Hi guys! Im about to build my own lock up kit for a th700 in my skylark -70, and need to find a adjusteble vacuum switch in the span of 1 to 20 hg/in.... Normaly closed (NO). Any of you out there that knows where i can by one?
Maybe something here? http://content.honeywell.com/sensing/hss/hobbscorp/catswitch.asp Do a google search. I'm sure there is something out there. Bruce Roe uses a vacuum switch on his switch pitch control box.
The best way to get the converter to lock up is to get the appropriate wiring harness for the valve body. No outside wiring needed. it locks up when the trans goes into OD and disengages when it comes out of OD. Or just goto the parts store and get a vacuum switch for an 85 chevy 1/2 ton 2wd with a 305 and 350c trans in it. A buddies dad has one and the switch is mounted on the firewall. I'm not sure whether they are n.o. or n.c. tho. Parts store could probly tell you. hope that helps
I use such a switch which can be wired either NO or NC. Another thing to think about is hysteresis, the difference in pressure between opening and closing. Without some, things can get into hunting. The Honeyw*ll switches are pricey and have virtually no hysteresis. It will be hard to cover 1 to 20 inches with one switch; I use around 4.5" on a DIGIK*Y switch with a couple inches of hysteresis. Am looking at a far cheaper solid state switch, but needs an amplifier. Bruce Roe ++++++++++++++++++++++++++++++++
