<VV> higher shift point for PG

[Brent Covey]

Hi Travis

>       I've learned that the governor in the powerglide for the 110 motor
has a maximum shift point of only 4060 RPM.  The governor for the 140
powerglide only goes up to 4600.  The way we'er building the motor, it would
be okay to rev it to 6000 occasionally, and I would sure like a shfit point
under full load of at least 5200 rpm to make full uyse of the motor's power
band.  Clark's does not even have the 140 governor.  Does anyone re-build
corvair powerglides and modify the governors for a higher shift point?

The stock 140HP governor is a very good match for the 140 and the very high
rpm shift point does not materially improve performance with a stock 140
engine (especially after they changed to the 95HP cams)- you will find two
things happen if you adopt a 4500+ WOT upshift-also keep in mind 4600 at the
transmission is close to 5000 at the engine under WOT conditions due to
converter slip.

#1 the belt will get eaten about the second WOT upshift

#2 the engine cooling fan will eat so much output running faster than 5000
doesnt make much difference to overall acceleration.

In experiences I had with a 140 engine with the 3872304 ('turbo') cam and a
3.55 Powerglide best performance was obtained with an upshift at 57 mph.
This is about 5000-5300 rpm. This was more a case of the engine making good
power in direct at the 2800-3100 rpm it dropped to after the upshift than
the output at the 5000ish in low range. The upshifts were inperceptible
aside from the change in engine tone, as the torque output was pretty well
matched both sides of the shift.

The 140's also use a different transmission valve body, apparently tinkered
with to allow easier detent touch and part throttle downshifts that dont
favour top gear as much for better town and traffic performance.

The Governor could be modified quite easily by reducing the mass of its
flyweights (like drilling holes in them) or reducing the spring pressures
but its a sealed can that would need to be cut open, and the flange rewelded
or otherwise sealed. The outer bell shaped housing provides the bearing for
the governor so attention needs to be paid to retaining its original
spacing. I would imagine you could probably grind along the seam in the
governor case and get the halves apart to play with it. Kits are availible
with a selection of governor springs for regular GM automatics that may have
some parts you can use. AFAIK there is nobody doing this modification
commercially for us.

There might also be some scope in the valve body to temper the governor
signal slightly to reduce its effect on upshift speeds, but I am not sure
about this.

In your situation, I'd try to find the factory 140 governor and try it out
to see how you like the performance. You can compare the automatic upshifts
to a manually-selected low upshift at a higher speed and see if the
difference is greeat enough you feel modification is worthwhile. Factory
140/Powerglide parts (valve body, governor, torque converters) are
identified with a splotch of orange paint dabbed on them, originally.

Hope thats some help, wish I had more information for you,
Brent Covey
Vancouver BC