spluttering like hell

[dogfather]

ive not long fitted my stage 1 the timing is in as my buddy checked with a strobe light but when he took it for a spin it ran fairly well low revs but as soon as he put he puts his foot down it splutters like hell. Could this be : my needle needs replacing or the advance retard diafram????? Or could it be somthing else. How do i determin this,AAAAAARRGGHH im so frustrated i could burst. Advice urgently needed as i get my lisence bak a few days and i cant drive her in this state, once again thanx in advance for your advice and happy new year

[hengti]

what, exactly, have you changed?

[dogfather]

i changed the complete exhaust system, cone carb filter, breathers, gaskets, inlet manifold

hengti said:

what, exactly, have you changed?

[dogfather]

and also when i sucked on the pipe thats conected to the dizzi vacuum the engine tone changed does that indicate that the vacuum has gone???

hengti said:

what, exactly, have you changed?

[hengti]

if you've changed from the standard airbox to an aftermarket cone filter but haven't changed the needle to suit, i reckon it's most likely that you're now running so lean that the car won't pull at higher revs.

put the standard airbox back on to see if that helps. if it does, that suggestion will be correct and you'll need to get yourself a richer needle or have one made during a rolling road session.

[dogfather]

hengti said:

if you've changed from the standard airbox to an aftermarket cone filter but haven't changed the needle to suit, i reckon it's most likely that you're now running so lean that the car won't pull at higher revs.

put the standard airbox back on to see if that helps. if it does, that suggestion will be correct and you'll need to get yourself a richer needle or have one made during a rolling road session.

excellent thanks for the advice only problem is my new inlet manifold has a pipe positioned on the top running to the servo this is in the way of the of my air box going on, have you got any solution to that???

[hengti]

providing you're mindful of the fact that the brake pedal will be much stiffer, the car should be fine running without servo assistance; i'd disconnect the hose from the inlet manifold and plug the inlet manifold with a suitable temporary bung.

[dogfather]

hengti said:

providing you're mindful of the fact that the brake pedal will be much stiffer, the car should be fine running without servo assistance; i'd disconnect the hose from the inlet manifold and plug the inlet manifold with a suitable temporary bung.

awsome thank you i will try this in the morning thanks again and ill let you now how i get on.

[dogfather]

unfortunatly i could not fit my air box bak on cuz my original inlet is designed to have a diffrent style air box even with the air pipe off that runs to the servo it wont go on so im going to try the vacuum on the dizzy first, as the engine DOES change note when i suck on the pipe.Im assuming this is an indication of a dodgy vacuum (am i correct??) as i am going with advice i saw on another forum whilst browsing the net lookin for answers. thanks again...neale..

[hengti]

this may stand correction but i thought that the operation of the vacuum advance unit only affects part throttle fuel economy and not power production.

if testing it as you describe is altering the idle speed, the unit must be working.

i'd give the supplier who sold you the kit a call - from memory, some of these kits come with an appropriate SU needle.

[dogfather]

hengti said:

this may stand correction but i thought that the operation of the vacuum advance unit only affects part throttle fuel economy and not power production.

if testing it as you describe is altering the idle speed, the unit must be working.

i'd give the supplier who sold you the kit a call - from memory, some of these kits come with an appropriate SU needle.

I didnt actualy buy a complete kit i bought it part by part although the complete exhaust system was supplied by Ashley, the inlet was bought sepratly . its an original cooper inlet with water supply . so the needle is the only thing i didnt purchase hoping it had worn and would be ok.
A lot of people have said the engine pitch shouldnt change, i only have a small amount of knowledge so my trouble shooting skill need honeing in, so should the engine note deffinatly change?? if i revv up while stationry it not to bad low revs driving not to bad either it just when he put his foot down it spluttered but he didnt drive through the splutter to see if it cleared he just eased off, changed gear and used low revs throughout.

[hengti]

it's worth taking it for a short drive to make sure it isn't just a flat spot but, in my experience, it's likely to be running lean at the top due to the filter change.

i've not fiddled with minis for quite a while and may not be recalling correctly but i thought that sucking on the vacuum pipe to the distributor would pull the arm, advancing the ignition (revs will increase).

has anyone else suggested it might be the carb needle?


edit. thinking on: the vacuum advance unit contains a diaphram that, as it is sucked in by the vacuum, pulls an arm which is connected to the advance plate inside the distributor - they fail as the diaphram is pierced and no longer operates. if yours is altering the idle speed, it MUST be working.

Edited by hengti on Tuesday 1st January 17:19

Edited by hengti on Tuesday 1st January 17:22

[dogfather]

thanx hengti youve been great and you are spot on with what say about the vac, i stripped a old dizzy earlier to get an idea of how its put together and how it operates. I conected a pipe to the removed vacuum and sucked which resulted in the little arm on the underside raising, this would then turn the magnetic ring attached to the other end of the arm and result in change in note. It must be working.thanks.
a needle has been suggested but i think this requires a rolling road to determine what size taper the needle needs . have you any idea of the cost of a rolling road session and to make me a needle to suit. thanx agen.

hengti said:

it's worth taking it for a short drive to make sure it isn't just a flat spot but, in my experience, it's likely to be running lean at the top due to the filter change.

i've not fiddled with minis for quite a while and may not be recalling correctly but i thought that sucking on the vacuum pipe to the distributor would pull the arm, advancing the ignition (revs will increase).

has anyone else suggested it might be the carb needle?


edit. thinking on: the vacuum advance unit contains a diaphram that, as it is sucked in by the vacuum, pulls an arm which is connected to the advance plate inside the distributor - they fail as the diaphram is pierced and no longer operates. if yours is altering the idle speed, it MUST be working.

Edited by hengti on Tuesday 1st January 17:19

Edited by hengti on Tuesday 1st January 17:22

[hengti]

you're welcome - glad it's of help

realistically speaking, you're looking at at least two hours on a rolling road - £200ish?

needles are available 'off the shelf' and in a number of different profiles though. it might be worth asking on the mini forums for what others suggest could be a good starting point.

you'll want it setting up on a rolling road sooner rather than later though - there's no other way of being sure that it's set up to run efficiently and safely (especially if it's running lean at the top end).

good luck with it :-)

[dogfather]

hengti said:

you're welcome - glad it's of help

realistically speaking, you're looking at at least two hours on a rolling road - £200ish?

needles are available 'off the shelf' and in a number of different profiles though. it might be worth asking on the mini forums for what others suggest could be a good starting point.

you'll want it setting up on a rolling road sooner rather than later though - there's no other way of being sure that it's set up to run efficiently and safely (especially if it's running lean at the top end).

good luck with it :-)

thanks ill let you no what happens, shes gettin expensive now but shell be worth it in the end (i hope) speak to you soon hapy new year