Oil leak at the head gasket
- Thread starter comnoz
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Hi, are they 24tpi, or 26 tpi ................?
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the Johnson Cams people recommend waisted head bolts for Triumph.
cNw
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Hey guys,
Short back ground to the cNw/ARP head bolts.
ARP never made any 26 TPI hardware. So when I approached them a few years back, they were willing to make them but I had to pay the tooling they needed to make this thread for my application. Quite honestly, it was a bit crazy what the hardware cost due the the tooling expense but I really wanted these parts since ARP really does make the best hardware for performance applications in the world.
I have used and offered the ARP kit for a few years now with great results and feedback. I personally have noticed that I don't have to re-torque the bolts but maybe one time. I only use genuine Flamering gaskets on my builds
Early on I did send a set to Jim to run on his bike. As he mentions, he uses copper gaskets and his modification has really changed they way the hardware works when used with a copper gasket.
He contacted me last week and we talked about his findings and the best way to offer this. The hardware is of course new and not just modified old bolts. I sent him 125 bolts to modify right away. He is only doing the 5, 3/8's bolts going through the head as the 3 studs don't need to get done since they are going through cast iron
As soon as I get the hardware back from Jim, the cNw kit will include these waisted bolts (5). Even tough an additional expense of course, I have decided to initially keep the price the same for my kit with the new bolts.
To anyone that have bought the cNw/ARP hardware and have yet to install it, I will exchange their unused kit with this new one at no extra charge. Contact me to see what exactly needs to be returned to me. I will cover shipping sending them back to you, regardless where you live
Thanks to Jim C. for doing the research and testing to make this available to all of us
Matt / Colorado Norton Works
www.coloradonortonworks.com
Short back ground to the cNw/ARP head bolts.
ARP never made any 26 TPI hardware. So when I approached them a few years back, they were willing to make them but I had to pay the tooling they needed to make this thread for my application. Quite honestly, it was a bit crazy what the hardware cost due the the tooling expense but I really wanted these parts since ARP really does make the best hardware for performance applications in the world.
I have used and offered the ARP kit for a few years now with great results and feedback. I personally have noticed that I don't have to re-torque the bolts but maybe one time. I only use genuine Flamering gaskets on my builds
Early on I did send a set to Jim to run on his bike. As he mentions, he uses copper gaskets and his modification has really changed they way the hardware works when used with a copper gasket.
He contacted me last week and we talked about his findings and the best way to offer this. The hardware is of course new and not just modified old bolts. I sent him 125 bolts to modify right away. He is only doing the 5, 3/8's bolts going through the head as the 3 studs don't need to get done since they are going through cast iron
As soon as I get the hardware back from Jim, the cNw kit will include these waisted bolts (5). Even tough an additional expense of course, I have decided to initially keep the price the same for my kit with the new bolts.
To anyone that have bought the cNw/ARP hardware and have yet to install it, I will exchange their unused kit with this new one at no extra charge. Contact me to see what exactly needs to be returned to me. I will cover shipping sending them back to you, regardless where you live
Thanks to Jim C. for doing the research and testing to make this available to all of us
Matt / Colorado Norton Works
www.coloradonortonworks.com
MS850
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Working at several car dealers, some engine head bolts are the waisted (stretch) head bolts, they have to be replaced if head is removed. The head bolt torque on car engines are much higher though. So I guess with the bolt size and small torque they should be able to reuse them.
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MS850 said:
The head bolts that are not re-usable are "Torque to yield" bolts. They are tightened beyond their ability to return to the same length when released -as a way of increasing the clamping pressure.
Waisted shank bolts are different in that they are not tightened beyond their elastic limit.
They are used where high operating temperatures or long clamped lengths mean there is enough expansion of the clamped material [the cylinder head in this case] that the clamping force overcomes the integrity of the clamped material.
The waisted shank lets the head expand more without the large increase in the clamping force you would see if the bolt could not stretch. Jim
MS850
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comnoz said:
Great info
thanks,
I have CNW head bolt kit on the engine now, any idea if you will be able to just get the waisted bolts only instead of the whole kit?
I say this because I probably be pulling the head off to replace valve stem seals.
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To answer Marks question:
The advantage of the triangular bolts is that they have been tested and proven for years now. Being triangular also makes it convenient to grab them with a crescent wrench for installation/removal (instead of locking two nuts together etc). Other advantages are spelled out in my previous post. But doesn’t really matter much whether they're waisted or triangular except that you might as well modify existing hardware if you need Whit worth threads. Both the headbolts and the studs should be triangular or waisted so both can stretch. The two 5/16” diameter bolts at the front of the oil leak prone pushrod tunnels are important and they clamp through a thickness of expanding alum cylinder head. The other two 3/8” studs near the pushrod tunnels will need to stretch from expansion when using aluminum cylinders. I’ve used them in motor building but haven’t been selling them outright.
You can see in the photo that there is a steel insert in the Alum head and these allow for the use of American threads for the three head studs.
The advantage of the triangular bolts is that they have been tested and proven for years now. Being triangular also makes it convenient to grab them with a crescent wrench for installation/removal (instead of locking two nuts together etc). Other advantages are spelled out in my previous post. But doesn’t really matter much whether they're waisted or triangular except that you might as well modify existing hardware if you need Whit worth threads. Both the headbolts and the studs should be triangular or waisted so both can stretch. The two 5/16” diameter bolts at the front of the oil leak prone pushrod tunnels are important and they clamp through a thickness of expanding alum cylinder head. The other two 3/8” studs near the pushrod tunnels will need to stretch from expansion when using aluminum cylinders. I’ve used them in motor building but haven’t been selling them outright.
You can see in the photo that there is a steel insert in the Alum head and these allow for the use of American threads for the three head studs.
cNw
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MS850 said:
After thinking about this further, I will be offering an exchange program for my customers that bought the kit cNw/ARP head kit. In other words, even if you have used the bolts I will exchange them with waisted ARP 12 point bolts.
Mark, get a hold of me at the shop and I will let you know what to send back
nortonworks@fone.net is the direct email
Matt / Colorado Norton Works
www.coloradonortonworks.com
comnoz said:
Hello Jim
Can i ask what the Belville part number of the these 5/16" washers is?
Over the pond here in the UK I can only find a metric version listed on the Belleville companys website http://www.bellevillesprings.com/
The stainless ones listed are not thick enough
The only item that comes close to the 80 thou thick x 3/4" dia are the heavy duty bolting washer part no CW 18842
Your hardened stainless washers under the head bolts, do you make them yourself or are they an off the shelf item?
Has anyone tried using these washers under a standard ( non waisted) head bolt with a reduced torque setting?
Regards
Peter
MS850
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I found these, not sure if there up to sunff.
http://www.ebay.com/itm/151823782941?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
http://www.ebay.com/itm/151823782941?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
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