Possible to use Webber carb from 1275 on 1500

[ChasR]

I have been offered a Webber 40 DCOE carb off a 1275 Midget.

However, My midget uses the Triumph 1500 engine.

I know that the manifold is different, but I believe that the Dellorto 40 is used on the 1500 engine, and possibly the DCOE.

It comes with the Filter too, but I am wondering that if I got hold a Webber 1500 manifold, if the Webber would work on the car.

[slater]

Yeh it will work but it will need to be re setup after you fit it.

[Davenger]

I dare say most proper parts suppliers (Moss etc) will be able to sort you out with the right manifold.
I reckon it'll need re-jetting to suit the 1500 but you can get the needles and advice on what ones you need from whoever you get the manifold from.
Or, from the resident petrol heads here ;D

[Deleted]

Yeah the chokes will be too small to be able to get anything out of the 1500. If it's a well fettled 1275 and the 1500 is stock then it should be fine, just a minor jet change might be in order (probably not), but if the 1500 is breathed on it might be restrictive. You'll need 34mm chokes but the 1275 will probably have 30's or 32's depending on the state of tune.

It'll basically be like using a carb that's a bit too small so it'll restrict the top end.

[filmidget]

S'gonna be a bit of a compromised short crossover manifold to fit the single sidedraft?

Would it be any better than the std twin SU's? (I like SU's)

Doesn't seem worth the hassle...

[ChasR]

Cheers for the advice so far.

It currently is on 2 SU 1" 1/4 I think or 1/2s. But the 2 on there currently have seen better days if I'm honest. Even when running them lean, the car will still kick out alot black smoke when revved hard, meaning getting an MOT may be tricky. As a result it also diesels sometimes when it turns off.

I do have two spare SUs, which are in better condition, but the Needle is bent on one, and the spring is missing from the other (the large spring inside the dashpot. That's why I was considering a Dellorto 40 or Webber.


It's a stock 1500, but apparently the head is ported/polished, but it's not a great revver.

Do you guys think that I am better off rebuilding the decent set of SUs with new Springs and jets? How easy is it to change the jets, and how much would it cost? I know that setting up the current set has been a bit of a nightmare lol.

[Davenger]

rebuilding the SU's will will probably be cheaper than buying a manifold for the Dellorto

[filmidget]

You should have twin inch-and-a-halves.

They are extremely easy to rebuild, long s nothing actually damaged. and throttle spindles not worn.

While you are at it, get rid of the 'waxstat' jets, and fit new plain throttle plates (no over-run pop valves).

My 1500 was RR'ed at 85@wheels, and that is on SU's, and does not seem to have any fueling issues at all.

If you are anywhere near the Midlands, Pete Burgess really knows his MG's/Triumphs.

Cheers, Phil

[Blown_Imp]

yeah i say stick with the SU's, they are great carbs that give good fuel economy and decent power. I had a fixed choke carb on the imp, 22mm choke solex (slowlex!), it was hideous giving very poor fuel consumption, then again I'm not used to carbs with accelerator jets. I put the SU off the turbo imp on to my new one and the car became smoother used much less fuel.

So yeah id stay with your constant velocity SU over a fixed jet DCOE, it makes so much sence to have the air moving at a steady speed with just the volume changing, rather than changing the speed and volume. CV carbs have worked on motorbikes for aaaagggees and if its ok with honda, then its ok with me

J

[ChasR]

Right cheers for that. I think I will be sticking with the SUs .

The throttle spindles don't seem to be worn on the other set of SUs (they both have the Waxstet jets though, which is probably why I can't get the car to idle correctly below 1.8krpm). I'm also getting around 20ish MPG :S.

The other set are yet to be fitted, as they came with the new engine I got (Old ones were reused), but can someone point out to me what the Throttle Spindles are on the SUs? I think I know what they are, but I can't say that I'm sure.

Cheers for the opinions and help so far

[Seth]

Hey,

Like everyone said the SU's can be made to work well. I like em too!

The throttle spindle is the one that carries the throttle butterfly. Its the shaft that runs right through the body close to the engine side of the carb that gets rotated when you mash your foot on the loud pedal.

If it and/or the carb is worn then you'll be able to see some lateral movement ie up and down not in and out. This results in an air leak that can make them difficult to set up properly. I recently rebuilt the single 1 1/2" SU on the 1500 in Katies Herald and found that it was the spindle that was worn more than the body and just changing that removed almost all the play.

Haynes do/did a small manual on the SU and its well worth getting hold of a copy. Its really thorough and will help you no end.

If you let me know the numbers on the little tags by the float chamber on your existing/spare sets then I can at least tell you what they're from and what needles etc ought to be in them.

[filmidget]

When I rebuilt my SU's, I did it without a book... they are dead simple, and afterall you will have another one (in fact whole set)to compare with

On mine the spindles showed little or no wear - certainly after fitting the new spindles that came in the rebuild kit the movement was negligable.

Just remember when you are cleaning up, not to use anything abrasive on the inside of the float chamber or pistony bit.

[Seth]

Forgot to say, check out www.burlen.co.uk/ They're the people who have the manufacturing rights for SU and make everything Website is pretty useful - plenty of exploded diagrams.

[ChasR]

Many thanks for the help so for .

I may soon get onto you about the Needle stuff Seth.

For the time being I have a new needle on order to replace the bent Needle, and have found a spring . The spindles on these carbs are near perfect too . The old ones are very worn in comparison.

So by friday hopefully, it should be running again. I'll be adding this to My Ride section soon .

Cheers for the help once more guys