Joe Cummings

I am looking to purchase my first b-model alot of times you see on ebay "rare" scoop back B

are they any more valuable? What is a good model to buy? Looking for a tractor.

Any schooling on B's would be helpful. I love my GMC but I would love to sink my teeth into a good ol' mack for restoration.

Thanks guys,

Mike Wallace

I always hated them, but then again I'm 6'2" 280 pounds. If I was thinner I might be ok with them.

Joe

Have any of you guys shortened up your wheel base? And if so what did it entail and how hard was it? Anything specific to look out for, or make sure you get 100% correct? Thanks

To put the trunion in a Mack the right way you should use BODY BOUND BOLTS. You drill the holes with a drill bit and then ream them to fit the shank of the bolt. I've put them in the wrong way with regular grade 8 bolts and they lived but it really wasn't right. "HUCK BOLTS" probably do the best job, but the tool to pull them tight and crimp them is expensive and they really aren't original on an old Mack

Joe

Hi Guys. Lets hope I can explain this clearly.

My bogie drive has top mounted diffs.

I notice that the gaskets that are between the upper and lower housing assemblies have become brittle and are working loose, breaking off and therefore causing oil leaks. (After all, they are quite a few years old)

Is there an easy way to replace these gaskets (ie can you just jack up the upper housing?).

Someone has suggested that I just give it a good clean and use a silicone sealant without taking anything apart.

Suggestions and comments appreciated. Thanks. Rod.

Did you try tighten all the bolts including the two that are inside the cover on the top right side? You will probably have to cut/bend some box wrenches to fit on them.

Joe

Out here on the West Coast the engine of choice( at least in the Mack LT's) seems to be the Cummins 275 supercharged engine. Just wondering if anyone has had any expirience with them? I've heard they had a very different sound to them. I've got an LT needing an engine and was wondering how hard it would be to come up with one.

Thanks, Brad

A friend of mine had a couple of those supercharged Cummins around. I know I saw one at his place in December in an old air compressor. He would probably want to sell it if he hasn't junked it yet. If you have any 69 Z28 Camaro parts to wave under his nose I'll bet he could find you a good one.

Joe

WELL JOE, I CANT SPEAK FOR EVERYONE DOWN HERE, BUT IN MY CASE OF A 1O WHEEL DUMPER, WITH A 55000 TAG, WE ARE ALLOWED 10% OVER THAT FOR FARM USE BECAUSE OF NO SCALES HERE ON THE FARM. A LIGHTER TARE EQUALS MORE ROOM FOR SOYBEANS, MORE ROOM FOR SOYBEANS EQUALS MORE MONEY. SO I GUESS IT ALL BOILS DOWN TO THE ALL MIGHTY DOLLAR. IM SURE IT WORKS DIFFERENTLY FOR COMMERCIAL HAULING BUT FOR FARM USE A LITTLE BIT COUNTS. DOUG

Doug,

Up here in the north they wouldn't even let us register a truck with 38s and a 12 at 55,000. I know they will handle it but it is tough to raise gvw on a truck up here, they want to see the sticker on the door jam lots of times. And up here you don't get any 10% over. They pick on trucks pretty bad around here. Almost makes me want to move down south.

Joe

Didn't Mack used to offer a CNG powered engine for refuse truck applications? I was just on the website and didn't see anything about it. I know there were a few experimental ones around here. Have any of you guys played with CNG or propane? I understand there are some significant tax breaks involved.

Joe

I put my puff on an air operated switch. when we go to shows or truck pulls I can blow the black clouds. normal driving I just let it do its thing...unless someone likes to tailgate me!!!!!

I go the other way with the puff limiter. I set them up so I can throw a switch and they hold the rack almost all the way back. Makes them pass with flying colors.

Joe,

The pump has not been taken off yet. It is an American Bosch, but we can't read any spec on the tag.

Phil

I take it you are replacing the tappet cover gaskets. They are kind of a

common leak on 6 cyl macks.

If you only remove and replace the pump by unbolting it at the 3 bolt flange

you won't disturb the timing. That engine probably has the injection pump

drive coupling with the 2 tangs and it should have a pin in it so you can't

get it 180 degrees out.

The only way you can disturb the timing is by taking off the little round

cover that is located on the engine's front timing cover and losening the 4

bolts that are in slotted holes.

Joe

Nice Pete Paccar, what's in it for power? I'ts funny but I guess I'm getting old when 70 is an old truck. But it's older than my LF when I started running it.

MiKe I got to say I love that B83 I have always loved macks. I used them for years in the salvage and scrap metal business. Nothing stands up to that kind of work like a Mack. I would rather drive a Maxidyne powered 5 or 6 speed 20 year old truck than a new one. As long as I can turn the fuel up a bit I run right along side the newest stuff. But it is getting tough around here with all the smoke checks and stuff. You have to cheat and make up some controls for the puff limiter but you can never get drivers that understand how to use them when they get stopped.

Joe

Can someone please give me some detailed instructions on how to time an END-673. I needed to replace the gasket behind it and now need to get it back together. Thanks

Did you disturb the timing adjustment under that little round cover that is on the top right of the timing cover? If you just took the pump off and are putting the same pump back on you really don't have to time it if the timing is right to begin with. If you want to time it you can "flow time" it but I have to know if you have a Robert Bosch or an American Bosch injection pump. It helps if you can read the tag on the pump because the timing spec is there.

Joe

I was thinking today that I haven't seen an L or a B working around here for Quite a long time. I ran a 48 LF and a 53 IHC R210 in wrecker service untill the late 80's but even I gave it up. Parts were hard to get for the LF and The R210 with it's 450 Red Diamond was really slow.

