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Howdy, I am mocking up the driveline on my 41 chevy 3/4 ton. I need to drop the rear of the motor 3 degrees. I was wondering if I could take that measurement from a flat spot on the block? for example where the distributor mounts or the thermostat in front. All I have is the block. I really need help. Everything is centered up between the frame rails. any help or suggestions are appreciated. thanks James

Mount the starter and measure the angle of the housing. It is parallel to the drive line.

I don't have a starter, is there any other way with just the block.

James B,

I must not 'comprende'(?). Wouldn't anything that was parallel with the crank be a accurate reference. This would include the top of the naked block, the top surface of the head, the bottom of the block. Three degrees is a minute amount isn't it...could you guesstimate three degrees?

Stuart

Get a cheap magnetic based angle gauge from a home improvement store and stick it to the end of the crankshaft or the bellhousing flange or the timing chain cover or whatever. You'll need it to set your rear-end anyway, might as well invest the $10 now,
Scott

The top of the block had darn well better be parallel to the crankshaft! The first thing I do to a race engine is align bore the main bearings, then I deck the block, using the mains as a reference. Just put a magnetic angle gauge on top of the bare block, with the bubble set at 3 degrees, and do whatever shimming of mounts is necessary to level the bubble.
Jerry

If all you have is a bare block, how are you setting the driveline? It seems to me you need front and rear mounts to set the driveline angle. What engine are you talking about?

I wouldn't sweat 3 degrees! Main thing to do is get NEW motor mounts fore and aft. If the aft mounts are shot, you'll have the bellhousing resting on the crossmember.

I think my garage is off by at least 3 degrees.

I know that there's all kinds of formulas for doing this, but I found that if I made the carburetor base on the intake manifold level the engine was sitting at 3 degrees offset.

No muss, no fuss!

Why do you have to drop the rear of the engine? If it's a 216, make sure you have all new motor mounts and you'll know the position of the motor is where it needs to be.

I installed a mustang II front suspension. I plan to install a 350 small block with a 700r4 tranny. I don't have a motor to install right now but I borrowed the block from a friend to mock up the driveline. This is my first project and I don't have any engine parts laying around, heads,intake manifold, carb. I am saving up some cash to purchase the motor & tranny. so that is why I am trying to do it this way if I can. sorry I left out the info. I saw on trucks with Stacey David about dropping the rear about 3 degrees. I do have a magnetic base angle gauge.again sorry about the confusion & I appreciate the help. James

james b I would put a carpenters level on top of the engine block dead center, from front to rear.Set angle finder on top of level. set engine 3 degrees, to check measure, move angle finder to bottom of block where oil pan bolts up and see if both measures are 3 degrees.

jbennett
40 burb

With out a transmission crossmember or even the transmission, what good does it do to set the engine 3 degree? You need the rest of the drivetrain setting on its mounts before anything really matters. There is more than 3 degrees of movement in any rubber mount. You must have all three mounting points or its a waist of time right now! Joe

Thanks for the suggestion jbennett. Joe I have the tranny shell bolted on the block & have a universal crossmember. So I should install tranny crossmember, bolt tranny to it then set the engine to 3 degrees? James

Keep in mind you'll need your frame sitting at it's final rake to get your engine properly set at 3 degrees. If you set your frame up level, drop the tailshaft to 3 degrees then finish the truck and it sits 5 degrees towards the front, then your engine is 2 degrees on the other side of level.
Just a thought,
Scott

To heck with the engine block angle, just eyeball it for level and to where it looks nice. This angle is not important but if you could borrow an intake and just set it on the block, even without heads, then a level on the carb flange would put you dead on. What is important is that your pinion angle is down 3 degrees (2-4 degrees) from your crank centerline. This is supposed to rotate the needle bearings in the U-joint cups to extend life and push the slip joint deeper onto the trans output splines under acceleration. Your concern for correct angle needs to be when you install the rear end housing. If engines had to be at a precise angle to run then no cars with carburetors would be able to be driven in San Francisco.

Thanks for the help guys! I appreciate it James

The 3 degree angle is just a good starting point. The 3 degrees is the right amount of angle for u-joints to work properly. Go to much more and they will bind up or wear to quickly, go less then and they could wear just as fast due to not rotating the bearings.

Set the motor in the frame and bolt it to the mounts. The frame should be setting at the approximate angle of a completed truck. You will have to guess at this, with a drop axle it will be lower in the front the normal. Now move the transmssion crossmember up or down to get the carburator level or slightly leaning back. This has nothing to with how it will run, its all about looks. Don't worry to much about this, just get it close, its the driveline angles that matter.

Once you have the engine where you want it, set the driveshaft in the rear axle yoke and transmission case. Measure the transmission angle then the driveshaft angle. They both should be pointing down. Subtract the driveline from the transmission and you better be in the 2 to 4 degree range. Now go to the rear axle and measure the driveline angle and the rear axle angle (use the yoke flange or pan gasket flange). These two should be pointing up the same amount as the trans is pointing down, with a 2 to 4 degrees u-joint angle.

Thats it, thats all that you need, the driveline angles, the motor and rear axle angles will be the same, one up the other down. It doesn't matter what they are as long as the u-joint angles are in the 2 to 4 degree range. In a ideal world, the motor would point down 3 degrees and the rear axle will point up three degrees with 2 degree u-joint angle.

Under a hard launch like a drag car, the axle will want to twist upwards so a little extra angle is added to the rear. This way under a load, the u-joint is still in its proper range. A easy going 6 cylinder parade truck will not have to worry about the extra torque angles, but if you plan to drive your truck hard add a extra bit to the rear axle angle.

To get the rear axle in the proper ride height, use ratchet tie strapes to pull the frame down to the axle to simulate the weight of the bed. Ask someone with a finished truck for the measurement. Your driveshaft angle will change a lot once you start adding weight. Joe