8V71N Idle Speed

[Stormcloud]

Hello,all:

I just connected a Dixson tachometer to my bus via the 'R' wire from the alternator, and it appears to work.
There are no adjustments on this alternator that I can see, but it indicates an idle speed of around 700rpm.

In the maintenance manual, it says at 65mph the tach should read about 2050, but doesn't say what the idle or fast idle rpm's should be.
I won't be licensing the bus for another month or so, so I shouldn't take it out for a spin.......

Does 700rpm sound about right for idle speed?

Thanks in advance.

Mark

[TomC]

Yes

[Utahclaimjumper]

  Ive got mine at 600 and like it better than 650-700.>>>Dan

[Sammy]

I set idle speed to 625 on MUI engines. 

[JackConrad]

Best bet is to stop by a shop or find someone with a digital Photo Tach to verify your actual engine RPM.  Where are located?  Might be a busnut close by with a Photo Tach.  Jack

[larryh]

I set the 8v71 at 700 fast idle 1125 worked fine for all these years almost 50 years in the industry  senior moment if you are idleing any length of time (not recommended) 1200 fast idle don't idle any length of time at the slow idle. these baby's like to stretch their legs.

LarryH

[Stormcloud]

Thanks to all for your replies.

Jack - I'm located near Brandon, Manitoba, Canada. We have a few repair shops in the area familiar with DD and others; I'll see about getting the RPM's verified.
I don't think there are many bus-nuts close by, but there are several around the province.

Thanks for the info.

Regards.

Mark

[Timkar]

Hi Mark,
Do you know Wayne McLeod in Brandon? He is a busnut located there. It's been a couple of years since I spoke with him. He was doing up an MC9 at the time. Send me a PM if interested and I'll pass along his #.

[Dallas]

Hi Mark,

According to the Detroit Diesel Field Service Data Manual, April, '74..

The V-71 series engine, with a Limiting speed governor is set at 400 - 500 with 400 being for city coaches only.
With a Variable Speed is set to 550.

I'd post the others, but they aren't pertinent to our application.

IHTH,
Dallas

Go Busing!

[Stormcloud]

Thanks Dallas. I think the tach must be reasonably accurate.

Timkar:  Wayne is a neighbour just 1/2 mile away; I even have some of his air tools he kindly loaned me for cutting the 20guage which replaced the windows on my MC7.

Small world...

Regards.

Mark

[superpickle]

Interesting, I have been wanting to put a Tach on my Bus.
What should I get ?
If looking on Ebay, What do I want to look for ?

And, How about a Gas Guage, I have NONE. So is a Guess as to Whats in the tank ??

Thanks... Paul. in NM.   

[belfert]

And, How about a Gas Guage, I have NONE. So is a Guess as to Whats in the tank ??

I think you have a transit bus.  Transits often don't have fuel gauges as they were fueled up every day and had plenty of fuel to run the appointed routes.

Some of the fuel tanks have a place to mount a standard fuel sensor.  You'll still need to run wires to the gauge and install the gauge.  It might be just as easy to dip the tank often at first until you get an idea of fuel mileage.  Then just fill the tank plenty early and don't worry about a gauge.

[Dallas]

Interesting, I have been wanting to put a Tach on my Bus.
What should I get ?
If looking on Ebay, What do I want to look for ?

And, How about a Gas Guage, I have NONE. So is a Guess as to Whats in the tank ??

Thanks... Paul. in NM.   

Paul,
While you could string a taxh cable and tube 30 some odd feet, they are a real pain and have a tendency to screw up.

I used a VDO Electronic Marine Tach (0-4K RPM).

You could also use a tach from Stewart Warner, Isspro, or just about anyone else, as long as it reads 4,000 or less. The reason for this is that in the higher reading gauges you will lose accuracy and a difference of 50 rpm on a detroit can make a huge difference.

On your bus you should have a Delco 50DN alternator which is a huge monster to deal with and has an even larger price tag to replace or repair. You can hook your tach to the 'R' terminal of it and set the pulses to whatever it needs to be.

For a fuel gauge, I personally use a stick, but some people like to go high-tech and put in an electric gauge. Most likely there is an extra access cover on the tank. Remove it, measure the depth of the tank and purchase a tank float that is either built for that depth or get one that's adjustable. Also get the matching gauge for it.... Some units read open when full and others read open when empty.

Good Luck,
Dallas

[TomC]

As for tach, because of the distance from the engine compartment, would not consider a mechanical tach.  As to electric tach, you could use two different types.  One is wiring into the alternator-just have to find the tach that is compatible with the tach that you have. Second, is the way I am going to go, is that on most engines, there is a tach drive coming off the blower.  I will just buy a instrument generator (similar to the speedo generator driven off the transmission-if that's your version) then connect two wires up to the front. (recently ran 5 3-wire extension cords from the engine compartment to the drivers compartment-using 5 different colors.  Was a pain, but now have extra wiring in place.  Would suggest that you do this at building time instead). Good Luck, TomC

[Stormcloud]

I searched for tachs on the e-place by referring to "MCI" and scanned the items available. I have seen identical tachs for sale by same seller on a few occasions before I purchased.. will likely see them again. The maximum RPM on this tach is 3000.

As for the fuel guage, my '7' didn't come with one either. There appears to be a couple of access ports or openings on top of the fuel tank where I could install a sending unit. I will investigate this a bit further prior to purchasing and installing one. Our travel for the next year or so will likely be limited to 400 mile round trips, so it shouldn't be a problem to maintain the fuel level by the dip method.

I'm in the process of insulating/sheeting my bus now and will be running some extra wires and conduit from engine compartment to drivers area in the aisleway before sheeting the floor.

I have left the existing insulation in the roof (approx 1.5 inches of fibreglas insulation).
I will strap the roof with 1/2 inch thick plywood strips, install a layer of 'reflectix' type bubble-foil insulation, then another strap of 1/2 inch thick plywood, then sheet the entire ceiling with 1/4 inch plywood. This should give me a dead air space above and below the bubble foil of .5 inches, plus the benefit of fibreglas above.

Will the fibreglas insulation left in place cause any problems? Comments would be appreciated.

Regards.

Mark