	Re: Main bearing bolts No.

03-09-2024, 03:39 PM	#29
Gene F Senior Member Join Date: Mar 2012 Location: Ohio Posts: 1,973	Re: Main bearing bolts What Bob said goes for me too. I have a center pressurized main in my engine, and the microscopic amount of oil that may get past the shank of the bolt is insignificant. In fact, I have never even noticed such a thing on my car. I used to fix things (and equipment) for a living. We used to say tinkeridus has ruined a lot of equipment. Just put the engine together, do a good job, and go on. No magic washers needed.