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Triumph TR6 - Noise with vacuum retard attached

I have been trying to track down a tapping noise in the upper backend of the engine. I thought that the problem was my rocker assembly, but I just rebuilt that (it needed it), and I still have the noise. I rechecked the valve clearances 53 times, so hopefully it is not that.

I was starting to think that my valves and/or cam also needed work, but the curious thing is that the tapping goes away when I disconnect vacuum retard. Of course the engine revs up when I do this, but if I leave vacuum retard on and rev it up, I still hear the tapping.

Does anybody have any clue what this could be?

Thanks,

Ignatius
Ignatius Rigor

Can you locate the source of the noise more precisley? Try screwdriver to ear method.
Peter Cobbold

screwdriver to ear?
Michael Parkhill

Hi Michael, I think Peter is talking about using the screwdriver (or a stick for this matter) as a stethoscope. The noise carries up the stick from where you put it, and should be loudest near the source.

Peter, I will try this when I start up the car today and let you know.

Ignatius
Ignatius Rigor

Peter,

Are you the same Peter who built a super charged tr6? If you are, could you give the board details of your website regarding the building of the super charged tr6.

Simon
Simon

Well, I tried narrowing down the area that the noise is coming from, but could not find it. Putting the rod to all parts of the engine sounded OK actually, i.e. no tapping or knocking although I can hear the noise just looking at the engine. ...bizarre.

Now that I think about it, I wonder if it is somepiece external to the engine?

...ugh.
Ignatius Rigor

Ignatius
Does the noise frequency increase with engine RPM? Will the noise go away if you push the clutch all the way in?
Rick
Rick Crawford

Rick C.,

Ya, the noise frequency does increase but tends to fade with RPMs, and no, it does not go away when I push on the clutch.

Ignatius
Ignatius Rigor

Ignatius
UUMMMM...turn up the radio? Seriously...that is a wierd one. Does it happen only when engine is cold or no difference. Just thought of this...Fan motor????///Leaf from a tree??? It is at the back of the engine. Maybe your fan is on at low speed try high speed. I know this is heading away from vacuum retard but that does not make sence either.
Rick C
Rick Crawford

Iggy,
Grasping straws, really, but with your stick/screwdriver, did you listen to the distributor itself? The noise does seem to be intimately connected to the vacuum in some way. Could this be a loose base plate in the Dizzie?

John
JohnD

Rick C, The noise is louder when it is cold. I will play with the fan motor speed, but if that is it, I am giving up on automechanics. :) I did just run a new wire for my stereo and will reinstall that in the next couple days. Plus the weather is supposed to get better in Seattle for the next few days, I will have the top down and that should help drown out this tapping BS even more.

JohnDDy, I have not thought about the Dizzie. I will check that tomorrow. I wonder if there is something that vacuum retard could be sucking into the rotating parts? This noise was much louder than I would think a distributor could make/handle though.

I got an appointment with a local mechanic who is supposed to be a TR god. Hopefully he can diagnose the noise. I will let you guys know whatever he finds.

Ignatius

Ignatius Rigor

UK TR6s never had their vacuum advance capsule attached to the inlet manifold. The device serves merely to advance the timing to give more time for the weak mixture to burn when the engine is on the over-run. So it wont affect performance or damage the engine if you disconnect it and block the air leak into the manifold.
The blown TR6 article was kindly put onto his web pages by Kai Radicke at:
http://www.pil.net/~felix/supercharger/cobbold.html
Peter Cobbold

Hey All,

I found the tapping!!!

It turned out to simply be the gasket on the exhaust manifold being blown/worn, so when exhaust was being pumped out, a metal part of the gasket flapped against the cylinder head and/or exhaust manifold causing the tap. ...man, what a bizarre problem but it sure is relief that it was not anything major.

Now I can worry about funner things like tuning the car.

This is probably a topic for another thread, but would the leak throw the sync of my carbs off? E.g. through the EGR system? I sync'ed them early last week before I found the exhaust leak. Well, I will check their sync just in case. This is easy enough to do.

Thanks,

Ignatius
I

...and can somebody explain why a noise like this would go away when I disconnect retard? This boggles me.
Ignatius

Ignatius
sorry but off topic..have u been getting a lot of spam lately? I notice u have changed your e-mail. I have been getting a lot.

P.S. congrats on the discovery..have fun changing it. No idea as to your question.
Rick C
Rick Crawford

Rick C, Ya, the spam has been awful! I get about 10/day. A friend suggested opening a Yahoo account to use for surfing so I could minimize traffic to my work email account.
Ignatius

This thread was discussed between 14/04/2002 and 22/04/2002

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