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MG TD TF 1500 - Carburetors for TF 1500 - Are They Correct?

The attached picture shows the SU Carbs on my recently purchased "Survivor" TF 1500 (Chassis # TF 8263). My questions are:
1. Both carbs have the numbers AUC 6020 cast into the body of the carbs. Are these the right carbs for a 1500? Are these H4 carbs?
2. The picture shows that the carbs have different suction chambers (I call them domes). Note the back or left carb has an angled casting (facing camera) where the large portion goes to the smaller top portion. The right or front carb does not have this feature. The pistons in both carbs have casting numbers of 3182/1. Both domes have vent holes inside from the large portion to the smaller neck where the dashpot plunger fits. Does the difference in the domes matter?
3.The dashpot plungers have no outside vent hole. I believe this is correct for these carbs?
4. The front float bowl has a casting number of 3495. The rear bowl has a number of 3496. They look the same. Any foreseeable problems?
Thanks,
Mark Stolzenburg
Chesterfield, Missouri, USA

Mark Stolzenburg

Here is another picture of the carbs on the TF 1500
Mark Stolzenburg
Chesterfield, Missouri, USA

Mark Stolzenburg

mark, i have a TD, so i defer to others..i can say..vented domes = non vented dome caps (dash pot plungers)
the float bowls have different numbers for front/rear so the bowl will be level when installed in it's appropriate location
1 1/2" carb throat is the H4..those big domes look like H4's to me.
good luck with the car.
regards, tom
tom peterson

From the shape of the dashpots Mark

The left hand one is a non vented one and the right one (front) is a vented dashpot. It should have a small hole in the brass nut on top but the LH one should not.
I believe from other posts on this forum the tell is the small cast tube seen on the top front of the LH carb.

Normally they would/should have been a matched pair I think. But I'm no expert and if they work - what the hay.

Rod
R. D. Jones

Mark,
The fuel line between the two looks to be some sort of plastic,,,neoprene,,, I'm not sure if I would want that type of fuel line so close to the heat that comes off of the exhaust manifold....

SPW
STEVE WINCZE

They look right to me. Not sure when the vent in the dome was changed to a pin hole in the brass cap or which was first. Here's the ones on my 1500. PJ


Paul sr

Another shot,


Paul sr

Mark, don't mean to hijack your thread, but while on the subject, my rear carb has no tickler pin and is a solid top, probably a replacement. The front carb was designed for one but it's missing and the hole was plugged with something, who knows when. Since mine isn't going to be a concourse restro, is there a solid top for the front carb without a tickler? PJ


Paul sr

Paul,
Are those period restrictor plates?
SRA
S. R. Ashworth

Paul,
Are those period restrictor plates?
SRA

Not sure what you mean? PJ
Paul sr

Must be Scott..they have the official tamper proof zip tie seals :-)


He's talking about the cardboard covers Paul.
L E D LaVerne

Just being a smart a**. Beautiful engine, Paul.
S. R. Ashworth

OH!! I'm a little dense this morning! Grin. You mean my wasp stops! Ha ha. We have the worlds largest supply of black mud wasps! Surprisingly they hardly ever sting anyone but they are a royal pain this time of year! I opened a tool box the other day that I haven't been in a couple months and low and behold, there was a mud nest inside one drawer! Maybe I should patent those, I have plenty of cardboard and wire ties! Grin. PJ
Paul sr

paul, on the carb with the ticlker, did the air cover come with a port for the valve cover vent tube? What brand ar the air cleaners? On my TD (maybe on all TDs) the valve cover vent pipe is vertical and I've installed a small K&N filter to allow it to vent (the original oilbath airfilter is long gone). Piping the vent to the air cleaner looks like a better option.
Thanks.

Jud

J K Chapin

Vertical breather for TD's to attach to oil bath.
Horizontal breather was stock for the TF's and attached (as Pauls shows) to Vokes air cleaners on 1 1/2" SU's. (Just the "forward" carb)
They sell repro Vokes ...but I am not sure if mount on 1 1/4" SU's is the same as 1 1/2"?
The Vokes are "angled" to allow fitting the limited space in TF bonnet due to fixed side panels.
David Sheward

Mark.
Back to your original question:
The carb on the left has the original internally vented dashpot, the one on the right is from an H4 dashpot externally vented from before the TF was built and should have the external vent in the cap. The cap on this should be round not hexagonal and have the vent hole. In any case it is not part of the original matched pair of the H4's on a TF. It is probable that the whole right carb has been replaced by the externally vented earlier version.

