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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - SU Carbs

I used this thread title deliberately as a result of an archive search. I'm looking for a pair of float bowls to suit 1 1/2" SU's so I figured I'd try the archive. There are two 10 year old threads using this title. The first is very funny, the second with just one entry, even more so. Check it out. When you're done laughing if anyone has the float bowls I seek email me pjbm at bigpond dot com. Yeah I know 1 1/2"'s aren't original to the TD. I have the 1 1/4" setup however with the cam & a 10 to 1 CR I think she'd appreciate a bit more fuel. Cheers
Peter TD 5801
P Hehir

If I'm not mistaken you can buy them new from Burlens.

Cheers

Bill Chasser
TD4834
Bill Chasser Jr


Peter, I'm no authority on Su Carbs or a racing expert, but I believe the H4 1 1/2" SU for the MGA, TR3, Austin Healey all use the same float chamber as the MG TD.
Hopefully someone who races the TD series can tell you what they do to increase fuel availability at the carb. I have seen but have no experience in heir use, Float bowl extensions that are designed to make the bloat bigger in capacity. See this link:

http://www.swiftune.com/Product/683/swiftune-h4-su-float-bowl-extensions-with-small-floats.aspx
Richard Cameron

Thanks Bill but I'd rather find some originals. Seems 1 1/4" bowls are the same as the 1 1/2" & so will fit. I'll try & also find a rear bowl here in Sydney as I now have a front bowl. Richard my standard pair of H 4"s will suffice as I just need to up the delivery from H2 to H4.

I'll need to clean the 1 1/2" carbies up as they're pretty gunked up from years of disuse. I've tried carby cleaner which did absolutely nothing. I'd like to immerse them in something like either a weak acid or alkaline solution, but not too savage a brew, once I've completely stripped them down. Looking for a cheap & effective chemical. Diluted caustic soda maybe? Any suggestions? I have a buff but the heat generated can distort the piston chambers so I'll avoid that approach. Cheers
Peter TD 5801
P Hehir

Soda blasting looks to be very good for carburettors.

Google for DIY soda blasting for inspiration.
Willem van der Veer

Peter,

I can confirm that the H4 and H2 float bowls are the same.
They are both refered as "T2" type, 2 5/16" OD.
SU parts numbers are:
AUC 4814 right and AUC 4815 left.


John

52 TD

J Scragg

John, could you please email me at efhask at roadrunner dot com
Thanks,
Ed
efh Haskell

SU "H" float chambers come in horizontal, 20 and 30 degree angles. I think ours are 20 degree.
Ray TF 2884
Ray Lee

Thanks John & Ray. Ours are the 20 degree jobs. Apart from soda blasting any suggestions on the chemical cleaning?

The really odd thing is one of the carbys doesn't have provision for a damper. When I removed the piston chamber the tube that the dashpot lives in is capped & appears to be a solid rod. The carbys were picked up at a swap meet & carry the number 4031. There is no AUC number. They are identical in every respect except for what appears to be the solid, capped at any rate, dashpot housing on the rear carby. Both carbys had brass caps with knurled edges & neither had a dashpot damper however I was able to fit one from one of my spare 1 1/4" SU's to the front carby. Anyone shed any light on this? I'm able to post some pics if that would help clarify things. My terminology is descriptive rather than accurate. Cheers
Peter TD 5801
P Hehir

Peter

Here you go, untested however seems viable;

You do not need to scrub your aluminum pots and pans to death to keep it clean and shiny. There is a homemade recipe that you can create to clean your pots and maintain their luster. You need cream of tartar and vinegar or lemon juice for this homemade recipe.

All you need is to fill up your pan or pot with water making sure that you use about 2 tablespoons of cream of tartar for every quart of water. Add ½ cup of lemon juice or vinegar into the pot. Allow this solution to reach rolling boil. Let it boil for 10 more minutes before you remove the solution from the pot. Let the pot cool. Once the pan or pot is cool, wash it and allow it to dry. This will effectively clean your aluminum pots and pans and at the same time restore their shine.

Graeme
G Evans

Well there is conjecture re the bowl P/Nos, my original bowls are embossed with AUC 3495 and 3496D. Have not removed the complete Burlen set to observe if they are identified.
G Evans

Tried the tartar & vinegar brew Graeme but no joy. When I restored the 1 1/4" 's about a year ago I used 0000 steel wool & finished with Autosol metal polish. Took hours which is why I'm seeking a chemical immersion which actually works. I don't expect a pristine highly polished finish straight from the mix but something that eats away the gunk & then polishes up would be nice.

