[Roadsters] su carb problem.

[Keith0alan at aol.com]

Hello Bob,
 
    It sounds like it is running a bit lean in the mid  range. Try raising 
the engine speed to 2500 and setting the mixture there. A  quick test would 
be to cruise at 2500 and pull the choke out just a little. I  normally set 
the carb mixture at 2500 and let the idle take care of it's self.  If the mid 
range is good and the idle is rich you can set the needles out a few  
thousandths of an inch. While this does have some effect overall it effects idle  
primarily. 
 
keith
 
 
In a message dated 6/16/2011 3:42:03 P.M. Pacific Daylight Time,  
rksmith46 at hotmail.com writes:

 hi keith, im working on a 69 2000, that belongs to a  friend.
it idles, ok, and pulls resonably well, from idle to 6k rpm.
the  problem is, part throttle cruising at 2.5k--3k rpm.
it sounds like the  engine is missing a little, and the throttle 
response is kind of  flat.   3200-3500 rpm or above, the throttle
responds  better, more like MY roadster. fuel press. is 4-4.5 lbs.
ive ckd, and  raised the float level 2 mm.,  ckd, cleaned points,
tried another  condenser, all no help. point dwell is pretty steady
when reving  engine. the timing is: 15 btdc, vac.disc., raising to
about 30 deg. at  2500-2800 rpm.  total mech.adv. is 35-36 deg.
ive synchonized  the carbs at idle, and with throttle. ive got
the mix. set where it idles  good, hot. ive messed with su's
for many years, but im stumped on this  one.
if you have any ideas, please call or email  me.

thanks, bob smith, ohio   614 418 9911

p.s. i changed the cam timing, when i first  had this
problem. it was almost 1 cam toothe retarded. i changed
the cam  forward 1 toothe, and now it is just a fraction on 
the advance side,  much closer to being correct, than before.
the engine seemed  to  pull better in the lower rpm range,
but i still have the part throttle  problem. 


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