Subject: [TR] TR4 vacuum port

From: Allen Hess <[email-masked]>
Date: Fri, 6 Jul 2012 15:09:46 -0400

I've had occasional but persistent oil fouling of the #1 plug for a  
few years and a hotter plug in that cylinder has helped. Symptoms  
point to worn valve guides. I was going to get a vacuum gauge and try  
to do some more diagnosis. However, I don't have any manifold vacuum  
port other than the advance line in the carburetor. And I'm not sure  
that would work as it lies beneath the throttle plate.

The intake manifold has two bosses cast into the balance tube which  
certainly looks like Triumph was thinking about this but it would have  
to be drilled and tapped. Anyone else been down this road?

Allen

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From: <[email-masked]>
Date: Fri, 6 Jul 2012 15:31:35 -0500

Maybe I'm all wet but what test would help you to isolate the #1 hole valve
guides by tapping a fitting into the balance tube?  If I suspect that I have
a valve guide problem, a good wiggle test will usually show it with out
having to pull the head. 

Any reason not to suspect that you might have a broken or frozen ring?

Bill

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]] On Behalf Of Allen Hess
Sent: Friday, July 06, 2012 2:10 PM
To: "triumphs list"
Subject: [TR] TR4 vacuum port

I've had occasional but persistent oil fouling of the #1 plug for a few
years and a hotter plug in that cylinder has helped. Symptoms point to worn
valve guides. I was going to get a vacuum gauge and try to do some more
diagnosis. However, I don't have any manifold vacuum port other than the
advance line in the carburetor. And I'm not sure that would work as it lies
beneath the throttle plate.

The intake manifold has two bosses cast into the balance tube which
certainly looks like Triumph was thinking about this but it would have to be
drilled and tapped. Anyone else been down this road?

Allen

Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
Unsubscribe/Manage:
http://autox.team.net/mailman/options/triumphs/[email-masked]

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From: Allen Hess <[email-masked]>
Date: Fri, 6 Jul 2012 17:15:31 -0400

Thanks for the photo. I do have the same manifold as your TR3B but it  
is not tapped and plugged as yours is. From what I've read, worn  
guides will cause a noticeable fluctuation of vacuum at idle.  
Compression in #1 is higher than 2, 3, 4 (172 lbs. / 165 lbs.) which  
may be due to carbon build up. I haven't tried but can you wiggle the  
stem with the spring in place??

Allen

On Jul 6, 2012, at 4:31 PM, <[email-masked]> wrote:

> few

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From: "Randall" <[email-masked]>
Date: Fri, 6 Jul 2012 16:31:16 -0700

> However, I don't have any manifold vacuum

Right, not what you need.

> to be drilled and tapped. Anyone else been down this road?

My 3A had the earlier manifold without the bosses.  I drilled and tapped
anyway, in two different places, one in the center of the balance tube and
the other on the front.  The walls appeared to be thick enough to hold 1/8
NPT threads without any trouble.

If you look closely (best to zoom in, sorry I don't have a higher res photo)
at
http://goo.gl/2cQS1
maybe you can see the hex head plug that is in the hole in the balance tube;
and a rubber cap on the added fitting at the front.  The fitting at the
front was the one I used for a vacuum gauge, while the one in the balance
tube was a leftover from an abortive attempt to add water injection.  (The
duct tape on the air filters covers two more holes, where the water was to
go in.)

-- Randall