<VV> Rough idle

Stephen Upham contactsmu at sbcglobal.net
Sun Oct 4 10:38:57 EDT 2009


I drove the car yesterday.  I took it to our 50th anniversary party.   
This was almost an exclusive highway trip being on street roads only  
for about five of the 150 mile round trip.  The car started up and  
ran well to the highway from my house which is about mile.  It ran  
great to the celebration site.  I was late and was going 65 to 70  
most of the time for the 60 miles.  When I came off of the highway  
and hit my first stop light, the rough idle appeared.  It stayed that  
way as long as I was idling.   Once the gas was applied, even  
sparingly, the condition seemed to improve.  We took a look at it at  
the show.  Removing a spark wire from the left side cylinders gets  
the anticipated response of loping of the engine, and in fact, if any  
one of them is left off, the engine acts like it will die.  When the  
same thing is done to cylinders on the right side, there is no effect  
on the running of the engine at all.  I took off the carb top and  
again tried to see if the idle circuit was clogged.  I used a  
telephone wire, first sheathed and then unsheathed.  It will go down  
the tube 1  1/2 inch and stop either way.  One other interesting  
thing, is that, although I have a 110, I have dual exhausts.  After  
idling in the garage during the idle circuit work, I put my hand to  
the exhausts to see what the force of the exhausts is; the left side  
was predictably warm, the left side was cool, indicating, to my  
admittedly limited knowledge, that there is no fire on that bank.  I  
do have a set of new plugs, they are the R44F's, but have not  
installed them, nor pulled the plugs on that side to check them yet.   
The electric components are less than 7K miles old on an engine that  
also has less than 7K miles on it.  That includes the Pertronix  
ignition, the distributor cap, the Flame Thrower coil, the plugs, and  
the Emerson silicon wires.  The carbs are less than 500 miles old  
after a complete and profession rebuild.  I have an inline filter  
before the electric pump (working great) and a Purolator fuel flow  
restrictor set at 2 1/2 (though probably not necessary as the pump  
meets the original Corvair specs for fuel flow).  I have pulled the  
hoses for the possible vacuum leak areas for the carbs and found  
absolutely no problems.  I have sprayed the base of the carbs with  
carb cleaner an not seen any appreciable rise in rpm.  I have re- 
torqued the carb attachment nuts to 11 ft. lbs. and retightened (not  
over tightened) the air horn screws.

Thoughts?

Stephen Upham


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