O-ring manifold sealing

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Skip
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O-ring manifold sealing

#1

Post by Skip » Fri Mar 09, 2007 7:54 am

Ok guys...need more help...tested my manifold and readjusted several times and still bubbles...not bad or many...but there all the same...what's the damn trick...by the way I am using one of Mr. Beam's testers at 12 to 14 lbs air...new aircraft type clamps...new o rings and manifold....thanks again in advance....Skip



Cotten
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Re: O-ring manifold sealing

#2

Post by Cotten » Fri Mar 09, 2007 9:31 pm

Please explain: "new aircraft type clamps": How big is the screw that tightens them?

....Cotten

Skip
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Re: O-ring manifold sealing

#3

Post by Skip » Fri Mar 09, 2007 9:37 pm

normal screw size...1/4 inch I believe...clamps are new to me...maybe not a "new style"...they just do not seem to tighten right...slip off slightly...small "leak" on carb side on front and small leak on rear...thanks

Billy
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Re: O-ring manifold sealing

#4

Post by Billy » Sat Mar 10, 2007 12:46 am

Skip-

How does your intake line up w/out the 0-rings ?? Big gap or ??
Sometimes it helps to loosen a head(s) & twist it for better alignment. Which would then also require need new H gasket(s), but if your 'fit' is way off, that could be the ticket..

Cotten
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Re: O-ring manifold sealing

#5

Post by Cotten » Sat Mar 10, 2007 6:36 am

Skip!

The clamps are probably your problem: the ones with 1/4" fasteners work for exhausts, but they often distort and overtighten for intakes.
Get some with a #10 screw fastener (like OEM), and only tighten until the bubbles stop.
They are a lot easier to install as well!

....Cotten

Skip
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Re: O-ring manifold sealing

#6

Post by Skip » Sat Mar 10, 2007 8:31 am

The manifold fits pretty well...semi tight going in...with no gap when installed...will try different clamnps...thanks Skip

1950bobber

Re: O-ring manifold sealing

#7

Post by 1950bobber » Sat Mar 10, 2007 11:15 am

Skip....

I have found that the manifold clamps that work the best for me are the stock Shovelhead style THAT HAVE A SPLIT RUNNING DOWN THE MIDDLE of both clamps.
I think that split, correct me all if I really reaching here, spreads the pressure applied to the rubber gasket and provides a better seal.
I admit that I heaven't read this entire thread (stupid me but I'm lazy this morning!)...so if my 2 cents here is off base....forgive me! BUT...if it does make sense and you need pics of this clamp style....let me know...I'll get some pics for you.

Jim in Seattle "1950 Bobber"

Skip
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Re: O-ring manifold sealing

#8

Post by Skip » Sat Mar 10, 2007 12:32 pm

If that is the 2 piece clamp you speak of...a friend just brought me a set...has the grove for the o ring to set in...he suggested i use a light coat of grease in the grove...Thanks and will kee[ posted.......Skip

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Re: O-ring manifold sealing

#9

Post by Panacea » Sat Mar 10, 2007 5:28 pm

50 Bobber, those split clamps might work better on the rubber band type intake,I think the flat sealing surface would apply a more even pressure on the o-ring type seal...Mike

Skip
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Re: O-ring manifold sealing

#10

Post by Skip » Sat Mar 10, 2007 7:32 pm

Ok guys...don't mean to sound despriate here, but I'm just about ready to climb the clock tower...bought 3 different type clamps...2 different size o rings...took everything back loose and started over...after 8 hours...still intake leaks...manifold fits well I think...tight fit going in and sets square...may have a hair line gap on the under side that the o ring should cover...started with the clamps loose to tight...still same thing....bubbles....every where stinking bubbles...Oh manifolds gods...enlighten this poor soul before we become a statistic...thanks Skip

1950bobber

Re: O-ring manifold sealing

#11

Post by 1950bobber » Sat Mar 10, 2007 8:03 pm

Mike...are you sure? I actually thought that the split clamps put pressure on both sides of the O ring, with the O ring seated between the splits....but I could be mistaken!
There is a kit I believe that actually uses BOTH the O ring AND the band.....the band sealing over the O ring...anyone ever tried that set-up?

Skip...NO!
I get mixed reviews on the two-piece brass type clamp...many have had very bad luck, with the O ring being crushed...but then again, I have had others who say that two-piece set-up works...I think I would suggest you try the split-band first...

Jim in Seattle "1950 Bobber"

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Re: O-ring manifold sealing

#12

Post by Pantony » Sat Mar 10, 2007 8:51 pm

Skip, Back up a sec, take the clamps and o-rings out and put the manifold in there and tell me with a set of feeler gauges how much clearance you have between the heads and the manifold.

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Re: O-ring manifold sealing

#13

Post by Skip » Sat Mar 10, 2007 9:06 pm

when it is setting as square as I can get it I can force my smallest gauge into it.. .010...that is on the rear and the front is flush all around as far as I can tell with the gauge and a light...is that bad...Thanks Skip

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Re: O-ring manifold sealing

#14

Post by mbskeam » Sat Mar 10, 2007 10:38 pm

as for 2PC clamps read this......viewtopic.php?t=468&start=0" onclick="window.open(this.href);return false;

this is the type of clamp I have. they overlap the ends and have a plate that finds it 's sweet spot, the threads are 10/32.....

Image

the ? I have,........ is the manifold square to BOTH ports
when held up to each intake port, you should not have the manifold vary when held to either port,and is your manifold round, and or the head ports.
mbskeam

shoveled71
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Re: O-ring manifold sealing

#15

Post by shoveled71 » Sat Mar 10, 2007 11:01 pm

I always get the manifold in place with the o-rings then give it a tight wrap of duct tape, only overlap enough to seal all the way around, then use the SS factory type clamps but not to tight to distort the o-ring or tape, the heat from the motor melts the glue on the tape and makes it seal that much better. Spike

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