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post #1 of (permalink) Old 06-29-2001, 09:53 PM Thread Starter
 
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Replacing the head bolts during a rebuild

Is it recommended to replace the head bolts during a rebuild? Yeah, I know it would be better than not, but $80 is worth asking. What do you guys do?

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post #2 of (permalink) Old 06-29-2001, 10:46 PM
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Re: Replacing the head bolts during a rebuild

No, don't reuse them... $80 is a small price to pay to do the job correctly. I always use new head bolts. It's cheap insurance and if I have the money and time to do it, I do it right and don't have to worrry. I can sleep at night when the wind blows.....

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post #3 of (permalink) Old 06-30-2001, 12:04 AM
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Re: Replacing the head bolts during a rebuild

Head bolts are designed to torqued one time.I can't remember specifics,but that's what I've been told.Could cause you problems as far as head gasket sealing[after a period of time] if you use old bolts.

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post #4 of (permalink) Old 06-30-2001, 12:44 AM
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Re: Replacing the head bolts during a rebuild

There are two types of head bolts. Those that you use once, and torque to yeild bolts.

The 4.2L has the type that you can use many times.
The 4.0L has the torque to yeild bolts.

The torque to yeild bolts will acutally strech when torqued. This applies bolt thread pressure to the cylinder block threads, securing the head. If you attempt to use this type of bolt a second time the stretched bolt often will snap in two. Then you're in for a treat removing the bolt. The stretching also makes re-troquing the bolt impossible because the bolt no longer holds manufacture tollerences.

It's personal oppinion of mine to repace the bolts regardless of the type because you may not be aware of the boltsí history (overtorque, etc.). I don't need a used bolt snapping, binding, double threading, or causing more headaches such as a warped head.

Though I'm cheap, I'm cheap for a reason. This is one time where I defer in the area of extra cost. In the long run when a head bolt problem never occurs it is money well spent.

I always install headbolts with a drop or two of light oil on the threads. It eases insertion. A couple of drops under the head of the bolt also eases contact with the head during torque. Some installers install dry because they feel the oil throws off the torque seting. Though I can agree in principle, I can't agree in practice.

Thighten the bolts to specification by dividing the total torque setting into three steps. Use a criss-cross inside to outside pattern when torquing and you'll end up with a quality job.

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post #5 of (permalink) Old 06-30-2001, 06:02 AM
 
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Re: Replacing the head bolts during a rebuild

Since I was just doing some research on this subject.....

Check out ARP's website for some interesting info on bolts (head bolts too):
http://www.arp-bolts.com

'79 CJ-7
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post #6 of (permalink) Old 06-30-2001, 07:57 AM
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Re: Replacing the head bolts during a rebuild

I would just like to say this bulletin board is a gold mine of information!

post #7 of (permalink) Old 07-02-2001, 02:06 PM
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Re: Replacing the head bolts during a rebuild

If you are doing an entire rebuild, I would replace the connecting rod bolts too. I lost one once, and the engine was a total loss. Bolts are cheap compared to the cost of an entire engine.

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post #8 of (permalink) Old 07-02-2001, 04:08 PM
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Re: Replacing the head bolts during a rebuild

I have never replaced the head bolts of any engine, and I've never had a problem. fwiw

post #9 of (permalink) Old 07-02-2001, 05:42 PM Thread Starter
 
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Re: Replacing the head bolts during a rebuild

I replaced the connecting rod bolts, kept the main bolts and was wondering on the head bolts. In case I decide to replace the main bolts, can I just remove one at a time and retorque or should I go through the plastigage thing again?

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post #10 of (permalink) Old 07-02-2001, 06:50 PM
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Re: Replacing the head bolts during a rebuild

No need to recheck it.. I don't understand why you are so concerned about the bolts, unless it's a real high-perf engine, it should be fine.

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