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MG TD TF 1500 - Experience new carburetters from Burlen?

I'm not satisfied with the result of sealing my carburetters. Idle is too high, one is still leaking from time to time and misfire with closed throttle valve is still there in the exhaust. I can avoid misfire by putting foot down a very small amount, but leaking is not what I want to see and high idle (1200 cold -1500 warm rpm) causing by wrong air through the axes is a mess. They have been overhault 5 years ago and a master of automotive has spent some hours the last weeks. I'm considering to buy a new set of SU H2.

Are the Burlen parts of good quality or are this parts from India or china with the well know circumstances?
W_Mueller

I have bought plenty of carb parts from them and the quality is fine, except some occasional question marks over the thickness of washers. Their leak tight jet seals work much better than the cork originals, which they also sell. I doubt they make everything in house (who does these days?), but who knows.
Dave H
Dave Hill

W (sorry, I don't know your name), if the carbs were properly rebuilt 5 years ago it seems likely that sealing problems may be due to a lack of running time, with shrinking and drying seals. Your automotive expert ought to be able to sort this out, particularly if good seals are found.
I do know how frustrating this sort of thing can be, but buying a new set of carbs shouldn't be necessary unless these are thoroughly worn out.

The best of luck with your problems, and please do let us know how they work out.

Regards, David
D A Provan

If your carbs have been rebuilt and the idle is too fast check the throttle spindle bushes. The ones that are available from suppliers are square shouldered and should be pressed into the carb body so they protude into the bore and then dressed back to the same curve as the bore. If this is not done there is a small space where the throttle spindle enters the body and air leaks through this even when the throttle is closed and prevents a slow tickover.

Jan T
J Targosz

Mr Mueller - NO! Don't waste your money. Your carbs need to be re-manufactured (not just rebuilt), since it appears they have throttle-shaft wear. The uneven idle comes from ever-changing gaps between the shafts and the carb bodies.

The bare bodies need to be accurately mounted in a jig and the shaft holes re-machined to accept bronze inserts, and the shafts need to be replaced. The average rebuilder does not go to that length, and so the carbs never quite function as intended.

My (limited) experience is that the material of new carbs is not as strong as the older material. Although I have access to new carbs for my supercharger kit (see mgtrepair.net), my customers have had excellent results with re-manufactured original carbs.

Please contact me off-line, as I can put you in contact with an excellent and conscientious carb expert. I also have a set of NOS TD carbs on the shelf.

Tom Lange
MGT Repair
t lange

One way or another its probably an air leak, caused by worn throttle spindle bushes, or throttle disc not closing properly, or leaking manifold joint. There are also carb experts other than Burlen in the UK, who can do an excellent job in restoring the carbs, if that is what they need.
Dave H
Dave Hill

Thank you all - so many hints. I have to sort it.

W_Mueller

Hi,

I have bought 3 sets of Carbs from Burlen, no problem with any of them and I found it cheaper than having my old ones refurbished even including shipping and taxes. You get everything, so no more worn linkages or spindles.
B W Wood



I agree with Dave Hill. I just went through a similar problem on one of our other TD owners that has had a problem getting his car to idle below 1500 RPM even with the idle screws were all the way out and not touching the carb body contact points.

I've found that the engine should completely dye and not idle at all if the screws are backed out and the carb butterflies are centered and fully closed. Nice tight shaft bushing clearance is important for consistent idle and overall smooth repeatable performance, but they have little to do with an engine that just won't idle down below 1500 RPM. Remember the carb butterflies are connected to each other by the inter connect shaft that has those wavy fittings and little bolts. So the problem may well only be associated with just one of the carbs butterflies not closing completely because they are tied together by the inter connect shaft.

After completely disconnecting his throttle linkage and loosening a bolt on the interconnect shaft he found that one of his carbs wasn't closing completely because the coiled shaft return spring on it wasn't working. Also, During the trouble shooting for a possible vacuum leak, he used a propane torch to squirt gas around the manifold and base of each carb to see if RPM increased. He found the two lower bolts on the two carb flange mounts were loose, and the aluminum carb flange was not seated and was making contact on the manifold stud steel clamps preventing it from fully sealing on their gasket. My point in telling you this experience is that some times the simplest issues can cause us to blame the SU carburetor when another issue is the root cause. Sorry for the lengthy comment
Richard Cameron

Is there a recommended supplier of the reamer, bushes etc for someone planning a diy rebuild on a pair of H4s? The only supplier I have found was from the USA and claims not to post overseas.
Chris
C I Twidle

Burlen supply them Chris, and those are the ones that I fitted. If I remember correctly they were split and had PTFE liningss. They worked ok, but next time I would make my own and make them from brass. I have an Emco 5 lathe and that is what I used to install the Burlen bushes.
Dave H
Dave Hill

The reamer has to be long enough to ream both bushes at the same time. Short single reamers are in ready supply; long ones less so.

