Hi All just a quick question on the possibilities for my mini K which I have just got re-registered.
I have a LCB with 1.5in SU with K&N filter and standard inlet cut down. The carby has had a kit through it.
The needle is ABX which I have discovered is for a 998.
Running a Pulsar distributor DR83 with vacuum advance.
My problem is that I have a flat spot on acceleration, that seems to disappear with higher revs.

So I'm thinking change the needle to CZ to start with, but any suggestions for other tuning techniques with this combo are welcomed.

An ABX needle is a springy type, a CZ is a fixed type. Basically needles with 3 letters are springy, needles with 2 letters/digits or 2 letters and a number are fixed

but!

CZ is a leaner needle than ABX - the higher the number, the leaner the needle is - it's a thickness measurement

http://www.morrismini.com/SUNeedlesV2.a ... &size=.090

flat spot on acceleration is often due to not enough or too thin oil in your dashpot

have you had an O2 meter on it?

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Thx Simon

I'm using 10W 30 engine oil in the dashpot...unless the service company replaced it. Is that too thin?

Interesting info on the needles...I need to research that more.

As for the O2, does that mean exhaust gas analysis? I had the car sorted for roadworthy by a mini specialist, who pulled apart the carby and reset needle seating and float gap to try fix the flat spot to no avail. I had already done that prior to taking it in after I had put a carby kit on it. They stated that the car simply had the wrong carby on it and made the mixture richer to compensate. :/
I thought the 1.5in was suitable for an 1100, perhaps I should return it to the 1.25in.

Thanks for any input.

Depends on how warm the head is for the carby, a wonderful mod on a basic 1100 is a simple addition of a 12g202 or 295 head, a 1.5" su with a decent needle and some extractors. I've got a rather warm head on my 1100 and run a 1.75"SU with a very pointy SY needle.

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Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

I'm pretty sure it's a 12g202, and using LCB extractors, so maybe a richer needle would help. I'll double check the head. I don't know if the head has had any work done to it, but I don't suspect so.
The other unknown (to me anyway) is the advance the pulsar dizzy provides and if that needs investigating.

dunno who said mini specialist is, but saying that a 1.5" is the wrong carb for an 1100 is very odd - most would say it's ideal....

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Sounds like what you have is a "stage 1" kit.
If you buy a stage one you basically get what you have plus a nice new Red dash pot spring and an ABY needle.

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WD40'll fix it!
If it don't, use a big hammer!

Agree, stage 1 kit but with cast iron inlet. Said mini specialist appears to have given up and blame the wrong carby...so yeah not impressed believe me. Thx for that info, will source an ABY and red spring.

check the spring in it at the moment, keep in mind there is something stupid like 700 needles so try a few and get someone with an AFR to get it tuned right

_________________
Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson

OK, update...
I have discovered the vacuum advance is not working correctly. Sucking on the vac hose shows it holding for a moment and releasing the vacuum. Disconnecting the advance I see the spring section do its thing then release until i suck again. Looks like the diaphragm is failing. I did test this before installing the dizzy but it must have failed almost immediately after installation. This explains why there is pick up initially then lag, and pulsing the throttle gives momentary improvements. Also no go on the highway as it drops to only mechanical advance.
I need to replace this vac unit, so will have to try and source one or try a wrecker. Once I've done this I'll revisit the spring/needle combo.
Thanks to all inputs to this thread. You would have thought the 'mini sevice specialist' would have found this. Surely it would have been obvious with just a timing light...sigh wasted money.

not really, you're meant to disconnect the vacuum advance when setting the timing.

Vacuum advance is only an economy device, there is only ever vacuum when the throttle is at a part opening - any amount of opening will cause the vacuum advance to drop right away

I had a pulsar distributor for a while, never had the vac advance connected

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998 Clubbies and 1275LS with that HS4 carby on them had NO vac advance fitted when built.
As Simon says it's just an economy device, it's not your problem.
[edit] Cooper S didn't have it fitted either.

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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.

Sounds like it could be a leaning out problem, but without checking it with an O2 meter you won't be sure.
Could be vacuum leak, wrong needle, wrong spring, wrong oil in dash pot or any number of other things.
First thing I would do is blank off your vacuum advance at the carby because you say it isn't working. This could be creating a vacuum leak.
Second thing is make sure your timimg is correct.
Third thing to try is thicker oil like 20w50 in the dash pot. This will slow the speed of the piston in the carby down and make the mixture richer on acceleration.
Good luck and let us know how it goes.

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1970 MK II Cooper 'S' Supercharged 1310 with Megajolt.
1970 MK II Cooper 'S' Original resto project (SOLD)
1962 850 Original. (Under restoration)
1973 Leyland S (My first car. Now rebuilt, so my kids can learn how to drive a real car).
VMCI # 215.

Results are in.
Spot on advice from everyone. I blocked off the vac ad at the carby and solved 80% of the flatspot. It was sucking air through the vac advance and leaning the mixture out. I've now put a red spring in and changed the dashpot oil to 20w-50 and now there is just a lack of power on hills and at some revs. So I now think that a fiddle with the timing/ mixture will now produce the desired outcome.
My thanks to everyone on suggestions and advice, it has helped me get the car on track.

If you are running a stock Pulsar distributor it has too much internal advance.
It needs the 2 advance slots shortened by welding or brazing.
See my thread in the mods form (it used to be a sticky but with the new board, it isn't...)
I will find it and give a link here.
[edit] here ya go.
viewtopic.php?f=5&t=1498
It's a bit of an epic, scroll down to p23 for advance slot mod info.

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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.