karim.marouf@cancom.com wrote:
>
> I just finished rebuilding some early 60s SU carbs, and I think I
> finally
> go almost everything right. The one problem is that the rear carb's
> piston rises very slowly when pushed up with a screwdriver. It falls
> just as nicely as the front carb's piston, but there's too much
> resistance
> in the dampner for it to rise as easily. If I take out the dampner
> (the
> little
> rod that you remove to ad carb oil), the piston rises correctly.
> Also, pushing the dampner back in requires more pressure than doing so
> on the front carb. I am using the correct weight of oil.
>
> Any suggestions on what might be going on? I haven't tuned the carbs
> yet,
> but I
> imagine that if I left it this way, then that carb would rob power and
> always run lean
> since the piston would rise too slowly in response to greater throttle
> openings.
>
> Karim
> *****************************************************
> Karim Marouf
> Canon Communications LLC
> Tel: 310-392-5509
> Fax: 310-392-4920
> Internet Address: karim.marouf@cancom.com
> Home Page: http://www.cancom.com
> *****************************************************
Karim,
Try swapping the damper plungers(the little rod), if the front damper is
the sluggish, you need a new damper plunger. If not, check to see if
the damper plunger tube is out of round. Just a couple of thoughts that
may help.
Larry Zink
1964 Spitfire4 Mk1
Houston
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