On my TF, the rear (left) carb body has the casting # 6020 as does yours, but the front (right) carb has that number ground off and # 6030 etched in it's place, implying to me the the two bodies are somehow different.

I do not know if it will give the correct performance as a non matched pair. Might I suggest that you talk to the real SU expert, Joe Curto.
He could supply the correct H4

I would exchange it for the correct H4

Originally the float bowl lids all had the tickler pin and it's hole, an engineering goof since it allowed bowl flooding to bypass the overflow tubes and fuel to flow directly on the hot manifold.

Later models of this cap no longer had the tickler pin hole drilled but still had the provision for it in the casting. A still later version revised the casting and removed the place for the tickler,

For safety's sake it is recomended that you seal the tickler pin or plug it
Don Harmer

If the rear carb is numbered 6020, being different, what is the front carb supposed to be numbered? PJ
Paul sr

Paul,

Front is 6030, rear is 6020 on the body
Don Harmer

Thanks Don, I haven't looked at the numbers on mine even though they look right, but over the years who knows for sure. They are both 1 1/2 bore though. I'll check the numbers this evening. PJ
Paul sr

Well, both of my carb bodies are 6020s! ?? PJ
Paul sr

As a follow-up to my original message, I contacted Joe Curto per Dan Harmer's suggestion. Joe said the carbs are the correct ones for a TF 1250 and 1500. He also said the Domes should match and the float bowls are correct. Bottoml line, I'm going to get a dome and matched piston from Joe.
BTW - I checked the "Piston drop" per John Twist's method and the piston on the front carb is not correct. In fact the left piston will not fit into the right dome.
Mark Stolzenburg
Chesterfield, Missouri, USA
Mark Stolzenburg

Both carbs on my TF 1500 (AUC 6020) do not have the 3/32" hole drilled through the suction dome "rib" as is standard. Instead, they have a 1/16" hole drilled through the dome at the top as shown. The hole slants upward and emerges on the inside very near the top of the cap threads. One carb has a 1/16" hole drilled through the cap, the other does not. Any thoughts on what's going on here?

JC Elliott

Non-original, I would think.

Tom Lange
MGT Repair
t lange

Question! While on the subject, My carbs both have vented domes and the front carb has a non vented cap, but the rear carb has a vented cap. The engine is the sweetest running thing I've ever heard, but I've never had it up to speed as the car isn't done, far from it. Should I put a non vented cap on to replace the vented one? PJ

Paul sr

Paul,
My suggestion would be that to fill the hole in the cap with a sealer (bath tube caulk would work fine) and see if it makes a difference in how the engine runs, especialy when you blip the throttle. I'd do this before you go out and buy a non-vented cap.
The rule of thumb is that non-vented domes need the hole in the cap or a vented cap and internally vented domes (like yours) don't need the hole in the piston cap. Supposidly the TF had the "dirt free" internally vented domes so no dirt got into the domes or piston!
I also see the arrows you have for the pins on top of the float bowls. I have the same as you, but my back one has the pin and the front one doesn't. My understanding is that at a later date SU produced replacement float bowl covers without the pins mainly because it didn't really make a difference other than with the hole plugged it assured no gas leaks. Personally I liked having the pins on my TC. I could feel where the float was especially if the car sat awhile.
Another topic is what oil to put in the piston dome. I've seen and heard of all kinds of variations based on temperatures etc. Interesting I was at a tech session given by John Twist of University Motors. He suggested 90 weight SAE oil. Seem awful thick but I tried it in the TC and I think the engine responded better. Tried different weight oils in the TF and stayed with the 90 weight because the engine seems to respond better. Anyway, that's my opinion -- and I'm sticking with it!!!!!
Mark Stolzenburg
Chesterfield, Missouri, USA
Mark Stolzenburg

This thread was discussed between 26/06/2013 and 22/07/2013

MG TD TF 1500 index

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