64OLDSPILE

Just got my switch pitch components installed back under the hood today and had a couple questions.

First off, 1964 F-85 330 4 BBL A/T A/C.

The wheel or disc that actuates the idle switch was made of plastic and deteriorated over the years, it was just a small hub about 3/8" diameter left. I used 1 1/2" dia. large area washers in place of the original plastic item and I think the original was a little smaller in dia because I can't back the dashpost/idle switch far enough away from the washers to make the proper adjustment to it according to the manual. It seems to be working fine otherwise. I noticed the difference right away this morning when I put it in reverse to back out of the garage, no chirp from the back wheel. And she'll roll backwards down the driveway now when I pull in and let off the gas and no braking.

Anyone know where I could get a new plastic wheel/disc for this?

Next question should there be a noticeable difference when it transitions from high pitch angle to low pitch angle when just putting around town? Or is this normally pretty smooth and undetected?

Also should there be a noticeable change when running the trans selector in low, I'm off the idle switch but not on the throttle switch yet, then get on the gas pedal hard, should there be a noticeable shift from low pitch to high pitch when I get onto the throttle switch? Or maybe in that state, it can't change to high pitch anymore? Say maybe like at 30 mph get on the gas.

I've had this car for twenty six years and took the switch pitch stuff off about 23 years ago when I was just a kid yet and pulled the motor to overhaul and just never put it back on. And I didn't even know about switch pitch until about two weeks ago when I purchased a carb from Forum member F-85. He asked if I still had the original switch pitch linkage and right away I knew what he was talking about, but I didn't really know what it was for until I did a little research on it. Good thing I kept it all these years. Basically it all seems to work good, downshift solenoid and pitch change solenoid.

White_Knuckles

I have a switch pitch Jet-Away. My '67 has a larger, round switch contact assembly on the back of the linkage. It is a 4 wire unit and serves a couple functions. It engages the high torque pitch setting from idle through low range throttle position. This gives better take-off torque. The second function is at wide open throttle where it has a second contact that activates the passing solenoid. As far as transition, at low speed you feel nothing but if the switch were disconnected, the car would be a slug off the line.

I have an aftermarket carburetor on a swapped in Rocket 350 engine. There's no way the linkage will close the switch contact when wide open due to my setup. I had no kick down at all. I found a switch made for this by B&M. I left the idle to mid-range connection alone as it works. I removed the kick-down wires from the round switch and relocated them to the B&M switch mounted on a carb bolt. It's adjustable, so I set it to fire when the secondary's just start to open. The switch-pitch effect is great making the car scoot when engaged but not like going into low gear. It's somewhere in between first and second. You can hit it at 60 mph+ and it'll launch her. Jet-Away for sure!

Pretty cool technology for the day!

64OLDSPILE

Yeah I think I came across a thread about this where you talked about the B&M stuff you got.

The 64 has the idle switch on the idle dashpot, mounted on the front left side of the carb and the high speed switch/downshift switch is a linear switch about 10 or 12 inches in length, (like a collapsing unit or a trombone) attached at the carb linkage about the same place where your accelerator/foot pedal rod connects and the other end attached to the intake manifold.

It all seems to work fine, I see from the manual, that there is no procedure for adjusting the high speed switch pitch activation, just the idle. Must be that if you've got the downshift switch properly rigged you automatically have the switch pitch rigged in turn.

White_Knuckles

You can use a volt/ohm meter and read continuity or voltage through the wire pairs to see if the switches are making as you move the linkage by hand.

There must be two solenoids in the trans? The kick-down selection changes pitch but the idle-mid switch may open a different valve or something? I don't know and am guessing. If it were simply pitch selection, they would have used a 2-wire setup with one solenoid to select high/low pitch range at idle and again at WOT.

I'm thinking these linkage switches are rare to find. I reconditioned mine and sealed her back up. I talked with a trans shop and when I asked if I should just go to a TH-350 when it croaks? He said no, the 300 is still rebuildable and works well.

What I can't figure out is, if pitch (high stall) is active on take-off in first gear, it's in slip mode and gains RPM launching the heavy car. Now it reaches mid throttle and drops the solenoid to select more efficient (low stall) or near "lock-up". That makes sense but wait, it shifts to second usually before mid is even reached. What's going on here?

64OLDSPILE

I do know that all three of my throttle linkage switches are working and that both solenoids in the trans are working.

But my question is similar to yours, you don't really feel it come out of high pitch into low pitch and I think maybe that's normal. Seems to me I read here somewhere that it tranitions so smoothly that it's almost undetectable.

There's a lot more going on inside the trans than just the solenoids, different hydraulic pressures and it probably sees manifold pressure of the engine and I think the switch pitch is effective or should I say detectable in low rpm but at higher eng rpm I don't feel much change.

And to address you question about the solenoids, there are two in the trans. One for downshift and one for switch pitch. There are three switches connected to the throttle linkage, one for low speed idle switch pitch, one for moderately high to wide open throttle switch pitch and the downshift switch that actuates at basically wide open throttle. Just a little bit later than the high speed switch pitch switch actuation.

White_Knuckles

Three switch points? Wow, mine has only two. I disassembled the round device. It's like a clock where linkage advancement rotates the switch poles around to maintain or make contact points. The idle-mid is maintained by a long copper contact that clearly opens after mid range. The kick-down (like yours) is an isolated switch with a small contact at WOT.

Good point about other voo-doo going on with these. The trans guy I had look at it road tested my car with me as a passenger. He's an older guy that knows these mysterious devils. He said it was working perfectly where you/we cannot detect any pitch business going on from stop through second gear.

It's strange GM only used these in Pontiac's, Buick's and Olds. Seems like a better solution then Power Glides but Chevy never saw them.

Also, there's info. out there that these were used in manually controlled racing applications! Electrically operated variable pitch stall converters. Hmmmm?

This keeps getting stranger.

64OLDSPILE

When I was really young, I had a nice 1967 Pontiac Firebird with the 326 motor and two speed trans. I suppose that maybe had the switch pitch too, I didn't know anything about switch pitch until just a couple weeks ago. Didn't know my F-85 had it either until then, pretty cool stuff.

My F-85 has mainly been stored for the past twenty years, it's really fun to have it out again and learn all this cool stuff about it that I had no idea of when I first bought the car back in 1986.

Sounds like your switch pitch is controlled by just one switch, but still has two switch points for it and then you've got the downshift switch also I presume? Two or three speed trans?

White_Knuckles

We're almost there. I have the two speed and one switch assembly. The first switch point (solenoid 1) is maintained idle through quarter throttle. Then as the throttle advances, it opens (drops pitch solenoid 1) with no other switching until kick-down (solenoid 2). You may have a second contact point after quarter throttle that I don't? Mine has one, yours has two and we both have kick-down.

There is considerable info. describing the torque converter having two stator fin angles. A piston (from solenoid activation) moves the turbine fins from laying down to a more aggressive angle. They explain this action but never talk about how the bugger is used with throttle position input other then switching to high stall at idle and passing. Not sure why yours has the other switch selection point?

You may find this interesting: http://www.webrodder.com/article.php?AID=424&SID=6