Tom Lange
MGT Repair
t lange

As I remember it with the Burlen bushes they recommend that you leave a shoulder on the inside face for the bush to butt up against, so a through hole with a reamer is not possiblr, I think that I set it up with the old spindle in the chuck and the carb held down on the cross slide. Then replaced the spindle with a drill, then a reamer on each side, perhaps non- optimum but worked.
Dave H
Dave Hill

Thanks guys, it's the long reamer 3/8 Dia with a 5/16 // shaft that I can only find in the US that I am looking for. I wouldn't trust the accuracy my little Atlas lathe. The processes are well documented in a video by Joe Curto and include the trick of leaving the original shoulder to make a better seal between the butterfly and the throat. I guess I will have to try a few engineering suppliers while I am still in the UK.
Chris
C I Twidle

After all I see no other way than buying a new set.

The thread of the jet assembly inside is worn. It is a little bit crooked. Or does anyone know how to fix such a worn thread in the aluminium body?


That seems to be the reason why the carburettor is always leaking and why it may be not tight at the upper bearing so gas can flow beside the jets. It leaks at the buttom too. It leaks at the buttom too and idle is still high with 1300 rpm. The plugs indicates more a lean mixture than a rich one.

W_Mueller

Mr Mueller:

the carbs are made of pot metal, and it is generally hard to repair them. I have an excellent set of nearly-new TD carbs that would be much less than a Burlen set.

Tom Lange
MGT Repair
tlange@acadia.net
t lange

Thank you Tom

do the air intake manifold flanges have two or 4 holes?

I'll send you an email for further actions.
W_Mueller

Winfried - You say in your first post that you will look for a set of H2 carbs, which are 1-1/4" carbs. They only came with 2-hole flanges. The H4, 1-1/2" carbs, came with two or four holes, depending on the venting system of the dashpot and damper cap.

I have H2 carbs.

Tom Lange
t lange

Thank you Tom

I'd asked because pictures in online shops some times shows H2 with 4 holes (it's only to confuse the russians).

I got the carburettor dry - but the jet stucks and idle is too high with new sealing parts, a new needle, new bearings and a new jet screwed to the top. Therefore I'd removed the clevis pin and now the choke cable only moves the front carburettor. That's a workaround but not a solution. So new carburettors are the option.
W_Mueller

Hello,

As for how to DIY reaming and rebushing the carbs with a not exotic reamer, you may want to look at this link:

http://www.chicagolandmgclub.com/driveline00/1001/jasw.html

Jesús
J Benajes

I just did my first carb using the method Jesus referred to. (And watching Joe Curto's video) I found I had to create cutting edges on the 'wrong' end of the reamer with a miniature cutting disc in a dremel. The manual drive then seemed a little laborious so I used the nut as a depth stop instead of a drive mechanism and ran the reamer backwards in a power drill. I will still run a 5/16 reamer through the new bushes as there is still a small amount of 'tightness' in one position. Nowhere near as daunting as it originally sounded.
Chris
C I Twidle

Thanks to Tom

he send me some pictures of his set. They look fine and as seen from the pictures they are a recommendation - but for buyers in D shipping, customs and VAT are too much.
W_Mueller

" The only supplier I have found was from the USA and claims not to post overseas.
Chris "..............

Chris, If you still want that Reamer, let me know. I can ship it to you if they won't. Can not imagine it would be too expensive. Just a small part.

Mike
TF-8257
M Brand

Thanks for the offer Mike, I picked one up in the UK on a recent visit. Front carb is back together now and looking nice and shiny, the baking soda blasting cleans the body up very nicely. just about to start on the second.
Chris
C I Twidle

Chris Twidle,
Note from your comments on BBS your are working on a TF plus are in Queensland. Working on a TF as well and live between Cooroy & Tewantin - are you in the Sunshine Coast area? If so would like to make contact and compare notes. 0421 998447.
Cheers John
J.K. Chester-Freeman

I purchased a new complete set (BURLEN). The order has the status backorder and I guess it will get a place under the Christmas tree.

Because I collect the original parts, try to get them operational and a new one is made out of different material I'm looking for one old carburettor body (like AS # 09-001) for SU H2 1 1/4" (Burlen AUC 549T) only.

Does anyone have this part in a good condition - preferably from Europe because of the shipping costs and customs?
W_Mueller

This thread was discussed between 20/06/2017 and 30/10/2017

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