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[barneye]

Hello all,
I overheated the 3 sometime back and after doing alot of cleaning and replacing everything I could think of, I found that the motor will not start and run without full choke and will not keep running without it. My results of the compression test were: #4-140lbs #3-175lbs #2-160lbs #1-164lbs. All were taken with three plugs in and two squirts of 20w in each cylinder. No signs such as water in oil or unusual noises. Any suggestions?
Thanks,
Barney Emberton OKC COVTR

[charley fitch]

I see two issues that you have.  The compression does not seem that bad except for the difference between the cylinders.  But as I understand it 140# is reasonable as a low top end.  On the TR3/4 motor the #4 cylinder has a very close tolerance to the water jacket at the rear of the cylinder bore.  The result is that it is the easiest spot to have a leak of compression into the water jacket.  But if it is at 140#s I would not suspect that you have any leak.

The second issue is the car not running without the choke.  I would start looking for an air leak between from the carbs to the cylinder head.  Your car is getting a lot of air and apparently can not run with the air coming in the regular intakes plus the leaks.  The choke is blocking the regular air. You have two sets of gaskets to look at.  The first is between the carbs and the intake manifold, I would not guess this is the problem.  The second is from the manifold to the cylinder head.  This is more likely the problem area.
Hope this helps.
Charley Fitch 

[noskcire001]

You might want to put some gas in a spray bottle and spray around the gaskets. If there is an air leak, the RPM's will increase.

Good luck

Mark

[TR3driver]

Check that the carburetor pistons move freely.  With the choke released and the air filters removed, you should be able to lift the piston with your finger and it move smoothly (against the resistance of the dashpot) all the way to the top.  Then when you release it, it should fall quickly and smoothly to the bottom, landing with a distinct click (engine not running, of course).  While the filters are off, make sure the gaskets are installed the right way up, so the air holes match the holes in the carb face.

Also check the valve lash.  If you've got a valve that is way too tight, it can both upset mixture and compression (and may indicate valve recession triggered by the overheating).

BTW the usual way to check compression is with all of the plugs out, and the throttle propped open.  That big a spread, with oil added, probably indicates a leaking valve.  You may need to pull the head to correct it.

[barneye]

Hey, I appreciate all the help and have tried all, but it looks like the head will have to come off... Darn! Might as well go for a valve job while I'm at it.
Thanks again! I will post again when I get it going.

barneye

[TomMull]

I'll be interested to hear what you find. I've had TRs that ran nicely with much lower (and varied) compression than you had although a coolant leak along with a slight loss of compression might cause your issues. Pulling the head is fairly straightforward and easy. I'm sure I don't have to tell you to be careful of the liner seals. Tom Mulligan

[barneye]

Hello Tom,

Turned out to be a couple of things. The head gasket was leaking out the exhaust/intake side and, the exhaust seat was bad a #4 cylinder. I dropped the head off today and should get it back this week. They are going to check everything out so I hope that is all they find...

[JimmieD]

Gentlemen,

I happened upon this forum and this thread this morning, after remembering my great TR3B from years ago. I quickly registered to join after reading this thread, and in horror, one post!

In the interests of preventing someone from getting killed, maimed, disfigured for life, burning up their Triumph pride & joy as it explodes in a ball of flames, maybe incinerating the garage, and house it's attached to:

DO NOT PUT A LITTLE GAS IN A SPRAY BOTTLE AND SQUIRT AROUND INTAKE/CARB AREAS LOOKING FOR VACUUM LEAKS!
Man, cannot quite believe that wasn't removed by a moderator!

To correctly check for intake leaks there's 3 methods, far safer. One: using a common propane soldering torch with pencil tip fitting, direct the UNLIT, NOT LIGHTED gas jet around intake area. When speed increases you've found your intake leak. The second method, use spray carb cleaner, but this can possibly remove poor quality paint. Third, use good old WD40, but of course there will be some residues left that need cleaning up.

Any of these three sprayed around intake areas at gasket surfaces will reveal a vacuum leak as engine speeds up. None of the three will cause the engine compartment to explode in a ball of flame from a minor electrical spark or lit cigarette, cigar, pipe, water heater kicking on etc.

Happy motoring, gents...

JimmieD
.

[TomMull]

JimmieD is of course correct and will get no argument from me. We should, in fact, consider the safety issues of our recommendations. However, some of us grew up during a different time. I, for one, worked in a shop that kept a 5 gallon can of gas for cleaning parts (and hands) in the corner. We dumped and sprayed gas down carburetor throats, spark plug holes and other engine orifices daily. Our town spread our drained oil on dirt roads on a regular basis to keep the dust down. I could go one but perhaps you see why I (and others) didn't give the comment a second thought (I use acetylene now).
Tom Mulligan