Freshly Rebuilt 350-Crankcase full of coolant

c1500deathtrap said:

Please stop perpetuating this. Not all head bolts are trashed after 1 torque cycle.

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tom joyce said:

Wheel studs do not hold 42000+PSI and are designed to not torque to yield. LOL. I doubt you understand that...lol

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tom joyce said:

Hope I'm not too late. Once you torque these head bolts they reach their limit. Some say you can reuse them, BUT I WOULD NOT.
Even though they are not tty bolts, they get weaker after torquing. You should install NEW head bolts EVERY time you loosen and/or remove them. IF you reused the same head bolts during the rebuild, then this is probably your problem.
New head bolts usually come with sealant on them. Even so, I put this stuff on the new bolts every time...

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tom joyce said:

Yep, that's correct, but the stock head bolts used in a stock vortec usually are, cus they were designed to be torque to yield (tty).

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evilunclegrimace said:

Neither do head bolts.
A 7/16 x 14 grade 8 bolt USS applies 9550 P (lb) of clamping force at 70 Lb Ft dry or 55 Lb Ft lubed.

A corresponding wheel stud 7/16 x 20 SAE applies 10800 P (lb) of clamping force at 80 Lb Ft dry or 60 LB Ft lubed.
Also since the wheel nut torque is higher than the values shown the clamping force will be much higher than the 1088 P listed.

I am quite sure that i understand.

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skylark said:

Gen 1 small block including the vortec has been using the same head bolts since 1955. If you look them up for a 1955 or a 1998, you'll see that they are the same part numbers.

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tom joyce said:

And?

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tom joyce said:

Clamping force/torque/size and the has nothing to do with what I said. A combustion chamber in a stock 350 produces 42k psi + at ignition. It is this force that the head bolts must hold. In the chevy 350 there are arguably 5 bolts to hold this pressure around the cylinder. The respective bolts clamping force/torque/size has NOTHING to do with the bolts 'ability' to perform this task. The head bolts ABILITY to stretch and retain enough clamping force/torque to hold the head gasket in place is what is the single most important design characteristic of a head bolt. Some head bolts can do this repeatedly as they are removed and reused. Some head bolts -like the ones in a chevy 350 vortec - do not have this design.
A wheel stud is designed to hold way more clamping force/torque. Wheel studs are designed to stretch repeatedly over long periods of time. They also are designed to hold a COMPLETELY different force that is applied to them...
Comparing wheel studs to heal bolts makes no sense at all...

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tom joyce said:

Clamping force/torque/size and the has nothing to do with what I said. A combustion chamber in a stock 350 produces 42k psi + at ignition. It is this force that the head bolts must hold. In the chevy 350 there are arguably 5 bolts to hold this pressure around the cylinder. The respective bolts clamping force/torque/size has NOTHING to do with the bolts 'ability' to perform this task. The head bolts ABILITY to stretch and retain enough clamping force/torque to hold the head gasket in place is what is the single most important design characteristic of a head bolt. Some head bolts can do this repeatedly as they are removed and reused. Some head bolts -like the ones in a chevy 350 vortec - do not have this design.
A wheel stud is designed to hold way more clamping force/torque. Wheel studs are designed to stretch repeatedly over long periods of time. They also are designed to hold a COMPLETELY different force that is applied to them...
Comparing wheel studs to heal bolts makes no sense at all...

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evilunclegrimace said:

You obviously don't have a clue. To say that a bolts clamping force/torque/size has nothing to due with a bolts ability to contain the combustion pressure is ludicrous. Using your analogy, 5 grade 2 one quarter inch bolts torqued to 30 Lb ft.can do the same thing correct? After all a bolts clamping force/size/torque have nothing to due with the bolts ability to perform this task.

I am not disputing the fact that there are TTY bolts that are one time use.

ALL bolts are designed to stretch when a torque load is applied to them their grade, diameter and thread pitch are all a factor in the design parameters.

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