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MG TD TF 1500 - Carburetor - O-Ring Sealing Washer

Looking for an O-ring to replace the large cork sealing washer on both SU H-4 carbs on my MG TF-1500. (Not the gland washers)

> Local source?
> Type of rubber?
> Size / part number?
> Comments?

I installed a gasket kit from Joe Curto in each carb last week. Soaked in oil for 36 hours. Tightened the sealing nut as tightly as I could. Carb dripped two drops of fuel per second from the sealing washer. The washer appears to mushroom out at the carb body and pull away from the lower jet bearing as I tighten it. It seems to seal inside the aluminum sealing washer OK.

Replaced the new cork washer with an old cork washer. Drip stopped, but the washer was old, too flat, and oozed fuel. I repeated the changes multiple times expecting a different result (duh)

I discussed with Joe Curto and he is sending replacement cork sealing washers to me, but he also said that O-rings could work.

I searched the archives, the web, and my local club. I found some references to using O-rings. Various types of rubber and sizes were mentioned. Looks like Vitron is the material of choice. Is that still true?

I'm trying to get back on the road by Thanksgiving, so I want to buy locally. I can replace with cork if necessary when the ones from Joe arrive, assuming the new cork washers fit better than the first ones.

I appreciate any tips and info on sources, types, rubber, part numbers, etc.

Lonnie
TF7211

LM Cook

I think Moss has them. PJ
Paul S Jennings

Lonnie - The cork jet sealing washer can be replaced with a Parker 2-211 'O' ring that should be available from NAPA. Cheers - Dave
D W DuBois

Lonnie,
I purchased a set of Teflon O rings for the jets and the large Jet Screw Nut from
Thomas Bryant <thosbryant at gmail dot com> and have not had a problrm with them
Dave D also said to file the holes in the jet to chamfer them a tad so the sharp edge does not cut the small O rings. 2 of which go to the top and 2 go to the bottom in place of the Gland Washers. The Large one replaced the Jet Screw Nut washer.
Our modern fuel will not effect them.

Rod

Rod Jones

Wait...Lonnie, are you experiencing fuel drip from the jet, at the bottom of your carb? That's where my fuel drip is and I was told that the carb would need to be rebuilt to stop that. The car runs great, but that fuel drip is a hazard and an annoyance that I would like to remedy. Am I to understand that I can use O-rings to fix it?
Cheers,
Frank
Frank Bice

Frank
If you replace the Jet (Copper) washers with the correct size new ones (thin one on the bottom - Wide one on top) and replace the gland washers and Jet screw sealing washers with the Teflon ones. You should not drip fuel from the bottom of the jets.
Mine are also easier to move up and down with the choke leaver now.
I also soldered the choke cable end (the last 4 inches) to help push the jet leaver back up when the choke gets pushed off.

Rod.
FWIW
For 40 years of TDing I had no problems with the cork gland and Langite packing washers. But since coming to the USA and Ethanol. My fuel hoses became sieves and the carbs dripped. New hoses and the O rings fixed the problem.


Rod Jones

Are you sure that both tapered upper and lower aluminum seal rings are in place? I've never had one leak there.

Tom Lange
MGT Repair
t lange

Rod,
Thanks for the comments. Can you tell me more? Are those parts available in a kit, or do I need to procure them individually? Where do you recommend I get the parts....from Joe Curto? About how much can I expect to spend? As you can tell, having no carburetor experience, I'm trying to make this as easy (and inexpensive) on me as possible :-). Not that I'm lazy or cheap, but I just don't want to chase the wrong parts, you know? I've looked at Moss....seems they have a Master Rebuild Kit for $170. Will that include the parts you described, and the quality/type you mentioned? Thanks for any help you can offer.
Cheers,
Frank
Frank Bice

Frank - You can get the 8 teflon 'O' rings and the 2 large Banna N 'O' rings from Tom Bryant at the e-mail address in Rod's post above. The complete kit of 'O' rings is not very expensive and will definitely cure the drippy jets. I did the jets in our TD somewhere around 15 years (or more) and haven't had a drip from either carb in all that time. Cheers - Dave
D W DuBois

> Frank - Buy Lawrie Alexander's video on rebuilding and adjusting SU carburetors. Moss has it. Don't know the item number. Start and stop it as you rebuild your carbs. It's really good. 'Course my carbs are screwed up, so take my advice with a grain of salt !!

> Dave - I'm on the way right now to buy Viton O-rings. Gonna try three sizes ...
-210
-211
-313
I'll see which fits and seals best. Probably reject all but the -211 that you recommended.

Lonnie
TF7211
LM Cook

Suggest you contact Burlen at http://sucarb.co.uk/ they are SU manufacturers and supply rebuild kits. A completely new set of carbies cost me <$A1200, best purchase I have made restoring my TF, bolted them on, no tuning required except for setting the idle revs.
G Evans

Lonnie,
You recommended a video by Lawrie Alexander. Is that Moss part number 211-036 for $52.95? That's the only one I find.
Cheers,
Frank
Frank Bice

Frank -

Lawrie Alexander made the VHS video in 1987. I assume that the Moss video is the same one updated to DVD.
http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=30277&SortOrder=10

Someone in your local MG club may have one to loan to you.

He is a past president of the Sacramento Valley MG Car Club. A few years ago the video was available for sale by the club.
http://www.svmgcc.org

Note: The SU H-series carb that Lawrie rebuilds in the video is for an MGA and uses rubber washers between the float bowl and the carb body. SU carbs on T-series cars use fiber and metal washers. He mentions in the video but does not show. This diagram on Joe Curto's site shows the difference. T-series float bowl is shown in "Float Bowl Variation B".
http://media.virbcdn.com/files/16/e94d4d04e7414e5f-HTYPEEDIT8-10l.pdf

FWIW - I like the SU Master Rebuild Kit from Moss. Real SU parts.

