Well, I haven't written about this but I wanted to encourage anyone to try
these mods on their SUs:
1969 AUD328 carbs with springvalves in the throttle plates
1) disassemble carb and use complete rebuild kit
2) install solid throttle disks made for earlier smog-free SUs
3) let dremel tool fall into rear of carbs to smooth out backside of
piston bore in carb bore
4) use some sort of radius lip in aircleaners at carb mouths
5) fiddle with adjustment on stock AAC needles until it runs right
6) use Marvel Mystery Oil in the dashpots and top up with 30wt when
they need it (I figure the looser carb will leak down
faster and therefore get more thicker oil and eventually
balance out with the other)
This is all I did and without a rolling road or anything I could really
notice a huge difference in the way the car revs and drives. It freely and
regularly goes to 4500+ with plenty of power all the way to 5000+. My
engine is totally stock besides these mods and a little smoothing of the
radii in the inlet manifold (and oh, did I forget to mention a little
radiusing of the inlet ports of the exhaust manifold?)
All of this was done with an electric rotary hobby tool with a small sanding
drum attached (okay I used about 6 sanding rolls). These mods were very
easy and very conservative considering I didn't even touch my throttle
shafts as Vizard recommends. If you've got a '68 to '74 with smog carbs I
recommend you at least put new throttle disks in without the springvalve.
It seems to have been worth way more than the effort in real
seat-of-the-pants feeling to the car.
Shawn Tobin
'69 Midget 5spd daily driver
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