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post #1 of (permalink) Old 09-13-2003, 12:45 AM Thread Starter
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why do engines slope downward toward the rear?

I've always heard that they tilt toward the rear, but never thought much of it till we had the motor out of the B2 and I saw how the carb is mounted tilted forward so that it sits flat once the engine is bolted in. What's the reasoning behind this and would it be bad to lift the tranny mount a couple inches to get more belly clearance? Obviously the engine still works fine when going up and down steep hills so I don't think a couple degrees is that big a deal? The fan won't be perfectly square to the radiator but as long as it doesn't hit it that shouldn't amount to much. Whatcha think? It would probably take a body lift to accomplish this since my tranny is only 1" from the tunnel as it is, but generally speaking, is this a bad idea?
Sorry if this seems dumb but I've been dreaming of a flat belly of late [img]images/graemlins/chairfall.gif[/img]
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post #2 of (permalink) Old 09-13-2003, 04:15 AM
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Re: why do engines slope downward toward the rear?

If I'm not mistaken, its to help keep the driveline angle from beign to steep. If you space the trans mount up, you may run into a binding problem with the U-Joints.
post #3 of (permalink) Old 09-13-2003, 08:29 AM
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Re: why do engines slope downward toward the rear?

When measuring my rear for the hi-angle 1350 cv driveline recently I was suprised to find that the rear output of the BW1356 is tilted 5 degrees downward. This was a huge help because the driveline angle after a 10in lift gets pretty steep but you subtract from the BW and your still in business. Dont forget also the rear pinion to driveshaft should be within 2 degrees idealy according to the driveline people out there.

I dont know if that is the single reason for the engine tilt or if its just an effect from it and some other reason exists but depending on how much lift you have or plan to have youll want to consider it. Also before you make the change you might want to measure your corresponding angles between the rear driveshaft and the pinion. If your on the cusp of the 2 degrees now you might need to change out your rear axle shims after the adjustment. Im not the expert on angles but im sure there is some calculation to figure the effect of the engine tilt on the other anlges angle.
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post #4 of (permalink) Old 09-13-2003, 04:53 PM Thread Starter
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Re: why do engines slope downward toward the rear?

I guess the drivetrain angle could be the primary reason, but then I have to wonder if it's tilted like that on longer trucks because they don't need the extra tilt and it hurts the front angle as much as it helps the rear. This of course is ok for us Bronco guys because our font shafts are so much longer than the rears. Somebody should come out with a top-loader chunk for the 9" that turns it into a mini-rockwell, then driveshaft angles are no worry at all [img]images/graemlins/cool.gif[/img] I guess a MOG9 or HUM9 would affectively do the same thing, but damn those ain't cheap! I measured my front shaft at ~7° but haven't measured the rear... the CV can soak up a lot of angle but I'm not sure how much. I guess if I was really dedicated to this project I could buy one of those fancy cv shafts that can still function at 80° [img]images/graemlins/blush.gif[/img] [img]images/graemlins/smirk.gif[/img] I don't care that much, I just think it'd be cool to flatten out the belly if it wouldn't break the bank, or the truck [img]images/graemlins/40BEER.gif[/img]
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post #5 of (permalink) Old 09-13-2003, 05:15 PM
 
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Re: why do engines slope downward toward the rear?

Holy Cow !! It's rare that I know the answer to question posted here !!

Don't go screwin' with that tilt in the engine - it forces any air in your cooling system to rise to the front of the motor (then on to the radiator). Air pockets aren't very good at cooling & you don't want any of them in your motor.
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post #6 of (permalink) Old 09-13-2003, 06:11 PM Thread Starter
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Re: why do engines slope downward toward the rear?

[img]images/graemlins/goodpost.gif[/img] So basically if I do this, I need to put a couple extra inches suspension lift up front to keep the air headed upward [img]images/graemlins/chairfall.gif[/img]
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post #7 of (permalink) Old 09-13-2003, 08:08 PM
 
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Re: why do engines slope downward toward the rear?

To be honest My 10 yr old asked me the same thing a day ago, and I told him, because some damn Tech thought it would be funny to see all the mechanics work on tilted engines. I still have no clue! Although the air in the engine does sound a bit far-feched.

Like the gravitational force helps the moving parts move easier. [img]images/graemlins/chairfall.gif[/img] A passing by neighbor told my son that and I laughed hard! [img]images/graemlins/chair.gif[/img]. It sure does keep the rearmost bearings and such more oiled down.
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post #8 of (permalink) Old 09-16-2003, 06:18 PM
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Re: why do engines slope downward toward the rear?

Motors tilt to the side the sump is on.Sumps in the rear....motor tilts to the rear..It helps keep oil on the pickup.
post #9 of (permalink) Old 09-16-2003, 07:55 PM
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Re: why do engines slope downward toward the rear?

thats odd [img]images/graemlins/crazy.gif[/img]

all my previous fords had the sump in the front and those motors didnt tilt towards the front...
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post #10 of (permalink) Old 09-21-2003, 08:22 AM
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Re: why do engines slope downward toward the rear?

[img]images/graemlins/40BEER.gif[/img] Posed this query to a buddy of mine with a shop and he explaind that it is an optimal performance issue. Although the joints allow for the different part angles to work together the less stress there is the more productive the part and the combination there of. [img]images/graemlins/givemebeer.gif[/img]
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