8 replies to this topic

[imaparana]

Helloooo,

 

Just put a rebuilt 1330 in my mini and done about 70 miles on it and runs lovely however due to the fact that in jersey we don't have anyone that would be able to properly rolling road a mini and in fear ill do damage without having it set up properly ive bitten the bullet and bought an AEM wideband gauge.

 

ive got a few questions about what sort of ratios I should be aiming for and different points

the articles ive read have mentioned say 12.5 at what, is this correct for a mini?

14.7 at part throttle?

14.0 cruise?

havnt found anything about what the idle ratio I should aim for is.

if someone could help me out here it would be greatly appreciated

 

last question, I understand that needles have different profiles but not sure how id go about finding what 'profile' I need at which different point on the needle in relation the the one ive got in at the mo. 

 

Cheers in advance

[David128]

Hi From what I've read about ratios,  that looks about right 14.7 is ideal above 15 is bad ie too lean.

 

How does it drive?

Edited by David128, 03 December 2015 - 08:23 AM.

[imaparana]

thanks for the reply,

drives fine, was just worried looking at the plugs as there abit black but I know you cant really tell until its done a fair few miles

[Mini Manannán]

I'm in the same boat as you re. rolling roads, nothing on this rock either!   For the same reason I have the very same AFR gauge.

 

14.7 is the holy grail. 

 

The first thing to mention is you need to get the car up to temperature.  You'll need to do a full lap of Jersey for that, I know, I've been to Jersey many times to go fishing.

 

15/16:1 on the cruise will be fine - light throttle is economy mode.

[mini13]

aim for stoich at idle, so 14.5-15 would be fine.

 

cruising, lean it off a bit if possible, i have run as lean as 17:1 at cruise with no issues, but thats probably pushing it a  bit, basically if it misfires its too lean. also on an old engine you could be runnign the risk of burning valves out, if you have race valves like mine then no probs.

 

foot down yeah about 12.5 for max power, bit for a road car a bit leaner wont hurt, aim for say 13:1?

[jaydee]

Most road cars will benefit from a rich top end and a lean cruise, while on a tuned a series engine, i never go over 12.8 AFR at full power but cruising are around 13,8-14

A wideband lamba is a good move now the hard bit will be identifying the correct needle stations, but you'll soon find out.

The pick up from a SU carb usually requires a 14.0 AFR at idle for a more consistent driveablity.

Experiment different thickness oils for the dashpot, better if using synth oils for this.

Take in account at gerchanges mixture will turn out rich as its how the SU works, the piston lifts under load and falls with no load, this means you a second when the piston falls that gives a very rich mixture. This means that a heavy dashpot oil that can give a good pick up from stationary will get you a wrong fuelling at gear changes.

[imaparana]

brilliant cheers all so:

14.0 ish idle

15/16 cruise

accelerating around 13-14

12.5 ish flat out/what

[Mini Manannán]

brilliant cheers all so:

14.0 ish idle

15/16 cruise

accelerating around 13-14

12.5 ish flat out/what

 

That's the ball park, though you'll find it easier with a logger such as this: http://www.xenontuni...ensor-3837.html

[Steve220]

14.7 will cause the engine EGT to rise, a little richer will allow piston crown cooling, especially for the middle 2 cylinders.