b-75 engine choices

[jimtruck]

I've finally been able to start driving my truck around a bit and have discovered that the 711 has got a knock at idle. I narrowed it down to the #3 cylinder. The injector and valve lash are correct and the rack s in the pump are correctly timed. Since the 711 already has a bad rep, I've decided to start looking for a different engine to swap in. The truck is a '64 b-75 and its going to haul various loads with a low boy trailer. I'm not going to be using it every day, but it will get used,,,if that makes any sense. I also want to keep the triplex transmission. What do you all suggest? I've heard good things about the 237 and the 673c on this site. I just want a good reliable engine that I wont be afraid to drive.

[Underdog]

I think you should buy the 237 that I have sitting in my yard. Good runner around 100k miles.

Gregg

[AZB755V8]

Any Mack engine between 237-300hp would be a good choice, 70-80's vintage. The limiting factor is the Triplex transmission you want to keep. Depends how you are going to use the truck. The torque from any of these engines is over what the trans can handle on a daily bases. If you take it easy with the right foot and are the only one driving it may stand a chance pulling loads. You can always turn down the injection pump to limit the power output as well. In that case any of these engine will out live you with no problems, the trans.... maybe.

[jimtruck]

I'm pretty good at not hot rodding equipment, and the truck wont be used every day. It will see the occasional heavy load, but its mainly going to haul the occasional backhoe/mid sized crawler. If I were to shift it like it still had the 711 in it...not skipping gears... would the tranny hold up for a while, or is it a guaranteed death sentence?

Thanks for your help,

Jim

[Maddog13407]

drive it like normal, don't lug it and youll be fine with a 237, 300 is pushing it but if your the only one driving it it will probably hold up. 673B and C engines are like hens teeth unless you find an old firetruck

[terry]

If the trans is in good shape it should last a long time with not lugging it down like you would do with a 5 or 6 speed.

[Freightrain]

Just put a 237 in my B.   Loving it!   I skip along the first few gears, then split 4 and 5.  I'm only 27K lbs loaded.  It moves along well and I'm very careful to keep the RPM over 1500 rpm.  Splitting it up a gear usually keeps it at speed other then a big hill might take two gears.  My old triplex is pretty loose so I drive it by feel of the shifter.  If it starts to feel like it is not liking it, I split up a gear and it smooths out.

Edited July 12, 2016 by Freightrain

[jimtruck]

Thanks for the replies

How many things do you have to change to drop that engine in there? All the mounts and tranny bolt right up? Clutch parts interchangeable?

Thanks,

Jim

[BOB DINGSDALE]

friend of mine in washington state has a big cam cummins in his.around the 400 hp range.nice runner.

[Freightrain]

It is a bolt in.  Just with a B61 you have to run the 673 water pump and balancer to keep it short enough.  Not sure if a B75 has the same problems?  If not, then not a worry.  I still run the original 673 single disc clutch.  Had DW Clutch in Baltimore rebuild it and use an upgraded material(I think it was Fibertuff).  Good place, good prices and quick turn around(like 3-4 days).  Took a few miles to break it in, then it started biting and holds fine.

http://dwclutch.com/

 

[j hancock]

My recollection is the front of this 1985 Maxidyne engine stayed stock for installation in a 1959 B75.  The stock 1985 clutch and six speed were also used because the truck had no drive train at all. 

With care, the triplex may live with the modern engine.

 

[terry]

The B75 has more room to use the 237/285 engine but in a B61 you have to use the shorter water pump and the shorter crank hub.   terry

[Maddog13407]

is that a 285 or 315 Jim? god that looks sweet in there. I'm assuming a 286 with 6 speed?if so how about some shifting lever pics and motor mounts?

[j hancock]

It is a 285 with a Maxitorque X107A air shift 6 speed.  Using an X107 2 stick 6 speed would have looked more correct in the cab than seeing the air lines but I didn't have one at the time.  Don't have any pictures of the rear mounts but they are the stock 1985 R model trans mounts with new holes drilled in the frame to attach.  The front engine mount is the OEM B75.

[AZB755V8]

13 hours ago, j hancock said:

It is a 285 with a Maxitorque X107A air shift 6 speed.  Using an X107 2 stick 6 speed would have looked more correct in the cab than seeing the air lines but I didn't have one at the time.  Don't have any pictures of the rear mounts but they are the stock 1985 R model trans mounts with new holes drilled in the frame to attach.  The front engine mount is the OEM B75.

Man that is a beautiful interior, GREAT job, lets seeee the rest of the truck!!! Correct coloring, nice seats,air shift... whats is not to like.

[j hancock]

1959 B75 with the optional CA 31 cab.

[HarryS]

Oh that's nice.

[Maddog13407]

now theres a truck that could get me in trouble.....

[Maddog13407]

so was that ca beige originally or did you do a little L model vintage magic? and in not up on the L cabbed B models,were the reset buttons for the circuit breakers always in the middle of the dash?

[j hancock]

28 minutes ago, Maddog13407 said:

so was that ca beige originally or did you do a little L model vintage magic? and in not up on the L cabbed B models,were the reset buttons for the circuit breakers always in the middle of the dash?

I don't know the official breakdown of the colors with regard to the B model CA 31 cab.  My truck interior paint was actually Mack green when I got it.  The Mack CA 31 brochure list the interior colors as tan and brown with no mention of green.  I like the tan/brown so that is what was selected.

Yes, the red buttons are for the circuit breakers.  I believe that system was used for the CA 31 cab through its production run.

[Maddog13407]

interesting. I know some of the newer B models had the push button resets, don't see many tho