40 replies to this topic

[mike.]

mine did that, it was timing.

on the dizzy theres a nut - 7/16ths i belive, loosen that off till you can just about turn the dizzy. start the car up and with the engine running turn the dizzy one way and see if the revs rise or fall, if it falls, go the other way. keep turning it till the revs stop rising, then do up the nut. give it a blast down the road and see how it goes after that. after id tweaked mine the flatspot totally dissapeared. although you may need to adjust the idle screw on the carb, its a little stop screw on the side where the throttle cable connects. should be able to adjust with your fingers (mine does anyway, screws about 6mm).

if that doesnt work, id suggest checking the rest of the ignition out, plugs, rotor arm, points, condensor, HT leads & so on. either way, id bet on it being ignition related. if that doesnt solve it id put it down to blocked air filter/carb settings.

good luck

Cheers i'll try doing that - No messing with a timing light and marking pulleys then? Thats what my dad was going to try doing

[miniboo]

yeah check it with a timing light first!!

[mike.]

I've just been checking the ignition components - Everything looks fine and dandy.

I also took a quick vid of the problem. You can hear it at its worst on the last couple of revs. You can hear the engine sort of bog down sounding pretty rough - Then get a sudden blast of power. The problem is obviously made worse when theres load on the engine:

[mini_turbo_pete]

It sounds like the diaphram has probably gone in the dizzy... this unit advances the timing on idle to help with pulling away. try pulling the pip off of where it goes onto the carb and suck on the pipe, you should only be able to suck a slight bit, if the engine is running the revs should pick up a bit..

I wouldn't advise doing what piromaniac_yeti suggested unless you know what you are doing as when the timing is at the peack of where the revs start dropping off it will be too far advances and will pink and cause detonation.

[mike.]

Right just tryed that - pulled the pipe off the carb, covered the hole in the carb and sucked on the pipe - The revs didn't increase.

[mini_turbo_pete]

could you just keep sucking through the pipe? if thats the case then it sounds like the vacum unit is knackered

[mike.]

Yeah i could...

I've just checked the timing - with an...intresting outcome.

Basically i check the timing and rather than 8 degrees it was more like 30 -Acording to the pointy timing scale and nick on the pulley.

So we adjusted it to 8 degrees like it said it should be in the hanyes and basically the problem got so much worse that the engine would barely run. My dad test drove it and came back saying it was undrivable. So we adjusted it back to the sort region it was in and it went back to a little worse than it was but at least driveable.

How can that be? If we adjusted to 8 degrees how did it get worse!

Edited by minimadmike, 01 May 2008 - 05:51 PM.

[mini_turbo_pete]

you when you set the timing make sure that you set it with the engine at 1500rpm, everytime you adjust the timing slightly you need to adjust the rpm to keep it at 1500, once you have set it all upt then return the idle to 800rpm..

If you can keep sucking then the diaphram has gone in the vacum unit, you will need to replace the unit.

Edited by mini_turbo_pete, 01 May 2008 - 06:12 PM.

[HARBER07]

Pooing myself now as i adjusted the timing till the revs were fastest too, Have i done serious damage although the car is running smoother (and sounding different)?


Ps. Sorry for hijacking

[mike.]

Can you just replace the unit? Is it not a fixed part of the distributor?

We've found that when the timing is at 30 degrees like it always has been then the car runs better - But a slight misfiring car be heard at the exhaust every couple of seconds. But when we set the timing to 8 degrees - Where it should be then the exhaust sounds perfect - No signs of misfiring, but the engine can barely rev above idle speed.

So shall i speed the tickover up to 1500rpm and try again with the timing?

At the moment i've pulled the vac advance pipe out and stuff a match stick in the carb hole - The car seems to run a little better that way.

Edited by minimadmike, 01 May 2008 - 07:14 PM.

[nathansminis]

my new mini is doing exactly the same! only got it sunday and its giving me more trouble than the mini i had for over a year ever did.

let me know if you work out what it is.

cheers. and good luck.

[pyromaniac_yeti]

harber, provided theres no misfire/backfire it should be okay. mine was perfectly alright, and has remained that way scince i did it. the other thing was it was timed with a light, admittedly a very bad one, and by my dad and grandad who diddent realy seem to know what they were doing, and it ran a LOT better after id timed it my way, much smoother power delivery, no backfire and a lot more power all round.

idealy though, if youve got access to a timing light then time it up with that - problem is the only timing light ive got is at work, and finding the time for someone else to time it up propperly (A: ive got no idea how to use a timing light, and B: ive got epilepsy so strobe lights are a no no)

***forgot to mention, if you're reading this and considering doing any tweaks to your car - its worthwhile putting a line on the dizzy and block at the bottom of the distributor with tip ex or white household paint or something so that you've always got the option to go back to how it was set before.***

[pyromaniac_yeti]

have you checked the vac advance hose itself for cracks,breaks, tears or any other damage?

id try knocking up the idle a bit and see how it goes, but it does sound like the vaccum advance is causing a problem with tickover. not too clued up on the problems with them/solutions. but id check the hose for any obvious wear and tear.

either way, by the sounds of it you're better off running it at 8 degrees where theres no misfire. set it to that then adjust the carb to match. may just be that the whole lot needs a bit of sodding around, timing and the carb setup to get it running perfect.

good luck!!

apologies for the essay, and the double post

[minimender]

Don't forget to take the vac advance pipe off when setting timing to your 8 deg with a light

[mike.]

Right i might have another go at the timing at the weekend with the revs runnng higher and the vac pipe off. But seriously the car was so bad at 8 deg it could barely run - Made the problem 30 times worse. So you reckon i should set it to 8 deg and the adjust the mixture to match? How will i know when the mixture right? Is it just trial and error, revving, test driving and listening to see when its right?

Can you just buy the vac advance unit or do i need a wholew new distributor?

Edited by minimadmike, 01 May 2008 - 09:56 PM.