What AFR readings do people get from their Minis? That is old technology A series, with SU's and distributors with springs that work.
I have a big bore with single 1 3/4 worked road engine. Needle is KV, RE83 cam.
Under load it is often around 13, 14, and full load high speed sometimes up to 15, 16. A little leaner than I would have liked, but will it do damage?
Cruising is 13, 14 so happy with that.
On over- run / take your foot of the accelerator down hill it goes up to 30 or 40. Is this standard?
This is using a Innovate LM1 wide band meter.
What are peoples experiences on the road?

Full load aim for 13-13.5 with an SU.
KV should be richer than you have.

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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.

Where are you testing from? is it with the O2 sensor in the tail pipe?

I have a similar setup - 1275 + 0.72", RE83, HIF44 but my static compression is low - around 9.5:1, I'd set it up for boost but took the blower off

I'm using a BBC needle, which shape-wise is similar to your KV, but leaner across the board. You probably have the KV set up with the top of the jet very close to the bridge?

Is the nylon plug that keeps the piston from touching the bridge intact? the piston should be sitting 1mm up from the bridge, funny things happen if it can fall all the way down

Any idea what spring you're using?

needles compared: http://www.morrismini.com/SUNeedlesV2.a ... &size=.100

I can't remember what needle I started out with, but it was like you described so I researched and came up with the BBC. The only problem with that was too lean on cruise so I sanded it around S6,7,8 which cleaned it up. There's a distinct change in shape you can see on the chart

Now I get idle at around 12, cruise & normal driving at 14.5 and power in the 12-13 range

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did I tell you that I won a trophy?

I had to look up what a "Innovate LM1 wide band meter" was so thank you now i need one

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1968 Morris Mini Cooper S

I found the main problem. The needle was an OA6, not the KV, which explains why it was on the lean side.
So I will try the KV again and maybe something between the two.

But what do you guys see on the over run - when you take your foot off going down hill?

I am testing from the tail pipe so the idle readings don't mean much, but the rest should be good.

Thanks for the reply's.

it sure does explain it!! I didn't want to say "are you sure you have that needle??!!"

I get a rich (11:1 ish) spike on overrun (like reaching the peak of a hill then backing off over the other side), then it leans off to a normal mixture after a few seconds



get one of these instead, install it permanently... pretty gauge to look at...

https://www.diyautotune.com/product/inn ... auge-3802/

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did I tell you that I won a trophy?

Laingy went through all this recently, from OA6 to KV then to others. it's running real good now, I'll post tomorrow what he's using.

As for wideband meters, I put an Innovate MTX-L into a Jaycar box so it's portable. Probably cheaper than LM-1.

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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 like something portable so that I can use it on different cars. Plug one end in the exhaust and the other in the cigarette lighter.

so how do you plug it into the Exhaust all the ones i am looking at are screw in how do you make that portable

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1968 Morris Mini Cooper S

Make a tube to clamp inside the end of the exhaust and weld sensor thread bung into it...

or buy one https://www.amazon.com/Innovate-Motorsp ... B000CO9MF8

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Videos - Turbocharged A-Series on Dyno & at Wakefield
Mafs waz not my strong subgeckt at skkol

This is what I use on the exhaust. Basic but works - only down side is the need to put an extension on it to check the idle mixture to overcome the "hunting" from the cam. (I put the clamp on properly when it is on the road).

Here's mine- pipe is 1" OD, spud nut is M18.
It slips into the tailpipe.

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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'm using an RB needle in an HS6 on a stroker 1387cc with 1.3 roller rockers & 10.4:1 CR. The KV needle was used for dyno testing the motor on its own - it didn't matter how much fuel was being used as long as the engine didn't "starve", and produced as much output as it could. But when it came to road use, the KV was just too rich. I did go from an RE83 cam to a 266SS cam also and this gave an even larger torque curve - can pull away in 4th from 1500 rpm. The air/fuel ratio is 11 - 13 which is spot on according to Doc.

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77 Clubby Van - Brooklands Green 78 LS Fitout -1100S Rebuilt 2015, 1387cc stroker, 105HP ATF @ 6200 rpm, RE266SS cam, 1.3 roller rockers, 10.4 comp, remote S Box
71 MG Midget - 1298cc - Sebring Bonnet & Lenham GTO rear in Jag BRG + 14in Chrome wires.

I think I'm going to do the same for my next rebuild....

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did I tell you that I won a trophy?

It was GR's recommendation when I had to do a rebuild due to ring failure at 2600km - one hell of a shock, but with GR's pistons and Nippon rings all seems to be ok, and the cam is that much better too.

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77 Clubby Van - Brooklands Green 78 LS Fitout -1100S Rebuilt 2015, 1387cc stroker, 105HP ATF @ 6200 rpm, RE266SS cam, 1.3 roller rockers, 10.4 comp, remote S Box
71 MG Midget - 1298cc - Sebring Bonnet & Lenham GTO rear in Jag BRG + 14in Chrome wires.