Before you get to worried about tearing apart carbs, make sure you've got the
basics covered first. Good spark plug wires (compare all w/ ohm meter if
possible - 10Kohm/per foot max - all ##'s should be about the same. ) New
plugs are in order also (autolite 404's or NGK equiv) This could be
something as simple as mixture adjustment. Remember turning the mxixture
knobs UP is lean ( looking down on carbs that'd be CCW). Try turning them
both in all the way then backing them out equally either 1 or 1-1/2 turns.
"Balancing" is important too... it can be done by listening to the air flow
w/ a chunk of heater hose - but usuing a "Unisyn" tool is much more accurate.
Another favorite of mine is the little glasss sprkplug device - a "Colortune"
It will let you see just how things are burning inside. You can get these for
about 30-40$ from www.brooklandsbritish.com. Your local Brit car shop may
have these in stock as well. I know Brooklands has them for sure. Correct
linkage adjustment comes into factor here.
After a proper tune up and its still running rich - look for Nozzle
replacement first. Needle wear also happens too. I'm sure someone on the
list can point you to some wonderful SU tuning guides that will make this
less of a mystery. I'ts not too hard to change those out.
Pop the tops off the floats and make sure they have no holes & still "float"
too - and the jet in jet top of the bowl should wiggle up & down freely
also.
SU's are wonderfully simple little beasts so if you have any mechanical
aptitude try getting them straight yourself before resorting to a mechanic
who may be unfamiliar w/ them.
Let the list know how far youve got - we've got plenty of tricks up our
sleeves for fixing these !
Laurie :-)
70 SPL311
69 SRL311
Chandler, AZ
|