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MG TD TF 1500 - 8 port head (& Header?)


I think this showed up once before.

http://www.ebay.com/itm/221534426250?item=221534426250&viewitem=&sspagename=ADME:SS:SS:US:1120&vxp=mtr

It says the header is with it but no picture of the headers.

It says factory?

Jim B.
JA Benjamin

The last two eBay pictures show the exhaust
Header. I know nothing further about the head

RW
R.T. Walsh

I don't understand the "RARE" part,,,
SPW
Steve Wincze

Read the description, in deed very rare. Wish I could afford it. George
George Butz

george,
In my haste, I didn't get down to the bottom of the page!!
Thanks for pointing it out!!

Steve
Steve Wincze

I'm not seeing the "uniqueness"...looks like a standard XPAG/XPEG head with the water holes brazed shut. Don't ALL XPAG/XPEG heads have "8" ports?

Granted, the one pictured below is a Laystall but still...

Gene Gillam

It looks like the separated the intakes slightly for four individual intakes runners, rather than the typical two runner intake.

BUT, BUT, BUT, note that they eliminated the studs between the intakes for improved breathing. One would have to drill & tap the block for new studs. I wouldn't be all that concerned about flow to that extent if it was supercharged.

I'd have to drill some holes for some circulation in the block, too.
JRN JIM

Nevermind...I see it now!
Gene Gillam

Ok, I know I'm not the sharpest tack in the box when it comes to the T series cars and most I've learned about them comes from you fellows but, why is this 8 port head so special when I have an 8 port head on my engine? All mine would need is to be ported and relieved and it would look the same. Here's mine. PJ



Paul S Jennings

Paul, it does not have the head studs between the two inlet ports, so there is more room to have enlarged ports.
Rod Brayshaw

Thanks Rod! Now it's clear. Were those two studs relocated in the block? More knowledge gained! PJ
Paul S Jennings

Paul, 8 original and 4 new of smaller diameter in line with the manifold studs
Rod Brayshaw

I suspect I am the person the seller mentions, as I have indeed got one that came to me on an EX176 engine block. The engine had been raced in a Lotus that is still racing today, with the same engine that replaced mine - a Maserati engine. The head from this engine also has removed intake separators, and extra head stud holes. I suspect his cylinder head is not factory, since the water passages are filled in.

I say this since, more interestingly, I have an NOS head that was CAST without water passages, and is marked to accompany an EX176 engine. In that genuine EX176 engine, neither the head nor block have water passages between head and block, and the engine was run without head gasket. Apprentices spent long hours lapping the heads to the blocks for a perfect seal - it is called dry decking.

For those who have forgotten, the EX176 engine is the prototype XPEG 1466cc engine made in the early 50's, but an entirely different casting intended for racing (think Ken Miles, etc.).

Tom Lange
MGT Repair
t lange

Tom, just curious, why were the water passages closed and no head gasket. Seems to me the gasket and water would be an improvement. The extra studs should have handled the needed clamping pressure lost by the exhaust port stud removal.
Richard Cameron

With a lapped engine and no head gasket you can run much higher compression without fear of a blown head gasket, since the head will momentarily lift and release excess pressure. I have a running second EX176 engine in a TD, and it screams - I suspect it has in excess of 75 HP.

Tom Lange
MGT Repair
t lange

I know I am probably stating the obvious but ... The 8 port head has 8 separate ports from the gasket face to the valves. #1 valve ONLY gets its supply from port #1. The original and Laystall heads have 8 ports at the gasket face but they re-join behind the stud/separator before the valves. #1 valve gets supplied by port #1 AND port #2.

My race TC s/c (Laystall head) is dry decked and lapped exactly for the reasons Tom explained ... There is black spatter on top of the water pump and when the head is removed there is witness of leakage over the lapped surfaces.

Tom, do you have photos of the two heads you mentioned? I don't know what a NOS head is ... is it 8 port? Is it possible the first head you mention is a modified factory 8 port? A friend of mine has one (see image) and it has the gasket water holes. So does the matching block which was cast with the extra meat where the extra head studs go. His does not have the cast water manifold pad on the right rear of the block so perhaps there were two parallel developments ... Or do the blocks with the extra water manifold pad also have the extra head stud "meat" indicating they were a later development? I have only seen one factory dry deck block and I didn't see these details because it was inaccessible and I was in "dinner" clothes! I am keen to learn more about this stuff!

