Jarrid,
I have looked local for a replacement head bolt with no luck. Did a
search for Aircraft Spruce and looked at their bolts, is the thread
length long enough? I may not understand how the bolts are measured but
it looks to me as though the thread length would be short. Stock under
head length is 4 3/16 and the thread length is 7/8 or there about.. The
two bolts they list that are close in length are 4 1/8 and 4 1/4 both of
which have a 7/16 thread length if I am interpreting the spec correctly.
Which of their listed bolts is the one you were referring to? The two I
looked at are AN6-41A and AN6-42A. Thanks Jim
Jarrid Gross wrote:
>Jan,
>
>You are a brave soul, and I wish you luck building engines.
>
>All bolts stretch as a function of load, mostly determined
>by the diameter, not the material. Modulous of elastisity
>governs the stretch rate, and with most common steels this doesnt
>vary too much. Yeild and shear strengths are very material
>dependant, which is why more exotic materials can be stretched
>further before the yeild is exceeded, and the fastener fails.
>The sunbeam head bolts are not magic, they are 3/8 24 automotive
>bolt/studs. they were made 30+ years ago, and torqued/loosened
>many times most likely.
>
>You can purchase new bolts from any supplier that sells AN type
>hardware.
>
>Aircraft Spruce is one that is on the internet than will sell
>you AN hardware, just learn how to spec an AN fastener before hand
>because the length spec is different on the AN hardware.
>They have the right length in stock, I checked a few months ago.
>The will cost about $4 each, less in qty.
>
>Use good thick HARDENED washers underneath, and through away the
>rootes washers, they are junk.
>
>Although AN fastener will be better than the stock bolts, I would
>ONLY use them in a stock engine with the stock torque setting as
>AN fasteners are designed for high shear strength not yeild.
>
>Jarrid gross
>
>
>-----Original Message-----
>From: owner-alpines@autox.team.net
>[mailto:owner-alpines@autox.team.net]On Behalf Of jumpin'jan
>Sent: Friday, August 24, 2001 6:06 PM
>To: Alpine List
>Subject: Re: Question: head bolts
>
>
>Matthew,
>I wouldn't replace the head bolts at all. They are very specially made.
>Keep them! However, in today's engines it's a different story because
>they are designed to stretch and need to be replaced after each head
>gasket replacement.
>Jan
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