Geoff Weeks

Is it air braked or juice brakes? If hyd it will be hard to find a new rear fitted out for hyd brakes that will meet all the other requirements.

Being a pumper, it just about eliminates and aux trans, as the midship pump drive takes the same real estate. That leaves tires (not much change available, looks to have 10.00 x20's), trans or rear ratio. Trans, is 5th up against the dash or down toward the seat? If toward the seat, a O/D trans may be an option, but be aware, that could change the speed to the pump as well. Have to make sure everything plays well together. Rear ratio, we would have to know what is there now to know if a different ratio can be fitted or if a whole new rear axle would be required.

Plot out any changes you are considering on paper first. Note how the truck does now over differing RPM, where it seams to pull the best, and how it does starting (esp under load if you intend to still pull a load). When I re ratioed mine, it took several sheets of graph paper and trying different ratios, looking at engine speed and road speed in each gear, both at speed and at starting. Lots of math, but when I was done, the truck preformed just as the math said it would. Seat of the pants, guesses often lead to unhappy results. Tire Rev/mile can be obtained from the tire mfg catalog, often available on line. If you have spoke wheels, you are limited to rims sizes for those spokes, to go bigger requires a hub change and that can be expensive and, on an older truck hard to find. Disk wheels you can jump more sizes, but still some rims (24") can be hard to come by and some tire sizes also. A simple O/D of .73 should put you around 55 MPH top speed, but check the driveline 1st, you may have to make changes to keep it from critical speed. The problem with gearing up in the front only to gear down in the rear, is much of the energy goes into heat in the boxes. In a low powered truck, you could easly end up with something that could go fast on paper but not in the real world. Air resistance increases to the square of speed, double speed and the air resistance goes up 4x. Add to that, the inefficacy of changing the driveshaft speed faster to slow it back down, and all the gains you "thought" you'd get can be eaten up in friction and air resistance. All this says is to do the math before you buy the first thing or turn the first wrench.

It has been well established, that it is a Herc, re badged with Mack cast into the manifold. Hp rated at less than 100HP .

1st take stock of what you have. tire size, power, transmission even tube size and length of driveshaft. As I found out, some of the old truck were driving their driveshafts into critical speed. Tires will only gain you a little. Rear ratio changes can make the most difference, with a small amount of change to the driveline. Adding an aux trans can be another way but you have to replace the driveline and set it up carefully not to overspeed the driveline. Of course this all assumes enough power to drive the truck faster. I have one truck that will top out at 68 MPH on paper but doesn't have the power to do more than 55. Little gained by making changes if the power isn't there.

The low output would make me doubt that. In the 40's my K-7's were 21000 GVW and had more HP than that. I just can't see Mack putting less than 100hp in any truck they made. I admit I have no paperwork to back my statements on what Mack did or didn't do. What were Mack gassers in terms of Hp?

Yep, they are easy to get out. Often when the pin is worn out so is the bushing. Since the ones in the springs are new, those should be fine. The fixed one on the frame may need to be replaced. IHC used threaded in all positions, others may not.

Is this what you are looking for? Not cheap, but quick way out. https://www.vanderhaags.com/detailview.php?part=24898211

Try finding anything for a Gardner or Leyland in this country. Start calling yards, Even if you don't need one, finding out what can be had is money in the bank.ld If it were I, a used head, that can be re-worked, would be something I'd be looking for. It doesn't have to be new or rebuilt, just no cracks and good valves. There are my ways to repair guides and seats can be replaced. I guess it comes from working on old, orphan engines, you 1st look for what is available then go from there. Cracked heads can be repaired, but not cheaply. Rings can be ordered by size and shape, even if full ring sets are not available. Heat the nuts, slit the nuts, there are many ways to go forward. Look at what is important, The nuts aren't as important as the studs, and are easier to replace.

I can only give the following: Depending on if it has factory or aftermarket A/C or not there are close to 1/2 dozen possibility Airsource list 2 for trucks without aftermarket: 1050 is a 5 terminal lever operated switch 1150 is a 5 terminal rotary knob operated switch https://www.amazon.com/AirSource-1050-Toggle-Blower-Switch/dp/B01IB1BOIQ https://www.finditparts.com/products/17065/mei-1150 If it doesn't look like either of those, then I'd need a picture.

You will not know till the head is off. Not much room between the valve and piston at TDC. I have the head of a valve that broke off and planted itself in the piston crown on my wall of shame. Wasn't a Mack but a Leyland 680, which looks an awful lot like a Mack. I hope you get away with just a new valve, but I would be surprised if that is all it took. If you need to get the truck running ASAP, cost be damned, then get a head, have it gone through and a piston and tear into it. If you can wait, then disassemble and see what you need. I've "patched" a lot of engines where parts were not available, but it is never a quick process. If your loosing money every minute the truck is down, then sourceing used parts and new gaskets while they are coming tear the engine down is the way to go. IF the valve hit the injector tip, then you'll need one of those, but you can't tell until the head is off.

