Erratic idle is more likely carburation, as in worn shafts and/or bushings.
Could be two problems.
I don't buy the sticky valve/varnish story.
Is the guide material 'bronze' and not 'brass?' Brass is too soft for guides.
Your guides might be incorrectly reamed, as in too tight a clearance. That
could hang them up.
1957 MGA #311
From: "Robert J. Guinness" <email@example.com>
Subj: [Mgs] Sticky Valves
Date: Tue Jun 24, 2008 7:54 pm
To: MG List <firstname.lastname@example.org>
You may remember my recent thread about loss of power after a cylinder
head rebuild. The group's consensus was that my valves were sticking,
possibly because the machine shop might have used brass valve guides
that expand at a greater rate when heated thereby "choking" the valve
stems. I contacted the machine shop that did my cylinder head rebuild
and he said he ordinarily uses brass valve guides, but he insisted that
was not my problem. He said it was more likely that " varnish" in my
gas was causing the valves to stick . I told him the car had been
driven regularly the fall and early winter before the rebuild (about
once every two weeks) and that the car had not had this problem before
the rebuild. He suggested that I put fuel additive in my tank to see if
it cleared things up. Is this guy blowing smoke? He is used and
recommended by our local MG repair shop and he has experience with these
engines. If I should give gas treatment a try, what brand/type does the
group recommend. I heard that Seafoam was good for both the gas tank
and crankcase. Is this true. Will I be doing more harm than good if I
do this experiment? I should add that I am also getting erratic
idling. It will gradually climb to 1200 to 1500 rpm after driving for
20 minutes or so and sometimes goes to 2000 to 2500! Thanks in advance.
1961 MGA with a 1963 1800 3 main engine and stock SU's
You are subscribed as email@example.com
Support Team.Net http://www.team.net/donate.html