Welcome to our resource for MG Car Information.



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 - Belt for Marshall Supercharger

Does anybody have a part number or length of the belt used when installing a Marshall Supercharger

I'm using a crank pulley with an OD of 4.125”

Steve Averka

I have that info back at my shop. I'll have to measure the double pulley purchased from Moss. I bought a Magnacharger from them and then later, a belt for the Marshall for $36. They'd substituted a different belt- different width and length- which does not even come close to fitting either blower. Bought the Gates belt locally for a small fraction of the cost.
Jim Northrup

Steve, I use a set of Browning AX45 belts, they're 1/2" wide for my Marshall s/c. My crank pulley is about 4.25" dia, s/c drive pulley is 3.25". I could probably go with a size smaller belt. At the time I brought three home, sized for best fit and returned the unneeded ones. Marvin

Marvin Stuart


Thanks for the quick response. I will be running a single belt, 4.125 crank and 3.5 blower pulley so I
might end up with a slightly different belt

You may remember sending me some great info 5 years ago, when you were putting your blower together (I still have that email)

I think I have most of the parts to rebuild my blower so Iím getting ready to mount it. The thing Iím missing is a suitable 1 ĺĒ carburetor.


Steve Averka


My TD has a Marshall Nordec J75 blower that may have been an original installation. The overall diameter of my crank pulley is 4.22".

After reading the responses above I get the impression that the length may depend upon the size and swing of the idler wheel.

The respondents above indicated 45" but I am quite sure that mine measures 50". It is slightly too long but I would not go less than 49".

Here is the link to the belt I am using:

You will note that the outer length is listed as 50".

I plan to be racing it at Lime Rock in April. Stop by and say hi.

Mark Sherman
mrkshrmn at

Mark A. Sherman

Mark, what's the date? Marvin
Marvin Stuart

I saw your mention of a 1 3/4" carb, and then looked at your picture... interesting carb adapter. Our Marshall sports a 1 1/4" SU and the Magnacharger came with 1 1/2".

If you haven't already run your oil return, I thought about running a line straight down to the road- everyone would think it is just another normal drip! What made me think of that is the hex plug on your exhaust pipe, like you could run the drain right into that!!! What's up with the plug? I planted an O2 sensor on the backside of one exhaust for an air fuel ratio gauge.

Is there a fitting on the intake manifold for a boost gauge?

IF you haven't committed one way or another on your oil supply & return lines, you might elicit examples from members to see what looks easiest or best. I like those lines so much, I'm installing some on the Magnacharger!

Keep the pictures comin' on blown engines, guys (suprcharged, that is).

Double sheave pulley!
Jim Northrup

Mark, I stand corrected my crank pulley measures 4.22. Idler is 2.74 where the belt rides. Iíd love to get over to Lime Rock.

Jim, The carb adapter was engineered by Karl Frank, who tested various setups with a flow bench. He offered to make a batch of them here on this board, but that was before I had bought my supercharger. The one I ended up with is a compromised version that is necked down on the ID do to a manufacturing defect. I plan on looking into having one made the proper way. For now I'm going to use it as is.

The fitting on the intake is, I believe, for a boost gauge . I have a boost gauge Iím just not sure I want to disturb my dash in order to install it.

The supply and return lines. I screwed up royally. My engine was just rebuilt, I had planed on using the unused clutch pivot on the sump as a return location. The engine is back in the car and there is no way Iím messing with the sump now. So my next idea isÖ I have an after marked tappet cover that looks like a great spot to use as a return.

What belt are you running on your J75?

Marvin, I looked at the VSCCA web site and they list the Lime Rock ďSpring SprintsĒ on May 6 & 7. maybe we could meet somewhere and check it out.
Steve Averka


The dates May 6 and 7 are correct. Generally we start after lunch on Friday and finish around 2pm on Saturday. As a club event it may not be open to the public so contact me a few days before and I will arrange your entry.

Typically the oil return line goes around the front of the block to the tappet cover plate.

Mark Sherman
mrkshrmn at
Mark A. Sherman

Moss originally supplied the Gates TR22474 with the Magnacharger and works with our Marshall-Nordec. The Bando is wider and too short. These don't have much room for error. In fact, I've got to remove the pulleys to get the belt on & off, not much adjustment.

The dimensions are a nominal 48" (actually 47+) and 11/16" and it is notched. Here's Gates data on it.

For our engines, crank pulley is about 4.2", blower pulley 3.1" and the idler 2.5"

I've drilled & tapped 1/4" NPT thread in one aluminum tappet cover and did a 3/8" NPT thread in a stock steel cover, it is actually a pretty good thickness. Brass 1/16" NPT male thread screws into oil galley below tappet cover.
Jim Northrup

Sorry, that URL didn't work.

