Geoff Weeks

If it is a Shepard gear, I think the correct repair is to cut the shaft to a smaller OD and shrink a sleeve on where the seal rides. You could possibly have the sleeve made from hard chrome stock, making the repair better than the original. These repairs need a qualified machine shop that can do the work. It would take tooling that can cut the hard shaft and sleeve. I was working on a car that had some brake parts that are NLA anywhere, my machine shop made a repair like the above and was surprisingly reasonable. You just have to think "outside the box" and remember anything made by man can be re-made by man.

Generally, here if the rear mounts are on the engine 1/2 of the bell, a rear transmission "leaf spring" type or rubber bisket mount is used. On set-up's where the rear mount is on the transmission 1/2 of the bell (thinking Volvo/White) then there is nothing at the rear of the transmission. It may have something to do with how much weight is cantilevered off the back of the bell housing, esp when aluminum housing are used. Just an observation

Not trying to say it will not work, just wanted to point out somewhere to check. The new mount is in a "different area code" as you put it, so needs checking, which it sounds like you have done. New things in different real estate is always a concern.

Yes, but what I see of the nodel mount is above the transmission.

clutch shaft higher also. will the added height clear the body/cab?

Ok that make sense. If the main air is lost, the spring brakes will apply regardless of what position the control is in.

Bendix pressure regulating valves Here is what I think you have. No pressure regulation, just adjustable hold off until the pressure is reached.

It looks like a pressure protection valve. It will hold off pressure until its setting is reached, then pass system pressure after that. In N-A they are used for air ride and such so a loss in the suspension will not drain the brake tanks below the setting of the valve. Yes, they are known to plug and stick. I have had several and sometimes if a truck or trailer sits for a long time they stick. Good find. Not knowing your system, I wonder if it has a separate tank for parking release and stuff like air ride? The weird thing would be that a loss of pressure in the main (before the valve) would still keep the spring brakes off as the tank after the valve would be isolated.

It was the "mechanical" aspect that makes me say no.

Oh, Jojo, you led me wrong LOL. I don't know all the Mack engines like you. I still say 500hp out of a mechanical inline six below 14L is going to take some compromise in the lifespan. Even at 14L it is going to be a stretch. Electronic sure changed that equation.

Then drop the "mechanical" ( and 11L ) requirement and choose one of the fine electronics already made at that power and drop (stuff?) it in. As I stated any two are possible, not all three.

They do!

early days of the Big Cams and 3406 A and B sure, they need bearing rolls. later they were good for 1m or more if cared for. I have a 3406B in my Marmon with over 750K on the bottom end. Overhauled a NT88 at 1.4m and 750K on the bottom end which could have gone much longer on the bearings. Oils have got much better. Big Cam 3 oiling made a huge difference over that of the 1 and 2.

I was thinking inline 6 but yes there were others that broke the 500 hp barrier. I was incomplete in that statement. With the 3 "requirements" of 500hp, mechanical, and "bullet proof" remove any 2 and the 3rd is do-able. Remove only one and it is in the range of possibility. all three together and I don't see it happening.

There is a huge difference between what can be done with a mechanical engine and what can be done with electronics. You said you want a mechanical controlled engine, that limits what can be safely made in terms of power. At best mechanical can only have a speed based timing. That alone limits what can be done. Same on boost control. it would be a fixed map. If he wants that kind of power, then start with that powerplant. The hard work has been done, but there again it is not mechanical. Adding 10% to that would likely hold together, but may not. It wouldn't be the 1st powerplant that was discontinued/down rated after they came out when it was found they couldn't stay together long term. I stand by the comment that 11L mechanical engine @500 hp is not realistic, esp with your other requirements, of 500k to overhaul, and not being "babysat". The only fully mechanical truck engine to break 500 hp from the factory was the K-19 Cummins AFAIK. a 19L engine. Many did so when electronic controls and the items that are controlled were developed. All this to pull a "regional end dump" around? I pulled double your weight and much more wind resistance with ~430 hp. If you want an engine of any size that you can mash the go pedal and not watch the gauges, and I'm not sure there are any that fit that requirement, then it will a stock engine. drop in a 460 and play with that.