Engine alignment

[jmacqueen]

Well it's time for me to mock up engine mounts for the 4bt cummins in my M37. I've modified the oil pan so clearance is all set, transmission is on the engine hanging in the frame from a hoist now.

Before I do I though I would ask here what methods and tools etc you other guys used to get your engine aligned in the frame straight.

Any tips, rules, tools, advice?

[pieter]

first and foremost thing that I would do is to make sure the frame is square, plumb, level and is sitting correctly as it pertain's to ride height. Ride height may mean that the rearof the frame is 2" heigher then the front. It all depends. If you have the truck sitting on rims and tires, just make sure things seem level and good.

you want to center it in the framerails if possible. Some will kee[ the engine level and others will slope is down in the rear a few degree's. Often it is best to set it up the same way it was in the donor vehicle.

Some 4BT's slanted vertically. You will know what mounting method your engine used.
As fas as tools, various levels, tape measure and I'd use a magnetic degree finder. There should be a true edge that is parallel or perpendicular to the crank that you can reference off of.

Just be patient and work through it. Don't forget you have to be able to close the hood. Also keep in mind getting to bellhousing bolts and such once it is installed. As in you don't want it tight to the firewall. Keep some space will also help airflow, thus keeping the engine cooler.

Pieter

[Gordon Maney]

I can easily endorse the centering left to right idea, but also have to say I read about some who offset somewhat to the right to better clear a steering gear assembly.

The nice thing about what you are about to do is you can get it hung, propped, as the case may be, and study it. Leave it for a few days, come back, and look some more.

Driveline angles and crank center line are critical. The magnetic protractor Pieter mentions will be vital to your task.

The relationship that will vex you is the front axle. The crank, transmission, transfer case, and rear axle rotational centerlines can all be parallel, but the front is going the wrong way.

Some have resolved that with CV joints in the front drive shaft.

Keep us posted as to your method and progress. It is all interesting.

[jmacqueen]

Well drive line angle for the front and rear drive shafts are set with the divorced transfer case. It's not going to be moved though..

So all I have to worry about is transmission to transfer case angle. That is make sure the intermediate shaft doesn't vibrate.

So far I'm not able to get it square, that is get the engine trans assembly positioned so that the trans output flange is parallel to the transfer case input shaft.

Not without making a new center floor piece.

How critical is the angle of the flanges to each other? Or maybe I could just use a CV joint in the intermediate shaft?

I guess my question is can the transmission output be about 5 degrees or so different angle than the transfer case input shaft and not cause problems.

So far I'm measuring angles side to side with two straight edges horizontal on the flanges, measuring that they are parallel by measuring at both ends.

Vertical angle with one of those magnetic protractors.

[Paul Cook]

Crankshaft centerline is off set

I hope your tape measure showed you that the crankshaft centerline is about four inches left of the frame centerline.