Hi All,

I'm having some issues with fuel.
I run an 1100 with a 731 Cam and 1.5" carb.

Today it began spluttering and refused to go.
It has a new fuel filter and plenty of frsh fuel (98RON). Spark is good delivered via an electronic distributor.
I have checked the carb and the needle ( I think it's an AAB but i'm unsure, might be an ABX or AMB).
The needle jet is approx 2mm down from flush.

Breathers are connected between the tappet cover and the carb. All holes in manifold are blocked. Manifold has been tightened as has the card as I thought maybe air was getting in.

The issue now is it runs (poorly) for upto 10 seconds at about 500RPM and then it goes straight up to about 2500RPM and cannot be kicked down or lowered. This is when I turn the ignition off!

I'm stumped - the choke is in, the piston moves freely, accelerator pedal and cable move freely.

What do you guys think......?

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Justin

Probably a little to obvious but can you see down the throat if the butterfly is closing fully?

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

It sounds a lot like a manifold leak, or as above the butterfly is not closing enough.
What work have you done to your carb of late?

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SooperDooperMiniCooperExpertEngineering

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

Thanks for your responses.

There has been nothing done to the carb lately.
I think the butterfly is moving but I will check to make sure.

It was fouling plugs so I leaned it up but nothing major. It was fouling plugs within 10mins of running. (BP6ES)

One thing I did notice, I took all 4 plugs out and number 1 was clean (had spark marks) but the rest were black carbon.

Another time, I took the plugs out and exhaust came out of number 1 (about 5 mins after the car stopped).




Justin

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Justin

Ok. I adjusted the idle and now it's running but only on choke. Butterfly is ok.

When you put your foot on the accelerator it dies or it almost dies then revs.

Thoughts?


Justin

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Justin

I got it running although not 100%.
I took this pic;
This is number1 plug. 2-4 were black.

What would do that?



Justin

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Justin

That plug looks fine.
Clean the dizzy cap inside and out with WD40 and some tissues.
Check the resistance of your plug leads unless they are near new. If any are 5K ohm or higher, bin them and buy new ones.

What plug gap are you running? Many plugs are sold now pre-gapped to 1.1mm which is too big, even for a mini with electronic dizzy.
The gap should be .025" for std ignition, you can get away with .030" or a little more with yours.

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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.

Thanks Doc.
Yes, that plug is good but the other three are pure black! Weird......

All leads are between about 800ohm-1.2Kohm.
I think it's ok now. Adjusted the timing and carb. Found the coil spade terminals bad so reterminated and tested.

Now it just hesitates when turning left and giving some throttle. It lags a bit but I think it's abit lean.



Justin

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Justin

Ok, so I took it out for a squirt tonight. It was timed yesterday at approx 7degrees.

When cruising at 60kph and then accelerate it wants to lag or splutter for a few seconds then picks up ok and moves to 80kph.

Also when slowing down from 4th to 3rd then accelerating it lags again.

When coming up to complete stop it wants to idle just above stalling then after about 5seconds it comes good.

Any ideas? I was thinking it's still to lean.


Justin

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Justin

Sounds a bit lean to me too.

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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.