Cylinder heads?

[pfenlon]

I note from the forum that the TR250 cylinder head is slightly different then a TR5 head.

 

when I get my 250 (its still in the USA) I would like to run it with SU carbs, would a TR6 cyl head be the same as a TR5, as many more were made,

 

it wouldnt be hard to find one. Is it worth going to the trouble, I dont want to supercharge.

[marvmul]

I note from the forum that the TR250 cylinder head is slightly different then a TR5 head.

 

when I get my 250 (its still in the USA) I would like to run it with SU carbs, would a TR6 cyl head be the same as a TR5, as many more were made,

 

it wouldnt be hard to find one. Is it worth going to the trouble, I dont want to supercharge.

I believe that SU's can be mounted on the original TR250 inlet manifolds as Stromberg and SU (HS6) have the same flange on the manifold side.

Both are 1 3/4".

[Red 6]

I concur.

 

I have su's on the origional manifold.

[Richard Crawley]

Little point in upgrading the head unless you upgrade the rest of the motor to go with it! Assuming you are & at the risk of upsetting the SU fans (sorry lads ), I would give that choice some serious thought as well!

[pfenlon]

Little point in upgrading the head unless you upgrade the rest of the motor to go with it! Assuming you are & at the risk of upsetting the SU fans (sorry lads ), I would give that choice some serious thought as well!

 

Come on Richard dont be shy, tell it like it is and what should I do to the rest of the motor. I do NOT want fuel injection!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

[Richard Crawley]

Come on Richard dont be shy, tell it like it is and what should I do to the rest of the motor. I do NOT want fuel injection!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

If it’s already & rightly on carbs, I would see little point in switching to PI either unless you really wanted it; much easier to stick with a decent carb set up on a decent manifold & for me there would only be one - triple Webbers. I would convert to an unleaded head & get it uprated to stage 2 but think carefully before fitting bronze guides as they can lead to disappointingly high oil consumption. There have been several threads on uprating US import motors so a search in the archive should reveal some useful info. From memory, you will also need to fit a decent cam, change the dizzy or it’s advance curve to suit & possibly tweak the valve timing to suit the cam but, personally, I would fit a standard CP cam; it’s really pretty good. The pushrods may also be different but I believe the block & pistons are the same but am not 100% sure. Get the bottom end rotationally balanced & for that little bit extra, fit one of those ever so nice Phoenix manifolds; but the choice of rear silencer system would depend on how much noise you want to make; personally I’ve got a Y adaptor & kept the standard rear box.

 

It rather depends on how far you want to take things but the above will give a very decent increase in power over a standard CP PI let alone a carb import unit. If you go much further, it can start to get rather expensive for diminishing returns as you need to start changing some of the major engine internals to cope with it.

[pfenlon]

Thanks richard thats pretty informative, I shal delve the archives and try and learn.

 

thanks and regards

 

peter

[piman]

Hello Richard\Pfenlon,

 

"a decent carb set up on a decent manifold & for me there would only be one - triple Webbers"

 

Horribly expensive for very little if any gain for a road car. (Albeit an impressive sight)

 

Really a pair of S.U.s will perform as well on the road. Being a progressive choke they keep a high air flow over the jet at all times. Certainly the Webers are a good carburettor but very complicated and basically designed for racing.

 

Alec