head bolt replace - Pontiac GTO Forum
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post #1 of 14 (permalink) Old 12-10-2017, 10:16 AM Thread Starter
 
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head bolt replace

I'm having a co-worker who is a mechanical engineer and drag racer who builds his own engines (and others) rebuild my '72 400 engine. He rebuilt the lower end and heads and assembled on block. He used ARP head bolts. But, I need the special head bolts that have studs. He didn't know that, because my engine was apart when I bought it with no bolts. Is it ok to replace these one at a time and torque, or should all bolts be loosened and start the sequence from scratch. I haven't discussed this with him yet, but he probably knows what to do.
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post #2 of 14 (permalink) Old 12-10-2017, 11:16 AM
 
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Originally Posted by tjs72goat View Post
I'm having a co-worker who is a mechanical engineer and drag racer who builds his own engines (and others) rebuild my '72 400 engine. He rebuilt the lower end and heads and assembled on block. He used ARP head bolts. But, I need the special head bolts that have studs. He didn't know that, because my engine was apart when I bought it with no bolts. Is it ok to replace these one at a time and torque, or should all bolts be loosened and start the sequence from scratch. I haven't discussed this with him yet, but he probably knows what to do.
Here is what you should check. Sometimes the ARP bolts have a little different torque spec than the factory spec. Looking at the ARP website, it would appear the ARP head bolts torque down to 100 ft lbs. The factory head bolt torque is listed as 95 ft lbs. The ARP vs factory bolts are most likely of 2 different metal compositions. Not only is there a slight difference in torque values, but maybe in bolt material - so you could develop a problem by mixing them.

I would contact ARP to get your best answer if you are going to mix ARP and factory bolts.
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post #3 of 14 (permalink) Old 12-11-2017, 07:00 PM Thread Starter
 
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My dilemma is if I decide to leave the stud off, where do I attach some of the wiring (AC) or whatever else hangs on the stud? I also have chrome valve covers with no baffles. So, I'm not sure if this engine came stock with the oil drippers either. Anyone know? I also see pushrod guide plates offered and am not sure if I'm suppose to have those attached either. Anyone?
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post #4 of 14 (permalink) Old 12-12-2017, 07:31 AM
 
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If you want to replace them (all of the bolts), I have used the one by one method many times without issue.....That said I would likely just keep the ARP bolts as they are great. As PH pointed out, you don't want to mix the two bolts though.

1965 GTO Convertible 3 speed tri-power drum brakes originally

Current setup:
400 cu in with tri-power
4 speed Muncie
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post #5 of 14 (permalink) Old 12-12-2017, 09:54 AM
 
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ARP also makes studs as well as bolts. I would contact their tech line to find out what they can offer you.

800.826.3045

ARP | The Official Web Site

Hope this helps.
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post #6 of 14 (permalink) Old 12-12-2017, 12:33 PM
 
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The chances of one studded head bolt, @ the front lower position of #1 cylinder causing any form of harm being mixed with ARP's is minimal. It's not like the engine is seeing a 300 shot or double digit lbs of boost. The installing one or two factory studded bolt situation has unfolded countless times, even more since the introduction of Edelbrock heads. Over 20 years ago, after the first gen Edelbrock round port heads came out I provided a factory roundport studded head bolt to a local friend for just such an install on his 464. Engine was assembled with early E heads & with the Edelbrock supplied ARP head bolts. No sealing problems. Those original factory length round port head bolts & studded bolts didn't fall off trees. Finally, about 7 or 8 years ago, those hard find round port head studded bolts were reproduced. Similar deal with the 3.75" studded D port head bolts. My .02 for anything short of extreme applications, good used factory head bolts will suffice, no reason to even use the ARP's.

Something else to consider. When '66 & 67 Pontiac V8's were shipped by rail car out of the Pontiac engine plant to other assembly plants, does everyone think they shipped X amt of engines with the tall shank studded head bolt in the #4-6 center exhaust area, & then Y amt of engines with just a regular headed bolt in that position, just because some of those engines were going in factory AC cars & many were not? When these assembled '66 & 67 era engines made it to the assembly plant, they all had the bolt in the center exhaust position, original pics have noted this. When such an engine was readied for a factory AC build, the bolt was removed, and the special tall shank studded head bolt was installed to support the rear AC brace.
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post #7 of 14 (permalink) Old 12-12-2017, 08:27 PM Thread Starter
 
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I did call ARP tech and they didn't recommend mixing due to getting the torque correct for the replacement. I mentioned welding a bolt upside down to the head bolt to act as the stud. They said they didn't see a problem with that affecting their bolt.
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post #8 of 14 (permalink) Old 12-12-2017, 08:50 PM
 
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I did call ARP tech and they didn't recommend mixing due to getting the torque correct for the replacement. I mentioned welding a bolt upside down to the head bolt to act as the stud. They said they didn't see a problem with that affecting their bolt.
Interesting. I didn't think mixing the bolts was a good idea because of the torque differences between ARP and factory, but then I would have thought that the heat from welding a stud to the top of the bolt might affect tensile strength.

I would tack the stud, let it cool to room temp, then tack the opposite side, and repeat all around the stud to keep heat at a minimum. I would also have a qualified welder do this who would knows the best type of welding - Mig/Tig/Stick - to use.
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post #9 of 14 (permalink) Old 12-13-2017, 04:46 PM Thread Starter
 
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I'm finishing this build with my co-worker (he's a mechanical engineer and I'm a machinist) at work. I plan to have our seasoned welder at work do the weld for me. I do understand the heat issue, so I will allow it to cool as it gets done. It will be easy on the engine stand.
I'm still not sure if the oil drippers are necessary or if I am better off finding baffled valve covers. I have no way to attach the drippers if I use them, unless I also weld studs to those head bolts.
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post #10 of 14 (permalink) Old 12-13-2017, 05:10 PM
 
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Originally Posted by tjs72goat View Post
I'm finishing this build with my co-worker (he's a mechanical engineer and I'm a machinist) at work. I plan to have our seasoned welder at work do the weld for me. I do understand the heat issue, so I will allow it to cool as it gets done. It will be easy on the engine stand.
I'm still not sure if the oil drippers are necessary or if I am better off finding baffled valve covers. I have no way to attach the drippers if I use them, unless I also weld studs to those head bolts.

OK, sounds like you are in good hands and know what you are doing.

No, you don't need the drippers having the stud mounting. You can get the valve covers which have the drippers. Different types. The pics show the ones that are painted and have "double" dripper tabs and the chrome ones have the "single" dripper tabs. These changed depending on year, but cannot tell you specifics - some do not have them at all as I read the lower HP engines did not get them.

The only engine I had with the drippers that attached to the head bolts under the valve covers were on a 1967 GTO with the "670" heads. I don't think it is a critical item, just an extra (or concours correct) - in my book. Your aftermarket valve covers & others do not have them and if that important, they would all have the drippers. The best thing is to make sure your rocker arm balls have the oiling grooves machined in them versus the solid, no groove, balls. The grooves will channel the oil to the base of the rocker arm cup where all the wear/heat takes place.
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