6BT, CUCV Axled M715 Build

[Barrman]

Here is the 1993 engine in the truck. Angle iron holding it up for now.

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[Barrman]

We went ahead and put the front end on just to see how it looked:

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It looks pretty darn goofy compared to Pistolnut's truck in the back ground. Those are 32' tall tires on the 6BT truck. The 12.50-20's should look just about perfect in there.

Oh, the engine has some 1/4" angle iron c-clamped to the frame holding it up. It is about 4 inches too high and about 2 inches to far forward from where it is going to live. We needed to clean the floor and the best way to get the front end out of the way was to put it on the truck.

[ryanroo]

thats what mine looks like. sermis's is a little taller though. i also pushed the front axle forward an inch.

lower and further back is always a good thing for engine placement

[jeepman3366]

Tim its looking good sermis is ready to drive it away lol

[k8icu]

So the M35 transmission was keeping the motor from moving back any further? Interesting.

[Barrman]

Joe,

It wasn't the transmission. It was the huge SAE bellhousing/rear motor mount back plate on the Cummins. Since it is made for a bigger flywheel, the starter is located waaaayyy out away from the engine and up compared to a stock Cummins. Even if we cut off the rear motor mounts from the bellhousing, I think the starter would still hit.

Then there is the turbo. The P7100 IP 6BT engines have the turbo down near oil pan gasket level and around the #5 cylinder front to back. So, even if we could have gotten the engine in all the way after much modification, the exhaust pipe would start about 2 inches in front of the passenger side M715 firewall.

We could have looked for a Chevy pattern rear engine plate, used the same bell that everybody uses to connect the 3053A to SBC's and made the engine/transmission fit just fine. Then the turbo would have been a problem. Then the front sump oil pan would have to be turned around along with oil pick up tubing. Basically, we could have "made" it work. But, since we had another engine 10 feet away, it wasn't worth the effort.

[CHRIS UNGER]

What did you change on your stock motor mounts ?

[Barrman]

Do you mean on the 6bt truck? The stock motor mounts were cut off the frame by the previous owner, so we are starting from scratch.

On my truck with the 396, I used plates to connect stock 230 mounts to the big Block.

[Barrman]

We have two 6bt engines to make one unit out of. The 92 model is the one going in the truck for a number of reasons already listed. However, we switched all the belt drives and accessories over from the '97 model to get a 24V alternator and the a/c compressor. That was all well and good until we put the front clip back on today for a test fit.

The fan is waaaayyyy to big to clear the front core supports and is further forward. Using this fan will mean a firewall cut for sure. There is enough room for a pair of electrics though. Once we took the fan off, we decided to see if the a/c compressor was far enough down to clear the hood. The hood for this truck is at my house, so we bolted on the hood from Pistolnut's truck.

Here is the hair or maybe a little less clearance we have:
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We will be lowering the engine another inch or so soon. Here is a shot of the truck with the hood on just to give Sermis something to drool over and for Pistolnut to see his hood and truck in the same picture for the first time in years:
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Oh, while we were changing out the belt drive stuff, we also peened the Killer Dowel Pin even though it was still where it was supposed to be.

[Barrman]

All right, I have never had to figure out wheel back spacing for a custom set of rims before. Not knowing what to do, I just did what I thought was right. If anybody has any better suggestions, please post up.

The tires are Michelin 12.50-20 XL's. I mounted one up on a M34 rim just so I would have something to measure off of and the tire would be at its inflation size.

M34 rims are 8" wide the nearest I can tell with a tape measure. The same as regular M35 rims. If somebody has the actual measurements, again, please post them.

We started out by lifting up the rear of the frame, taking off one of the roll around the shop rims and fitting the 12.50 up and seeing how far from the frame seemed right.

Here is the distance we settled on:

[IMG][/IMG]

You will notice the back side of the rim is even with the back of the brake rotor. The back of the brake rotor is 4-1/4" from the wheel mounting surface. Does that mean the back spacing needs to be 4-1/4"? Or do we need to figure it from the outside in to the wheel mounting surface at 3-3/4"?

Anyway, here is another shot of the same rim spaced the same to show the brake rotor relationship:
[IMG][/IMG]

We then did the same with the front. Turning the wheel full lock both directions gave 1/2" or more clearance from the spring. Here is a shot of the tire lined up with the back of the front brake rotor at full lock:

[IMG][/IMG]

I couldn't get a picture of it because the tire had to be held in place and no part of my students can legally be photographed. But, this spacing has the outside of the tire exactly even with the outside of the fender flare or maybe just a hair wider. The engine was out for motor mount fabrication and getting these axles to flex is about impossible. However, I think making the rims to this back spacing or maybe 1/4" further toward the frame is going to be the answer.