Apparently the 4031's are the rare & highly desirable original TD MK 11 H4 carbys. Gordon Lawson found a pair in 2009 & was quite chuffed about it. See below & the pics in the archive. A carby specialist here in Sydney, CSC, says that the heavy brass pistons in the 4031's didn't require damping. He's checking his archive before we meet as I want to be sure I have all of the original ex Abingdon fittings. Cheers
Peter TD 5801

P Hehir

As there have been no suggestions on my search for a chemical clean I've adopted the following. Start with carby cleaner to remove oil & grease using an old toothbrush. Using a stainless saucepan, (specially bought from St Vinnies to keep she who must be obeyed off my back), immerse in the vinegar & cream of tartar brew & simmer for about 15 minutes. Rinse then repeat this step with new brew. I found it necessary to ensure total immersion otherwise white scale settles on any exposed areas. Wash thoroughly in soapy water again using an old tooth brush, rinse in clean water, dry & then get to work with the 0000 steel wool & Autosol. Takes a while but the end result looks great.

Still need a pic or two of the original arrangement & detail of the spindle set up i.e. mixture screws, idle screws, lever, springs etc. I have a few swap meet 1 1/4" carbs which I can cannibalize for the correct bits. Cheers
Peter TD 5801
P Hehir

Peter

I did some more web browsing and found considerable conflicting views, however there was some consensus that sodium hydroxide ( caustic soda) in a diluted form gave good results.

Immersion time, dilution rate and the application of heat seemed to have differing opinions. If you have a carby that is surplus I would be giving this a quick test at a dilution rate of 50%. You apparently will not end up with a bright finish however from my limited reading apparently original carbies never had a polished finish.

Also check out the Youtube vid where the guy boiled a carby in lemon juice. Propriety carby cleaning products received mixed reception.

Graeme
G Evans

I have two 1 1/4" carbys with pistons that are frozen to the chamber. I've been soaking them in WD 40 for a couple of days but still no sign of shifting. Any suggestions?

Can anyone with an original TD 1 1/2" MK 11 carby set up confirm that the sketches showing the arrangement of the mixture, idle, lever etc in the Driver's Handbook are accurate? Cheers
Peter TD 5801
P Hehir

I would heat the carbs up very carefully. The outer shell should expand and the pistons inside, not so much.
Geoffrey M Baker

I'll shove the chamber & piston in the saucepan & cook them up in the vinegar solution Geoff. I'll let you know how I get on.

Graeme, I concur with your numbers except for the AUC bit. The bowls I have now are front 3495 PDC & the rear is 3496 PDC. Picking up some original second hand W clamps, a lever & spindle return springs tomorrow as well as the service kit on Monday, complete with jets, seats & needles.

Can anybody advise on the best needle for the 1 1/2" H4 SU 4031 setup? The car has a 10.1 to 1 CR with a 210 210 08 cam & roller lifters. I'd like to get the appropriate needles with the kit, or is this something that can't be planned & is just a case of suck it & see? Cheers
Peter TD 5801
P Hehir

Need to see what Dave Braun uses when he rebuilds carbs. They come back looking fantastic.
Bruce TD4139 Cunha

Peter. You and I are using similar engine configurations with re to cam and compression I think I'm one step higher on the cam chart. My MK II carbs are a bit fickle and not sure how correct they are. Tom lange would be the go to guy on carb info I would think. I currently have a set of H4s that were off a TR 2 or 3. They are identical to the TD versions linkage wise though the levers have to be swapped end for end because the triumphs sat on the opposite side of the engine vs XPAG? I am starting with the std MK II needle to start. I believe it is a GJ. The Bowers WSM gives the lean/std/rich needle sizes in the stage I-IV bulletins.

Re Chemical cleaning I use Berrymans Carb Cleaner. It comes in Gallon and 5 gallon cans. I buy the larger for convenience. It's gotten quite a bit more expensive the last ten years. Don't know if it's available down under. Works very well at cleaning gunk and carbon deposits. The dash pots I machined polished with progressive rouges. But the best rouge I make with a mix of comet cleanser and bees wax as the binder.

Hope this helps

Cheers mate

Bill Chasser
TD4834
Bill Chasser Jr

Peter

Can I suggest you call Peter Fogarty for I gave him some old SU parts not so long ago, he may be able to help you. I think they may be what you are after. As you know he is very good with SU's. If you rather I can drop in to see him and come back to you. Just let me know.

With respect to polishing I have restored a few MG's in my life my MGA being a concourse winner and of all the carby's I have polished I have used a 100mm rag mop on a 1/4" arbour inserted in my drill. The drill was held in the vyce and I polished all my aluminium pieces this way. Use Autosol metal polish as a medium. I get great results the final finish becomes mirror like.

Do not use wet and dry for you will then have to work hard to get the scratches out.

