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Old 05-20-2008, 08:09 PM
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how do you determine

when you make a chassis how do you determine on what level should you put the engine. do you measure if the drive shafts sit straight or at an angle?

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Old 05-20-2008, 10:17 PM
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Depends on a lot of things. Mostly its a matter of choice. You need to situate the engine/trans centered in the frame side to side if at all possible and the height depends usually on the body being used. You also want the output of the trans to be about 3 degrees down.

Those are generic parameters I usually try to keep in mind when I'm mocking up a chassis. Your results may vary.
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Old 05-20-2008, 10:45 PM
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You also want the drive shaft to be in phase with the differiential. The tail shaft of the transmission must be down at the same angle as the pinion shaft on the diff points up. If the tailshaft is 3 degrees down then the pinion shaft must point 3 degrees up. If they are not at the same angle in opposite directions then you will get strange vibrations when you drive it.
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Old 05-21-2008, 05:29 AM
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I had the tires and wheels on and the weight on the rear as complete then set. engine centered andset down 3* later put rear in 3* up. Worked so far.
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Old 05-21-2008, 06:33 AM
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Also it matters how low you want it to ride. You want to make sure the oil pan will not hit the ground at ride hight.
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Old 05-21-2008, 06:37 AM
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Don't forget that the Carb needs to be level as well, put a level on the intake manifold to establish this. Unless you are using EFI
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Old 05-21-2008, 01:17 PM
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Everything said so far is valid.
As far as the placement side to side in the engine bay, you can move the motor to wherever you need it to miss other components, but the motor must be parallel with the centerline of the car. In other words, if you looked at the car from a birdseye view, the centerline of the car and the centerline of the crankshaft/transmission output shaft must be parallel with each other, like railroad tracks are parallel with each other. The ujoints will absorb several degrees of angle. Mopars from the factory have been found to have the motor moved to the passenger side of the car by as much as 3" in order to clear the power brake booster. I moved a 302 Ford to the passenger side by 2 1/2" inches on a swap I did on a Mitsubishi pickup in order to clear the steering gear at the driver's side exhaust manifold. I ran it for years with no problems at all.

As far as viewing the motor/trans from the side of the car, you will want the centerline of the crank/trans to be within a degree or two of the pinion at the differential. If you install the motor at a 3* down angle (carburetor mounting pad angle level), then you want the pinion close to that same angle, but on an upbubble. On a leaf spring rear suspension where there is quite a lot of give in differential housing rotation from torque being applied, I will set the pinion at 1* upbubble with the crank/trans on a 3* downbubble. When you are cruising, some small amount of power will be applied to the pinion, causing it to climb the ring gear slightly and rotating the diff housing against the springs. If you start with a 2* difference and the housing rotates 2* under power, then the ujoints are lined up while cruising. It all depends on the rear suspension. Like I said, leaf springs have quite a lot of give to them rotationally. If you are using a 4-bar or similar arrangement, I would lay the motor in at 3* downbubble and maybe lay the pinion in at 2* upbubble because the 4-bar will not allow as much housing rotation under cruise power.

When push comes to shove, we really don't know how your particular application will behave and it's pretty much a guess based on previous experience. That's the best I can do for you.
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