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MG Midget and Sprite Technical - 1500 44 MM SU`s

Hi
I'm in the process of modifing my 1500 midget.
The planned spec is a large valve head with 9.5 cr, Piper 270 cam, Maniflow 4-2-1 manifold and exhaust, K&N twin alloy filter with stub stacks and converted the carbs to plain butterflys and fixed jets.
My question is, has anybody tried 1 3/4"/44mm SU carbs on an engine with similar mods?
It seems that a 45 DCOE Webber is the next tuning step on this engine, so why not larger SU's?
Steve Deakin

Steve
Twin 40s are nice on the 1500. Webber or as my car Dellortos. Can be found on old Alfas and Fiats but you will need a manifold. I have seen them come up on e-bay may be worth looking on the Triumph pages. They look the buisness as well as doing the job.

Good luck Carl
C Bintcliffe

Hi Carl
I know about the twin 40's, but there are plenty of twin 1 3/4" SU's around, and I was wondering if they would give a worthwhile improvement at low cost.
Steve Deakin

Steve,

With the 40mm DCOE carbs you will stress your engine beyond breaking (I went through two spitfire engines that way) look into a DGV set up.

You could fit larger SU carbs but they might not clear your bonnet and you would need to modify the inlet manifold possibly.

Either way you need to make sure you pin your thrust washers in place and make sure you never sit at a stop light or hold the clutch in, instant death for a 1500cc.

Stefan
Stefan

Steve
You are welcome to come to Warwick and have a look at my setup if you like. I don,t know of any twin 1 3/4" set ups and I would of thought that twin 1 1/2" s would be more than enough for a 1500

Cheers Carl
C Bintcliffe


How much power you planning on?
I reckon twin 1.1/2" SU's are good for an easy 120lbft/110bhp so why go bigger?
A set of twin 40's may get you 5 or 6bhp more than SU's but my experience of these on the 1500 is that it loses too much tractability at low speed. This especially the case if you have a spicy cam and it might end up real difficult round town.
That was one of the reasons I tried an injection system.
http://www.tooke.org.uk/inject.htm
Why not modify the std carbs by smoothing the flow and fitting some nice big filters? Prob far easier!
Bob T

This thread was discussed between 17/03/2008 and 18/03/2008

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