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MG TD TF 1500 - 1 1/2' Intake Manifold

When grinding, enlarging, a 1250 intake manifold for 1 1/2" carbs; IMO you have the job done when > a socket of 1.3" dia. /1.50" long, can fall through, 1.50" dia. on the carb side, 1.4"x2.1" on the head side, with a 2.2" diagonal measurement. (not for low RPM requirements, 3,000- 5,500 or so RPM.)
Len Fanelli

I assume you would have to port and polish the inlets in the head if doing the 1.5 SU's?

Gordon, It would help, but not mandatory. Not a hard job, just a few tricks of the trade to keep in mind.
Len Fanelli

hello len, i have a set of 1 1/2" carbs and i have a large valve head. i have been looking for a 1 1/2" TF manifold but after reading your post i am now thinking of going the boring out route you mentioned. my question is if i do that will i have to fit a different manifold than the standard aluminum with oil bath? regards, tom
tom peterson


As far as I know, there was never a special casting for the TD Mark II. If I'm not mistaken, the standard 1¼" cast alum. manifold was opened to 1½" to accomdodate the 1½" SUs of the Mark II.

This way of course, with your similar TD, you will retain your standard oil bath air cleaner.

However I am quite suspect of the ability of the convoluted airway of the TD air bath system to flow clean air to a TD, and I'm inclined to think that the TD could be made to breath much better with a straigt through and less restricting air cleaner (like the TF).

I suppose it could be argued that this is no longer "stock", but what the heck, if you store the air bath plumbing away, it can always be re-installed if a prospective buyer should want it.

Gord Clark
Rockburn, Qué.
Gordon A. Clark

As Len has suggested I have been running 1 1/2 in. carbs with a bored out 1250 manifold. For air cleaners as Gordon suggested I selected TF type, they have seemed to work very well.



Hi Tom,

I think that I have a TF manifold in my garage.

Contact me and I will send photo if you are interested.

I am not computer literate at loading a photo onto the bulletin board, advice would be appreciated.

Regards to all


Gordon, the image attached is of the MKII manifold.

Bud Krueger

Gordon Clark -- If the same castings were used just opened up for 1 1/2 in. carbs then how come the Mark II's had the bulge on the right side of the hood (bonnet)and the standard TD's did not need it? Could it be that the air manifold from the air cleaner to the carbs was the big difference?

In fact I have been told that the Mark II carb body castings were special in that they were a little shorter than the MGA 1 1/2 in. body castings.( We would have to get conformation from Joe Curto or John Twist on that).

My "Service Parts List" shows P/N SA2440/1 for the intake manifold on a MK II but a SA2440 for the standard TD. So The "/1" could indicate a second machineing operation to open it up. The pipe to the air cleaner is more confusing, the std. Td is P/N X24237 but that description does not appear in the page of changes for the TD/C. The closest I could find was "Carburetter Pipe" P/N 168437.

Does this agree with your findings Gordon?



I recall at least the later MkIIs had a diferent larger oil bath air cleaner, as well as a markedly larger aluminum manifold to the cleaner which results in the bonnet bulge. Len is talking about the cast iron carb to head manifold. The carb bodies are different, with only two holes at the air cleaner manifold flange (like the 1-1/4" TD carbs), vs. 4 on the TF and A (I think)George
George Butz

My source of information came at the 2006 "mg spares Day" at Stoneleigh, at the booth of Barry Walker.

I asked this specific question and was told that because of the limited production numbers of the Mark II, the works saw no need to invent a new casting amd merely machined a standard TD 1
Gordon A. Clark

Gordon C. The original 1 1/4" carb. manifold on my TD, has the no. 24280 on it. The manifold I modified for the 1 1/2" carbs also has the same no.
George Raham
TD 4224
G. L. Raham

Tom, the TD intake manifold can be enlarged to better than the Mark 11 specifications. The standard TD air cleaner manifold will not fit. The Mark 11 air cleaner manifold is almost impossble to find, then you need the bubble in the bonnet side panel, or just use the thin aftermarket filters, no bubble needed.But it will be more restrictive than the thin aftermarket filters. Almost all of the 1 1/2" carbs in use today are MGA/ A/H 100/4 carbs, their bodies are longer than a real O.E.M mark 11 carb.(As bobj50 stated,and confirmed by Joe Curto.)P.S. 1 3/4" carbs are too big for a 1600 MGA. Len
Len Fanelli

Gordon, look at the Service Parts List MkII Supplement. The Part Number for the Gasket- exhaust manifold is 168433, the Joint- carburetter to manifold is 168436, the Carburetter pipe is 168437, Joint- carburetter pipe is 168438. Now I have to go back to finding that missing link again.
Bud Krueger

thanks to len and all. i have set of 1 1/2" S.U.'s in storage. (somewhere!)i will have to drag them out and see how they fit before i start any boring. regards, tom
tom peterson

Guys; Heres some pics of different versions of intake manifolds. Bottom manifold is from my MKII-casting #168434 like Bud's--second one is a 24280 bored to 1 1/2--top one is a stock 1 1/4 24280. Dan

Dan Craig

Here is a comparison of the air cleaner side of a stock 1 1/4 (lower right),an MGA 1 1/2(lower left)and a set of original TD/C or MKII 1 1/2 carbs. As Len said,the air cleaner manifold is a physically larger casting than the normal TD unit-bolt hole spacing is wider at the carb flange and it mounts a larger diameter oil bath assembly. I would even post a picture if someone would care to part with one of these old fashioned,power robbing relics. Seems most of the stock units were discarded first thing in favor of the individual air cleaners. Gives me something to hunt for in the name of originality. Dan

Dan Craig

dan, thanks for the pic. regards, tom
tom peterson

This thread was discussed between 22/08/2008 and 28/08/2008

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.