1275cc Upgrade

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gucu
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1275cc Upgrade

Postby gucu » Tue Jul 14, 2015 1:10 pm

Hi All

I have obtained a 1275cc engine and a 5 speed gearbox. It is currently in it's stock format with 1.25" carb and joint manifold for carb and exhaust.

As I am fitting this to my car shortly I would like to upgrade the current set up and possibly fit:
1. 1.5" SUs but don't have a manifold
2. Long branch manifold + exhaust - but can't find one. Moss do a mini one but I don't know if it will fit.

Has anybody got any ideas on where I might get one or suggested changes to the above please?

Thanks

Rich

bmcecosse
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Re: 1275cc Upgrade

Postby bmcecosse » Tue Jul 14, 2015 2:39 pm

A long branch manifold will lose you power on a standard 1275 engine - and obviously a Mini one won't fit anyway! The 1275 never ran with a 1.25" SU - are you sure? A single 1.5" carb on a good alloy inlet is the way to go - and just keep the standard exhaust meantime , until you upgrade the engine.
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Sparticus
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Re: 1275cc Upgrade

Postby Sparticus » Tue Jul 14, 2015 2:44 pm

Maniflow do a nice exhaust for the 1275 :). As for the carb I'd say go for the HIF38 or HIF44, the 44 if you plan to 'tune' it up a bit. Whilst they appear on ebay they go for silly money, go to any mini show and check the auto jumble :)
Grant, 23, Morris Minor traveller - Saloon. Merlin traveller 90% finished!
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bmcecosse
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Re: 1275cc Upgrade

Postby bmcecosse » Tue Jul 14, 2015 3:42 pm

44 is too big for a standard 1275 - even more power loss as it gasps and wheezes..... :roll:
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Sparticus
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Re: 1275cc Upgrade

Postby Sparticus » Tue Jul 14, 2015 3:48 pm

Like I say if you plan on tuning it up use the 44..... 8)
Grant, 23, Morris Minor traveller - Saloon. Merlin traveller 90% finished!
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bmcecosse
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Re: 1275cc Upgrade

Postby bmcecosse » Tue Jul 14, 2015 10:30 pm

Modify the engine first - upgrade the carb (and exhaust) last.
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Roni
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Re: 1275cc Upgrade

Postby Roni » Wed Jul 15, 2015 12:47 am

I have a std 1275 in my truck.
Initially it had a long centre branch exhaust but now does not. I found that while it breathed well at higher revs, it was flat and sluggish in the lower rev range where I do most of my driving. A std 1275 Mini cast exhaust manifold is on there now and while it looses out above 5500 rpm it gains much more lower down and is much more drivable. Be wary of the Marina 1275 cast manifold. They have a tendency to crack around the flange. It is a pity, as these were bigger bore and worked very well.
The carb is a Hif44 on an alloy inlet manifold. I have also had a 1.5" SU on this motor in the past. There wasn't a big difference
in performance but the HIF44 was an improvement in both performance and fuel economy. The HIF44 pulls well from very low revs. Doesn't gasp and wheeze. You need to get the needle, spring, dashpot oil correct, as with any carb.


gucu
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Re: 1275cc Upgrade

Postby gucu » Thu Jul 16, 2015 12:40 pm

Thanks for all the replies. Reading through the various responses it seems the best thing I can do is to set it up with it's current set-up and then gradually retune the setup.

Thanks for all the help.

Rich


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