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TR2/3/3A Carb Jet

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BillyB62

BillyB62

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Ok, I'm at a loss. I've been fighting with my TR3 running very rich for several years with black smoke spewing from the tailpipe. After my Buddy made fun of me this weekend I've decided to do something about it. I had my carbs rebuilt by a carb shop several years ago but they leaked so I took them apart and did them myself. My problem was that I could screw them all the way lean and it didn't seem to matter. I thought I figured it out last night when I noticed the jet never came up even with the bridge so I took pulled one of the carbs today to see if I did something wrong because the top of the jet as always slightly below the bridge. If I remove the top copper washer, the jet comes even with the bridge....but that obviously isn't right. I've looked at hours of video on YouTube and from the attached picture, I see the top of this guys jet is even with the bridge. Am I doing something wrong?

Jet.jpg

Thanks in advance,
 
It should be pretty close. The choke also affects the level of the jet. Have you looked over the choke assembly to make sure it is not binding, sticking, mis adjusted or bent so as to hold the jet down?
 
I just finished rebuilding my carbs for the second time, correcting several things I did wrong the first time. I strongly recommend you read Tom Bryant's blog posts about rebuilding SU carbs. They are very well written and illustrated. My car is running better than it has in 20 years.

Blog: https://thosbryant.wordpress.com

Tom also sells Teflon jet seals which are a big improvement over the cork.

A couple of things right off the bat that could cause it to run rich would include an incorrect jet needle, or a worn jet. The jet can wear internally from being incorrectly centered (either now or in the past). You can't see this with your eyeball, but Tom shows how to test for it. He uses a .100 gage pin, but I found that the shank of one of my reamers was almost exactly right, so I used that.
 
Thanks to all that responded thus far....looks like I've got a lot more reading to do. I reset the float levels and put the carb back on...she starts right up, but still smokes.
 
Bill-Many years ago, I fought the same battle-couldn't get the jet to the top of the bridge and mixture lean enough. A couple of things to check-make sure the jet is against the adjusting nut. Make sure the cork seal (Moss #97)is fully compressed. Also, make sure there isn't another copper washer lurking in the carb body.

In the end, I machined about .020" from the shoulder of the upper jet bearing, which allowed the jet to reach the top of the bridge. In thinking the problem over, it probably wasn't necessary. I achieved the proper mixture with the jet about .040" (its been a long time ago) below the bridge. So if you use a dial caliper to set the starting jet depth, it shouldn't make any difference.
I guess I should have asked how far the jets are from the bridge with adj. nuts full up and if it is equal on both carbs.
Berry-The guy that sold you a float chamber lid a few years ago.
 
Billy that sounds like Barry Nelson; do you still have his phone number? We are old friends and my computer crashed and I lost his stuff years ago right when he moved.

Something is wrong!! You might not have strong enough jet return springs like what CJD was getting at. Does it take some real strength to pull the choke out; it should, that way the jets go back. Havinge the car not respond to adjusting the nuts sounds fishy. I have seen cars that have aftermarket springs that are very weak and the jet never comes back.

You can buy a whole jet assembly for not much from Moss and pop that on there.

How do you keep the car running change or clean the plugs once week?

If you do not have the electronic ignition, The old distributor might not be returning when you let off the gas or just stays in advanced mode when you are taking off and the fuel will burn wrong and rich.
steve
 
Steve-I am not Barry Nelson, but I remember him showing up with a trailer of TR parts at swap meets in Portland, OR. Nice guy and was a wealth of Triumph knowledge. He kind of dropped out of sight and I have wondered what happened to him.
Berry
 
I'll try to check all the recommendations that members have posted for me tonight. I have a guy putting a roof on my woodshed and had to go get materials last night....didn't have time for the TR.

Thanks to all again,
 
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