just gonna say that, and i believe they were using that setup at least into the early 90's on some of the R-series trucks, if memory serves me.

also, how effective is a jake w/ an automatic transmission? not being wise, just asking as i have no experiance w/ a big truck and an auto trans.

 

yo would have to runa converter lockup system.

I used to drive a mack with a 500 hp 998cu in v8 mack engine the jake didn't do anything but make noise. I would have been better off throwing a 10lb anchor out the window.

 

Diesel Doc and Monty, have you guys ever worked on a Cummins ISL with jake brakes ?
take a look next time , there is no injector rocker arm there to activate a exh crosshead. pretty much looks just like a ISB , electronic injectors
and YES it will take a redesign of the ISB block and head to design a jake to work on the ISB. and that will be a roller tappet and a higher volume oil pump, since the oil pump sits in a volute of the block, a redesign of the pump only would not work. the volute area in the block would have to be deeper for the larger gerotor oil pump.
If you guys would like , I can send you a little video on how the jakes work on the engine without a injector rocker arm.

 

no I havn't messed with a ISL I was talking with a friend that said the same thing. I usually only work on large c-15's and the like engines but I think you are correct it would be way too much work to get it to work properly.

I don't think that even if you did get it working with only 359 cu inches it would be very efective.

 

It's been well over 30 yrs since I had big trucks but I bought a bunch of goodies (pan, front cover, oil pump and cooling nozzles, the Jake brake and some other rare stuff) from a wreck with a NTC 350 to put on my NTC 280. That Jake turned the engine into a vacuum pump, not a compressor. The Jake consisted of 2 hydraulic cylinders with an oil passage between them - one over the injector rocker and the other over the exh. crosshead. The Jake switch opened a solenoid from the oil galley and pumped the cylinders up so that when the inj. pushrod came up, the rocker hit that cylinder and forced the other cylinder down on the exh. crosshead and relieved the compression pressure. Then there's no more compression so the piston pulls a vacuum on what would have been the power stoke. If memory still works, the clearence from the rocker to the Jake cylinder (to be set when running the overhead) was .018" and I used to run mine tighter to make the Jake come on quicker and stronger. And yes a good working Jake will lock up the drivers on a loaded truck on a wet road - it's definately a thrill! Those Jakes have been known to break crankshafts. These are just some thoughts - It would definately be a serious project but you'd have to build a custom camshaft for the B and put an injector lobe on it and build a follower to push the Jake hydraulic cylinder. I guess it would have to stick out the side of the block cuz there's probably not enough room inside. Then build the opposing cylinder with a fork to straddle the exh. rocker and hit the crosshead - just like the big Jakes do. Then of coarse, build the solenoid valve setup to activate the hydraulic operation - that would be the only easy part. I used to have a machinist friend that could have done it but he's long gone. I don't recall needing unusual oil pressure to make it work. That old 280 of mine went down to 25 psi at idle and the Jake worked fine. It's not engine oil pressure (directly) that does it. It's the oil that's trapped between the two cylinder that does the work. Craig

 

BaldHog is right, the flat tappet cam would not hold up to the hammering it would see with engine brakes.
But if you are really persistent about doing this, I don't think the actual brake would be hard to design for a 24v. You can copy the design used for a Caterpillar 3406B. This is an old mechanical enigne, with no injector rockers. They used the upward movement of a rocker arm on another cylinder to actuate the master piston. Engine oil is used as a hydraulic medium and a slave piston would open the exhaust valves at the right time. There is two engine brake heads, one for the front three cylinders, one for the rear three cylinders. There is a spacer housing installed between the the valve covers and rocker housings.