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MG TD TF 1500 - Float Bowl Needle Valves

From Dean's comment in the thread on engine starting:
"Also check the bowls for fuel, could be stuck needles."

I don't know if it's just that I'm snake-bit or of this is a gratuitous feature of SU carbs but on my '62 TR-4 back in '67-'71, my '65 TR-4A from '71 - '80 and now on the TD the needle valve in the #1 carb has a habit of sticking at the most inconvenient times. Most recently last weekend I was driving up to Saluda (NC) to meet the better hald when just as I was approaching Tryon it seemed like the mill just fell apart (XPAGs don't run well on 2 cylinders). Neither tapping nor cussing had any beneficial effect so I limped back home and started checking. Electrics working and all plugs firing. Fuel a-plenty to both carbs. Removed the #1 float bowl cover and the needle dropped. Reinstalled without doing anything else and she ran like a (here insert something good because Singer is a competing marque).

Sorry for the long intro but there is a question. Will replacing the needle and seat assembly (Moss 371-060) cure this or is it just a feature of SUs. Once freed the needle moves freely and there is nothing visually wrong with the existing assembly.


J K Chapin

I wouldn't worry too much about it. If you have the float seats with the neoprene tips....I would replace them. Other than that.... keep the tools handy.
C.R. Tyrell

Generally from dirt or scaling. Doing what you did, or sometimes tapping on the bowl lid, seems to be the best remedy.

These cars break down fairly frequently but the fix is usually trivial so its just part of the experience. They are not appropriate for 'namby-pamby' drivers :-)
Chris Couper

I have recently rebuilt a MGYA to complement my TD and fitted the new float needle pin with the neoprene tip supplied by the SU parts supplier Burlen.

For the first couple of weeks I suffered with the constant problems which turned out to be the needle valve sticking, not letting fuel into the bowl, the neoprene seemed to be sticking to the valve seat. I refitted the old brass needle pin and had 700 miles trouble free motoring. So my advice would be to steer clear of the new replacement, sometimes the old design is better.

Cheers Chris

C A Pick

Mine were stuck after a six-month storage after rebuild. (See my recent posting). The cylinder (aluminum) and piston (brass) are different materials. I believe they suffer from electrolytic corrosion, which is induced by the contact of dissimilar metals. It is a design defect. Checking for piston free movement is the only preventive measure I can suggest.
Corey Pedersen 1951 TD #7169

Thanks all for letting me know I'm not alone being stopped on the side of the raod tapping on the D@^^ned float bowl chamber. We have a 50+ mile tour tomorrow and I have spanners to tap on and, if necessary, take off and shake the danged things.

J K Chapin


Years ago whilst serving in Germany [1968] I have the same issue. Sticking fuel needle in the float chamber.

A German friend gave me a set of Gross needles and I have never had a reoccurrence of the issue again. 40 years + later.

I recently re-did my carbs to overcome a running rich issue[another story] and in the carb kit I received a set of the nitrile? tipped needles and seats.
I noted that gravity would not pull down the needle when the forks dropped - so put back the Gross valves. Why change something that has worked that well for so long. Possibly fuel pressure would have opened the valve needle but I decided not the change the working arrangement.

R D Jones

Yup, and I have some correspondence that makes me thing the #1 carb has the nitrile installed. I'll look back and see and, if so, replace the danged thing.


J K Chapin

I have found in the past that this can be caused by the fuel. Some fuels can seem sticky. Name brand high test appears to have the additives to clean this stuff out.
I have had no problems with nitrile tipped needles but have not used regular fuel with them.
D Hanna

hello, since chris posted his experience on this thread i feel compelled to post mine for consideration to any possible newbies on this site.
my experience with the MG TD series is wildly different from chris couper's. (these cars break down frequently) my experience is limited to a decade and well over ten thousand miles without a hiccup...but in that time i have traveled from illinois to texas to canada and all parts in between. next summer i plan to drive to the westcoast and down the pacific coast highway from illinois without worries or a large spares inventory. the car has been bullet proof, but as i said that is only a decades worth of driving..there are guys who post on this site with more years and miles.

regards, tom
tom peterson

That 50 mile jaunt ended on being 250+ mile with not a burp or a studder - probably because I put a decent set of tools on the boot in anticipation of problems. I've been up in Foggy-bottom ever since so I'm looking forward to taking the TD out for a spin Saturday.

Part of the jaunt was from Tygerville up the Saluda Grade to Chimney Rock. I was with a TR-6 and an MGB. The TR-6 was running # 2 and I was # 3. When we crested the ridge and pulled into a service station for an RC and a Moonpie the TR-6 driver asked if I had some big engine in the TD. I'de been flying throught the gears twisting between 4500 and 5000 and staying right on his tail through some pretty good hairpins. "Big engine?" I took it as a compliment.

J K Chapin

I put in a set of the Gross ball valves many years back. Never had an issue one with them.
Bruce Cunha

I have had the grose float valves for 8years with no issues. Regards, Tom
tom peterson

Hi Guys
I have found that rotting fuel lines can produce little bits of black rubber or whatever they are made from. There is a filter in the SU fuel pumps that catches it to that point, but from there on there are no filters (at least not on my TD) to stop the junk generated in the 2 lines to the carbs. Since I put on new lines I have had no leaky float valves.
My 2 cents worth!
cj schmit

I believe that, in the H series carbs, on the inlet to the feuel bowel, at leas in mine, there are screens, similar to the ones that are in the SU fuel pump.

Jim B.
JA Benjamin


You are correct re the filter screens in T Type carbs. Unfortunately they are either slightly damaged and let debris through them
or as you say,they are missing altogether.

Rob Grantham
Rob Grantham

I had grose jets in my TD, TA and my Model A Ford. I had constant sticking problems, especially in the Ford. No amount of cleaning or adjusting helped for the long term. Replaced all with original type brass needles and no more problems. It seems that the ball in the grose jet has more surface area to get gummed up and stick than the tapered point of the needles.
John Masters

Like John Masters, I had nothing but trouble with Grose jets with the slightest bit of debris or gummy in the gas. Replaced with needles. no problems since.

I notice that John Twist says get "rid of them" as the first step in a Tech Topics on Carb problems in the current "MGB Driver"

Be sure to treat your gas with Stabil to minimize "gummy"
Don Harmer

A correction: John Twist's comment about Grose jets was not in the current Car and Driver, but in some source that I read recently and I can't find it again. Don H.
Don Harmer

My experience is 180 out from that. I've had Gross Jets in my TD for over 15 years and never had a problem. I just returned from a quick 1,000 mile trip (in Lazarus) to PA to solve a rough running problem in the 53TD that I sold in May. Long story short - the problem was sticking new-style tipped needles. Replaced them with 2 Gross Jets from A/S and the car is running like a top. If anybody has any unused Gross Jets that want to get rid of, I'll be happy to take them. Bud
Bud Krueger

My experience mirrors Bud's. I am not sure how many thousands of gallons I have run through my car. I also had a fuel tank that put out debris for most of that time...rust dust in the float bowls i would clean out every several hundred miles...and never an issue with the Grose float valves.....even after a couple of long sit times with ethanol (treated with sta-bil) but still old issues. Regards, Tom
tom peterson

I've had both the grose jets and the us needles stick. The front carb on the TF is sticking now. Not too bad, it stops with the vibration of the engine, but it is still unsafe to start the car with the overflow tube spewing gas. I may try the grose jets again.
D. Sander

This thread was discussed between 17/10/2013 and 26/10/2013

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