View Full Version : TR2/3/3A Creeping RPM (TR3)

05-01-2006, 01:59 PM
I had adjusted the set screws on the carbs to just about the nubs to keep it below 1200 RPM at idle; but after a few minutes driving, it eventually creeps up to ~1700. Pretty hard to get it into first gear without scrunching at that rate. I noticed that I could pry the gas pedal toward me a little and the RPM's would drop to the level I set it. Then I remembered that one of the springs on the throttle linkage had broken earlier. I replaced it but was not sure exactly where it was supposed to be attached (especially that front one). Maybe I've got it in the wrong place to get the best return. Any help here?

05-01-2006, 02:46 PM
Personally jayhawk I find that to be a problem on tr3s because they are older and are more prone to be wore out in spots: Often times a high idle is a vacuum leak most commonly around the throttle shafts and sometimes the problem is a vacuum leak in the distributor that lets the timing advance, and sometimes the carburetor dampers are low on oil, and sometimes the linkage is not returning all the way or a combination of problems. I would start with the linkage and make sure that it is ok, but yours sounds like a vacuum leak and perhaps a distributor problem. I once had a tr3 that the idle would move around on and I chased that thing all over (carbs, linkage, springs in carbs, rebuilt carbs, vacuum ..) then I replaced the distributor with a brand new one(NOS) and fixed the problem.

Geo Hahn
05-01-2006, 04:34 PM
My recollection is that there is a fair amount of pre-load on those springs. If I recall correctly you can increase that by loosening the clamp that the forward end of the spring hooks on and rotating it. If you are able to significantly lower the idle RPM by toeing up the accelerator then I would think more spring tension is in order.

Don Elliott
05-01-2006, 08:40 PM
Don't scrunch it into 1st. Snick it into the gate for 2nd gear. Then flip it forward into 1st. It'll go in as smooth as silk. I've been doing this for 48 years.

Don Elliott, Original Owner, 1958 TR3A, TS 27489 LO

https://mysite.wanadoo-members.co.uk/trebor/don3a_big.JPG (photo take at VTR in 2001)

05-01-2006, 09:50 PM
If I recall correctly you can increase that by loosening the clamp that the forward end of the spring hooks on and rotating it.

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Geo-- that's part of the question-- since the spring was thrown when it broke, it was no longer connected-- can you tell me where it connects? I don't see the spring or clamp in the Moss type catalogs. Thanks. (and Don-=- you're right-- I don't scrunch when I can avoid it). I had a routine before I discovered that I could pull the gas pedal back a little-- clutch, third, second and then first-- no scrunch even at 1700 RPM. But that's not much fun in city driving as you can imagine.

Thanks again for input.

05-02-2006, 07:34 AM
I have had cases where I couldn't get the idle speed to drop back down and it turned out that the choke cable had been adjusted too tightly. That will give you the same effect as cracking the throttle.
If you have not had the throttle shafts rebushed, you can check for an air leak by spraying some starting fluid on either side of the carb where the shaft enters (while the engine is running). If you have a vacumn leak it will suck in the ether and you will get an increase in RPM. You can also do this same test by spraying a higher viscosity oil on the shaft and trying to block the leak which will drop the RPM, but I have tried that and ended up with an oily mess.