Help with SU Setup (Na)
Turbo Mini Forums

After being plagued by numerous electrical problems, Ive just got my british open classic running for the first time in about 4 years!!

Anyhow, the engine is std apart from a K&N and one of JohnK's delicious s/s LCBs

Problem is, the carb has been rebuilt and Im struggling to get the engine to idle correctly.

I have adjusted the idle speed to 1200rpm but cant get it any lower, which is annoying me somewhat

I have tried winding the mixture screw all the way out (to the bridge) and then turned it back slowly 1/4 turn at a time.

At 1200rpm its about 4 turns out it that it sounds really sweet, and revs up instantly with a tickle of the throttle, 1/2 a turn either side it bogs slightly, but then if i try to lower the idle speed any lower, I cant seem to find the same sort of sweet spot, and the throttle will hesitate and stutter, sometimes die.

Also at idle the centre branch of the exhaust glows cherry red, is this normal for a s/s manifold?

The timing is right, and checked for air leaks around the manifold, oil in dash pot, etc, everything seems fine?

Can anyone shed any light on the matter?

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Joe how have you tested the timing that sounds alot like a retarded ignition to me

i marked the block/dizzy years ago, ill check with the light tomorrow, but that shouldnt be an issue

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Actually thinking back, when i killed it before coming home for tea it did run on for about 10 seconds...ill get the gun on it tomorrow morning

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

That could have been caused by the high idel speed and hot EVT

Yes i moved to the darkside

Instagram @jdm_brett

it was a fair way out, about -4 degrees at 1200 rpm lol

i must have mixed the dizzy up with a spare or something!!

It running ok now, was still dying when blipping the throttle, but a bit more oil in the dashpot sorted that.

cheers guys

Joe

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Your Welcome joe

Righto, bled the brakes on the british open classic, and took it out for a blast tonight, surprisingly nothing fell off it drove and braked in a straight line haha

felt REALLY good driving a mini again (not had one on the road in years!!)

running ok ish but has a slight hesitation when talking off, and a little flat in places, its std late 1275 apart from a k&n cone and s/s lcb and 1.75" system, i have put in a stage 1 needle from minispares, but i dont hold much hope in it being spot on haha

gonna whack my wideband on tomorrow night, what sort readings should i be after for decent performance with reasonable economy?

cheers all

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

around 13:1 should be pretty good is what ive heard...

there are much more experience people than me out there though!

thats for best power i think? on cruise shoudl i not be aiming for stoic (15 ish) or leaner? maybe 16/17?

i know all engines are different, just dont want to do any damage lol

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

what sort of afrs do stad engines run?

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

im hitting google!

EDIT: turns out google can take a few punches...

right couldn't really find much but im tired so im just going to give my opinion on my understanding.

14.7:1 is stoich as im sure you already know and this will give perfect burn of all of the fuel. turns out most modern cars generally run a leam burn at low load to give good emissions but then this is adjusted to around 13/12.5:1 under acceleration/ high load.

so judging by that i would say a happy medium of the two. so between 13.5-14:1

but at the end of the day how stable is this going to be on a carbed engine? are you going to be able to get it that accurate that your worrying about 0.5? anywhere between 13-15:1 i would say you'll be doing good. (although thats a big gap i know)

personally i would aim for 14:1 not really rich but not lean to cause damage.

but like i said earlier im nowhere near as clever or experience as some of the others on this subject so thier opinion/knowledge will probably be far more usefull to you.

Edited by James_H on 8th Dec, 2008.

right, bit of an update

hooked up the wideband, and under 'normal' driving (engine warm, choke in, running like a dog!) it never once got rich enough (even at wot) to even register on the aem gauge, (so 17+:1) haha!! so well out!

but with the choke pulled out i manages to get it to run around 14:1 and it drove alot better, but then idled at 2000rpm..

so it obviously need richening up a shade

tootled back to the garage, and turned the mixture screw in a turn to richen, took it for a spin, again,, but after 4 turns, its still too lean, but its all the way in now, so cant make it any richer?

so where do i go from here?

another thing ive noticed is that now ive richened it up, i cant get it to idle below around 1400rpm, any lower and it just starts to stall, surely this isnt right?

btw, i rechecked the carb connections, the timing at 1400rpm with the vac disconnected is bang on @ 10 btdc, so thats fine, no leaks around the manifold, and around 175psi on all 4...

any ideas would be appreciated as im all out!!

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

i had something similar...have you tried driving without the vac advance connected...the module on the side of the dizzy may be knackered.

Obvious question, but is your wideband reading right ???

I can't imagine the engine would run under any sort of load at >17:1

Which wideband is it and how do you calibrate it ???

Schrödinger's cat - so which one am I ???

the widebands fine, its an aem one and been using it on other cars

and yes, it barely ran at all with the choke in, VERY flat and hesitant..

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

just been having a gander at this:

http://books.google.co.uk/books?id=CTz2EAp...result#PPA44,M1

page 44, says that on a road going engine the afr should be around
13:1 at idle when the jet is the 0.050" down from the bridge

will give this a shot tomorrow and see if it makes any difference

Edited by joeybaby83 on 26th Dec, 2008.

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Sounds about right, this is from about two weeks ago (in my MS trials thread)

http://www.turbominis.co.uk/forums/attachments/259705-1.pdf

Graph shows AFRs settle at an average of just below 13 as engine reaches temperature and "choke" taken off, so dropping to normal idle. (ignore RPM reading, it's actually half that, ~900 RPM, I had the multiplier set wrong in the controller !)

That's a standard HIF44 from an MG Metro with all settings pretty much the same as when it came off the Metro (all I had to adjust was the idle).

So it sounds like your jet setting is really wrong or you have a massive air leak.

Edited by Rod S on 27th Dec, 2008.

Schrödinger's cat - so which one am I ???

ha, set the jet 50 thou down from the bridge, (wasnt far from this anyhow) and bosh, like magic the thing purred away like a kitten @ 900 rpm and 14.7:1 afr

had a little tweak after a 10 min burn, and got it to idle spot on 13:1 @ 800rpm, could give des hammill a kiss

on full throttle it drops to 12.2 ish which is good
on cruise its teetering on 17:1 maybe leaner (often drops of the gauge)

the only area that i need to tweak now is the transition from cruise to moderate acceleration, like in 3rd or 4th, cruising at about 30, if you go to speed up a shade, say to keep up with traffic, its a litte flat, and grumbles at 16:1, would thicker dashpot oil or maybe a firmer spring in the dashpot help this?

*edit2* would blocking off the 'part throttle lean off pipe' help this, ill give it a try tomorrow, but will this have any adverse effects? or just fuel economy?

Edited by joeybaby83 on 27th Dec, 2008.

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

The spring strength detemines how high the needle sits for a given depression, so it will affect the whole drive range.. I would leave that for now.

Blocking the part throttle leanoff will enrichen things in the midrange but may screw it up in other areas.. only thing to to is try it and see what happens..

Thicker oil will help with the transition, 20 weight is normal but 30 or even 40 wt may be needed in the winter.

Thake a look at my SU polishing post for more ideas, Des Hammil helped me too!!

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=159683

Terry

website:- http://www.terryhunt.co.uk