engine angle?

this may sound like a stupid question but, when installing an engine into a chassis, what is better -- engine parallel to ground or sloped toward it? any advantages or disadvantages of either?

im fitting a 302c block and c4 into a mitsibishi utility chassis (cheaper to strengthen this chassis than build new!) have made up new engine mount adaptors, to set back the engine 4.5" and the motor sits comfortably perfectly parallel to the ground. Problem is the diff head is about 8" lower than the output shaft of c4... should i tilt the engine down to lessen the universal joints angles? diff is about 52" away from output of c4.

thanks for any help with this one...[img]/phpBB/images/smiles/icon_confused.gif[/img]

I would think you need some angle there,not much but some.Pretty sure you will be trashing driveshafts or tailshafts if its level.

If you're running a carburator, you probably want to level the carb to intake manifold flange by tilting the engine down to the back(to keep the carb level). All the intake manifolds that I've seen have an angle built into them.

The rear of the engine should be angled toward the ground. 2 to 3 degrees is a good angle. Never exceed 6 degrees. You can buy a cheap magnetic angle finder at most tool stores. The purpose of the angle is to cancel driveline vibrations.
Equally important is the pinion angle on the rear end. It should be rotated the same amount (in degrees) as the engine, but UPWARD. In this way, the engine/trans is parallel to the pinion, and the angles cancel out to minimize vibrations.
Be prepared to fabricate spacers for your trans bracket. You can buy wedges to rotate the rear axle.
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I always set a level on the manifold where the carb mounts. Makes a good easy way to figure it out. Done it twice while makin my own mounts to put 460's into 78-79 broncos.
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Look for an article in the next Car Craft magazine, due out in another few weeks. They'll do a whole article on this subject, including pinion angles.

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On 2002-10-11 18:26, Luv70sFords wrote:
I always set a level on the manifold where the carb mounts. Makes a good easy way to figure it out. Done it twice while makin my own mounts to put 460's into 78-79 broncos.

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That's what I did when I put the 460 in my Galaxie.
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3 degrees nose up, or make sure that the carb platform is level at ride height.
Funny HankyJ should mention pinion angles - One of the last articles in Bracket Racing mag by John DiBar(sorry, won't attempt to spell the rest) indicated that pinion angle "science" was bogus. Meaning - the car doesn't care.
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I hope this helps you understand pinion angle and what they mean by that and some clues as to when you install the engine and tranny with respect to alignment in the chassis.......


Actually the terms used for driveshaft alignment is "in phase". They can have different centerlines, but they must run parallel to each other. And they can be inline with each other under torque conditions.

Since the rearend moves up and down, you want the phasing of the u-joint angles to be in the same plane when the rearend is under torque conditions. That is, if the output shaft of the tranny centerline (when extend is the crankshaft too) is at say a 10* down angle at the rear of the tranny, then the centerline of the pinion gear (which the yoke and u-joint attach to) should be in a 10* up angle.

This brings up the question as to why do you hear about having the pinion angle pointed 4-6* down? This is due to the fact that the rear axle housing will torque under load and bring the pinion angle centerline up to match the centerline of the outputshaft.

Now, when they say 4-6* down angle, they are referring to 4-6* down from the phasing of the u-joints not 4-6* down from 90* (horizontal). So, if the output shaft is angled down 12* from horizontal, then the pinion shaft should be 6-8* above horizontal to obtain this 4-6* down angle.

The same applies to the pinion and output shaft centerline in left to right relationship. If the engine centerline is offset to the left or right, then the tranny centerline should be offset the same amount. You wouldn't have to offset the rearend if the centerline differences do not exceed the u-joint's specifications and tolerances.

Hope this helps and make sense. Just remember that driveshaft/u-joints deal with phasing.

JMO

So, when you install the engine and make the mounts.....use a level on the carb pad of the intake....set it as close to level as possible.....if the front of engine slightly higher than the rear of engine or tranny, you can work with but generally not when the front is lower than the rear of the engine......and then have the same offset of the engine and tranny in the chassis....that is, is the front of the engine is shifted 2" to the passenger side then the tranny must be also.

hope this helps....
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Thanks for pointing that out. Very good info. Phasing IS very important and I really didn't quaify my remarks. The article I referred to (and I'll go find it - maybe we should start a new thread?) dealt only with the driveshaft/yoke relationship as it is used for traction tuning.
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