Classic Mini - Help diagnose my problems!
Discussion
Elan159 said:
Mini_Lund said:
The carb has recently been refurbished by myself with a new jet and float chamber needle. The standard needle still remains.
Did the rough running coincide with your work on the carb? If so I'd concentrate here first - does the piston rise and fall easily? You may not have centered the needle correctly.Mini_Lund said:
The spark plugs are set to 0.0025" thou with points on.
As others have suggested, work through stuff methodically. I start from the points gap then the static timing. Ensure that the dizzy will advance centrifugaly by attempting to rotate the rotor arm by hand - it should move a short way against its direction travel on the springs. If it doesn't and the shaft is solid then it will not run well. The vacuum advance can be ignored as that's just a touring economy device.
onomatopoeia said:
Mini_Lund said:
The spark plugs are set to 0.0025" thou with points on.
As others have suggested, work through stuff methodically. I start from the points gap then the static timing. Ensure that the dizzy will advance centrifugaly by attempting to rotate the rotor arm by hand - it should move a short way against its direction travel on the springs. If it doesn't and the shaft is solid then it will not run well. The vacuum advance can be ignored as that's just a touring economy device.
Surely the enine note should change if the vacuum advance is taken off?
When the crankcase breather is disconnected from the carb, the engine stalls. Should it do this? If not, without taking it off, could I run an airline into the tube and pressurise air inside, to free things up abit?
Wiggling of the needle is not surprising 'cos I think the later SUs have a floating needle. Still think problem may be the piston binding in the dashpot.
Remove air filter assembly, reach a finger in and lift the piston manually - Any sticky spots?
What are you setting the points gap? 15thou would be a good start.
The engine note rarely changes when removing the vac advance because the vac loss at the manifold is minimal and the system only works when accelerating by the increased depression in the manifold 'sucking' the points backplate around the rotor to advance the ignition.
It's a fact that on today's cr4p quality unleaded and with any sort of a worn engine the vac advance is counter productive because it advances the ignition into the pinking zone just when you're calling for power. Best block the pipe from the manifold then replace it on the distributor to look right.
Just a thought... What do we think about float level being the cause?
I'm thinking over fuelling because the needle valve is closing too late.
If this car was on my driveway I would lean the mixture and retard the ignition until we got smooth running and then 'tune' things from there.
Remove air filter assembly, reach a finger in and lift the piston manually - Any sticky spots?
What are you setting the points gap? 15thou would be a good start.
The engine note rarely changes when removing the vac advance because the vac loss at the manifold is minimal and the system only works when accelerating by the increased depression in the manifold 'sucking' the points backplate around the rotor to advance the ignition.
It's a fact that on today's cr4p quality unleaded and with any sort of a worn engine the vac advance is counter productive because it advances the ignition into the pinking zone just when you're calling for power. Best block the pipe from the manifold then replace it on the distributor to look right.
Just a thought... What do we think about float level being the cause?
I'm thinking over fuelling because the needle valve is closing too late.
If this car was on my driveway I would lean the mixture and retard the ignition until we got smooth running and then 'tune' things from there.
freddytin said:
Have you a spare carb, and or coil to substitute ?
I have a spare carb but its an early HS2 (1.1/4), whereas mines a HS4(1.5). I tried the coil off my old mans land rover series 111 and still had the same problems. The series 111 coil could be dodgy also, but would be a coincidence!I pushed the piston up with my finger, it moves up slowly and fall slowly, but smoothly.
Here's what we're working with by the way:
Not the best of pics, need some decent weekend weather to spray the bonnet vermillion:
Edited by Mini_Lund on Thursday 8th May 22:34
freddytin said:
OK , remove the oil filler cap, pull the breather tube off at the carb end, then blow into the breather as hard as you can. You should be able to hear air coming out of the rocker cover, if not the breather is blocked.
I'll attatch an air line from a bike pump to the end of the crankcase breather and listen for bubbles. It might not bubble much as I have her running on minumum oil. I just reminded myself. I need to watch that closely. Will give it a go tomorrow. 
Mini_Lund said:
freddytin said:
OK , remove the oil filler cap, pull the breather tube off at the carb end, then blow into the breather as hard as you can. You should be able to hear air coming out of the rocker cover, if not the breather is blocked.
I'll attatch an air line from a bike pump to the end of the crankcase breather and listen for bubbles. It might not bubble much as I have her running on minumum oil. I just reminded myself. I need to watch that closely. Will give it a go tomorrow. If it is a blocked breather you'd know with the A series, as they have a habit of pissing oil out everywhere. Mine did this when I blew the headgasket. I think a quick trip to a garage to get a compression test done would be a good idea, as the knocking noise that the OP has described sounds a bit dodgy.
t, extactly sound like you described. 
I'd check that first.It's encouraging that the engine bay looks just right - and the car generally a credit to you Tom - Clearly the motor is not freshly cleaned and there is no sign that oil or water being chucked anywhere therefore chances are that the engine is serviceable.
Not sure about the 180 degrees out theory, I have heard of this happening but never experienced it.
Not sure about the 180 degrees out theory, I have heard of this happening but never experienced it.
pat_y said:
Bit left field but dont suppose you could have a blocked exhaust (collasped silencer), this will make it run like a total bucket guaranteed.
Its a straight through system rc40, less than 6 months old, I think its fine 
52classic said:
It's encouraging that the engine bay looks just right - and the car generally a credit to you Tom - Clearly the motor is not freshly cleaned and there is no sign that oil or water being chucked anywhere therefore chances are that the engine is serviceable.
Not sure about the 180 degrees out theory, I have heard of this happening but never experienced it.
Thank you, Im unsure about the 180 degrees out too. Its running ok for now belive it or not. Sounds a bit tappety but will sort that out when I fit the unleaded head. Theres no difference in engine note between the choke halfway out and fully in, suggestin that its running lean. Need to weaken it off. Not sure about the 180 degrees out theory, I have heard of this happening but never experienced it.
Edited by Mini_Lund on Friday 9th May 10:53
Mini_Lund said:
pat_y said:
Bit left field but dont suppose you could have a blocked exhaust (collasped silencer), this will make it run like a total bucket guaranteed.
Its a straight through system rc40, less than 6 months old, I think its fine Gassing Station | General Gassing | Top of Page | What's New | My Stuff