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 Midget and Sprite Technical - Plug for 1500 Exhaust Manifold?

Anyone know what the specs would be for a plug for the air injection opening in the exhaust manifold on a '79 North American spec 1500 midget? I've had it plugged with the stub of an old injection pipe that had the pipe cut off and crimped. That came out today and I found the pipe section has a large crack and is leaking. The threaded section seems to be about 3/4" in diameter and fine threaded. I have seen earlier ones that were coarse threaded. Don't know if it's a pipe thread or anything out of the ordinary. If anyone knows for sure, it would be a help when I hit the hardware store tomorrow trying to find a replacement.

This is a picture of the opening I'm trying to plug. The opening is in the center of the pic, into the exhaust manifold just beyond the mount bolt for the heat shield. The intake manifold shows at the top of the pic.

Kim Tonry

This is what I was using in the opening till now. The tube is cracked around half of the circumference and leaking.

Kim Tonry

With nothing to gauge its size I am not sure but it will be BSP and looks like either 3/8ths or 1/2 inch
Robert (Bob) Midget Turbo

Looks identical to the connector that goes in the back of the water pump for the heater circuit. That's 3/8" BSP with a compression gland/olive if I remember correctly. It's certainly 3/8" tube, I remember buying it!
Bob T

The inner diameter of the piece of tube that's in it measures 3/8".
Kim Tonry

Just cut the tube off near the nut and braze the tube solid. That will let you use the existing pieces and not damage the manifold - in case you ever want to refit the pieces - hah! Or you could get a 1/2" (I think) piece of rod and a new olive for tubing and use that as a plug with the existing nut. Not that it matters much, since the manifold will probably crack soon if it hasn't already. Then you get to buy a header. If you need to have a cat for emissions, you are screwt.

I care for a Spitfire that I plugged just like yours a few years ago; now it has multiple cracks, such that I think the manifold will fall apart when unbolted from the engine.

FR Millmore

Good idea on brazing or using rod. I also got feedback on the Spridgets e-mail list that a 1930 Model A oil pan plug fits. Fortunately I don't have to worry about the cat converter anymore. One of the few decent things our soon-to-be-sentenced ex-Governor Rod Blagojevich did for us in Illinois is drop required emission testing on pre-1995 cars. My cat converter had long ago blown out its ceramic matrix and the first time I pulled it off the car, I found an empty can. Which lead to removing the air pump since it wasn't doing anything with an empty cat can. I did have a manifold crack when I had had the car 3 years and the replacement that was put on in 1984 is still solid.
Kim Tonry

This thread was discussed between 29/11/2011 and 01/12/2011

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.