Tuned 2.25 Carb choice

Hi all,

I have got a 110 2.25 petrol engine in my series which has been given a workover by the previous owner having a performance camshaft fitted, a high flow oil pump, and a re-worked unleaded head fitted. i had my original series manifolds and carb fitted but recently a freind who'd driven it previously (when it was in another 2a) said that it is definatly underpowered compared to how it was in the past. seeings the only thing changed is the carb i'm very tempted to re-fit the twin-choke that it was fitted with but i also have an SU conversion sat around. which would be a better fitment and what are their good and bad points.
any advice welcome cheers, Ed

I'd be interested to know too. I nearly got the ACR SU conversion but decided to do a twin-choke one myself. If you've got both maybe you're the person to do the comparison!? What carb have you got now the 34ICH webers are supposed to be quite poor power wise...

Genuinely interested...I'm going to start fitting the DMTL this week hopefully.

SU, by far the best.

Ooh, have you tried em both? Why is SU best? Torque, power, mpg? I really am genuinely interested if you know.

No idea about MPG - never take much notice as they are work trucks,cars are better for that.I've fitted several of both,the Weber seems to strangle them and makes cold running a bit of a pain.The SU is the best carb ever in my opinion,a single jet,SO easy to set up,totally reliable,good cold starting,no hesitation and able to work well on steep banks.The only way to beat one is EFI.
My dear old IIA has an SU on it and has the best pickup I have ever seen on a 2 1/4 engine,you can literally stamp on the throttle from a very low idle and it will just rev up,no stuttering at all.That and Lumenition transform how they run.(And reliability)

When you're comparing to Weber are you comparing to the single bore 34ICH (known to be quite crap, but quite economical) or the later fitment DMTL twin choke which is a lot better?

I've got a pair of HS6's on an old dead Triumph TR7 that one day I might try...Where did you get your SU manifold? SUs look easy to set idle mixture....not quite so easy to guess what jets to fit!

The single choke one,is what I've done.But the twin choke as you say is far better,but still not worth it in comparison to an SU in my opinion.By amazing coincidence the SU on mine was built up as one carb from a pair off a TR7 I found under the bench ! The adaptor elbow was given to me by a mate.So total cost was nil....
All this is just from my experience,and I always think that the petrol series LR's were a fairly well balanced package in terms of power,brakes,steering and suspension etc.So a smooth running and reliable 2 1/4 is going to do no harm to the rest of the car,nor get you into any trouble.

Aha, so yours is straight onto the old intake via an elbow? I was half tempted by that idea....

dominicbeesley said:

Aha, so yours is straight onto the old intake via an elbow? I was half tempted by that idea....

Click to expand...

It works.

Did you rejet / needle the SU or did it work ok with the TR7 jets?

well like some have suggested i shall test all three carbs, even though ive got a downpipe for the twin choke webber i'm thinking of simpy fitting a four branch manifolf and system that can be used with either inlet manifolds. ive seen a few but where can i get them from. not sure whether to get stainless or not?

cheers Ed

I've got a ACR SU carb and manifold going on Ebay soon. Don't come on thsi forum too much, I'm an OLLR man myself, but even if you don't go with mine, SU is hte way to go, Simple to set up and ACR fit them for a reason. Rowland is a world authority on getting horses out of thsi lump, why fight it. Comapred to the Weber, I have a 2.5 lump in mine, it is great. Got a spare carb, as a result two purchases of ACR kit via Ebay. PM me.

Ashley do a header as do ACR. I suspect the Ashley one, is a f*ck-up, all pipes are the same length, they used to make it S/S though, (I have one of these spare too, but have never fitted ti to be sure) it must put the torque up the rev range. Fine for a Mini, but can't be good for a Land Rover. But you can't eaily make the ACR shape in S/S because of the bends, which aside form cost tells you why the ACR is mild steel.

Beginning to wish I'd just gone with SU as fitting this Weber is proving to be more of a faff than I'd thought! Now trying to work out how to mate the throttle linkage up...

i often use and make a bracket for a cable

I was wanting to leave the linkage there as I'm not keen on cables but am beginning to wonder...

i ve often used short cable as with some diesel and attach to were linkage crosses over to passenger foot whell top ,though i cant say i fitted your exact same carb

That's definitely an option that I've not rules. I didn't have any spare cable or collars or end pins handy in the workshop last night, though I was tempted to borrow some off my mate's bike! Im thinking I might do a bit of welding on the original crank and drill a pin through it instead of the two locating arms which get in the way. I should be able to make it reversible then but won't have the free play that the original has which might lead to the engine revving itself...

Did what you suggested James, its to my usual half-arsed standard....more here: http://www.landyzone.co.uk/lz/f6/exhaust-welding-accelerator-linkage-194325.html#post2073969

Certainly goes better than the old carb