# head bolt replace



## tjs72goat (Jul 20, 2017)

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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## PontiacJim (Dec 29, 2012)

tjs72goat said:


> 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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## tjs72goat (Jul 20, 2017)

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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## cij911 (Oct 25, 2017)

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.


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## 1968gto421 (Mar 28, 2014)

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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## Pinion head (Jan 3, 2015)

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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## tjs72goat (Jul 20, 2017)

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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## PontiacJim (Dec 29, 2012)

tjs72goat said:


> 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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## tjs72goat (Jul 20, 2017)

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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## PontiacJim (Dec 29, 2012)

tjs72goat said:


> 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. :thumbsup:


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## tjs72goat (Jul 20, 2017)

Thanks for clarifying the dripper issue. The pics are helpful too. I do have roller tip rockers I just bought from Butlers, so those should be fine.


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## tjs72goat (Jul 20, 2017)

Posing this issue of welding to Butler Performance, they say it would be safer to just replace the specific head bolt with the studded stock one. So, that puts me back to mixing ARP and stock. Different torque values. I'd have to use my old since they only sell new in a kit. Initially I thought I wouldn't have to weld (heat much up), but it looks like the rear AC bracket is one of the head bolts, so that has more of a strength issue and would need a good weld on the head. Dilemmas!


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## Pinion head (Jan 3, 2015)

would leave the MIG welder for practicing on welding, get ready for sheetmetal work. Reinstall an OEM 3 3/4" studded head bolt for battery ground position AND on the other head for the AC mtg studded bolt, the latter gets 100 ft lbs. 

Wallace Racing - Pontiac Bolt Torque Values

As mentioned earlier, it's not my first rodeo on substituting a stock Pontiac head bolt in a mix of ARP head bolts. On a stock to considerably above stock power Pontiac V8 build, my Pontiac engine builder (as well as myself) typicall, only use ARP fasteners for rod bolts, & flexplate bolts. Going short fill on a two bolt block, am also sourcing & installing ARP main studs. The stock head bolts are more than capable of several duty cycles, your engine assembler is obviously new to Pontiac V8 builds, or he would have noted, didnt need the ARP head bolt set.

Have a fun budget build ported 7K3 "400" going into our '72 LeMans 400 Coupe to get my son some seat time @ the track. On its engine, Number #1 exhaust position is studded oem head bolt, non AC car, so I eliminated the studded bolt center of passenger side head. Only reason the 447 has ARP head bolts is I picked them up last Spring at local swapper for $50. The prev owner was doing a little over a stock rebuild, & after ordering, also figured out he was going to have problems not being able to have 6 studded head bolts needed for the preheater shroud, oil drippers, as well as the two 3 3/4" studded bolts.


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## tjs72goat (Jul 20, 2017)

Thanks PH. That may be the route I take. The issue with the bolts are, I bought this 72 sport coupe convertible (t41 option) this summer. Motor torn down (numbers matching). I didn't have all the parts and only one head bolt (with stud) in bucket of bolts. My co-worker builds his own engines (mostly Ford and Chevy) for his high end drag racing. He does work for others as well. He's very competent, but yes have done only a few Pontiacs in his time. He wasn't (as I was neither) aware of accessory head bolt stud issues. So, I backtrack and luckily for me, with sites and helpful people like yourself, get this baby back on the road. Thanks for your input, as well as others that respond to my issues. I do appreciate it.
TJ


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