British-Cars.org

Welcome to the DMR Site for British Car Information.

Recommendations

Parts

TR parts and Triumph parts, TR bits, Triumph Car Spares and accessories are available for TR2, TR3, TR3A, TR4, TR4A, TR5, TR6, TR7, TR8, Spitfire and Stag and other TR models are available from British car spares and parts company LBCarCo.

Triumph TR6 - Sticking Air Valve

It seems like I have a lot of resistance when I try to lift one of my carb. air valves. It's been a few months, but if I recall, it's the came carb. that had little to no oil. It wasn't any better after I added more oil, but it almost feels like it's binding. It is very slow to come back down after it's lifted. Anyways, I'm pretty sure I need to replace the needle o-ring to correct the oil leak in addition to addressing this problem.

Thanks,
Mark
Mark Wright

Sounds like the one that is sticking might have a severe gunk build up....before taking them completely apart try sparaying some carb cleaner in the piston area from the top and bottom...but if your o-ring is leaking you may as well do a thorough overhaul to both of them. Rebuild kits are not to exspensive.
When all done you will still have resistance when lifting with your finger but both carbs should be the same and drop back down equally.

Charlie
Charlie B.

Mark,
Carefull with the carb cleaner as you do not want to soak the large rubber diaphram as it will swell and weaken.

It is very simple to remove the top of the carb 4x screws and simply lift out the air valve with diaphram attached. There is also a large spring. Then you can use a cloth soaked in carb cleaner to wipe the throat of the carb body and also the air valve. Note there is a slot at the rear surface carb body where a dimple in the rubber diaphram fits. The air valves were supposed to be a matched pair with the carb body, therefore the air valve is not supposed to be exchanged into another carb. Who knows if this has happened on yours or not?

You are correct the air valve is not supposed to bind at all for full travel. Granted the resistance to upward movement is governed by the viscosity of the oil in the damper.

The downward movement of the air valve by gravity should be a smooth movement ending in a "click" as it touches the bridge in the throat. It should not quickly drop down and slam into the bridge.

You may want to try swapping the air valves between your carbs to see if PO swapped them by mistake. You indicate only one carb is binding.
MRankin

Mark-You might check the diaphragm-they tend to harden with age and lose flexibility. Also, remove the dome and check the piston rod for scoring-this is the only part of the piston that contacts the dome or carb body and a little dirt can cause sticking. It is also possible that the damper rod could be bent. While the air is removed, check the needle for wear near the top.
I don't think the air valves&domes are a matched set on ZS carbs, because the diapragm provides the seal, unlike SUs' that depend on a close machined fit for sealing.
Berry Price
BTP Price

Thanks gentlemen. I'll tear it down this weekend as the weather is breaking now. I'm anxious to see what presents and destruction the mice have left me.

Admittedly, I didn't even drive it last year and I only started it a few times. A lot of those internal parts are newer 3-4 years old, so they better be good, but you never know. I never did replace the needle o-rings though. Thanks for the input. More questions to follow.
Mark Wright

This thread was discussed between 20/03/2007 and 22/03/2007

Triumph TR6 index

This thread is from the archives. Join this live forum now