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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - notes for Willy T

Hi Willy,
I am hoping that needles can be found to work with the DU6s. They were used on the 1500 coventry climax F1 cars, and I was thinking of those needles as a starting point. The other car that used them was the Le Mans Triumph, which is a much larger engine.

The head has slightly larger inlet valves (42mm) and has been ported (for road use) by someone who specialises in heads.

Ideally, a long runner would be needed for non-racing but space is limited. I haven't worked out what do do for a manifold.

I would be interested to hear any comments you have.

Cheers,
Mark
Mark Wellard

Yeah, that'll be interesting
I looked the climax needles up and they were VB and it looks like they were run without damper springs which is a bit strange but if it works it works, I'd have thought a very light spring just for keeping the piston from jumping around at idle, but only some testing will tell the story there-
There are a few different needles to choose from around that VB area and also VB is almost identical to SW and there are heaps of choices around the SW area in the 'S' series
Easiest for the manifold would be a pair of adapter plates onto a weber manifold if you happened to have one,but the throttle bores for the SUs look much closer together than Webers so probably a no go with that--
The SU spacing looks closer aligned to the T/C port spacing than webers from your pics--
I'm thinking you'll probably be fabricating a manifold- or making a mold to cast one----------------

willy
William Revit

Hi Willy,

I was also surprised that no spring or damper is used - perhaps because racing cars predominantly aim to reach full throttle as quickly as possible. I was wondering about using a light spring and/or a damper to make the mid range performance more stable.

You are right that the spacing is too narrow to use a Weber manifold. I would like to find someone who could help cast a manifold. 3D printing might also work if I can organise the appropriate file. Both skills that I'm yet to acquire!

Thanks for the suggestions on the needles but the documentation I read (the SU handbook) listed a ZB needle. Was your VB a typo or do you have documentation that says VB?

Cheers,
Mark
Mark Wellard

Far out---yes typo, ZB,sorry, that's what i get for having a beer(VB) while on the laptop,--- and SW is almost identical to the ZB
I'm sure you've been into the SU books, but just in case, The whole idea of the piston spring is to control the lift of the piston so that the piston reaches the top of it's travel at the same revpoint or just slightly before the point where the engine develops maximum power
Because of the large size of the carbs compared to the size of the engine it may well be that any spring at all prevents full travel---only testing will tell but the light blue (2.5oz)spring would probably be the only one light enough----even these might need to be cut down a bit to get a result-------testing will be the only way to find out

3D printing a manifold might well be an option, casting one and getting it all machined up would be an expensive little exercise I suspect,--- but a fabricated manifold might work out ok , I reckon that'd be your best option

willy

, I've had a little count up and I came up with 8 Twincams here in Tassy, fairly impressive really considering their rarity-
William Revit

Thanks Willy,
The light blue spring was what I was thinking of too. Good suggestion to consider cutting it down to make it lighter again (adding lightness- very Lotus). Careful planning and casting should minimise machining but costs of such an exercise are my main consideration at this stage.

The Australian twin cam population seems to be on a never ending growth curve, which is great to see.

Cheers,
Mark
Mark Wellard

Mark
Just flicking back through your engine build pics and noticed the Pauter rods--What did you think of them--warning--I'm a Brian Pauter fan from way back, I notice he hasn't got them listed for a Twincam anymore but that means nothing, they'd be available I reckon- just gotta ask-
William Revit

I bought the rods recently, Willy. I’m yet to start on the bottom end, so can’t tell you yet.

Cheers,
Mark
Mark Wellard

This thread was discussed between 01/05/2022 and 03/05/2022

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