Manifold Pressure Test - done, but found air passing........

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old1955
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Manifold Pressure Test - done, but found air passing........

#1

Post by old1955 » Mon Nov 23, 2009 1:09 pm

G'day,

I did another pressure test on the manifold 3rd one, found a problem with porosity leak
in the S&S manifold casting. These have just got to get bigger as manifold heats up.
Then I went deeper, found my spark plugs leaking from the
so called sealing washer which is actually a head surface problem not the washer.
Then after advice I read from a forum member, removed the timing plug.
I could here air in there, after the compressor cut out. Also found air coming out of the case breath pipe.

The pistons are letting air past, but I thought that might be OK as there has to be a 'ring gap'
on each ring, that will let air pass, but how much is too much? But the breathers got me beat!
Air coming out the breather? That's got to be too much, especial when I have the timing plug hole open.


What do you reckon?
Thanks, Pete
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Cotten
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Re: Manifold Pressure Test - done, but found air passing........

#2

Post by Cotten » Mon Nov 23, 2009 3:34 pm

Pete!

Is this the manifold porosity?
S&SPORE.jpg
(I appreciate the pic, as I collect them, and rarely fool with anything so modern!)

The sparkplug leakage would be best solved by machining, but in the meantime, a PEEK bandage sounds too easy.
(Please post me direct at liberty@npoint.net witha postal address, and I shall try to whittle a couple of repair seals, and send them to you for testing. My original intent was to make varied thicknesses for electrode indexing, but never got around to it.)

On to the blowby, yes, there is always some through the ring gaps.

I can't ever remember listening at the breather...!

Good idea, I guess, but unless you have lost compression, I would ignore all of the sounds until you are sure you really have a problem.

...Cotten
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Panacea
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Re: Manifold Pressure Test - done, but found air passing........

#3

Post by Panacea » Mon Nov 23, 2009 8:34 pm

Are you certain the intake valves were seated well?...Mike

old1955
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Re: Manifold Pressure Test - done, but found air passing........

#4

Post by old1955 » Tue Nov 24, 2009 2:12 am

G'day,
Thanks for the replies. On the manifold there were two spots. I didn't twig at first
I had to see them all three times, and they just kept turning up. Derrr Pete!
As you can see I put some stuff on it to seal it. It's some sort of epoxy metal composition (Kneed It)
it did the job, but looks very ordinary.

Thanks for your kind offer Cotten, but I have pulled the heads and barrels already, I was just looking
for an excuse to paint those barrels.Then I can really check the bore and the ring end gaps, I had it
stripped in an hour. Looks like I will have to make my own pilot arbour, for want of a better description,
for the plug problem I thought I might just use wet and dry stuck on the end of it. And do it in the drill press
This should resurface the area for a good seal. I have asked around, for a cutter but only getting very blank looks
so far. I don't like to hand my heads to anyone, I'm a bit protective over them. I would rather do it myself.
Oh Yeah! There was no listening at the breather, I could feel the air on my hand.

This was a kind of a bummer as I had just put reconditioned heads on. I found that the bottom
valve spring collars hadn't been put on, as luck would have it, no damage to the head. I guess, it was to give more
valve spring clearance when using heavier springs and a bigger cam. (Andrews BH) I did find someone had put
what looked like a hub shim under the springs, must have been their idea of a collar.
So the valve springs must have been wandering all over the place and consequently the bronze guides were shot.
(I didn't think anyone used bronze guides any more.) I mean really shot nearly 3/32 movement in the guide, that's
front and rear movement. So all that's in trash now. Wow! I think back on some of the big hand fulls of throttle i gave it,
makes me shudder.

Mike, As best I could tell they were sealed, I didn't remove the push rods to make certain. But holding air anyway, so the valves must have been shut.

Thanks
Pete
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NightShift
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Re: Manifold Pressure Test - done, but found air passing........

#5

Post by NightShift » Tue Nov 24, 2009 6:13 pm

Dear Pete,
Sparkplug decks can be cut with a wrench.
PLGDKCTR.jpg
Honestly,
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old1955
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Re: Manifold Pressure Test - done, but found air passing........

#6

Post by old1955 » Wed Nov 25, 2009 11:44 am

G'day
Good on ya Shifty! I like them, especially the bottom one with the spring
which would keep the tension as it wound in the plug hole.

I might copy that.

Thanks Mate!

Bosheff
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Re: Manifold Pressure Test - done, but found air passing........

#7

Post by Bosheff » Wed Nov 25, 2009 7:57 pm

Hats off to ya Nightshift. There's nothin I like better than someone who can and does manufacture a tool for a specific purpose that ya can't buy anywhere. That'll show them guys at Kent-Moore....bosheff

Cotten
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Re: Manifold Pressure Test - done, but found air passing........

#8

Post by Cotten » Thu Nov 26, 2009 4:33 am

They look like Olduvai Gorge tools to me.

....Cotten

FlatHeadSix
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Re: Manifold Pressure Test - done, but found air passing........

#9

Post by FlatHeadSix » Thu Nov 26, 2009 5:19 am

Cotten,
I think the sparkplug deck cutting tools that the archiologists dug up in the Olduvai Gorge were 18mm for cast iron flatheads, the tools in Shifty's picture may be more recent.

mike

Cotten
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Re: Manifold Pressure Test - done, but found air passing........

#10

Post by Cotten » Thu Nov 26, 2009 5:08 pm

If they chatter when they cut, they will still be Leakey.

....Cotten
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Panacea
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Re: Manifold Pressure Test - done, but found air passing........

#11

Post by Panacea » Fri Nov 27, 2009 5:44 pm

I had a leaky sparkplug hole on my 49 but the leak was between the threaded insert and the alluminum casting. Perhaps a Peek washer would help in this case...Mike

jlaley
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Re: Manifold Pressure Test - done, but found air passing........

#12

Post by jlaley » Fri Nov 27, 2009 8:04 pm

My S&S manifold leaked in that same area. I tried the epoxy more just to see if it worked. It didn't and I bought a new manifold, checked it and it was fine. The old one had to be 15-20 yrs old.

old1955
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Re: Manifold Pressure Test - done, but found air passing........

#13

Post by old1955 » Sun Dec 06, 2009 10:47 am

G'day, Well I have fixed the spark plug problem with a quickly
made up tool with a bit of course wet and dry paper glued to it.
and put it in the drill.

Although will still need to subject them to the bubbles when reassembled
to make sure.

Pete
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Cotten
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Re: Manifold Pressure Test - done, but found air passing........

#14

Post by Cotten » Sun Dec 06, 2009 4:44 pm

Panacea wrote:I had a leaky sparkplug hole on my 49 but the leak was between the threaded insert and the alluminum casting. Perhaps a Peek washer would help in this case...Mike
Mike!

It would be worth a try,..
Do you still have the leak?

....Cotten

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Re: Manifold Pressure Test - done, but found air passing........

#15

Post by john HD » Sun Dec 06, 2009 6:10 pm

i seem to remember this discussion in another thread, i think we determined the oem sparkplugs panheads used in the 50's had a larger crush washer than today's equivilents.

perhaps a peek washer would do the trick!

john

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