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Stromberg

Terry_M

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Good day-new to this site and i need a bit of help I started my 74 TR6 this spring , fouled the sparkplugs at the rear of motor It wanted to run only with the choke engaged.Now it seems to be running on only the front carb-(I tried to balance them and have air only being pulled into the front carb ) I must admit i have ajusted and changed the settings , thinking this would be an easy fix even blaming this wretched gas we seem to be using here--Any help in pointing me in the correct direction would be appreciated
Terry
 

dklawson

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How long was the car sitting before you started it this spring? You may find that the carbs are gummed up with varnish and deposits from old fuel. The only fix is careful cleaning which really implies/justifies a complete rebuild. At the end of the rebuild there will be several initial settings that have to be made to get the carbs in a condition that will allow the engine to start. Once started you will then have to go through the balance and fuel/air mixture adjustments. I am more of an SU person so I cannot tell you the initial settings for the Strombergs that will be on your TR6.
 

Mickey Richaud

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Hi, Terry, and welcome to the BCF!

Like Doug, I'm more an SU person, but the Strombergs have diaphragms that can fail due to punctures or wear and tear. Not sure if that is the issue, but I'm sure someone with more expertise will be along directly.

:cheers:
Mickey
 
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Terry_M

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Thanks for the quick replies --the car was sleeping from Nov to April started once during a warm spell with no issues
I inspected the diaphrams doesn't seem to be an issue , ordered and installed the pricey needles with no joy (no build up or crud on old needles , obviously no need for them )
 

TR3driver

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No air into the rear carb indicates that either the balance is way off, or there is something seriously wrong outside the carb. IMO you should deal with that first, just so you know better where to go next. So loosen the coupling and screw in the idle adjustment until you get the carbs at least roughly balanced. If you don't happen to have a Uni-Syn or similar, just listening to the hiss with a short length of heater hose will get you close enough. When it's close, tighten the coupling again.

After that, if it still won't run without the choke, likely you do have a passage somewhere that is blocked by fuel deposits. Most likely the float valve IMO, but could be somewhere else.

There is an excellent series of 3 articles on the Buckeye Triumphs web site that covers theory, disassembly, reassembly, adjustment and so on. I suggest reading through all 3 before disassembling anything.

You mentioned installing new needles, did you turn the mixture adjustment full rich afterwards?
 
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Terry_M

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I think i ajusted to full rich after the needle installation but thier does not seem to be a start or a finish to the ajustments on the allan screw
 

poolboy

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Sounds like the needle/needle carrier assembly has become unthreaded from the adjuster. If a person ever went counterclockise more than 2-1/2 rotations then it's unthreaded and will not respond until you get it back onto the threads.
Once you get the threads reengaged, go fully CW (ricH) until it stops, then CCW (lean) 1 rotation as a starting point.
You should find the correct mixture between 1 and 1-3/4 CCW from full CW.
100_0502.jpg
 

TR3driver

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:iagree:
If you didn't find a stop at full rich, then the adjuster is either stripped out, or not engaged in the needle carrier. If it is not engaged in the carrier, then the needle is positioned beyond full lean.

On my carbs, that also means the carrier retaining screw is not engaged in the slot.
 

poolboy

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TR3driver said:
On my carbs, that also means the carrier retaining screw is not engaged in the slot.
Also a possibility, that.
Once the screw is fully threaded into the air valve,the unthreaded shank allows the assembly to move vertically yet not rotate when making mixture adjustments using the allen wrench
TR6grubscrew.jpg
 
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Terry_M

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Ok--took the needle out again--when i look up into the bottom from the needle side i see a flat round piece that fits excatly--when i turn the allen screw it rotates , can't see how that would thread in--the old needle shows no damage
Terry
 

poolboy

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From your description the piece still in the air valve is the adjuster,.See the part in the middle of the first picture I posted ?
It has male threads. The part you pulled out of the carb is the needle/needle carrier assembly, the part on the left in my picture.. It has female threads.
Shove it back into the carb; align the groove in the needle carrier with position of the retaining screw; tighten the retaining screw, making sure it's shank remains in the needle carier groove; then push up on the exposed needle while turning the adjuster with the allen wrench. Once the threads are started, you'll be able to make 2-1/2 clockwise turns. At that point the needle/needle carrier is fully threaded and the needle is at it's highest (richest) posititon.
If you go counterclock more than 2-1/2 rotations in order to lean the mixture you will again unscrew the adjuster from theneedle carrier.
 

hondo402000

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not that this could be the issue, but maybe a a valve train issue, stuck valve or something like that, carbs work on vacuum, no vacuum no pulley the air and fuel to the cylinders

not that its the problem but I figure with over 1000 years of experience on the forum,,, min, someone will hit the answer

Hondo
 
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Terry_M

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Ok--like Poolboy advised, attached the needle to the ajuster-(easy when we have someone to point the direction ) i will reinstall this afternoon --you know when i changed needles loosened the grub screw it just fell out in my hands , i am thinking i might have had this issue ,since i brought the car home as it has always ran a bit rich-I'll check the other to determine it's status-will post my progress---thanks for the help
Regards
Terry
 

TR3driver

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The adjuster screw (which locates the needle) is only held in place by a spring clip inside the bore. You might want to check that the spring clip is firmly against the screw and not letting it wander up and down.

I might even be tempted to remove the clip & screw, to replace that O-ring. When they get old, they allow oil to leak out of the dashpots, which will cause a severe stumble when you open the throttle.

I forget the size offhand, but it's a standard O-ring, readily available. My assortment from HF had them.
 
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Terry_M

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Well ! about four-five hours it is running, not great ,but i must say slightly better than before Is pernickety the word to best describe these carbs. Stopped because my back was sore from bending over ajusting these little rascals This car has been designed with a pollution octopus under the hood ,over the years it has been routed rerouted plugged and unplugged as it has been passed from hand to hand, which has added a certain amt of difficulty to the task( Wondering if a older set of carbs would be the ticket ?)
The material i have been sent for homework should prove invaluable-i think it is better to ask here rather than buy parts when we don't need them-talk soon & thanks again

Regards
Terry
 

poolboy

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If it's any consolation the 74 engines had the most complicated plumbing of them all. The carbs however a pretty much the same from 73 thru 76 with only a couple of minor diferences.

100_0482.jpg

This is a 74 engine; I was able to eliminate quite a bit of the plumbing. However there is ONE thing you must NOT do. Never put a cap or plug on the nipple that I have colored red in this picture. You can remove the hose that is normally attached if you decide to disable the Anti Run-on Valve, but do NOT cap these nipples.
TR6ARVVent-1.jpg
 
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Terry_M

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That is a much cleaner compartment Our six has a bit of blowby , you are hooked directly into the back carb,, i wouldnt be pulling oil would i ?-do you have the front carb open or blocked or could i tee it from the engine to both carbs
Regards
terry
 

poolboy

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You can "T" the Valve Cover to both carbs as originally designed. I just use the rear carb with the nipple on the front carb capped off.. I find that there is adequate vacuum to relieve the crankcase pressure from just the one carb. I've also eliminated the Carbon Canister (CC) and the Anti Run-on Valve (ARV). I had no run on issues to begin with and I have the gas tank vent tube going to a small motor cycle carbon canister strapped to the frame about as far to the rear as I had room instead of the original large one next to the radiator.
If you have blowby, you also have excessive crankcase pressure. just an open tube from the Valve Cover to the atmosphere won't be much help with reducing pressure. You'll need to add a little suction. With that suction, you'll reduce the pressure and as a result of that probably a reduction of the amount of oil leaks, oil consumption and smoke.
 
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