Intake seal question

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jlaley
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1954 FL
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Intake seal question

#1

Post by jlaley » Sun Jun 08, 2008 2:08 pm

I don't know if I've seen this on here before but it's easy to ask again if it has. What are the best o rings and clamps to use on these? I pressure tested my intake and got a leak on the front head and intake. The clamps that I used came with the bike and I think they're the problem. Heads were done at Head Hog's. Heads are lined up with the intake and I have a .030" gap when manifold is held against one head and measuring the other. Time for new clamps I guess. So what's best?
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VT

#2

Post by VT » Sun Jun 08, 2008 3:07 pm

I use the same kind of clamps, but I let the buckle drop from the position yours are in, to where the buckle is at 9 o'clock. Are you putting too much clamp pressure on the O-rings? It looks pretty tightened down. I use James O-rings or H-D, but they're pretty much the same. 030." air gap between manifold and head seems ok.

jlaley
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#3

Post by jlaley » Sun Jun 08, 2008 4:13 pm

Thanks for the reply. I do have them snugged down pretty good. Not to where I couldn't tighten it more. The position of the clamps doesn't seem important right? I wanted the threaded bolt out of sight with the tanks on. I never thought to loosen them a little when it leaked, I tried tightening them a little more to no avail. The O rings are James now.
Jim

Cotten
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#4

Post by Cotten » Sun Jun 08, 2008 4:34 pm

Jlaley!

I seriously suggest a new pair of clamps that use a #10 screw instead of 1/4" exhaust clamps.

Please remember that the clamps do not hold the carburetor on. They only compress the o-ring. Even the screw design can be over-tightened, so pressuretesting while installing will help you find the sweetspot where it seals easiest.
Some O-rings swell twice their size in modern fuel, getting tighter by itself, and extruding rubber into the manifold.

A light hose between your gauge and the testplate would allow the manifold to 'float' rather than support your apparatus. The carb support should then be tweaked to allow the carb flange to mate to the manifold with no stress or bind.

Good luck!

....Cotten
Last edited by Cotten on Sun Jun 08, 2008 4:41 pm, edited 1 time in total.

jlaley
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#5

Post by jlaley » Sun Jun 08, 2008 4:39 pm

Thanks Cotten. These are intake clamps. The bolts are 10's not 1/4's, they just look big in the pics. 3/8" wrench size on the nuts. I'll try your suggestions on the install.
Jim

VT

#6

Post by VT » Sun Jun 08, 2008 4:57 pm

Your clamps are okay. No it wouldn't matter where the buckle was positioned. You might want to try and remove the clamps (not fun) and see what sort of squash pattern is imprinted into the O-rings. Use an extension mirror to look at the rings 360 degrees. Leaks seem to always be in the spot most difficult to see. Which side of the clamps do you see bubbles at (both sides?) ? Mark the leak area(s) on manifold before you remove the clamp.
Image
Was this the same amount of gap on each side of your manifold?
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I measured the gap to be close to 0.031" on each side of manifold.
Last edited by VT on Mon Jun 09, 2008 3:44 am, edited 1 time in total.

jlaley
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#7

Post by jlaley » Sun Jun 08, 2008 6:22 pm

The leak was on the front cyl. and to the manifold side of the clamp. I did mark where it was leaking and have it apart again. You're right, they are a pain. The gap you show in your pic looks bigger than mine but it's hard to say. Like I said, .030" is total of what I have. .015" each side. I'll try installing them again after looking at them closely again and see what I've got.
Jim

VT

#8

Post by VT » Sun Jun 08, 2008 6:31 pm

Okay. My big gaps seal fine. I'm wondering how lined up your manifold hole is to your head hole? Probably okay, but mis-alignment would keep the o-ring from a direct in-line seal.
This isn't a stroker motor or the heads bottom haven't been over-milled to flatten head bolt inserts have they? Clymers book has examples of those heads with the "footprint" flange milled down to nothing and it changes the alignment of the head intake ports to the manifold.

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#9

Post by fourthgear » Sun Jun 08, 2008 9:58 pm

Looks like the one that is leaking is cocked a little , you should make sure they do not twist when tightening down. Some times I use a screw driver or some thing for a wedge to keep the clamp flush to tighten.
I have used oem , # 10's,and 1/4 type clamps and I can get them all to work , it really doesn't matter which ones you use , its all about fitment and alignment .( and I point the clamps with the threads down, I don't mount the clamps in that position you have them in , they seem to hang up in that position. What ever works for ya.

jlaley
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#10

Post by jlaley » Sun Jun 08, 2008 10:40 pm

Well, I tried re-doing it being very careful and with the clamps bolt pointing down and it still leaked in the same spot. I got the magnifiers out and was surprised to see that it doesn't appear to be leaking from the seal. It's the manifold itself. You can see in the picture that there is a "bad" casting mark on the outside where the arrow is pointing. That is where the bubbles are coming from. I cannot see anything at all on the inside but this seems to be my problem. It goes to work with me tomorrow to be welded up. Nothing ever seems to go right on these things. LOL or maybe CryOL. Thanks for the help guys, I'll let you know if it works. Jim
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VT

#11

Post by VT » Mon Jun 09, 2008 1:13 am

It's the manifold itself. You can see in the picture that there is a "bad" casting mark on the outside where the arrow is pointing
Yea, it takes getting out the ol' 3' magnifying glass and peering in to the contact surfaces and casting porosity's. Good find though. Demon leak.
If you're going to replace it with a Colony replica, call Kick-Start M/C Parts (616) 245-8991 (EST) and order one.
We're working on a new media project for Panhead. Circle-the-wagons. We want to keep a tighter rein on quality control. Our motto is "Don't waste our time and money on repop parts that don't fit". Buy from a local outfit that knows what we ride and what we want, first time out.
No, Kick-Start does not give me a "cut".

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#12

Post by 51Hog » Mon Jun 09, 2008 2:12 am

I did call Kickstart about the belt drive I was looking for. I was not impressed with the guy that answered the phone or the attitude he had about pricing.

VT

#13

Post by VT » Mon Jun 09, 2008 3:32 am

Glad you mentioned that. Not all parts and problems and variables are the same.
Belt drives and their installation is a broad range subject, second only to what brand wt. of oil people have opinions on.
It wouldn't be fair to yourself, not to stick with Kick-Start, because it develops into a parts life-line sometimes, when you need onesey-twosey parts without having to buy a whole kit assembly, and that needed part can be sent to you in an envelope in the mail and not UPS'd. Therein lies the value of the relationship.
••••••••••••••••••••••••••••••••••••••••••••••••••••••••
My way of getting straight to the parts bin, is to look in their catalog first, and make a laundry lists of parts and the K.S. part number.
If there is no part number at least have your zip code memorized, because that's how they know who you are, after you've ordered once. Being prepared is a good defense against a Monday morning howdy-do train wreck.

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#14

Post by mbskeam » Mon Jun 09, 2008 5:00 am

I use the same clamps and they work well, kinda a bitch to get on tho...

on the S&S manifolds you might find that your clamps slide in, away from the heads. if you notice the S&S manifold necks down and the oem is the same size (OD) as the port spigots, my fix was this....

Image


it works well.

mbskeam

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