TR2/3/3A TR3 stumble

[ron wilson]

I have a 1959 TR3 with dual webber carbs and it does not run properly at rpm below 2500 or so.
It was suggested to me in a previous forum question that possibly I needed a fuel regulator but I canot locate that response. If that is possibly what I need would like to know what the pressure should be set at. Also I see Victoria British has one in their catalog but says it is to cure high end fade and my problem is the opposite.

Could it also possibly be the jets are not the proper size.

 

[piman]

Hello Ron,
is this a recent problem or has it always done it?
I wouldn't think that it is a fuel pressure problem, however. It is always worth doing a check on your ignition settings and plugs. As for tuning Webers, I'll pass on advising you as I have no experience of them.

Alec

 

[ron wilson]

I just purchased the car in Nov and the previous owner said the carbs always had what he called a flat spot and he just put up with it. That is not my nature I think things should run correctly. All ignition parts have been changed and the valves adjusted. Timing and compression have been checked and it seems the carbs are about all that is left to work with.

 

[Bruce Bowker]

Are you running a mechanical fuel pump or electric? I have dual webers on one of my cars and added a pressure regulator set at about 2.5 to 3 psi. I can't see where one would hurt but not sure it will help either.

What I would suggest is finding a super good mechanic and have that person adjust them. Make sure they know Webers and not just basic carb mechanics. If you were in NJ I know someone who can tune them to perfection. Tunes as many as 6 on one car. There has to be someone in your area the same.

How old are they? Do they need a rebuild?

"Could it also possibly be the jets are not the proper size."

Yes it could be worn or wrong jets. Car should run well and I am sure it can be worked out.

[ 05-09-2004: Message edited by: Bruce Bowker ]</p>

 

[Bruce Bowker]

Some more on the Webers. What model are they? I am guessing DCOE?

Fuel pressure should be set at about 3.5 psi.
If you are having problems below 2500 rpm it could be the idle jets are too small. There is also the idle jet adjustment.

How does the car act at 2500 rpm and less. Stalls?
Runs rough?

I have some Weber specs if you need them regarding sizing of jets etc. I can email them if that is easier.

[ 05-09-2004: Message edited by: Bruce Bowker ]</p>

 

[Dave Russell]

I hope you have 40 DCOE's & not 45's.

If your carbs have main venturis (chokes) larger than 32 or 33 mm it will never run well at lower rpm. I think that the most common mistake with Webers is over carbureting with too large venturis.

The main choke is the back or closest to the throttle. Pull one of them & find the size stamped on it. You have to pull the boost venturi first. Two 10 mm set screws (bolts) on the bottom of the barrels, with a locking tab. You might be able to look straight in the bore & see the number stamped on the end, without removing a choke.
D

 

[sammyb]

Another common problem is that the car stumbles (a little "blip-blip-blip") low in the rev range, and as the car gets warmer,the stumble goes a little higher up the rev range.

This can happen with a distributor that is slightly bent, has worn parts (such as weights,) or a vacuum advance leak. You can tune carbs until you are blue in the face, but often it's the distributor or timing that is the main problem.

If it's always at 2500RPM, then it is possibly the carbs, but just make sure your sparks are in order.

 

[ron wilson]

Thanks for all the good advice re the webers. I am by the way taking the car to a local shop tomorrow.

 

[Bruce Bowker]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by ron wilson:
Thanks for all the good advice re the webers. I am by the way taking the car to a local shop tomorrow.<hr></blockquote>

What were the results? Running better I hope.

 

[TRMark]

Check this site out for info on webers on a TR. https://www.cruzers.com/~twakeman/TR/WeberDCOEinfo.htm I had some 40's on my TR4 last fall. I removed them and returned to the original SU's . The only advantage that I noticed was an accelerator pump. Webers are very sensitive to changes in elevation which made them useless in Montana. Unless you seriously modify the TR 4 cyl. engine,it does not turn enough rpm to really take advantage of the Weber. I have DCOE 40s on an Alfa powered vintage sports racer and they work fine; the car is never in traffic and the engine is most always twisting above 4000. You should not have any trouble finding used jets etc. if you pursue your project, in fact, if you have gear head friends they will give you piles of DCOE parts; they have moved on to better ways of mixing air and gas.