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Triumph TR6 - back to the 'running with the choke on' thread...


I've gone through the archives (Good Newbie, Good) and found some rather interesting information.

Here's the situation. A 73 TR6 with NO vacuum hoses except for the one to the vacuum booster for the brakes and the PCV valve (or what I assume is such).

There is nothing going to the vacuum tap on the distributor (I assume vacuum retard?).

Since the engine VERY much likes the choke to be pulled to run decently at all I'd assume I've got a lean condition (duh) and since I cannot find a vacuum tap that goes to the distributor I have to assume that I've an open line to manifold vacuum and that's causing the lean condition.

The problem IS, I cannot FIND said vacuum tap ANYWHERE. I can only guess that I've not looked in the proper spot.

I've been an LBC person for some while (early Spit, Bug Eye) and this is my first "Six". I've only just bought it so am sorting out the DPO debacle. (if we all sort out the DPO debacle then how can there BE any DPO debacles left? Won't we, eventually, run out of debales? (debacli?))

I thank you all in advance.


Jim Deatsch

Hi Jim your vac. line connection is under rear carb. Looks to be left side from parts book.

Try checking your plugs for lean whitish glazed. Only way to know for sure.

Welcome by the way to the TR6 comedy forum. They say that the realy great comedians have had a lot of troubles in there lives. So buy a TR and get a funny bone :)

Let us know how your making out.
Bill Brayford

Thanks Bill,

Believe me, the plugs are lean. I'll look for the vac line in the am. I would bet anything it's not there but I'll look again.

Jim Deatsch

Bill, et al,

Actually it was the front carb. Apparently there was some switchin' going on. That 'tap' has NO vacuum present. None. The interesting part is THAT vacuum tap goes up into the throat of the carb too. How is it possible that THAT tap doesn't have any vacuum?

Plan B is in effect it appears.

I finally found a place to check vacuum and have 18hg at idle. I 'necked down' the hose that runs to the brake booster and there it was. Plenty 'nough to suit me.

The plot thickens. I took the car for a ride (3 miles) with the choke on most of the way. When I got home the fuel filter was EMPTY.

By Jove, we may be on to something here! The DPO has an inline, clear filter, (one of the larger 'cone' shaped ones) and it was MT. No petrol. Nada.

'Splain this Lucy. When the car had sat for some 20 minutes, after the ride, the filter was full. Now if I remember my high school physics... liquids seek their own level.

The fuel tank is nearly full. It DOES sit high up (relative to the float bowls) so I suppose... BUT, the pump isn't working lest the engine be revolving. N'est ce pas?
Is there enough 'slop' in the fuel system for the fuel to make it's way to the float bowls? Apparently.

What magic this? Yes? You there, in the back.


Jim Deatsch


I bet you have an in-line filter somewhere between the tank and the pump. If you have been unlucky enough to empty the tank you most probably clogged the filter with rust sediment of the tank. (I talk from experience .....hmhm)

E. Creyghton


A novel idea. I hadn't thought of that.

Have just bought this car, yesterday, I'm still sorting it out.

I will certainly check for another filter.


Jim Deatsch

If the tank is nearly full you can get gas to the carbs by gravity - I once had a carb with a bad needle valve that let gas flood the manifold and cylinders over night.

There is also a fine screen under the fuel pump dome top that could be plugged depending on where the in-line filter is located. Do a flow check - with the car running pull off one of the fuel lines to a carb and let it squirt into a jar. I don't think fuel delivery is the problem, though, unless you got alot of hesitation/stumbling on the drive with the choke out.

Check the carb diphragms, Get a unisyn or equivalent meter to check that the carbs are synchronized, and get a carb needle adjusting tool to set the mixture.

For the vacuum line to the distributor, the DPO may have plugged the port at the carb. It is a tiny hole, though, so some debris could have been sucked in as well. Many have disconnected the vacuum retard without ill effects.
Brent B

Hi Jim

From the last post you have fuel starvation going on?