I bought an assortment of Viton O-rings yesterday. I'll install today and post the results.

Lonnie
TF7211
LM Cook

Frank
Toms kit (for 2 carbs) came to $8.00
He has been fixing and rebuilding SU carbs for Volvo's for years and has a unique bushing for the throttle shaft as well. Take a look at his Blog.
Very imformative.
http://thosbryant.wordpress.com/2014/03/01/su-carburetor-rebuild-h-4/

TD's don't have these H-4's but most of the carb is similar to ours.
Rod.

Rod Jones

A new question and an update on my original question ...

> NEW QUESTION: What are the dimentions of the Teflon O-rings that some of you are using instead of cork glands on carburetor jets?

My jets are 0.248" diameter. Teflon 568-010 O-rings are 1/4" I.D. nominal (0.239" I.D. actual) X 3/8" O.D., 1/16" cross section nominal (0.070" actual). Is this what you are using?

I can buy locally from the same supplier where I purchased Viton O-rings to replace the cork seal.


> UPDATE: I replaced the cork seals on my carburetors with Viton O-rings.

O-ring sizes are defined by a "dash number." I bought four sizes of Viton O-rings and two sizes of Buna to see which fit the best.

I chose #568-210 Viton O-rings which are 3/4" I.D. nominal (.734" I.D. actual) X1" O.D. nominal and 1/8" cross section (.139" actual).

Dave suggested using the next size larger #568-211 which are 13/16" I.D. nominal (.796" actual) X 1-1/16" I.D. nominal and the same cross section as -210. If I'm wrong, I have plenty of extras of both sizes.

I chose -210 because it fits the jet screw better than -211. The cork seal rests in an depression at the base of the jet screw. The depression is 3/4" diameter. So I chose #568-210 O-rings which are 3/4" I.D. nominal. The rings sit in the depression in jet screw, but do not bind against it. I figured that there would be less chance of becoming off-center or distorting as the jet screw is tightened against the carburetor body.

The -210 O-rings compressed perfectly to leave only a sliver showing between the aluminum sealing washer and the body. No leaks.

I bought from Sterling Seal and Supply that has a local warehouse in here in Orlando.
Sterling Seal part number 210-7575
-210 Black FKM 75 O-Ring 3/4X1/8
Cost = $0.764 each. Minimum total order of all items is $15.00.

Here are the six sizes that I tried: #16 and #17 O-rings with 1/16" cross section; -210 and -211 O-rings with 1/8" cross section; -313 and -314 with 3/16" cross section.

But now the cork glands in one carburetor are leaking. The float bowl drips dry in about four hours. Probably from disassembling and reassembling the carbs at least six times in the last week. So I may try using Teflon. Two for the top gland and two for the bottom gland. That's the reason for my question at the beginning of this post.

Thanks for your continuing help.

Lonnie
TF7211
LM Cook

Lonnie, :)
Sorry to say I only brought one set from Tom and they are in the car now. Which is in the Cocoon for winter? 14" of snow yesterday...
You could try an email to Tom and ask him what he is using. I am sure he would help you with the dimensions. And yes, you use two each in place of each cork gland washer on the Jet.
It is important to get the size right as you want the Jet to move down and up with the choke and not bind. The return spring to not all that strong. I even soldered the last 4 inches of the choke cable to stiffen it up to help push the jet back up to prevent running too rich with the choke off.

Rod

Rod Jones

Rod -

I re-read Tom Bryant's blog that you previously linked. It answered my questions.

> He replaced the cork seal with -210 Buna-N O-rings. Same size that I used. I used Viton instead of Buna-N.

> He replaces the cork glands with -010 Teflon O-rings.

I wish that I had read the blog closer the first time, I could have bought the Teflon O-rings when I bought the Viton O-rings. Wouldn't have bought the other sizes to test and wound not need to buy another $15 minimum order at Sterling Seal and Supply.

You noted that you soldered the last four inches of the choke cable to push the jets back up after using the choke. Do the Teflon O-rings restrict movement of the jet more than cork?

Thanks again for your help,

Lonnie
TF7211
LM Cook

I rebuilt with a Moss kit. Finished and started the engine. Dripped right away.

As usual I assembled wrong. Cork was upside down. Took reassembled and all is fine. That was 4 years ago. Still holding up.

Peter 54TF
Peter Dahlquist

Lonnie,

With the Teflon O rings I think the Jets go down and up easier than with the Original cork ones. Don’t forget to file the holes in the jets to remove any sharp burrs or edges before fitting the O Ring seals.

I was having a problem with running rich (judging from the plugs) and noted that when I pushed the choke back in the return spring did not always pull the jets all the way back up to the Adjustment nut? With the O rings in it was better but just for a belt and braces type deal, I soldered the last 4 inches of the choke cable to make it stiff and it now pushes the jets back up to assist the return springs. Replacing the choke cable inner with piano wire would be another way to go.

The over-run when turning off the engine also has been markedly reduced.
Still thing I will need to get the head off and do a de-coke next year though.

Rod
Rod Jones

Thanks Rod. I'll buy and install Teflon O-rings tomorrow. And I'll make sure the jets have no sharp edges.

Lonnie
TF7211
LM Cook

This thread was discussed between 24/11/2014 and 30/11/2014

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