I've got to pick up a pair of needles for my twin 1.25 SUs on stock MOWOG twin manifold. Can I please have some opinions on starter needles to set my new engine up with.

I've got a 998 at 100 thou over for a displacement of 1075. The camshaft is GR's RE83. The head is a 295 set at about 9.5:1 and 3:1 extractors.

Can anyone give me a few selections to try out?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

CP4 or MME would be the preferred needles to start with
.

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i`d stick a pair of "M"`s in them first & see how they run

CP4`s & MME`s are more suited to a mild/hot-ish 1275 on twin 1.5 carbs

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Engine Size Needle Std Needle Rich Needle Lean Spring Type

850 comp
1071 S Comp MME - - Blue

997 Cooper
thermo jets MME - - Blue

998 Cooper
modified head AO - - Blue

970 Cooper S
comp CP4 - - Blue


Thats from a BMC Tuning page I found ages ago , they have same details on Seven Enterprises

( it looks strange as I cant make it line up properly )
.

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M's I would not have picked as a choice, I have always thought the selections were based on capacity first..shows I have a lot to learn still....I have a pair here as it is however, so it won't hurt.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Ms seem to work well in tuned 1098s so should in yours too.
AH2 is a bit richer than M, if you need this.

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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.

I even happen to have a pair of those too..

I'm set it seems!

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I'm using M needles in my cooper I bought new ones 3 & 4 cylinder and not firing plugs very wet the needle measured up at 75 thou at the idle end instead of 87 thou like the other one on cylinder 1&2

Actually Torque / HP. Find an engine with a similar torque / HP curve to what you expect yours will have. That will be a very good starting point.

And don't overlook the springs.

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yeah pretty right

I will add tho, that it`s more about "air speed" through the carb

a really big carb on a small , low reving, engine will need a much richer needle profile than a smaller carb on the same engine... the smaller carb will pull up the fuel from the jet far better with the higher air speed

& with a small carb on a very big high reving engine will only need a fairly lean needle profile,,, etc etc etc,,, that`s the part where GT mentions how the spring rate affects things

i recently sent a single 1&3/4 carb to a guy (way out west somewhere) to fit onto a massive 4.5litre straight 8 (of some sort) & i set it up with the same old OA6 needle & Red spring ,,, the very same "base-setting" that i do with every thing to start with

he rang me back telling me how he couldn`t believe how good it was & no need for any tune work,,, (his actual words were "It`s spot on" )
Now i`m sure we could have improved it a tad more with some time playing, but he was more than satisfied

however, if it were a race engine (higher revs & obviously much higher air speed through the carb) well i guarantee it would have needed much more than a play with to get it right (maybe add a few more carbs to be honest) but still,,, as big as the engine is , it still had fairly low revs, so air speed wasn`t too fast to cause any issue & my faithful old "std" base setting was sweet

so,,, there you go,,, think "air speed" more than anything & you`ll be on the right track

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Mick the "M" needles should be all you will need for this size engine (Im not 100% sure of specs of your cam but I dare say its "nice" ) but as the good Doc said if you need slightly richer AH2's will do the job.