When your pump sucks. Good Pump!

All the crap in the tank and lines tries to flow to the hole. Bad crap.

The tank does not have a top type P/U unit a few inches off the bottom like new cars.

By the way invented not for crap but for frozen water in bottom of tank in our cold climate.

Gas goes straight out down the sink bottom? 3/8ths/5/16 hole can't remember. Not big enough to take much without plugging.

When the suction goes away car off for awhile the crap floats up out of line and gas flows down!!!??? Filter pump and carbs now work. Till the pump starts to suck. Neat eh?

Try it in your bathroom sink with an outside operated stopper. Normal gravity flow can plug the flow with junk. Stop the flow for a few minutes and watch the junk float. No gravity suction. Now increase that by 2.5 GPM suction and you will have a longer wait.

Gas or fluid allowed to flow will seek its own level. Yes. Will it run your TR? Nope.

Do you need a new pump? Not likely until you clean up the input area and try.

The steel lines are suspect as well. If old gas and moisture has sat in them during storage they corode like a bear. Clean tank first though and blow out line.


Bill Brayford

The plot thickens.

I now have reason (sorry) to believe that I have different carbs than those which came on my 73. They are SUs. I'm being told that the car came with Strombergs.

Is this correct?

Perhaps that and the fuel 'feed' issue is contributing?

The deeper I go the shallower I get.

Jim Deatsch

Well, no diaphragms to check in that case...
Brent B

But, but, but, but...

Which witch is the right witch?

Are the SUs superior to the Strombergs or visa versa?

They APPEAR to be functional. Of course I cannot 'check' the action of the slides since they require more activation than I can produce in the garage. Darn, where's that dyno when you need it!

The float levels seem dandy. The slides move freely. They have lubricant. The butterflys move, obviously since it DOES go down the street rather nicely, and it has decent 'pep'.

I'm STILL driving with the choke on and I don't wish to do so. <G>

THIS time, when I came back from my spin, the fuel filter was not empty.

Riddle that one.

Oh, and don't think any and all contributions aren't GREATLY appreciated as they very well are.

And Bill? I'm going to remove the blasted fuel line and drain the tank. Blasted thing is 7/8 full too. Methinks I'll siphon most of the fuel out and spy down into the tank to see what's floating about. Suppose I'd want to bring along my trout rod just in case dinner is lurking about in there?

Jim Deatsch

Which carb is superior? Are you kidding? Actually, there are arguements on both sides. The only real difference is the solid SU vs. rubber ZS diaphragms. Too me, both are fine.

You're not running out of fuel supply (the car hasn't stalled and left you in an intersection yelling "Sorry, I just bought this damn car", has it?), so maybe the carbs ARE too lean. From my recollection of SU's, there is a nut on the bottom that adjusts the jet - move the nut so the jet assembly moves down and the mixture riches up.

The SU's on my old MG had little buttons near the front to lift the piston up in order to gauge the mixture - if the engine wanted to stall when lifted, you riched it up. If it ran faster, you leaned it out. Proper mixture gave a brief acceleration, then it idled back at original speed. So simple you'll never admit it wasn't obvious.

Now a question here - sounds like you just bought the car - have you done the requisite tune-up of plugs, point, cap, rotor, timing, ect? Ya mess with the carbs last, big boy...
Brent B

Hi Jim

Use a flashlight not a trouble light for spying. KABOOM!

Sorry siphoning will leave all the crap in tank. Very slow method will not remove junk. Drain it from the bottom. Remove the line where its easy and be prepared to do it several times or have it suction pumped and flushed. If the gas is fresh steal the wifes nylons to pour it through when you put it back.

Yes all original were Strombergs. S/U or Z/S bout the same. Some feel S/U simpler?

If you have just got the car? I gather from your post. Follow the fuel lines back to tank. Replace all filters. There is a strainer in the fuel pump. Clean all up.

