[Healeys] Odd misfire problem Cooper S

[Michael]

Well I listened to peoples advice... changing the cap and leads, a horrible
job on a Cooper S, made no difference.
Checked the valve clearances again.
Even put in a new plug and peered around inside the cylinder with my
neighbours"borescope". Nothing.
Checked the compressions again still all at  160.
Tightened the manifold stud nuts.
When the engine is idling blocking off a carb intake progressively makes the
engine slow down and stop...the same result for either carb.
Checked the valve springs....all good.
It seems that all I have succeeded in doing is make the problem worse...now it
never goes on to 4 cylinders...
Maybe if I store it for the winter all will be better in the spring.
Thanks to all for their suggestions.....I'm beat.
Michael S
BN1 #174

-----Original Message-----
From: "Michael Salter" <michaelsalter at gmail.com>
Sent: b10/b16/b2014 2:24 PM
To: "healeys at autox.team.net" <healeys at autox.team.net>
Subject: Odd misfire problem Cooper S

I figure that if we can discuss the merits of various brands of GPS I can ask
this question.
I have been around British cars for about 50 years and worked on them
professionally for 30 so I have a pretty good understanding of how to fix
them..i.e. no obvious suggestions!!
My daily driver (summer) is a 1967 Morris Mini Cooper S.

It has recently developed a misfire on one cylinder..the problem sometimes
goes away after driving for a couple of miles but not always.

The engine runs both at idle and higher RPM on 3 cylinders...

When I check the plugs #2 plug is wet and obviously not firing.

Swap #4 & #2 plugs and the same cylinder, #2 still misfires and wets its
plug.

Compression test shows all cylinders even at about 160 p.s.i.

Install a spark tester (gap) between the plug cap and the plug of #2 cylinder
and the engine runs, still on 3 cylinders, with a very healthy 3/4" spark
showing in the tester. This to my mind eliminates almost any ignition problem
as the likely cause.

Both valves for #2 cylinder open and close a lot (649 cam).

Checked the points cam and it opens correctly for all cylinders.

Fitted a replacement distributor cap and rotor...no change.

I'm starting to run out of ideas here..

Disassembled both carbs, and checked the fuel supply and float float level on
each.

Now I'm really running out of ideas!!!! Help......

Michael S

BN1 #174