Chevrolet/GMC ignition retarder/govenor

[Kirbystud]

What year of bus are these on????? Mine is a 87 I will look for it . Wouldn't that be cool if thats all it is...

[sward]

Did you have to by pass the governor electically or just unplug it. I have the same problem.

[hoser]

How many RPM can the 366 engine take before it goes poofkaboom and spills its guts all over the road?

I will look to see if my 87 chevy bus (366) has the same box or connector.

Thanks for the info.

[sward]

I'm not sure about the rpms. I am assuming that once the govenor is off, the rpms will drop with the high gear. this is just an assumption. I also think that 60 - 65 is probably the safest speed to drive. If you're on vacation, then time is a thing of you own mind. Speed should follow your instincts.

[EdsonBus]

This is an old topic, but I hope I can revive it to answer a couple questions.

I have a 1990 GMC 366 bus on propane with a 5speed manual transmission and I looked on the carb to see the govenor itself, I noticed in other threads that this two wire connector can be spliced to stop the govenor effect.

When I was driving the bus home, on purchase day, I found that it had no power and we had to work just to get it up to 60 mph. I live very close to the mountains and I found that when I approached a hill at WOT ( 60 mph )it didn't have the power to make it up the hill and powered down to 40mph.

I love the govenor idea for shifting without regard for needing a tachometer, so I thought an easy solution would be to install a toggle switch that I can flip on the highway to shut of the govenor to take "a run" at hills. The other choice is to find a 3700 rpm govenor and swap out the old one, but heck I can't find the control box under the hood or something on line for suppliers or a picture of a box to look for

I have done a complete tune-up and found that the air filter was plugged, one plug wire was burned through on hole 4 and hole 8 had a very wet electrode to tell me it wasn't firing properly. I replaced the bosch platinum plugs with AC Delco platinum plugs gapped at 45thou. Replaced the burned through wire and the air filter.

I am waiting on a new propane tank that will arrive Monday, so I haven't checked the performance since the tune-up. I am also going to recheck the rest of the plug wires,change the cap & rotor and double check the timing to ensure proper advance.

If any of you can tell me how your 366 5spd propane buses perform for climbing hills it would be appreciated! Any tips on timing advance on your propane bus would be a huge help as well.

I think the powering out was due to the mistuned condition, but I still wonder that with the bus capped at 3200 rpm, if it might still be underpowered for mountain trips. I am not a speed demon by any means, I am more concerned about safety as my bus dies out and people are forced to hold up or pass me unsafely.

So can the govenor be toggled and do the buses have more power than what I experienced?

Thanks everyone.

Jeff

p/s first post btw

[odyssess]

I think I might have found this box too!!! I just read this subject posting and I went out and looked under the hood. I'm going to take a picture of it and post it tomorrow and maybe someone can tell me if that's it. I have a diesel t444e 3800 int'l. That would be real cool if I could get my shortbus to 75mph on the open highway!!

Is this it? If not, what is this?

[EdsonBus]

I was really hoping that someone would have some input

[sportyrick]

Ok Ok here is my 2 cents since you guys are asking. My bus ('76 vintage) has an electronic governor controlling the carburator also and it's preset at 4000 RPM. It's under the dash by my left knee and is an off white color and if I remember correctly is has AC on it(my bus is a flat nose). Your little 366 will turn that or more but remember you are taking hours of running time off the other end if you fly above 4000 much. My other truck has a 366 in it also but the governor is built right into the carburator and works off springs and vaccum. There are 2 wires coming off the right front that turn a light on on the dash stating "overspeed" when it pulls the throttle back. These could be the wires you were stating that you jumped out.
Propane does not have the power density of gasoline, not much else does either. You may want to go to dual fuels and run on gasoline most of the time instead of propane. It does burn clean and makes an engine last forever but you will never get the power out of one that a gasoline unit makes.
If a transmission is shifting constantly between the 2 highest gears sometimes it's vacuum. If the transmission is getting a low vacuum signal it downshifts to get more RPMS and power. Some people call it passing gear. If you can let off the throttle a little and it quits you are going as fast as your bus will go in it's present condition. Something will have to be changed if you want more speed, at the cost of something else, everything in life is a compromise.
Some food for thought: if you can change a rearend to a lower numerical ratio and gain speed then why can't our buses do 80 MPH, or even 100 MPH with an even lower ratio? sportyrick

[EdsonBus]

Thanks Rick, I don't want to do 4000 rpm, I am thinking that I must be governed at about 3300'ish. I just want to do 3700'ish to approach hills, so when I crest I am still doing 60 mph.

I have looked high and low and I cannot see my governor anywhere, I have traced the wires on my 90 but they seem to disappear into a bunch of wires as opposed to a controller the original poster listed.

Worst case I need to jump the system, best case I can adjust a little bit to compensate for the lack of torque I am experiencing on hills to not be a danger to those around me.

Jeff

[the_experience03]

As I understand it the 366 is not very well balanced and the valvetrain leaves something to be desired. Something about cruising an industrial big block at pass gear RPM for a small block scares me a little. Of course I would probably do it anyway. What are you guys getting for mileage at a 4000 RPM cruise speed? I notice a measurable difference of about .2 mpg (hey...that's 2.5% difference in mileage by losing MAYBE 1 mph) on my 6.6 diesel between 2500 RPM and the governed ~2650 so I have to wonder what that is doing to your gassers to jump that much.

[EdsonBus]

The 366 is a technically a big block as it shares the same stroke/engine design of the other GM other big block engines. So I am not worried about 3700 rpm too much. Cruising on the highway 3300rmp would put the bus at 73% of it's redline, where 3700 puts it at 82%. 4000 is a tad high for my liking at 89% of maximum engine rpm.

Fuel economy to me isn't an issue, it will cost what it will cost to get me there My time/safety is worth more than the $50 more it might cost me on a trip.

That being said...

I have decided just to make a toggle switch that can connect the wires if I really have to bump the rpm, but in the meantime I am now convinced that my power issue was more tune-up related than top-end rpm related.

Jeff

[odyssess]

Doesn't anyone have an idea what the photo I posted is? Can anyone help with my 1996 intl. shortbus? Thanks.

[Bamboo Cowboy]

Most chevy tall deck electronic rpm limiters were set at 3800 or 4000 rpm. If you turn the engine beyond that, you can risk the valves kissing the pistons on deceleration or going down hills. A bus mechanic told me about the only way to destroy a tall deck is to try to push a higher rpm than what it was intended.

The governor on the carb is entirely a different device. Holley told me the function of this is.... is to provide fine control of the vacuum secondaries. That is, finer control than is already offered by the normal vacuum secondary diaphram. I interpreted this as meaning the secondaries would not open more than necessary to achieve best torque under load. Therefore, I would not try to "improve" this part of the carb by modifying it. It is already probably helping you achieve best torque.

If you unplug the rpm limiter, I would install a tach. And dont exceed 4000 rpm, esp. going down big hills. Use a lower gear.

My bus is geared to reach 58 max top speed at 3800 rpm. That is fast enuf, especially towing a car.