Low port versus high port head

[John McCormack]

When I bought my long door TR2 (in 3 trailer loads of parts) the engine had been completely rebuilt with a 87mm pistons, high port head and 1 3/4" SUs. I drove it for 2000kms with that combination to run it in and sort out the other issues with the car.

I had been told by a few people that around town the smaller carbies are actually better as the higher velocity through the smaller choke will give better low down performance.

I' finally installed the low port head and 1 1/2" SUs and took it for a very short run yesterday to check for leaks. Today I went out for a 30km drive in the local area. 

The car pulls very cleanly from 1100rpm in top overdrive on a flat road. In top it pulls away quite well indeed. Far better than the previous engine configuration. I took it to 4500rpm a couple of times and it felt much the same as before. I didn't go higher where the high port head comes into its own.

Unless you are in competition environments I would recommend TR2 and early TR3 owners to stick with the low port head and smaller carbies. They are a fine combination. 

A big thank you to David Ferry who sold me the carbies and to Paul J (I've lost the emails with your surname sorry) who paid for the carbies in the UK and bought them out here to Australia in his baggage. That story was in Traction recently.

As you can see they look great (I am still chasing the correct pipe between the two carbies) and they work very well with no leaks. The car started within seconds of fitting them, a quick balance and adjust the mixtures and it idles and runs beautifully.

 

 

[ianc]

The TR2 which I owned for 5 years from 1964 had a bog standard low-port head, 3.7 axle and overdrive. 

The engine was exceedingly well-worn, with low oil pressure (rattled badly when started on winter mornings and was down to about 30psi at 70mph on the motorway!), but the car went very well indeed.

It could accelerate slowly in overdrive top from below 1000 rpm, even when ascending the rise southwards from Wandsworth! 

It ran out of breath towards 4500, but as that was 110mph in overdrive on the motorway, it didn't worry me very much, and it would hold 4200 for mile after mile. 

Petrol consumption was good, even though it was driven hard wherever possible.

It had been converted to disc brakes, so was able to cope with its performance, but unfortunately had the Lockheed axle, so was forever wetting its rear brakes!  This was prior to the birth of the TR Register, so I didn't know about the advantages of a Girling rear axle.

My TR4, with its modified engine, can pull from 1800, and just gets better and better above 2500, but can run to 6000 when required.  However, fuel consumption much heavier.

The old TR2 was not unlike my much-missed 2-litre turbo Citroen Xantia Estate in its ability to pull at low rpm and its fuel economy.

Ian Cornish

[John McCormack]

13 minutes ago, ianc said:

The TR2 which I owned for 5 years from 1964 had a bog standard low-port head, 3.7 axle and overdrive. 

The engine was exceedingly well-worn, with low oil pressure (rattled badly when started on winter mornings and was down to about 30psi at 70mph on the motorway!), but the car went very well indeed.

It could accelerate slowly in overdrive top from below 1000 rpm, even when ascending the rise southwards from Wandsworth! 

It ran out of breath towards 4500, but as that was 110mph in overdrive on the motorway, it didn't worry me very much, and it would hold 4200 for mile after mile. 

Petrol consumption was good, even though it was driven hard wherever possible.

It had been converted to disc brakes, so was able to cope with its performance, but unfortunately had the Lockheed axle, so was forever wetting its rear brakes!  This was prior to the birth of the TR Register, so I didn't know about the advantages of a Girling rear axle.

My TR4, with its modified engine, can pull from 1800, and just gets better and better above 2500, but can run to 6000 when required.  However, fuel consumption much heavier.

The old TR2 was not unlike my much-missed 2-litre turbo Citroen Xantia Estate in its ability to pull at low rpm and its fuel economy.

Ian Cornish

This one does have a cam which comes on about 3000 rpm but low down the low port head and carbies are great. Drum brakes and Lockheed axle on this one, I have tried to build the car as close to how it left the factory as I could. The only mods are internal and can't be seen.

[stuart]

FWIW the original pipe between the carbs was solid and would crack very easily where the banjo ends joined the pipe. This was then changed  to a Metal sheathed rubber pipe, they do appear occasionally on likes of Ebay though I havent seen one for a while.

Stuart.

[Ian Vincent]

I think I have one although goodness knows what condition the rubber is in after all these years.

Rgds Ian

[John McCormack]

1 hour ago, stuart said:

FWIW the original pipe between the carbs was solid and would crack very easily where the banjo ends joined the pipe. This was then changed  to a Metal sheathed rubber pipe, they do appear occasionally on likes of Ebay though I havent seen one for a while.

Stuart.

My other TR2 has the pipe between the banjos. Apart from some difficulty getting the banjos to seal when disturbed I haven't had a problem in 44+ years. 

I have not been able to get one for this car, I suspect they are rare because they did fail. I'll find or make one eventually.

[Dic Doretti]

I took my TR2 over the Pyrenees from Scotland on a couple of occasions equipped with small carbs and a low port head, didn't hang about and 40 mpg and that is how I will rebuild the Doretti. My Xantia HDi estate is faster and more economical, but a diesel TR, I don't think so.

         Cheers

         Richard

[John McCormack]

Today I drove 40kms across Sydney and am so impressed with the performance of the low port head and smaller SUs. The car pulls from 1000rpm in overdrive even uphill. Potter around all day in top and od. It revs hard to 4500rpm but probably does lose a little bit when you get up there. Up to 3500rpm it is better than previously, because of the torque.

No dramas although a tappett doesn't sound right so will readjust tomorrow.

[2long]

Love the economical low port and H4 setup.  The ram pipes are a period item. 

Dan

[John McCormack]

5 hours ago, 2long said:

Love the economical low port and H4 setup.  The ram pipes are a period item. 

Dan

I've got the same 6 blade fan on this TR2. Does it work for you?

[2long]

Yes, the tropical fan, the recored radiator and a good engine flush has worked out fine.  Same exact things on my 2.

Dan

[John McCormack]

3 hours ago, 2long said:

Yes, the tropical fan, the recored radiator and a good engine flush has worked out fine.  Same exact things on my 2.

Dan

It has worked so far on this 2. On 30+ degC days the engine will get a bit above 185 in traffic. I haven't tried it on a 40+ centigrade day but I wouldn't intend to have the car out on such a day. My other daily driver TR2 has an electric fan. It struggles on the 40+ days.