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Manifold Clamps

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jdpan
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Manifold Clamps

#1

Post by jdpan » Sun Jul 31, 2011 2:54 am

Quick question..... So after discovering a huge manifold leak, I decided to trash the two piece clamps in favor of the stock style clamps. Do these clamps need to be cinched down even with the manifold squishing the o-rings or should there be a slight gap?.... Checking the two piece clamps revealed that they were oval instead of round, I'm certain they were pinching the o-rings causing the leak.. That is all..



Cotten
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Re: Manifold Clamps

#2

Post by Cotten » Sun Jul 31, 2011 2:31 pm

Jdpan!

Your question is not clear.
Please remember that the clamps do not hold the carburetor on the machine: a support bracket does that.
The clamps only compress the O-rings, nothing more. The assembly must "float" with the expansion and contraction of the motor.
Over-tightening creates leaks, so it is best to bubble-test while installing.

....Cotten

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Re: Manifold Clamps

#3

Post by jdpan » Sun Jul 31, 2011 9:01 pm

Perhaps a photo will help. As you can see, there is a substantial gap between the clamp and the manifold that is exposing the o-ring. My question is, should the clamps be tightened to the point to where this gap is not there... It just looks out of place.
I'm not concerned with the clamps keeping the carb in place, my concern is the seal..

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Re: Manifold Clamps

#4

Post by Cotten » Sun Jul 31, 2011 10:13 pm

JdPan!

With an aftermarket manifold, and apparently aftermarket "conversion" intake nipples as well, you are lucky it fits as well as it does.
They should be of similar dimensions.

The success of the 'seal' depends entirely upon the results of the bubbletest, and whether or not the clamps want to vibrate into a different position. This is a common problem when the outside diameters of the nipples and manifold are different.

....Cotten

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Re: Manifold Clamps

#5

Post by jdpan » Sun Jul 31, 2011 10:21 pm

They are of similar dimesions. What I need to know is, should I tighten the clamps so the o-rings are squashed into the groove to the point where the clamp is loosley tightened against the nipple and manifold. I realize this is tractor technology but Ive never seen one that had such an obvious gap. So just leak test and tighten as I go to eliminate leaks while minimizing the gap?

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Re: Manifold Clamps

#6

Post by jdpan » Sun Jul 31, 2011 11:06 pm

Never mind, I got it...

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Re: Manifold Clamps

#7

Post by jdpan » Mon Aug 01, 2011 5:28 am

Homemade acrylic adaptor, took an hour to make with parts I had laying around.

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Re: Manifold Clamps

#8

Post by duoglide58 » Mon Aug 01, 2011 5:59 am

I know what you mean about the 2-piece clamps. I think they could be built better. Don't know if ya'll have seen Victaulic fittings before, but they are used alot on fire water systems in buildings and in the oil patch. They clamp down more uniformly and have tongue & groove notches where each clamp halve fits together. The best way would be to have a grooved cut on the intake and head where some sore of victaulic clamp would engage the grooves. This would provide both mechanical strength as well as a seal. If only I had the skills and equipment to make it. A picture would make it more clear.
http://www.victaulic.com/content/plumbi ... utions.htm
http://www.victaulic.com/inCommerce/pro ... &site_id=1

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Re: Manifold Clamps

#9

Post by Cotten » Mon Aug 01, 2011 6:51 pm

Doug!

"Mechanical strength" is not an issue when the assembly is intended to float with the expansion and contraction of the cylinders.
The clamps do not hold the carburetor onto the machine.

The two-piece clamps fail for the same reason as any over-kill attempts: the O-rings swell enormously in modern fuels.
Gumiwurm.jpg
The solution is to use the gentlest clamps, and viton O-rings that do not swell noticeably (JAMES).

....Cotten
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Robert Luland
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Re: Manifold Clamps

#10

Post by Robert Luland » Mon Aug 01, 2011 11:48 pm

[quote="duoglide58"]I know what you mean about the 2-piece clamps. I think they could be built better. Don't know if ya'll have seen Victaulic fittings before, but they are used alot on fire water systems in buildings and in the oil patch. They clamp down more uniformly and have tongue & groove notches where each clamp halve fits together. The best way would be to have a grooved cut on the intake and head where some sore of victaulic clamp would engage the grooves. This would provide both mechanical strength as well as a seal. If only I had the skills and equipment to make it. A picture would make it more clear.

It won't work. The way a Victaulic fitting works is on pressure. It won't work in a vacuum. The pressure forces the seal back down on its self. All the cast iron coupling does is keeps the two pipes from separating. Nothing more, nothing less. Bob L

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Re: Manifold Clamps

#11

Post by jdpan » Tue Aug 02, 2011 7:23 am

Almost all of the leak is from the adaptor nip... O-rings were good at 5 psi. What thread sealer?

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Re: Manifold Clamps

#12

Post by Cotten » Tue Aug 02, 2011 4:49 pm

JdPan!

Please search the Knowledge Base, as repair of leaky nipples can be a real test of patience.

Since JBWeld is attacked by this year's P4gas in my region, I no longer have a good suggestion for a sealer.

....Cotten

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Re: Manifold Clamps

#13

Post by duoglide58 » Tue Aug 02, 2011 7:59 pm

It won't work. The way a Victaulic fitting works is on pressure. It won't work in a vacuum. The pressure forces the seal back down on its self. All the cast iron coupling does is keeps the two pipes from separating. Nothing more, nothing less. Bob L
Victaulic offers a flush seal gasket for vacuum service.
Mechanical strength" is not an issue when the assembly is intended to float with the expansion and contraction of the cylinders.
The clamps do not hold the carburetor onto the machine.
There are different styles of clamps, some of them have quite a bit of floating room or joint play for joint expansion. In fact, I have installed a series of them for use as expansion joints on piping. If a clamp provided some degree of mechanical rigidity above what the stock band clamps provide, the joint would be less likely to leak. The Vic connnection also has bigger gaskets compared to the small area that the Panhead's O-ring provides. The brace under the Linkert cannot keep the carb from moving out of alignment without some help from the clamps.
I'm just saying there is a better sealing method than the o-rings and band clamps, but the biggest constraint would be the room for the clamps.
Doug

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Re: Manifold Clamps

#14

Post by fourthgear » Wed Aug 03, 2011 1:13 am

Yes, the clamps do help hold & secure the carb/manifold & the carb bracket is to keep it level & is also another attachment point for the carb/manifold.

With stock clamps , you can not get them tight enough to prohibit expansion.

The after market ones ,like the two piece ,can limit the freedom of movement from exspansion.

I just get them aliened & torque them down & have no probems with leaks.

Its not rocket science. Just a clamp.

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