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MG TD TF 1500 - Type N

This is also off topic but was brought to mind by the recent thread about fitting an XPEG head to an XPEG block. While reading one of my MG history books I came across the following passage regarding the Type N Magnette (1934 - 1936):
"When the officials for the Ulster Tourist Trials ruled out blowers for the 1934 event, necessitating the scratching of the K3 magnette racer as observed [previously], a Type N, with a special body, dubbed the 'NE' was duly prepared. Despite rumors to the contrary through the years, only seven Type NE racers were built. They were specially modified N-types with bigger carburetors, compression ratio increased to 9.8 to 1, and a carefully machined head-to-block fit which eliminated the head gasket."




J K Chapin

Well, I should have said XPAG head to an XPEG block. I thought I could go back and edit it but failed.
Jud
J K Chapin

And I also forgot to include the question at the end: What would be the advantage of eliminating the head gasket?

The same book also mentions the EX127 car purchased and driven by German driver Kohlrausch with "a bronze head made in Germany which brought the brake horsepower up to 146 at 7,500 RPM with a supercharger running at high pressure." The car went over 140 MPH in 1938. I think this car had a 750 cc motor but there is no mention of whether making the head out of bronze eliminated the need for a head gasket. Why bronze?

Jud
J K Chapin

Here is picture of the NE that is in our club.

Butch Taras


R Taras

I have done quite a bit of work on the EX176 engines, which were prepared in the early 50's by MG for one of the Bonneville Land Speed attempts (these 1466cc engines were the prototype XPEG blocks). Their most distinctive feature is that there are no water passages cast between the head and block, eliminating the need for a head gasket. Instead, the water is routed out the back of the head and forward into the rearmost core plug hole, where a flange was cast into the special block.

The head and block were hand-lapped together for hours on end to obtain a perfect seal, which could not be achieved with a head gasket. High compression engines, especially when further charged with a supercharger, run a great risk of head gasket failure due to excess pressure, whereas when a lapped engine developed excess pressure, it merely lifted the head a minuscule amount, relieving the pressure momentarily. This hand-lapping procedure can be seen in factory photographs of the racing division in the 1930's.

Tom Lange
MGT Repair
t lange

Butch, that's one beautiful car, isn't it?

Tom, thanks. I guess the lesson is "Can't blow a head gasket that you don't have." Do you think using bronze (a softer metal that might conform even better to the top of the block) be for the same reason?

I remember the Bonneville speed trials as a kid but until I acquired the TD and started doing my homework I never realized how big a part MG played or how fast MGs went in those glory days.

Jud
J K Chapin

I have read that the RR Merlin engine, as made by Rolls, did not have a head gasket but used lapped heads and blocks.

When the US started to make them for the P-51 that was changed.

Jim B.
JA Benjamin

Since acquiring my PA, I have taken a lot of interest in these treasured Pre-WWII Triple M (MMM) MGs, as these models represent many pages in MG history.

The feature that makes these MG models unique, is the engine, with its single overhead camshaft, driven through the generator which stands vertically at the front of the engine, and which takes power from the crankshaft, and passes it to the cam via a pair of bevel gears. Capacity was from 746cc (4-cyl) up to 1271 of the 6-cyl engines.

In the mid 30s, the MG factory was able to extract up to 120 HP (161 HP/litre) from competition versions of this little 746cc engine. In its many variations, tens of thousands were made. And today, its still possible to buy a brand new engine c/w Phoenix crank and Cosworth rods!

The very desirable N-Type was the last (1936) sporting model made before the TA, and a total of 738 were made, plus 7 NEs. Of the 2 N-Types shown here, JB 4158 is an NA still registered in the UK. JB 3638 is the first N-Type made (chassis NA 0251, of course), a Magna (4-seat Tourer), and resides in NZ.

Gord Clark
Rockburn, Qué.
Gordon Clark

Carrying on Tom Lange's comments on closing off the water passages between the head and the block (all except at the very rear):

http://www.mg-tabc.org/library/cooling-system.htm
Gene Gillam

Just for clarification, the photo at the top is an N, later named NA. The NE was a competition model as seen here. (with yours truly at the helm and loving every minute of it)


Steve S

I used a solid copper head gasket on my XPAG when it had a supercharger. Hussey copper in PA. can make one for the banana head since they have my pattern. Could make one for the round hole but they do have a setup charge.
Tom Maine

Steve, at the risk of sounding like a bubble-gum chewing valley girl - OMG!!! That's one awesome MG. Safety [REALLY] Fast!!

With apologies to the TF crowd, all those fantastic cars {Magnas and Magnettes} culmanated (sp??) in the most beautifu midget - the TD.

Jud
J K Chapin

... or maybe the PB but who's counting?
J K Chapin

Steve,
You luckey dawg!
Gotta ask : Top speed you got it up to?
David Sheward

Not fast enough. :)

These cars sound mean and fast, but remember that while they are 6-cylinder models, the engine size is only comparable to our XPAGs. More bark than bite in reality. But they are still quick enough and there is plenty of room for performance improvements. Coupled with a blower they can become a fairly potent competitor. Handling is solid and nimble as a race car should be.
Steve S

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

MG TD TF 1500 index

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