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Twin HS2 carbs

Posted: Mon May 08, 2023 3:49 pm
by Blaketon
My Traveller has a 1275 Midget engine, with the 1 3/4" single SU. Like my late father's 1275 Midget, it has a Peter Burgess "Econotune" head, which is basically just gasflowed. The Midget has the standard twin HS2 carbs. Both have LCB exhaust manifolds, straight through exhausts and K&N filters. When set up, on the same rolling road, both gave 77bhp BUT the Morris had a mechanical cooling fan, whilst the Midget had an electric one. That suggests the Morris is effectively giving a few bhp more than the Midget.

Since inheriting the Midget, I have found it noticeably more flexible and it pulls better from low rpm (It's a bit over 2 cwt lighter, so not that much). It isn't quite so eager at the top end and I'd prefer it if the Morris were the same. I have a spare set of SU HS2, complete with manifolds and have a mind to try them on the Morris. However, the exhaust comes out less steeply and I suspect would foul the carbs and certainly the heatshield, which acts as the anchor for the throttle return springs. I think the servo may be a tad close too. Has anyone fitted twin HS2 carbs to a Minor and what inlet/exhaust manifolds did you use?

Re: Twin HS2 carbs

Posted: Mon May 08, 2023 4:17 pm
by philthehill
The Midget heat shield is the only problem with fitting HS2 SU carbs using the Midget inlet manifold to a Minor with LCB exhaust manifold.
If you want to retain a heat shield you will have to make your own or modify the Midget heat shield by taking a section out of the centre to clear the Minor LCB middle pipe..