Ok guys took my car for a drive from cowra to blaney then from blaney to bathurst watched a movie then came straight home now in 1st 2nd and 3rd gear are perfect but I change into 4th all still good but starts to miss when I hit about 60mile I have to hold the pedel off the floor other wise it misses on a cylinder can't floor it Any ideas ???????

spark plugs

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did I tell you that I won a trophy?

I agree with Simon, PLUGS

Could it be the P-plates fighting back?

air filter

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http://www.ausmini.com/forums/viewtopic.php?t=71255

My brother's Hillman Imp (Lucas ignition too ) did that, PLUGS.
Check their heat range, his were too hot- he had Champion N12Y instead of N9Y.

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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.

What is "it" that misses the cylinder?
Does the miss happen everytime at the same time (same road speed, same engine speed?)
What size is your engine?
What are your dissy bearings like? can you move the shaft sideways at all?
What carb/s are you using? If Su's what needle/s are you using?
What do your plugs look like when its been driven for a while before inducing the missfire (or you making the missfire occur)....have you pulled any of the spark plugs out and had a look at the electrodes?
White, light grey, black, black and sooty?
Have you checked the resistance of your high tension leads?
What about the wires to your coil? Are they good connections?
Are your points shorting out on the post (insulators gone soft with heat)
Is the dissy advancing or not advancing ?

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It happens same speed every single time doesn't matter wat day happens same time and idad and mum brought me the car running so I don't no condition of bearings

coil? coil lead? coil terminals?

I've had misses at high revs recently and all roads led to the coil.

Not saying that's the problem just saying don't over look it

cheers,
Skender.

Replace all the 'servicable' items in your ignition.

Plugs, dizzy cap, leads, points, condenser, coil

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I will have a look at it 2 morrow but y would it only do it in 4th gear I can rev all other gears out as hard as I want untill it started to valve bounce if I wanted to but 4th I can't it just misses

Have you got a fuel filter fitted??? could it be a bit dirty restricting the flow?

Maybe try to run the car really hard & high in the revs in any gear, like first or 2nd gear & hold it at those high revs to see it do the very same "missing" thing yeah?

it really could be any number of lots of reasons,,, but i`d "Guess" at the fuel filter first

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Usually constant missfiring at High revs means Plugh failure. But it also could mean that your condenser is playing up. Perhaps you should try fitting one of my electronic ignition kits to eliminate it being anything to do with the Dizzy. These kits fit in your original Lucas Dizzy so your advance curve stays the same. No more points to change and no more side ways pressure on the shaft to wear it and the bushes out. Ask people who one about them.

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DID I MENTION THAT I AM THE BEST SUPPLIER FOR MINI ELECTRICAL PARTS AND REPAIRS?
"Let us remove your "SHORTS"

Can't be fuel filter I haven't got one on it I was gunna put one on it but just never got round to it

Just wondering if you can help us with some of the questions asked here

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