Product ID 86200180 Part # TR22474

Features Advantages Designed for heavy-duty truck, bus and off-road equipment applications.
Absorbs normal shock loads without damage to belt.
Special notch design resists cracking while providing tensile member support.
Oil and heat-resistant construction throughout.
Meets SAE J636b and SAE J637 specifications.

Belt / Sprocket Specifications
Angle 36

Effective Length (in) 47.35

Effective Length (mm) 1203

Outside Circumference (in) 47.93

Outside Circumference (mm) 1218

Top Width (in) .6875

Top Width (mm) 17

Jim Northrup

Steve, please send an email to me again. I forgot to mention two subjects.
Jim Merz

Jim , Thank you for all that information. I should be able to get that belt and test fit it on my car.

But I don't understand the "Brass 1/16" NPT male thread screws into oil galley below tappet cover."

Please explain.

Steve Averka

I used to distribute Gates products. Spend $40 on a Bando hose from Moss, waste DAYS of fiddling around (trying different lengths), and then buy another Gates belt!

Where do you expect to pick up your oil supply? The oil galley (or gallery if you're an English teacher and not a mechanic) just below the tappet cover will accept 1/16" NPT male thread.

What are you going to run, copper or stainless tubing or plastic and what size? NPT? Compression? Metric? JIC? SAE? You tell me! Isn't this fun? (...not if you're in the hydraulic business)
Jim Northrup

Steve, here's a pic of the oil supply connection at the oil pressure gauge line. Also shows the return line into the tappet cover. The clear line attached to the copper supply line is the vac/boost gauge line comming from the intake manifold. Marvin

Marvin Stuart

Another pic of the oil return into the tappet cover plate. Marvin

Marvin Stuart

And a pic of the vac/boost gauge line connection to the intake manifold. Marvin

Marvin Stuart

Here's a pic of my air filter set-up, it's an MGA housing with K&N filter. The Marshall installation instructions called for using the original aluminum intake manifold, but was a bit more work. Marvin

Marvin Stuart

Marvin, thank you for the pictures. Your setup is close to what Iím planning on doing. I think Iíll tap into the oil supply were the oil line comes up to the head, by drilling into the banjo bolt fitting and soldering in a supply line to the supercharger. My tappet cover has one large breather plate. My plan for the return is to make up a new one of these plates and run my return line into it. That way I do not have to drill into the tappet cover.

I have a fitting in my intake manifold at the exact same place as yours for the vac/boost gauge. Where on the dash did you put the gauge?

Your carburetor looks shorter than the one I used as a mock up.


Steve Averka

Steve, my gauge. A simple home made bracket does the job. Marvin

Marvin Stuart

oil supply from oil gally

Jim Northrup

blower oil drain

Jim Northrup

Marshall Nordec in '50 TD

Now the vintage Marshall is in the '51 TD, with copper lines. The '50 is so customized, it will run the Magnacharger. I thin I'll hook up the stainless lines and drip oiler on the Magnacharger for grins.

Jim Northrup

boost gauge, plus....

Jim Northrup

Jim, Now... I understand your oil supply pickup. I like that idea and might use it.

thank you for the pictures

Steve Averka

Trick is locating 1/16" fittings. 2 examples on ebay, to 1/4" JIC flared, a straight and an elbow. auctions 310045212317 230597741790. The elbow would need to go to the middle of the block in order to turn. Straight can go on the font as pictured.
If you elect to go 1/8" copper tubing, as I did replumbing the Marshall on the '51, I can take pictures tomorrow on an elbow that tightens in up front, and uses that nice, older looking long nut which protects the tube better (notice the nut in the picture). I can also throw an elbow and a few nuts & ferrules in an envelope. I think I can also russle up a 1/8" female NPT elbow to 1/8" tube compression fitting if that is what your oiler takes.
I used up all my old 1/8" copper for cutting small holes with my EDM electric discharge machine. Picked up new coil 1/8" tubing at Advanced Auto Parts for about $7. Autozone wanted $12 for same package and O'Riley didn't ave any at my store.
Have fun!
Jim Northrup

Re: Steel vs. Copper Tubing.

Copper tubing becomes brittle over time. If you have long unsupported tubing runs, vibration will lead to cracks at the tube fittings. Been there...etc.

Go with steel tubing.

Mark Sherman

Mark A. Sherman

This thread was discussed between 23/03/2011 and 27/03/2011

MG TD TF 1500 index

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