info on air throttle

skihor · April 18, 2011, 04:17:37 AM

Our new to us MC 7 has an air throttle. When I step on the pedal it has a 2 second delay before anything happens. It's very hard to modulate. Our MC 5A has a cable that works like a car. Is the delay normal ?? or ...
Thanks
Don & Sheila

luvrbus · April 18, 2011, 06:12:34 AM

You can adjust the throttle with air pressure not knowing what engine setup you have in the MCI you could have a throttle delay or fuel modulator inside the engine causing the delay.
The air throttles,throttle delays and fuel modulators don't work real good together but you will get the hang of it

good luck

JackConrad · April 18, 2011, 06:59:55 AM

You probably have an 8V71 in your MC-7. I have never seen a throttle delay in a 8V71 engine. Does your air throttle supply airline have a pressure regulator in it? Sounds like you need to increase the pressure to the air throttle. What size tubung runs from the throttle pedal to the actuator that is installed on the engine?. Wrong size tubing might cause the delay. We run 85 PSI in the air line that supplies our air throttle (MC-8 with 8V71). Per Williams (air throttle manufacturer), we ran 3/8" tubing from throttle pedal to actuator. From the Tee in the engine compartment the lines to actuator and transmission modulator are to be exactly the same length. Jack

luvrbus · April 18, 2011, 07:14:24 AM

Must be a West Coast deal Jack you see quite a few 71 series here with both types

good luck

Oonrahnjay · April 18, 2011, 02:32:57 PM

Quote from: skihor on April 18, 2011, 04:17:37 AM(snip) Is the delay normal ?? or ...

My bus was built with a "hydraulic" speed control system. It was seized up and the metal components were corroded when I bought it. "No parts available". I changed to an air throttle (bought used from "NIMCO" in N. Jersey). It has been perfect. It feels like it's a steel rod from my foot to the speed control arm on the injection pump on the engine. (PS I have no throttle delay or transmission controller, etc. it's one line straight to the engine.)

gus · April 18, 2011, 04:10:41 PM

Look under the foot pedal. There is a gap between the roller on the pedal and the lever on the air cylinder. This gap may be too wide.

My 4107 air throttle has no noticeable delay but with AT it is not much of a problem.

skihor · April 18, 2011, 06:55:13 PM

It has a 6V92 with a 4 speed auto, (unknown model). I'll have to check the air pressure and the delay thing. I'll have to figure out what the delay "thing" is though and see what it does or doesn't do. Good points all.

Thanks
Don & Sheila

Barn Owl · April 18, 2011, 07:35:47 PM

No delay on mine that I can notice.