Carb - icing?

[lard]

Hi,

Having carb woes at the moment (eratic idle, stutter and fuel leak) - it's a bocar 34 pict 3 and looks a few years old, but is leaking round the throttle bushes, took it apart last night and the bushes are already metal rather than plastic (have brass ones to replace), quite a bit of play in the shaft, as it was couldn't get the brass screws out of the butterfly valve :| - I thinking the brass bushes I have are for repairing the plastic bushes on solex rather than the alu ones on my bocar?

anyhoo - when running it this morning noticed loads of condensation forming on the inlet manifold under the carb and on the body of the carb itself, my pre-heat isn't connected (need a stock filter which is next on the list!) - is this is what as known as icing? and is it normal for the carb to be so cold to the touch on idle?

Just curious if it's a sign of something else, light lean/rich e.t.c.

oh, and I've contacted Keifer on thesamba for a refurb'd solex carb, as mine looks so worn after such a short time thought I'd draw a line under it and get an OG one!

 

[67panel]

as the air gets squeased through the venturi it needs energy which it takes in heat ,this is why carb cold it can get cold enough to form ice on a hot summers day.if you have blocked off exhaust heatriser or have after market air filter no hot air to carb :!: icing symptons normaly dive along and cuts out but restarts after standing min or so ,ice melts from engine heat ,water on outside of carb just condensation its in venturi truble starts.have 2 or 3 oil bath filters if anyone interested.

 

[ronmidg]

when I had a no heat system and single carb it was difficult to get running smooth at any time, starts need lots of throttle pumping, then when it does run it over revs for a while then dies, running with open throttle was ok, but any stop for lights or whatever was a problem. Has your engine always behaved like this-icing, or is it new-something else?

 

[NickJ]

As 67panel says the heat risers block, these are quite narrow and block with carbon deposits over the years, if you can touch these when the engine has been running for a couple of minutes that is a major cause of the icing, you can clean these out (easier said than done) but it is quite a job removing the manifold but worth it.

 

[paul_q]

i had a after market exhaust with no heat risers and a k+n filter.i ran a electric manifold blaket http://www.cjroberts.com/steve/ht/imdu.htm" onclick="window.open(this.href);return false; for years with no running problems.dont know if there still available though.