I'm with David, There is something different about the conditions in that
cylinder. Since it only affects #2, I think you can rule out carbs, rotor,
points, dwell, condenser and anything that effects all the cylinders.
Intake vacuum leak, cap, spark plug lead, valve or cam lobe issue is what
is left.
I have seen cracked caps missfire on one cylinder but you said you tried a
new cap.
Since you say it goes away sometimes, this could also be a valve issue,
either binding in the valve guide, or broken valve spring. Broken valve
springs are sometimes not obvious, when you look at them.
Let me know what you find
Rick
On Thu, Oct 16, 2014 at 11:40 AM, David Nock BCS <healeydoc@sbcglobal.net>
wrote:
> Intake manifold intemittent leak due to heat
>
>
>
> David Nock
> British Car Specialists
> 209-948-8767
> www.britishcarspecialists.com
> -----Original Message----- From: Michael Salter
> Sent: Thursday, October 16, 2014 11:24 AM
> To: healeys@autox.team.net
> Subject: [Healeys] 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
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