Joe

How come I see so many tractors converted into 10 wheelers and roll-offs for sale south of the Mason-Dixon line? Is there something about the weight laws down there that I don't know about? I'm from Philly Pa and here and in Nj pretty much everything is on 44s and 18s & 20s with double frames. Is there some advantage to having 38s and 12s down there? I would guess the tare weights would be a couple of thousand lighter.

Joe

The repair that Joe Cummins mentions is done the most ( us old guys still have the art ) Randy

Are you saying I'm an old guy?

http://www.locknstitch.com/ I used to make my own pins/plugs but here is a site that explains it pretty well.

Joe

Hey does anyone remember the BCR kits? Back in the 60's mack made a kit to but a R Model style cab and hood on a B model. You could pick them out easily by the B Model steering collum and box they still used. They also had the fuel tanks mounted like a B Model, Not like an R Model with that bar that holds up the rear of the tanks and is the rear cab mount.

Joe

l have removed the old rectangular steel step tank from my 1960 B61T and want to install a round aluminum step tank that l bought from a friend complete with brackets, also from a B61. Now l have been told that to do this all new holes have to be drilled inthe frame. Has anyone done this that can verify this? thanks, Moose

I would keep the square tanks before I drilled extra holes in my frame,but hey that's just me.

Joe

36k payload plus 22k truck is 58k gross. You probably have a 12k front axle and a truck that statred it's life as a tractor. With 46k on 38k rears, something has to give.

I was just thinking the same thing. Not too many dump trucks were built with 38s

Joe

I've probably put maybe 300 or so miles on it since last year and that is empty so there is no real usage.

Thanks,

Rob

It sounds like you must have some kind of problem with a liner or a counterbore. if you have it apart again check the liner heights. Most times this isn't very critical on a inline 6 Mack but who knows these things are getting a little old. 300 miles is nothing on a turned up 711 they should last a couple of hundred thousand.

with a cracked engine block could you just weld it for a temporary use until you get another engine?

For a short non structural crack like in a cooling jacket we used to fix them with a series of threaded plugs. One plug overlapped the last. but it's a bit hard to explain. Really kind of a lost art

Joe

Joe, that is exactly what I did with a "711" motor. Had the pump rebuilt for more power with 11m barrels & plungers, did away with "syncrovance", adjusted timing and added a hopped up turbo. Upon chaining the truck to a dyno, the horsepower and torque were much higher, but I could not keep head gaskets in the engine. After three attempts to make 300+ reliable horsepower, and blowing the head gasket at #2 cylinder each time, I finally removed both heads, had them completely rebuilt, (including new valves, springs, and guides), put it all back together to have the same thing happen again!!

I have not given up on the project, just ran out of time. I "straight edged" the block, and it is within tolerance, and the engine does not burn oil so I therefore am not willing to dump a lot of money into rebuilding it. Would have liked to blame the head gasket manufactures, (Victor/Reinz, and Fel-Pro) but with the blown part of the head gaskets at the same place each time, I'm not so sure.

If you have any ideas of what I may have done wrong, please give me some advice!!

Rob

rob@autoaffair.com

Rob the 711 had 20 stud heads but it didn't have fire rings on top of the liners like a Maxidyne or an ENDT673C. Most of the 711s didn't have the oil sprays for piston cooling either or a provision on the block to add them so you had to watch how hard you pushed them when they were turned way up. I got away with hot rodding them a bit if they were in short duty cycle applications like dump trucks for around the city where you load them hard and then let them cool off. I'm just curious how long are your head gaskets lasting?

a 2 stick 6 speed is realy a 5 speed with the option of a low first gear for extream off road or heavy hauling.

the main box has 5 foward gears

the aux has revers, Low and direct

under normal use . you only shift the main stick (closest to your leg).1-2-3-4-5 the aux box stays in "Direct"

If you are very heavy or in a hole and need to climb out you would put the aux or compound box into "low" and use the main in 1st. After the truck is out of the hole mud etc...and on flat level ground you would shift the aux box from "low" to "direct" accelarate then shift 2-3-4-5 with the main. So basicly its like splitting 1st gear in half with the aux box. this gives you 6 foward speeds. However the shift from "low" to "direct" has to be done carefully as if the truck is still climbing out of a hole you likely will miss shift as the slow road speed will fall very quick.

Trent

There was also a another version of that low hole box with an extra low reduction in the compound. It was designed for concrete mixers so they could do curb pours without working the hell out of the clutch. I could get a few extra gears out of these if I shifted them right.

And then there were the "high hole" version of the 6 speed with that big heavy triple case. You went through 5 in dirrect and then shifted the compound into overdrive. I used to see these alot in DM600 & 800s with Maxidynes and rears #55,000 and greater.

You should see me behind the wheel in one of my concave cab B models,Larry.

I have the same problem with those. I think if those B-67s are put together right they have a smaller wheel. But even with the right one I never could drive one far.

Joe

I remember working on one of these back in the day. It was in a LJ and had a duplex behind it and a #29,000 rear axle. I kind of remember it looking kind of like a EN707 gas motor but with injecters going strait into the side of the head. I think it had some kind of American Bosch pump but I'm not sure.

Joe

I am wondering is any body has seen a 12v71 in a B81sx?..I heard some people had seen a 671 in a b61 ..the b81 has alonger hood and the 671 and 12v71 are the same length... but th v models are wider and not as tall .I am think a 12v71 may fit a b81sx.. I have a line on a 12v71 ..might make a nice project.

any ideas?

thanks

Deo

What's wrong with a 672 inch 2-valve mack with an APE pump with 11 mm barrels? I have gotten alot of power out of these engines with a little recalibration of the fuel settings. Move the stop plate in the govener foward and I'll bet you can get 400 HP or more out of an 672 with a turbo. But it will break that quad box, they were only rated for about 700 foot pounds of torque.

Joe