TR2/3/3A Rpm's at 10?

[Momikey]

So quick question. When I'm at a stop light or just in the driveway the rpm's are at 10.
Is this normal? Do I need to adjust something.

 

[TR3driver]

The books say idle rpm should be lower; but in general I'd call that low enough. The only problem with idling high is that the engine may show more of a tendency to "run on" after turning the key off.

One big caveat is that the old tachometers frequently read a bit high that close to 0, so if you do want to get it down lower, the first step is to double-check the tach reading.

 

[Momikey]

The books say idle rpm should be lower; but in general I'd call that low enough. The only problem with idling high is that the engine may show more of a tendency to "run on" after turning the key off.

One big caveat is that the old tachometers frequently read a bit high that close to 0, so if you do want to get it down lower, the first step is to double-check the tach reading.

Well my engine does run on when I turn off the key. What do I adjust to fix this?

 

[TR3driver]

There's a nice diagram in the Practical Hints manual (which is effectively the owner's manual for a TR3). Definitely recommended reading for any TR3 owner as it has a lot of information on lubrication, periodic adjustments and so on. You can download the last edition (suitable for 1959 and later) from https://drive.google.com/open?id=0B2H2NJt34OffNjQ4MTkyNjItZTVmYi00M2U2LWJhYWUtMjEyZDgxMzUyNzUw Or the usual suspects carry paper reprints.

Hmm, can't seem to upload the diagram at the moment. Back in a few ... Ok, Photobucket isn't working. Let's try this:

Ah, well, that's better anyway. So, to lower the idle rpm, back off both of the #3 screws by the same amount. I'd suggest trying 1/4 turn at first, then blip the throttle and see where it settles. Also, make sure screw #2 is not touching the cam underneath it. It should only touch when the choke knob is pulled out. (To give a bit more throttle when the engine is cold.)

 

[TR3driver]

An easy workaround for the run-on problem is to leave the gearbox in gear, foot firmly on the brake, then let the clutch out just after you turn off the key. With a bit of practice it becomes automatic and so smooth that you won't know if the engine would have run-on or not.

The engine in my previous TR3A was very well worn, and wouldn't idle reliably below about 1200 rpm. Before that, I had another TR3A with a "3/4 race" cam that didn't like to idle below 1500 or so. So killing it with the clutch is a habit for me.

 

[CJD]

Wow...where to start?!?

First, if you read the gage face, it says times 100, so "10" is actually 1000rpm, or revolutions per minute. 20 is 2000, 30 is 3000...you get the gist. 1000 is higher than it should idle, which can explain the run-on you are experiencing after shut down.

Do you have a service manual yet? If not, I would start by getting a copy of that, along with a smaller manual titled, "Practical hints for the maintenance of the Triumph TR3". I know...longer title, but much shorter book! The second is the best if you are just starting to maintain your Triumph with no prior mechanical experience.

 

[TR3driver]

Do you have a service manual yet? If not, I would start by getting a copy of that,

Most LBC vendors (TRF, Moss, VB, BPNW, etc) offer the Bentley reprint of the factory workshop manual "The Complete Official Triumph TR2 & TR3 1952 - 1961". Or you can download a scan from
https://drive.google.com/open?id=0B2H2NJt34OffYWZiN2VlZGMtNTkxMi00NGUzLWE4NzMtMGRkODRkYzU3MDU1

Many also offer an aftermarket manual by Haynes "Triumph TR 2, 3, 3A, 4 & 4A".
https://drive.google.com/open?id=0B2H2NJt34OffYTA1NTNmMGUtMTVjMy00NDEzLWJjN2YtNTc1OWRkNjE4MjY4
(The scans are an older version, the newer cover looks different but the contents are mostly the same.)

Of the two, I tend to prefer the factory manual. But it can be somewhat confusing, as it was originally written for a TR2 with an early TR3 supplement added in the back. Some aspects of the later TR3A (like how to check gearbox oil level without a dipstick) are simply not covered. (However, Practical Hints has at least some coverage of them.) The Haynes manual certainly has more photos and better step-by-step instructions (for most things); but is unclear on change points in many places and flat-out wrong in others.

 

[TR3driver]

FWIW, here's a used copy of the Bentley on eBay. Lots cheaper than new ones (unless it gets bid up of course)
https://www.ebay.com/itm/The-Comple...747972?hash=item41b2545ec4:g:cDcAAOSwIgNXvIYu

And a copy of the original factory manual
https://www.ebay.com/itm/TRIUMPH-TR...688355?hash=item25c27be0e3:g:3IwAAOSwRQlXfxGR

(No financial interest or other knowledge, just happened to see them and thot you might be interested.)

 

[Momikey]

WOW great info. I do have the Practical Hints manual and the Haynes manual.
This is a great help and tip:
"So, to lower the idle rpm, back off both of the #3 screws by the same amount. I'd suggest trying 1/4 turn at first, then blip the throttle and see where it settles. Also, make sure screw #2 is not touching the cam underneath it. It should only touch when the choke knob is pulled out. (To give a bit more throttle when the engine is cold.)"
Thank You.

 

[CJD]

Don't forget you must also break the connection between the carbs before adjusting, so you can get the idle where you want it and still ensure both carbs are drawing air equally at the new idle.

 

[TR3driver]

I disagree. No need to rebalance for a small change in idle rpm.

 

[Momikey]

Don't forget you must also break the connection between the carbs before adjusting, so you can get the idle where you want it and still ensure both carbs are drawing air equally at the new idle.

What do you mean by break the connection? I must remove a line that connects them together like the throttle rod or mixture rod? (see the great picture above)

 

[TR3driver]

He means to loosen one of the clamps on the connecting shaft, #4. Ensuring that both carbs flow the same amount of air at idle is known as "balancing". The procedure is covered in Practical Hints (which is where the photo came from, I just massaged it a bit to make it easier to see).

 

[Momikey]

He means to loosen one of the clamps on the connecting shaft, #4. Ensuring that both carbs flow the same amount of air at idle is known as "balancing". The procedure is covered in Practical Hints (which is where the photo came from, I just massaged it a bit to make it easier to see).

Thanks for all the help you have given you have given great help to a lot of my posts. I'm glad CJD mentioned the disconnect it's good to know as well for future issues.

 

[glemon]

I agree with Randall, with a couple caveats, no need to bother with uncoupling the shafts assuming they are synchronized properly to start with, and you turn both screws the same amount (although I guess if you don't loosen the clamps that doesn't matter much). I don't usually bother with the shaft clamps when doing an idle adjustment, but it is a must when doing a tune up or set up of the carbs, and as noted make sure when you turn the throttle down you are not hitting the choke stop, which may need to be adjusted too.

 

[CJD]

Interesting you guys aren't setting the carbs independently. I've always done it "by the book", and had a consistent idle between 500 and 700 with no run-on. It adds about a minute to loose and tighten the coupling.