Dump the bowels on the carbs. I don't remember if S/Us have a drain? Maybe someone else will let us know?

Get a good carb fuel injector cleaner and put in tank with fresh gas. Might be all you need? Old gas causes shelac and plugs things up. Should improve after a tank or so?

Bill Brayford

Gawd I love this place. All this info and senses of humor too!

Ok. To reply.

Yup. Just bought him. He's far from my first LBC though. Cap is new, wires are dandy, plugs are sweet though hard to get a decent reading what with running with the choke out.

I'll look into the mixture adjustment as Bret mentioned whilst he abused me. <G>

By the way, it's got the Crane electronic conversion kit in it. No gottum pointseses.

Ok, Ok. I'll drain the tank. Flashlight, no drop light. I'll clean the strainer in the pump. I'll double check the lines. <G>

Thanks much guys. I do appreciate the help.

Jim Deatsch

Curses! My clever ploy to obtain a free overdrive transmission was ruined by a horn...

OK - it sounds like it's tuned up pretty well. Why not spend some drive time to get the fuel tank level down before draining it? While you may indeed have crap in the system, if it was restricting the flow to the extent that the carbs were running too lean, then when the choke was pulled out I'd expect the engine to eventually stall because the fuel would then be used faster than it could be pumped.

If the car sat for a while before you got it, then Bill's point about varnish, ect is right on the $$$. A good drive with some gum-out in the tank may clean things up. And again, your carbs may indeed just be set too lean.
Brent B

The best laid plans of Mice and Brent!!

I shall do just that Brent. My plan is to attack the fuel storage and pumping system from stem to stern, or visa versa, this weekend.
I shall keep everyone apprised of the resulting battle, errrr results so as to leave this in the archives for the next poor twit who encounters such madness.

Suffice it to say I love LBCs but the HORN is driving me to drink.


I think I'll have a beer and consider that.

Jim Deatsch

If you're not really familiar with horns, if there is sound, but not much, there is a screw on the back that can be turned to increase the volume (in most cases). It's actually a pivot point of sorts that requires readjustment after years of hard use. I've been known to remove old horns and fire WD-40 down the throat (and into screw holes) to loosen them up - with good results.
Brent B

Thanks Brent.

I can spell horn. In fact, I also own a Honda 6 cyl bike (1982) and it had a hi tone horn out which I managed to repair. Good thing too since they're not available.

The silly thing was working. Now it doesn't. I've gotten the wiring diagram as mentioned above (thanks!) and will be fiddling later on today.

Jim Deatsch

Behind the horn button on the steering wheel is the real button - a little brass conductor that gets corroded ends from time to time. It may help to clean that.
Brent B

To all of you fine folk who gave input to my 'running whilst the choke be on' issue...


The problem was peculiar to the SUs. They adjust their mixture by screwing in and screwing out a brass 'nut' on the underside of the carburetor.

Tighten to lean, loosen to richen.

They were tight. The DPO, apparently, didn't want them coming adrift. Tight as in with a wrench. Fortunately he did not strip the things.

The car now runs dandily without choke. Heck, it even starts.

I'm a happy LBC owner once again. <G>

Jim (of the SUs)
Jim Deatsch

Ahh - now you're experiencing the feel of hair growing on your back! I'm not really sure what that means, but congrats - glad that's solved!!
Brent B

Yah Yah now your an SU expert.

Thats great!!!!

But what did you screw up on the horn is what I want to know???? :)
Bill Brayford

Laughing out loud here.

Careful Bill, I know where you live. <G>

Damn horn. OUT with it I say. I was SO pleased withmyveryownself by getting the car to RUN properly I forgot all about the horn last night.

I'll just come up and steal yours William.


Jim Deatsch


You might want to check the earth connection to the steering rack; it is a known concern to get the horn working properly.

E. Creyghton

This thread was discussed between 02/08/2003 and 07/08/2003

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