new carbs...a little help

Post by **callyspoy** » Sun Apr 06, 2008 8:42 pm

hi folks, ive just bought a couple of different carbs for my car.
1. 32/34 downdraught weber
2. single 40 dellorto

now this really is experimental. i know the weber will fit, as i have a nikki fitted atm, and the height looks similar. don't know if the dellorto will fit though...hum, not too keen on cutting holes!

basically though, was just wondering if anyone has any experience with either of these carbs fitted to a minor 1275...personally i've wanted a dellorto for ages, but never had the balls to go all italian!
and no "go back to SU" comments though!! i know...they are the best, simple etc...

thanks guys
*C*

Post by **Peetee** » Sun Apr 06, 2008 9:09 pm

You would probably find the Weber would be better suited because it probably won't be set up for your engine as is and it's easier to get the parts you need to do so.

Post by **callyspoy** » Sun Apr 06, 2008 9:12 pm

hmm...yeah i've thought about the whole carb tuning stuff. you know of many places around our general area that tune carbs? ive only ever done it by ear!

Post by **bmcecosse** » Sun Apr 06, 2008 9:42 pm

The dellorto is presumably the side draft 'copy' of a weber dcoe 40 ? It's really too small for a 1275 engine - would be better suited to a 998 engine. However - you can obviously use it provided it has the largest choke tubes fitted - do you know what's in it now ? Did it come with a manifold ?

Post by **callyspoy** » Sun Apr 06, 2008 9:51 pm

hi bmc, yes it has a manifold(mini), but i dont have the carb yet, so cant tell you what it has in terms of choke tubes...i thought the dellorto's were fitted to 1275 mini's...it is a "twin", but is called a single...dont know why really though!

Post by **bmcecosse** » Sun Apr 06, 2008 9:56 pm

Probably because they were sometimes fitted in pairs - with one choke only in use on each carb thus giving a straighter run into each port on the head - that's where the SUs have an advantage over the weber/dellorto - if fitted on a decent manifold. Hope the manifold is 'long' and not the dreadful 'swan neck' which is hopeless. 1275 engine needs 38 or 40 mm chokes - these can only befitted to 45 DCOE carb. A 40 DCOE/Dellorto can only take 34 mm chokes max. it will still work - just won't develop max power. However - these carbs are notoriously heavy on fuel - expect about 25 mpg. Is that what you really want??

Post by **callyspoy** » Sun Apr 06, 2008 10:02 pm

well lucky it didn't cost much then! well, i will try it out, see what it is like. the nikki i have is okay, so its worth a punt as the nikki chokes are tiny...
fuel consumption, isn't that much of an issue, i ran a supra before the mog, so am not horrified, but realistically, if the carb doesn't perform, then it would obviously make sense to change it back. but then there is always the downdraught to try afterwards!

Post by **Peetee** » Sun Apr 06, 2008 10:58 pm

This guy knows the a-series tuning game. He's about 20 miles from you but he aint cheap

http://www.aireytuning.com/

Post by **superchargedfool** » Sun Apr 06, 2008 11:02 pm

COUGH su

Post by **callyspoy** » Sun Apr 06, 2008 11:28 pm

HEY! what did i say!!!

Post by **callyspoy** » Sun Apr 06, 2008 11:31 pm

and pete...by not cheap...??

Post by **Peetee** » Mon Apr 07, 2008 9:32 am

He quoted me £160 last year. It would probably be worth it if your car is kitted with bits that you know are in fine order and your happy that the spec is your final choice.

Post by **callyspoy** » Mon Apr 07, 2008 5:06 pm

ah i see. so kind of a "no more tinkering" sort of thing? well that will never happen! haha!

Post by **Peetee** » Mon Apr 07, 2008 6:05 pm

well that will never happen! haha!

Thats the spirit

Post by **callyspoy** » Mon Apr 07, 2008 6:09 pm

i do try!

Post by **bmcecosse** » Mon Apr 07, 2008 7:41 pm

Vizard lists good starting points for side draft carbs on various engine sizes and stage of modification. Just go with that for starters and see how it runs. If you don't have Vizard book pass me your engine spec and i will look it up for you.

Post by **callyspoy** » Mon Apr 07, 2008 7:54 pm

what do you mean by engine spec? how indepth?? its just a standard midget 1275 engine, fitted with an lcb if that makes any difference!!

Post by **bmcecosse** » Mon Apr 07, 2008 8:00 pm

Ok -well based on that Vizard suggests Chokes 32 or 34 mm, Main jet 135 or 140, Air correction 200, Emulsion tube 5, Pump jet 40, Idle jet 4.5 . You really need to pull yours open and see what's there!

Post by **callyspoy** » Mon Apr 07, 2008 8:07 pm

thanks for that bmc. it is now saved ready to look when i get the carb.

Post by **callyspoy** » Thu Apr 10, 2008 6:01 pm

okay, i got the dellorto, turns out the chap who sold it didn't know what he was talking about...it is in fact a DHLA 45...so a little bigger, nice! only thing is...does anyone know if there is supposed to be a vacuum advance on it? i cant see one anywhere...if so, please let me know! if not, what do i do with the advance pipe?? when it's not misfiring...it is stupidly quick compared to the nikki and the weber...