MPG and Jakes

[Nick Badame Refrig/ACC]

Hi Guy's,

I'm back from my day trip to Hamburg, P.A. and burned 60 gallons. I left the jakes off most of the day and when I topped off this evening

my mpg was back to 7.5... Oh, and that mist out the exhaust is not there with the jakes off. Hummmm....

Thanks for everyone's help on this!
Nick-

PS, my 4 friends left over 2 grand with mr. Cabella...  And my middle bay loaded to the hilt! 

[DrivingMissLazy]

Hi Guy's,

Oh, and that mist out the exhaust is not there with the jakes off. Hummmm....

My guess is still unburned fuel. I do not think the governor is capable of shutting the fuel off entirely. Only down to enough for idle. To shut the fuel off completely the governor must be actuated by an air cylinder to stop the engine.

Richard

[Nick Badame Refrig/ACC]

Hi Richard,

I think you are correct..

Nick-

[Ncbob]

Nick, I added one of those plastic covers (like aircraft used to use on the landing gear switch or the rodders use on their Nitro switches) which is on the console to my left.  With the switch for the Jakes on I have a constant reminder that they're switched 'on'.

Leaving them constantly 'on' will not only take it's toll on milage but it sure is a hell raiser with the muffler too! I used to have a pretty solid muffler...now I sound like a freight train.  Shopping for a new muffler at present.

Anyone have a good aftermarket link for an MC5A muffler?

Bob

[uncle ned]

Bob

   I can get you a muffler like is on "Huggy"  Dallas seems to like it. He can tell when i am coming several miles away.

   Hope you and jackie are well and enjoying the warmth. Was 29 degrees and the wind blowing with sideways snow this morning.

uncle ned

Hope to see every one at jacks if all works out. will be leaving nc on the 26th.  321, 301, 17 then i don't know any thing but the interstate.

[HB of CJ]

Guys...I hate getting middle age. (old?)  Forgot you have a 2-stroke Detroit and not a Cummins.  Sorry.  In my old school bus driving days, the mighty idling 743 inch 220 Cummins in the 1963 Crown school bus would instantly stall if you let your foot off the gas pedal when the Jake was turned on.  Some switch wasn't working right.

The school bus mechanics were aware of it, but just told me to turn off the Jake when in town soosss that would not happen.  Also a neat thing about the Jake is that, after the oil gets a chance to warm up and the thing works, you could "burp" the engine while double clutching upshifing.  Very cool and the kids loved it.

This was considered abusive and not advised,  but from time to time I did it anyway, since it allowed me to up-shift under conditions that would normally be considered difficult or impossible, like climbing a short, steep hill.  Spicer 5-speed.  Anyway, the Jake Brake is one of the world's greatest inventions---next to red wine.  He he he. 

[Don Fairchild]

Nick:
   your millage is tied to your tune up. What were the injector settings before they installed the jakes. Go back to that setting and see if your millage returnes. You may also have an injector that is dribbling fuel into the cylinder when it is in the no fuel position ( foot off the go pedel ) comming to a stop or down hill operation with the jakes on.

Hope this helps

Don

[prevost82]

Nick .... do I see a trip out west to Don's shop coming up in the future LOL. Hard to find a good 2 stroke mech ...
Ron

[Songman]

Nick .... do I see a trip out west to Don's shop coming up in the future LOL. Hard to find a good 2 stroke mech ...
Ron

I hope so! I would love to see Nick's bus!

[missadventure]

Jakes on a mechanical 2-troke do not shut off the fuel. Jakes turn with the on/off swich in low, med., or high position, throttle switch closed and clutch switch closed. All 3 things have to met when jake work and a mechanical fuel system. The engine still has fuel fuel being injected even w/ no power stroke, and with the eng idling and all 3 switches set, it is normal for the eng to die if the on/off switch is left on. Electronic engines have no fuel injected at idle do to jakes are controlled by the computer, fuel is shut off by fuel solenoids completely. The mileage issue mentioned is directly relative to temp and driving condtions, wind, cool or warm weather, into the wind, w/ the wind, etc. The wurst wind condition to affect milage is a 45 degree cross wind.

[Don Fairchild]

jakes don't shut off fuel they stop fuel from being injected into the cyclinder by way of a plunger and fork on the injector rocker The rack on an mui engine will go to no fuel for a short time when you take your foot off the throttle. The gov will pick up the rack and return it to a fuel spot in relation to the throttle setting. ie idle, fuel rpm or any spot inbetween depending on foot position. Lets say you are crussing down the road at 70 mph and you come up on a construction zone and the posted speed dropes to 40mph. You remove your foot from the throttle and coast, the rack will go to no fuel until either your foot goes back on the throttle or the gov. picks up the rack to set the proper rpm.  You are corect about the wind. It has an effect on any box we drive down the road.

In nicks case he had a jake added to his engine and the millage was affected. This is why I said his problem is tuneup related. When the jake was added they should have retuned the engine and if they changed injector settings from lets say 1.520 to 1.470 this will have an effect on the way the engine runs. You must take in account the camshafts, blower (83% vs 100%) and turbo that is on the engine.

hope that better explanes where I am comming from.

Don

[Nick Badame Refrig/ACC]

Hi Don,

Yes, I understand what you are saying. It makes perfect sence!

I don't know the injector settings but, the engine runs like a "Raped Ape"    So, I'm not going to complain anymore...

Thanks for your help!
Nick-

[larryh]

Nick,

Don is right on with his statement I have installed over 500 sets of Jakes and never heard of a loss of fuel mileage. It is usually due to short circuit from left side of brain to connection to right foot. As you say it runs like a raped ape it was due to valve adjustment (ie tuneup) with installation of jakes. One person stated that valve clearance got greater when engine warmed up and that is just the opposite when the engine heats up valve clearance will decrease with the expansion of the metal parts. You want the ponies you got to feed em.

LarryH

[niles500]

Maybe I got confused here - Are you all saying that operating continuously with your jake on will NOT affect fuel mileage?