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VN V8 Head stud problem

Started by _LHoon_ , Sep 21 2006 08:41 PM

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28 replies to this topic

#1 _LHoon_

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Posted 21 September 2006 - 08:41 PM

Hi eveyone, I'm bolting on VN heads with an ARP head stud kit. But discover that there is very limited space around the end stud. I'm told the standard head bolt for this position may be a allen head bolt. But with a stud kit, the nuts are quite large and I'm having trouble getting a torque socket wrench onto it.
See the picture below (the right nut is the problem one)

So what's my best option? Do I remove that stud and just put a standard bolt back in? Or should I try grinding a bit of clearance around this nut?? Why is this particular head bolt different to the others? Has anyone else come across this problem?

Posted Image

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#2 _rorym_

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Posted 21 September 2006 - 08:45 PM

I would go for the std bolt...sheet! Look at those VN ports!! They will make my new motor hum!!
R

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#3 Struggler

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Posted 21 September 2006 - 08:51 PM

Correct, you must refit the original cap screw bolt. You will find the same thing at the back of the pass. side head.

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#4 _LHoon_

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Posted 21 September 2006 - 09:00 PM

Wow - Thanks for the quick reply guys!

Is there any reason why I can't 'create' some clearance? I mean, I may as well use those two head studs - considering I've paid for them and they're meant to be better and all....

Why is this particular bolt arranged like this, anyone know?

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#5 rodomo

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Posted 21 September 2006 - 10:17 PM

Can you fit your exhaust with those studs? Looks a bit close in the pics?

Edited by rodomo, 21 September 2006 - 10:18 PM.

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#6 _82911_

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Posted 21 September 2006 - 10:27 PM

The only way around it using the stud kit on the end holes is going to be by plunge milling the relief aroung the area that the head nut and washer seats on. To do this you are going to have to remove both heads and send to a competent machine shop (unless you have a mill).
Keep in mind though that you might still run into interferance problems with your extractors fouling on the studs..
CHECK EVERYTHING... if you choose this option.
Or put the factory capscrews in those 2 spots and clamp it all down.... Go have a beer...
Much simpler idea really........ :rolleyes:

Cheers Greg..

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#7 _LHoon_

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Posted 21 September 2006 - 10:33 PM

Can you fit your exhaust with those studs? Looks a bit close in the pics?

Hmmm.... I don't know, I haven't actually got extractors yet!! Maybe that's why I will actually need to use the bolt instead of the stud. Good point!!
Here's a slightly different angle:

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#8 _LJ355_

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Posted 21 September 2006 - 11:25 PM

Ive just got a set for my new engine are my extractors going to hit the studs ? i think il use the original allen bolts on the ends too what a bugger !

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#9 _bodallafella_

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Posted 21 September 2006 - 11:45 PM

You can use the ARP studs on the VN heads but you will need to get 2 ARP 12-point nuts for extra clearance. The thread size is 7/16.

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#10 warrenm

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Posted 22 September 2006 - 08:41 AM

Agree with bodallafella, a couple of 12 point nuts should solve the problem.

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#11 _LHoon_

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Posted 22 September 2006 - 05:04 PM

Good advice! Thanks.

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#12 Struggler

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Posted 22 September 2006 - 08:00 PM

A 12 point nut still doesn't address the fact that the exhaust won't clear the stud.

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#13 355LX

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Posted 23 September 2006 - 08:25 PM

My VN heads have been machined as Struggler mentioned for clearance around the nuts, and the ends of the studs have been machined down to allow clearance for the extractors. Just bite the bullet and do it right, you'll be happier in the longrun......or use the capscrews

Dave

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#14 _gtr-xu1_

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Posted 24 September 2006 - 01:20 AM

yeap as stated use 12 points and cut down the studs. I did this excercise back in the mid 90s with a group A VN headed 331 ofset stroker

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#15 _CHOPPER_

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Posted 25 September 2006 - 02:34 AM

Out of curiosity, would the issue still arise if using YT VN alloy heads?