If you do take apart the Trico motor, be very careful. Parts are not readily available, as Trico stopped making them in the early 80's. O rings will not be the problem, but the paddle seal and little parts, like the reversing valve may be hard to find. I have two of these motors that came from different trucks. I have not been through them myself, as Sprague HP 100's were the replacement in my trucks for the Trico's and they were easy to source. I like the Trico better, but the parts issue on a truck in service, was enough for me to change while I could. I was going to send off my Trico to Rome for overhaul, but never did as I had plenty of HP-100's and could overhaul them myself, and no problems if something broke as parts or parts units were easy to come by. If you only have the ones for you truck, proceed with caution, one lost or broken small part may leave you with no options. I should add, there is nothing difficult or special about air motors, they are simple devices, but anything without a source of parts can become a big problem, not because of the complexity but the lack of some small piece.

It definitely had a 2nd life as a power unit, but the vertical down outlet of the exhaust points to vehicle use. Most power units like the one I stole the picture of from E bay, have a straight vertical up exh. Any stationary use, I can't fit with the vertical down exhaust. Large fork lift? Airport tug?

OK, I just noticed this is in the fire truck thread. Many Fire trucks used alternators long before they became used in trucks. (I have a 6 volt 100 amp alternator) so lets start with some pictures of what you have. Just to be sure we are on the same page.

Also, assuming it has a Delco generator, any short to ground on the field wire between the reg and generator would "full field" the genny regardless of what the regulator tried to do. So look for frayed insulation on the genny wires.

less than 100 hp, makes it unlikely to be even a yard goat. No air compressor seen, so what was it used for? They bought enough for Herc to cast their name in the manifold. A real mystery?

I'm more curious what Mack put it in?

Does seam to be a Herc. Here is a pick with vertical exh but everything else seams to "line up". I'd say 100% on the ID. Thanks to the poster who first said Herc. https://www.ebay.com/p/1523084881

Got to start by knowing the charging voltage. Voltage reg would be a smaller black box most likely on the firewall. There must be a good connection between the reg and generator and also the ground path between the reg, chassie, body and engine. If the regulator doesn't have a good ground path, it can't compare what the voltage is to what it should be. Some(many heavy duty) regulators are mounted with a rubber mount to protect from rough vibration. They MUST have a ground path to electrically connect the rubber isolated regulator to the chassie. Often it is a thin tab connected to one of the mount screws, but these can either rust or break. If in doubt connect a ground wire between the regulator case and the chassie. I have found the regulators to be extremely reliable and have two that are close to or over 80 years old and still working.

Sorry I'M no help,but to agree it is not a Buda design. Conti was famous for casting a name into manifolds when a mfg bought their engine. I would guess may be Herc did the same? Never saw one like that either. Too bad we don't have Glenn or Mike H to pick their brains.

I think two reasons, One is they had a rep for parts prices being high, I never was on that end of things, so just repaired, and never saw the price of the parts. The real big reason I saw, was they "weren't cool, like a duelly pick-up chassie" Or "I wouldn't be seen dead in that termite head truck". Never mind the fact the cab had more room, they turned tighter, and had things like a engine brake from the factory. I looked to find a reasonable priced used one, but they were all more than I wanted to pay, Still, they were cheaper than other used trucks in their class. The lighter end of trucks never did all that well for sales as cabovers, The Ford C series is about the best known, but GM (or course the Mack N) and IHC cargostar were all low sales when compared to conventionals. Just think how many more Loadstar conventionals are still seen vs, the cabover version of the same (Cargostar). I think these were bought new by large companies, not O/O or small fleet, where the "looks" counted more to the buyer than the practicality.

I had one that drove me mad. It was the tooth gear on the back of the trans (If yours still use that type of speedo). All it was, the yoke nut was a little loose, not enough so you could feel play, just enough that the tooth gear would stop spinning. Drop the driveshaft and hit the nut with a big gun or torque it with a bar. It was weird, you start off the say and the speedo would work fine, then it would slow or cut out. Changed pick=ups, even subbed in another speedo and got the same. Couldn't feel any play in the yoke but just enough not to squeeze the tooth gear between the yoke and bearing.

Book mark "Rome Truck Parts" for those Trico motors. If you need motors or a rebuild they are the only ones that seam to know much about the old Trico's. Because those use air to park (when the button is pushed in) and I don't think you said where it is leaking from, it could be the valve in the motor as well. http://www.rometruckparts.com/

Some engines had a 'stat that is clamped in the upper hose near the engine outlet.

Rule of thumb, again from the late Glenn A, if the shutter thermostat is in the upper tank, it should be 10 deg higher than the engine 'stat if in the lower tank (as some are) it should be the same temp as the engine stat. Your situation sounds like a bad (or missing) engine thermostat, shutters are doing all they can to get the temp up (staying closed)