John
John Walton

Deja vu John! I'd already rung him & arranged to drop over about 2 tomorrow arvo with the carbys. He thinks he can help. I like Autosol as well. I buffed up the float bowls yesterday & they look great. Thanks mate. Cheers
Peter TD 5801
P Hehir

Peter - the stock Mark II 4031 carb needles are LS1; I use GJ, which is just a tad richer.

Tom Lange
MGT Repair
t lange

I had these rebuilt by a local carb re-builder, he's actually a member of our car club. These carbs were in pretty sad shape for appearance, but you can see them as they are now. I don't know his method for cleaning them up, but they look like new now. I'll ask him. PJ

Sorry for the pic being a little fuzzy.



Paul161

Peter, the saucepan may work but the real trick is to heat one part but not the other, causing expansion and separation. I would take a propane torch and just heat up the exterior, keeping the flame permanently on the move, and see if that eventually frees the piston inside.
Geoffrey M Baker

Thanks Tom. I'll get the GJ needles. Geoff I'm worried about the direct heat method because of the potential for distortion. I've been warned that even the heat generated by using a buff can distort the chamber. Be a shame to finally get it apart using propane & then discover it's unusable. I've managed to shift & separate one of the pistons using WD 40 followed by some time in the saucepan but the other remains obdurate. Cheers
Peter TD 5801
P Hehir

I know what you mean.
You could try plugging the top of the chamber and sitting it into boiling water upside down, with it remaining dry in the piston area. That might evenly expand the chamber, but not the piston as much....
Geoffrey M Baker

Just picked up some bits from Peter Fogarty & met up with John Walton at Pete's place. Exchanged a bottle of 2010 Zonte's Footstep for the carby bits which made us both very happy. One step closer. Cheers
Peter TD 5801
P Hehir

Peter

I would be requesting to commandeer your better half oven this will apply evenly distributed heat providing you sling the component of an oven shelf. The timing of the heat soak will be critical as you want the thin walled chamber to expand prior to the piston expanding.

I posted a link to a document that listed the SU sizing applications in another thread, will try to locate it.

Graeme
G Evans

Peter

This is a even better resource:

http://ttypes.org/ttt2/tuning-the-su-carburettor-on-the-t-series-mg
G Evans

Thanks Graeme. As both the piston & chamber are aluminium the timing will be crucial. Perhaps I could quench the piston with iced water while holding the hot chamber in an oven mitt & give the piston base a gentle tap or two with a hammer? I don't need this carby but I'd like to save it if I possibly can. Peter suggests that the GJ is the standard needle for the TF 1500 so as Tom has also recommended it, that seems like a good place to start. Cheers
Peter TD 5801
P Hehir

I like the idea of using the oven, you can evenly heat it hotter than by boiling. However, not sure about ice water, the sudden temperature drop could cause cracking.
I'd just heat it up nice and hot and try to remove it. If it won't work, let it cool soak in WD40, and repeat.
Geoffrey M Baker

Given up on attempting to free the stuck 1 1/4" piston. I now have almost all of the bits for the 1 1/2"'s, with the two coupling "springs" & a left hand float bowl lid with tickler coming from Graeme. I have 2 metres of 1/4" brass rod so I can cut the coupling spindle to the desired length, about 65 mm. The spindle return springs at the extreme ends of the carbies are now fitted & functional but I'm unsure of the length of spindle that originally protruded. Would it be about 6 mm from the end of each of the spring housings? My 4031's are probably from a Riley so the spindles are overlong. Still missing the rear mild steel lever that traps the choke cable housing & the mild steel threaded coupler that connects the two brass choke levers, so if anyone wants to unload these items, I'm a buyer. I now have the service kit & the GJ needles & I plan to strip the carbies, clean, polish & rebuild them over Xmas. Cheers
Peter TD 5801
P Hehir

Here is a set of H2s; The bodies are polished to an oil resisting (even fingerprints) surface; the brass polished, and the rest of the items replated and treated with oxides and sealed as appropriate. I use the same process Jeff Schlemmer uses for his distributor bodies, i.e. a proprietary machine that does a pressure tumble process.

Warmly,
dave

Dave Braun

They look pretty schmick Dave. The two components I'm missing are clearly visible in your pic. Do you happen to know how much of the brass spindle rod was visible beyond the return springs, when they left the factory? Cheers
Peter TD 5801
P Hehir

Had the 4031 carby with the solid piston rod drilled out today on a lathe to form a tube thus matching the other piston & both pistons now weigh less than 3 grams of each other (347 & 349.3 grams). The piston in the heavier carby still has, what I guess is the atmosphere hole, to be enlarged to match the hole in the other piston & I think both will end up weighing pretty much the same once that's done. Both now accept the dashpot damper should it be required. Obviously the carbys were never a pair but now should cohabit nicely. One step closer. Cheers
Peter TD 5801
P Hehir

This thread was discussed between 29/11/2015 and 12/12/2015

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