My car currently runs twin 1.5 SU's

However, I'm about to fit an original standard set of Cooper S 1.25 SU's. I'm after suggestions as to which needles may best suit based on others experience with a similar setup.

1275 bored out 0.060 to 1330
Standard Cooper S Cam (as far as I know)
1.5 rockers
LCB extractors

Cheers

Phill

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Hi Phil
Would run M needles and Red springs.
Why the change from 1.5" SU's?

Thanks

Ian

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850 Morris Mini
Morris Mini Traveller
Mini sports Sedan

Hi Ian,

Just would like to eventually return the car to original, or at least collect all the original bits (I now have the original steel "s" rims on the car ...if you remember I got them from you)

I'll keep the 1.5's, but they need servicing badly.

A couple of people have said with the 1.25's I may even find they give a little more pull low down and I'll just lose a little in the mid and top end.

Will be interesting to see the difference.

Cheers

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

M needles were original fitment, I played around with them a lot a while ago and M's were too lean even on a standard motor... todays fuels are different to what was available when they were new.

AH2's were OK I think, but maybe ended up too rich - Dad's car has AH2s

you just need a starting point - bung in what you've got, set it up as best you can then see what the mixtures are like

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did I tell you that I won a trophy?

Id start with M needles, but I think you may need needles a touch richer such as AH2 or H4 . . .

http://www.mintylamb.co.uk/suneedle/

Heres a link for a good place to compare . . .

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http://www.youtube.com/watch?v=nDMkVq1jRGU

Thanks guys, I have some M's so I'll give them a go, I also have some AH2's to try. I have 6's in the 1.5 SU's but I suspect they are too rich at the upper end, you can see fumes with hard acceleration at highway speed.

I was wondering with the physics of it all does the slightly greater capacity from the rebore make that much of a differece to the needle selection.

I guess a rolling dyno is the only way to be sure.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Hi Phill,
You can also attach a portable A/F ratio meter with a probe in the tailpipe and go for a drive... it's what I do with my Dellorto.
Only takes 5 mins to set it up,
PM me if you want to come up and try it...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Kev, that would be awesome. I'll PM when I'm ready. The 1.25s are still sitting on the workbench waiting to be fitted.

Would be interesting to see what the 1.5's are doing before i remove them too. I'll be in touch, much appreciated.

Phill

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)