Head Bolt Question

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Jun 29, 2004 | 11:46 AM

79F150400M

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Fleet Mechanic

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From: Arlington,Wa

Head Bolt Question

I have the Crane screw-in stud kit for my engine. The instructions recommend replacing the five bolts with reduced head bolts so one doesn't have to remove studs and guide plates to remove heads. I bought 10 allen head bolts of the same diameter but .25 shorter than the originals. I have 3 questions:

1. Does anyone think the shorter bolts will be an issue? (Im running the 268 Comp Cam and dished pistons in case your wondering about CR)

2. Dude behind the counter says the Allen bolts are better than Grade 8 bolts. Y'all think so????

3. Having a senior moment......do any head bolts need thread sealer???

I know ARP makes head bolts for this engine.....I'm trying to save a few bucks and some time. TIA for your input.

Last edited by 79F150400M; Jun 29, 2004 at 11:49 AM.

Jun 29, 2004 | 12:56 PM

beartracks

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From: Albuquerque

I have the ARP head bolt in a 400 but I don't think you can get to them all without removing the rockers anyway.

Jun 29, 2004 | 04:37 PM

Ecuri

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From: Houston/Hope BC

#1: I don't have my book with me but if I remember correctly you are supposed to have a min of 1.5x the diameter of the fastener of engaged thread... you will have to verify/measure this yourself.

#2: IF there was something better than grade 8 then SAE would sure have a name for it. Beware of anything claiming to be better than grade 8. Stock ford bolts are of excellent quality anyway. If the fastener is not specifically called out for this application by the manufacturer, IMO, do not use it!

#3: I never have used a sealant and have not had any problems, but that doesn't make me right. I believe the book calls for sealant on those that penetrate the water jacket.

GL

Jun 29, 2004 | 04:59 PM

Torque1st

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I would not be afraid to use socket head cap screws with hardened washers, but I would want the same or greater thread engagement as the stock bolts. Bolts normally have 1.5" of thread. You would not want to run out of thread either.

Jun 29, 2004 | 11:09 PM

79F150400M

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Fleet Mechanic

Joined: Feb 2004

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From: Arlington,Wa

Thanks for your input guys. I think I'll take the short ones back and get the longer ones and use the hardened washers Torque mentioned. So no sealer on the threads??? OK...didnt have it before so I suppose its not needed.

Last edited by 79F150400M; Jun 29, 2004 at 11:12 PM.

Jun 30, 2004 | 09:50 AM

beartracks

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From: Albuquerque

Black allen bolt actually do have a rating higher than grade 8". The scale doesn't stop at 8.

Jun 30, 2004 | 12:32 PM

Ecuri

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From: Houston/Hope BC

I stand corrected, somewhat. SAE stops at grade 8. The cap screws do have a higher rating but are rated by different standards from ASTM, ANSI, and ASTM. The point I was trying to make was if you are going to replace a fastener, know what you are buying and from whom. Also, do we need to consider that if we use cap screws on one side of the head and stock bolts on the other, do the torque specs need to be different for the cap screws to get the same clamping force? does it matter?