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TR6 Tr6 Carb alway lean

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Ricardo_6

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This carbs are so simple that some problems may go unoticed. I have a tri-carb setup in my 72 TR6 Front and rear carb are well adjusted. The center carb is the culprit . It is insensitive to mixture adjustments. Even when the needle are set to full rich or full lean the spark plugs on 3 and 4 cylinder come out white (lean condition). I have check for vaccum leaks and everuthing is fine. Float levels are all set at 17mm. Shafts seals were replaced, diaphragm are fine. By pass valves are working. I have even checked if the needle fell of the screw and it is okay. The only sympton that I have noticed is some hesitation at full throttle on first gear.
Any ideas?
 
Without seeing it, of course--Is the center carb manifold where the brake booster gets its vacuum? Maybe pinch off that line and see what happens. Or--engine off, pump pedal until until you've bled off all vacuum, then hold brake pedal down and start car. Pedal should sink. If not=bad booster (holed diaphragm).

Good luck--

BobH
 
Well, then. :smile:

Time to double check/recheck everything. You're either adding too much air, or you're not adding enough fuel, eh? Try switching carbs around? I don't know anything about the triple set-ups. Can they be switched around? Air filters nice and clean? Fuel lines to carbs nice and round, no kinks or bends? No internal obstructions?

And, for what it's worth, even newly rebuilt stuff can fail. Immediately upon installation. :wink:

Good luck-
 
I have trouble with my two carbs, let alone three, but the thought I have is that your issue might possibly be in the linkage, i.e. middle carb not opening with the front and rear. Tom
 
Throttle linkage connects to the center carb. All three are opening. As for the fuel lines i have the goodparts fuellines kit installed. These lines are steel. I have dissasembled them three times already,float levels were verified and everything else. I'll keep checking. An email was sent to palltech,were I got the carbs from back in 2006.
 
It could be the needle valve on the middle carb isn't opening up all the way or has some restriction in it. You might want to swap it out if a spare's handy. If that's not the problem consider lowering the float height to 16 mm to raise fuel level in the chamber.
 
As per Richard Good suggestions there are no leaks at banjo connection All of the 3 main jets are at the same height. All 3 needles are the same. I even check for a blockage in the Goodparts fue line. Everything is fine.

tdskip; these are Zenith stromberg carbs. I guess I'll keep hunting for the unknown.
 
Have you pulled the needle to confirm that it is a B1AF needle and not something else? That may help you, but the fact that you say it will not adjust up or down with any difference is a bit confusing.

This may sound crazy, but could there be anything inside the manifold ports that would be blocking fuel and air from getting in there properly?
 
All three are brand new B1Af needles. Today I adjusted the needle in the center carb to full rich. I went for a drive for about half an hour and the spark came out lean. The atrange fact ist hat the engine is running just fine. The only problem is a slight hesitation when pulling in first gear wide open. Temperature is okay it pulls great. Im justabout to give up and just leave it the way it is. Im still waiting for aresponse from Palltech, were i bought the carbs from in 2006.
 
What was your impressions of the carbs performance back in 2006 ?
Is this something that just started giving you problems ?
 
What is your ignition timing set at? Are you above 12BTDC? If you are, back it off to 10BTDC and drive it for a few days. Reading plugs with half an hour of drive time on them can be misleading.
 
Ricardo,

I just noticed that you're in Puerto Rico. I recently heard there are quite a few TR6's and British cars down there and that there is also an active club. Maybe you can catch up with some of those guys as well as coming here. I thought someone had posted a picture of a white TR6 with triples at a show down there about two to three months ago. Could that have been your car? If not, maybe you can ask around the club to see who has one and compare notes.

Of course you can always get answers here, but having another car sitting beside yours can also be a big help.
 
There is that "balancing" header between the carbs on 2 carb setup, that's the one that has the brake booster banjo connection on it. It's designed to bleed "some" air/fuel between the 2 carbs and smooth out the differences.
I'm assuming there's no such device on the intake header for a 3 carb setup?
I would expect that makes it difficult to get all 3 set up perfectly across all the variable load/rpm ranges.
If it's been set up that way for a long time then I wouldn't get too worried about it.
The idea above of raising the fuel level (via float height) a couple millimetres has merit though.
 
AltaKnight said:
There is that "balancing" header between the carbs on 2 carb setup, that's the one that has the brake booster banjo connection on it. It's designed to bleed "some" air/fuel between the 2 carbs and smooth out the differences.
I'm assuming there's no such device on the intake header for a 3 carb setup?
Click to expand...

It's there on the GP set-up.
 
Have you installed the thicker intake manifold gasket? (MOSS P/N 695-060)
Check to see if your carb vent at the air filter is not blocked. Are all three carbs the same. My middle carb is a different Stromburg ventage and the venting for the earlier carb is different. The problem I had was the middle carb was too rich.
 
Another thought is are your valves adjusted too tight?
 
Sounds like it's time to get out the vacuum gauge.....
 
big6 said:
The problem I had was the middle carb was too rich.
Click to expand...
Sounds like you fellahs need to get together and swap middle carbs!
It would involve a boat/plane trip though.
 
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