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#16 _[BOTTLEDUP]_

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Posted 26 September 2006 - 09:30 PM

yes.

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#17 Dr Terry

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Posted 27 September 2006 - 08:59 AM

Hi Guys.

Without opening up the old can of worms, I'd like to hear some of you guy's thoughts on a problem I've had with head stud kits. I've used them on several engines, mainly blown or nitrous V8s & have found that if you use the same torque figures as factory bolts they distort the deck & overcompress the gasket material. What I have found is that because the nut thread is UNF, which is a finer pitch than the UNC thread into the block, the same torque figure causes a much higher bolt 'tension'. In other words the bolt (or stud) is 'pulled' more because the pitch is finer.

It took me a while to find any info on this, but there are some engineering standards that allow the difference to a factor of 1.5. In other words a UNF bolt torqued to a 100 Nm will result in the same actual bolt tension as 150 Nm for a thread of the same diameter but with a UNC thread.

Anybody else had experience in this area. Many people don't even think of this & torque the studs to the factory UNC bolt specs.

Dr Terry.

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#18 _LHoon_

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Posted 27 September 2006 - 02:22 PM

Interesting point Dr Terry. It would definitely make a difference to the torque readings.

However, I just followed the torque specs that came with the ARP head stud kit, rather than using the Holden specs that came with the head gasket.

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#19 Dr Terry

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Posted 27 September 2006 - 04:04 PM

Hi LHoon.

What torque figures did ARP give. Much less than factory ??

Dr Terry.

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#20 _LHoon_

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Posted 27 September 2006 - 04:17 PM

That info will have to wait until I get home tonight.... gotta look in the garage for that little piece of paper. I can't remember off the top of my head.

Standby...

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#21 _82911_

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Posted 27 September 2006 - 05:08 PM

The comparison between UNC and UNF may well be true DR Terry. I can see the logic in it.
BUT....
I can't see the factor really being a straight 1.5:1
maybee there is a sliding scale??
Reason I say that is I can't imagine that the head on my 12;1 comp 202 is going to stay put for very long with only 42.5ft/lb on the studs!
I would be very keen to know what the end results of this search is........

Cheers Greg..

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#22 _bodallafella_

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Posted 27 September 2006 - 07:30 PM

I think the difference would be much less than 1.5. If you look at the torque specs on the ARP website they advise the following:

7/16 Stud = 71 ft/lbs
7/16-UNC = 73 ft/lbs
7/16-UNF = 80 ft/lbs

So it seems that the difference between a UNC and UNF bolt is greater than between a bolt and a stud but still nowhere near 1.5 times. This assumes that ARP have correctly compensated for this effect which they may not have. If you look at the tech info in the ARP catalogue you will see that they really know their shit and I doubt they would overlook something as basic as thread pitch. I have used ARP head studs on a number of high powered Holden strokers as well many other engines and have never noticed this problem but I always follow the recommended torque specs and use the ARP lube.

Nick

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#23 _LHoon_

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Posted 27 September 2006 - 09:47 PM

I've got the piece of paper that was in my ARP head stud kit. It says:

Torque values are based on 75% of the fasteners yield strength.� Use the manufacturers torque sequence but do not use the engine manufacturers torqu specs.� Torque nuts to 70 ft lbs for ARP MOLY ASSEMBLY LUBRICANT or torque to 85 ft lbs with 30wt motor oil.

So I used 85 ft lbs because I only had motor oil available as a lubricant at the time (and not the ARP assembly lube). I'm not sure what standard Holden specs are. So, by how much do they differ?

Edited by LHoon, 27 September 2006 - 09:48 PM.

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#24 _LX406_

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Posted 27 September 2006 - 10:05 PM

And some advice I recieved once of a wise well known engine builder is when you first put the motor in the car, bung some chemiweld in the radiator so the studs dont leak water.

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#25 _bodallafella_

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Posted 27 September 2006 - 10:48 PM

I just checked an ACL gasket set and it says 76 ft/lbs it also says that bolts 3 and 5 should only be torqued to 40 ft/lbs. I would assume that these figures are with motor oil as lube.