Which carburettor is better?

[Fingolfin]

Sounds like a game show, doesn't it?

My '59 948cc came with an H2 carb fitted, and it works fine, I think. (Once I had a gas leak, but I believe that was a bad fuel line.) But I've obtained a somewhat later 948 to use for parts and as a spare in case my engine goes bad -- and it came with an HS2.

Should I fit the HS2, or keep the H2? I've heard the later carbs are better -- but why are they better?

[mike.perry]

As long as the H2 does not drip then it should be OK. Both carbs are the same size so should do the same job.

[bmcecosse]

As items are developed - they get better - well, mostly they do........ So - the HS2 is an improved version of the H2 - but it won't give any more power. The original H2 inlet manifold is a horrible thing - does the HS2 come with a later (much better!) inlet manifold ?? I thought you had a mountain of welding to do - before worrying about carbs..........

[Fingolfin]

Haha, BMC, you're brilliant! I've been away on a trip and visited a fellow in Tennessee who had a mountain of Minor parts, and I got a spare engine (with the HS2) and a bunch of other parts I needed and wanted. I know I've got lots of welding to do, and I'll get on that soon -- but I want to be armed with information, ready to go, when the welding is done.

Thus, the fresh engine comes with the later manifold. I'll switch it over while the engine is off. But is continuing to use the H2 all right on the new manifold, or should I use the HS2?

[mike.perry]

As has been said, the HS2 is a more modern carb and will look more up to date on your engine but I doubt if you will notice the difference in performance. However the carb to manifold locations are different so you will have to swap the carb and manifold together.

[Fingolfin]

Ah, okay. My thanks to you both. Anything else I might need to know?

[Alec]

Hello Fingolfin,

the 'H' series were more troublesome as regards leaking from the jet seals, the 'HS' series had an improved method of getting fuel to the jet. The latter also came with a simpler float system in the fuel bowl.

Alec

[mike.perry]

I am keeping to the H Series on my Series MM, an HS would look out of place.

[bmcecosse]

The carb-manifold mounts are exactly the same........Use the newer carb. You sure the 'new' engine isn't a 1098 ?

[mike.perry]

Oops, my mistake. The manifold stud holes on the H2 and HS2 are vertical, the HS4 holes are angled

[Fingolfin]

Absolutely positive it's not a 1098, BMC, it's got '950' stamped on the block. But, just to make sure, the engine number is APJM - H - 59370, which looks odd to me for some reason. I'll have a go with the new carb, then, once everything's back together.

[bmcecosse]

950 it is then .........