Bob Schapel

R L Schapel

Looking at the Laystall head, it appears that a stock head could be ported, relieved and polished to accomplish the Laystalls performance. Possible valve enlargement? Porting and relieving blocks and heads were the norm building race engines back in the day, we did it all the time and these stock heads appear to have a lot of meat to work with. PJ
Paul S Jennings

Paul,

Yes you are probably right. I, like many others, have reshaped the combustion chambers on a few standard heads to "copy" the shape of the Laystall. Note the chamber shape of the 8 port head in the image with my last post is the Laystall shape. (The chamber shape of the 8 port on Ebay is not.) I guess the alloy material of the Laystall might allow a higher CR on the same fuel .... but I am not sure. The only thing which can not be easily copied from Laystall is inside the port. In the laystall head the gas goes in and curves more smoothly down to the inlet valve. It even seems to have a slight "venturi" before the valve. In the standard head the gas goes in to the port and turns more of a right angle down to the valve. Instead of the venturi it seems quite cavernous behind the valve. However, standard heads can certainly be modified to make the little cars really fly!

Bob Schapel
R L Schapel

Bob, from your experience of racing with an Alloy head is there known any issues with over heating?

Many years ago in New Zealand there were piston failures with supercharged engines running the Laystall head.

The cause was (correctly or incorectly)interpreted back then as extra heat generated by the alloy head that caused pistons to overheat and fail.

I was lucky years ago to be able to buy a Laystall head and a Shorrock from a TD that had constant failures.

I run a Marshall but with an iron head and have not tried the Laystall as yet.

Your experiences would be welcome.
Rod Brayshaw

Rod,
Piston failure could be due to detonation caused by other issues. A s/c engine should run less spark advance (and beware of weak mixtures)!

I don't find overheating a problem. However, before I dry decked my engine, It would pump out the coolant if I used lots of revs! That in turn caused the temp to rise if I didn't back off. The loss of coolant caused the overheating, not the other way round. The head was lifting as described by Tom a few posts back. After dry-decking, the head still lifts but it can't pump the coolant out. Maybe the Laystall is to blame in a way because it is not as rigid as a cast iron head. The relative softness of the alloy also prevents the use of high torque wrench settings which can be used on iron heads (assuming better quality studs are used). Use large, thick or hardened washers under the nuts of a Laystall.

BTW I run a Marshall too. It is a J 100. I have run a Laystall since I was 19. Marshall S/C since I was 23. I am now 62!

Yours oTCagonally, Bob Schapel


R L Schapel

We never dry decked our engines to mate the head to the block without a gasket, but we did have the block and heads decked so we could use solid copper gaskets which came in various thicknesses, plus flat, dished or domed pistons for compression control, which was needed depending what fuel we were running, pump gas, nitro methane, alcohol, even some home brew mixtures that could really get out of hand! Never liked the Nitro, had to keep it in a cooler to keep the temp down. Dangerous stuff, but really packed a wallop! Sorry for running off, but when we start talking about making engines perform better, it brings back some nice old memories. PJ
Paul S Jennings

I have the better head studs, as well as correct hardened steel head washers for use with the Laystall Lucas head.

I'll try to post some photos of my EX176 heads today.

Tom Lange
MGT Repair
t lange

Wow! Nitro in an XPAG! That sounds wild (but would be illegal in my class of racing).

The 8 port head seller mentions the "telltale OK OK" stamped on the head. I have never noticed it except on the 8 port owned by my friend. Can someone explain?

Tom, what torque wrench setting would you use on an original Laystall? I think the repro' heads have 50 ft lbs recommended but is the old alloy softer? I have been using about 45 for years but would like to go higher.

Incidentally, I would like to learn about racing T-Types in other countries. I started a thread named Historic Racing under the heading "MOTORSPORT" on this site but have not got any responses ... even from the Spridget, A, or B guys. The first post explains historic racing in Australia (which includes T-Types and other MGs) and asks for similar information from overseas. Any of you chaps know any details to contribute?

Bob Schapel
R L Schapel

Head bolts on my XPEG are set at 55 lbs. Just re torqued them. PJ
Paul S Jennings

This thread was discussed between 28/08/2014 and 01/09/2014

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