Hi,

Does anyone have any tricks to getting more out of 1 1/4 SU twins? I want to try at least. If it fails I have 1 1/2 twins to go on my Cooper S.
I bought the book by Hammil but I just wanted to see if anyone else had ideas??

I found this pic of a 1 1/4 piston that appears to have been modded on the bottom... Ive never seen this before . Any comments?

This was off a blog from a guy in portugal restoring a Austin Cooper S.
[img][img]http://i1089.photobucket.com/albums/i359/freddo3/supiston.jpg[/img]
[/img]
Ive tried to contact him with no success yet.

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66 MK 1 Cooper S
64 Grp N Cooper S
64 Grp N Cooper S (ex Bob Asher)
64 GRP N Cooper S (ex Fred Burley)

David Vizard's book "tuning the a-series engine" has some really good tips on SU modification.

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1963 Morris 850

Thanks,

Got that book as well too but no reference to this mod

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66 MK 1 Cooper S
64 Grp N Cooper S
64 Grp N Cooper S (ex Bob Asher)
64 GRP N Cooper S (ex Fred Burley)

Wow, that's a blast from the past!

That mod was documented by Clive Trickey in his Mini Tuning books back in the mid-1960's when he wrote for Car and Car Conversions (CCC) magazine. It's called a "quick lift" piston conversion. I can scan the relevant pages and post them here if you wish?

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

If you look at page 117 is shows 2 pictures of that mod and details it on page 118.

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1963 Morris 850

Thanks for your reply,

I see it now at page 117 but I don't think it is the same as the Vizard version. He only suggests a 30 degree champher on the leading face, where the picture I refer to looks as though they have blended in the champher much closer to the needle

The fellow from Portugal has got back to me in the meantime and suggests it is a Downton modification.

Either way, im going to stretch these carbies to their limit. Stay posted

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66 MK 1 Cooper S
64 Grp N Cooper S
64 Grp N Cooper S (ex Bob Asher)
64 GRP N Cooper S (ex Fred Burley)

Hi all, second post here. Those are my carbs. I'm using the pistons pretty much as I found them, ie, the modification was already done, I just made the curves smoother. If I'm not mistaken this was done by Downton and other companies back in the day (I've seen downton HS4s with a much aggressive chamfer, almost 45º). I don't think it makes any difference in a road car like mine though.

http://rsn-mk1.blogspot.pt/2012/11/twin-carburetters.html

Thanks Ricardo,

You are exactly right, and I do recommend your blog to anyone restoring a mini. It is excellent.

Hope your car is purring like a kitten

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66 MK 1 Cooper S
64 Grp N Cooper S
64 Grp N Cooper S (ex Bob Asher)
64 GRP N Cooper S (ex Fred Burley)

Hey Ricardo!
Took time, but you got here! Welcome on the forum, i'm no longer the only Portuguese maniac here!
You should put some pics of your beauty in the Members Gallery!

You will enjoy the forum for sure.

Cheers
Luis