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MG Midget and Sprite Technical - DCOE40 - woth fitting?

I have a Weber 40 and am considering fitting it to 1275. Is it worth doing this swop and if so any advice?
J. I. Jones

If you do the exhaust as well - yes
then it might be worth having the head reworked -- oh and then ....
Mick - The engine is in!

Beg, borrow, steal, a copy of David Vizards A series tuning bible and read and digest the contents, then consider where you want to go with it. I've fitted Dellorto 40 DHLAs, basically the same as Weber 40 DCOE, to a few 1098 and 1275 and loved them as working better than SUs in not needing regular tuning and pulling better from low down and better top end, but the concensus seems to be that a good single SU of suitable size is comparable for most use except racing IIRC. Both are likely to require careful set-up on a rolling road to get the best out of them and rolling roads/dynos with operators knowledgeable about carbs are getting thin on the ground as EFI becomes ever more prevalent these days.
David Billington

It depends on if you like chocholate ice cream, or vinailla ice cream, Im amazed you got 2 unbiased answers already.

If you like webber set-ups, you will swear by them, if your an SU Freak, you wont have much good to say about the weber, I think its a perferance thing, like castrol gtx oil vs. pennsoil


yep I said it, now to sit back and watch the blood bath begin, Oh BTW...I like castrol LMA brake fluid over STP dot 3....(that should do it) ...LOL.


Prop....lets get ready to Rummbbbllleeeee!!!!...Prop
Prop***The End in 2012

Don't know about the '40, but I fitted a DCOE45 to our 1380 a couple of year's ago as a back-to-back comparison at one of the 'power shoot-outs'.

Set the '45 up on the RR and it produced 4 bhp more than the HIF6 SU that replaced it an hour later. In summary the Weber gave a quicker throttle response, was noisier (wonderful for a while, but tiring on long trips) BUT much less low-down torque (RR figures) and town speed pick-up. It was running 38mm chokes, would like to see the comparison with 37's?

The conclusion seems to be that for all-round driveability and economy, fit the SU and for all-out power, fun (=noise!) and throttle response, fit the Weber. Much generalisation here!!

Interestingly for the next 'shoot-out' I had increasd the CR to 10.4, replaced an exhaust valve that was not seating completely and the same SU (with a needle change) produced 6 more bhp than the DCOE45 had previously on the same RR! Have not done the back-to-back comparison (yet?)

Richard
Richard Wale

Sometimes this is a hornets nest when discussed on this board and generally a lot of members comment who have little experience of dcoe webers so tend to spout urban myths only.

The DCOE weber is a great carburettor and IMO does everything that is required of it. The urban myths suggesting it is heavy on fuel is due to so many being in use that are not set up correctly and that is very important if fuel economy is of concern. The SU on the other hand when set up poorly uses less fuel than a dcoe that is badly set up.

A 40 DCOE is almost the same as a 45 except that the 45 can take bigger chokes than the 40. However for a fast road 1275 32mm chokes are the right ones to have and these will fit in a DCOE 40. The 38mm fitted by Richard are really too big and probably did not help the mid range to be strong. The reason why it performed better than the SU at max power is because SUs do not perform at their best at maximum revs and max power, they tend to run out of fuel.

The other major advantage of a DCOE weber is that once set up you can almost forget it forever, it will stay in tune for a long long time without adjustment.

for more information and a quick guide to st up try the MGCC website here
http://www.mgcars.org.uk/mgcc/midgetreg/Weber.shtml
Robert (Bob) Midget Turbo

This thread was discussed between 19/01/2009 and 21/01/2009

MG Midget and Sprite Technical index

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