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MG Midget and Sprite Technical - Bike carbs on A Series?

Anyone here tried putting bike carbs on an A Series engine?

If so, how did the conversion go and what carbs and manilfold did you use?

Just an idle musing from me from noticing that Minispares currently sell Amal inlet manifolds that would have gone with a quad carb set up on an 8 port (Crossflow) head on very few rallying and racing Minis in the 1960s and some tuners then moving on to mechanical fuel injection for such heads.

I know more recently people have shoved modern bike carbs on A Series engines, e.g. four Yamaha R1 carbs on a Bogg Brothers manifold.

Sounds like a fun exercise, but potentially frustrating in terms of set up as well as possibly futile in terms of conventional alternatives (twin SUs or a twin sidedraft Weber; K Series engine conversion) and financially fraught.

I am amazed eight port heads and manifolds are available, see:
https://www.med-engineering.co.uk/cylinder-head/8-port
https://www.minispares.com/product/Classic/Exhaust_and_manifold/Inlet/Inlet/C-AHT521.aspx?110202&ReturnUrl=/shop/classic/Exhaust~and~manifold.aspxBack%20to%20shop

Cheers
Mike
M Wood

I broke a very very rusty Speedwell in the 70's which had a 950 with twin Amals. Setting them up was a challenge as the throttle slides are operated by cables. It was quite quick I recall. I sold the engine to another Frogeye owner who broke the crank!!
The manifold was bespoke to Speedwell but was fairly simple steel tubes welded together. I am sure the likes of Maniflow could produce one.
Bob Beaumont

I have posted this before.

L Langley

Hi Bob.
Do you remember anything about the Speedwell? My uncle had A Red Speedwell bought from Speedwell in the very early 60s. I have tried finding it but had no luck. Regards. Simon

s page

I found it in a front garden in Beckenham (near Bromley) It was a sort of dark red I recall. Can't recall the reg number. It came with a yellow Monza bonnet and wide steel wheels were fitted. Grass was growing through what was left of the floors. I have still got the box and rack from it (smooth case).
Bob Beaumont

We fitted twin amal carbs on our rally mini that we used in the Welsh rally championships in the early '70s. I dont recall any of the details other than cutting the bulkhead and welding in a sort of box thing to give space for the twin air ram pipes. Didnt last long though as they were replaced with a weber
GuyW

I've read that Amals work fine but are very thirsty, as they have slide throttles that also meter the fuel. OK for hill climbing but not for touring. Hard to beat SU for road use.

Les
L B Rose

I tried Mikuni carbs on the B. I think that they were originally for an "Arctic Cat" snowmobile application.

The carbs were fine except for extreme heat sensitivity. They would flood in hot conditions, stranding the car in intersections. Not good in Manhattan in traffic.
Glenn Mallory

The first Dellorto DHLA40 I used on my Sprite engine came off a scrapped Alfa Romeo, the owner had kept the pair and fitted one to his Harley Davidson but apparently the performance increase scared him so he fitted the original carbs again and sold me the DHLA40 for £5 and later gave me the other for free. Maybe the previous SUs were not right but seemed to need tuning regularly and didn't pull well low down, the DHLA40 transformed that and pulled much better low down and high end. I know a lot more now and much more information available on the internet so maybe not fair but I always preferred the DHLA.
David Billington

Many complaints surrounding S.U.s are often unfairly levelled because the carburettors are worn out and need refurbishment. Many are now going on 60 years of age and have never been restored or re-bushed.
Alan Anstead

Alan,

I'm aware of the wear issues with SUs and the ones the DHLA replaced had been re-bushed and rebuilt and set-up with correct needles. A good test would have been a back to back on a rolling road but that wasn't an option at the time.
David Billington

Simon Page - are you aware that John Baggott in his Frogeye book has a short article on 4149 MV and its first owner John Tozer?

Bob Beaumont - would you consider parting with that smoothcase gearbox to a good home? I have a period competition Sprite and am looking for a suitable smoothcase box.

Tom
Tom Coulthard

This thread was discussed between 04/07/2020 and 12/07/2020

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