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Old 09-09-2019, 10:55 AM   #1
Mike Savelle
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Smile engine angle

putting together a second gen Camaro and when the motor is in , its higher in the rear, I'm sure the back should be lower but how many degrees ?
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Old 09-09-2019, 11:15 AM   #2
FireSale
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Default Re: engine angle

I've heard that the carb base should be level. Most manifolds are cut to slope down (I think 4 degrees).



Here's an interesting article from On All Cylinders regarding Jerry Bickel. It's not a Stocker, though.


https://www.onallcylinders.com/2016/...s-drag-racing/
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Old 09-12-2019, 05:58 PM   #3
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Default Re: engine angle

There's two things to consider, one is the driveline angle and the other is that the engine is at least one degree up from level in the front so you don't get air trapped in the engine when filling with coolant.



https://www.iedls.com/uploads/files/...in%20Setup.pdf
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Old 09-12-2019, 10:31 PM   #4
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Default Re: engine angle

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Originally Posted by Chevy55 View Post
There's two things to consider, one is the driveline angle and the other is that the engine is at least one degree up from level in the front so you don't get air trapped in the engine when filling with coolant.



https://www.iedls.com/uploads/files/...in%20Setup.pdf
Nice little guide. I need to redo the pinion angle of my Mustang over the Winter and this will help.
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Old 09-13-2019, 10:21 AM   #5
Dave Gantz
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Default Re: engine angle

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Originally Posted by FireSale View Post
Nice little guide. I need to redo the pinion angle of my Mustang over the Winter and this will help.
That is nice. I'm putting a 9" Ferd w/ladder bars in a Duster. That should help a bunch.
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Old 09-13-2019, 06:51 PM   #6
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Default Re: engine angle

If this is a typical big tire backhalf car with the rear u-joint CL higher in the car than the front joint CL, having the engine nose down will help achieve desired operating angles on the joints while keeping the pinion angle negative or nose down - which is desired in a drag car.

Otherwise, using the OE engine 3 degree down in the rear mounting, you get into the "broken back" arraignment.

Plus, the oil pan, headers, steering, etc all have to fit each other. It takes some planing and time mocking things up.
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Old 09-14-2019, 06:49 AM   #7
Mike Savelle
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Smile Re: engine angle

No big tires for me , its a stock eliminator small block Camaro, and I finally got it to 3 degrees. what does the broken back mean? Thanks for all the replies
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Old 09-14-2019, 07:53 AM   #8
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Default Re: engine angle

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Originally Posted by Mike Savelle View Post
No big tires for me , its a stock eliminator small block Camaro, and I finally got it to 3 degrees. what does the broken back mean? Thanks for all the replies
Due to the increased diameter of big tires, the axle centerline sits lower in the car than original. Essentially the car is lowered in the rear. The drive shaft has to travel "uphill" from the transmission to the pinion. We tend to want the pinion to driveshaft angle smaller on the upper plane for drag racing, think "positive pinion angle". You end up with the shallow driveline angle on the upper plane at both the transmission and pinion, forming a very shallow "U" or broken straight line, the driveshaft breaks upward at the transmission and again at the pinion. I have a friend that refers to that condition as the "skip rope angle". Not good. Doesn't "broken back" sound easier?

Ideally, you should be able to draw a straight line from the front of the crankshaft, through the transmission, and straight on through BOTH pinion bearings. That way, when you adjust the driveline/pinion angle at the axle housing, the included angle above the pinion is equal to the included angle BELOW the transmission. That way, just like the referenced guide, the "uncancelled angle" is zero.

Last edited by Tom Broome; 09-14-2019 at 08:17 AM.
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Old 09-14-2019, 12:29 PM   #9
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Default Re: engine angle

Here is a graphic that shows what Tom is talking about in slightly different words. The results of the output and input angles should be as close to 0 as possible in theory. In practice you need to add some down angle to cancel out the tendency of the differential to try to wrap up the springs under launch load. I've read 4 degrees down for the pinion but I don't know how bars like Calverts cancel that out.
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Old 09-14-2019, 01:06 PM   #10
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Default Re: engine angle

A common configuration on a big tire car with the engine in the stock location is having the engine 2-3 degrees down from level towards the back, the pinion down 2-3 degrees from level and the driveshaft very close to level - the broken back or skip rope effect. It's a compromise to avoid a positive operating angle on the rear u-joint.

An ideal situation is having the crank/trans CL pointing directly at or just below the rear u-joint CL with the pinion angle (operating angle) being negative (pinion down) to some amount which is determined by suspension/traction device used. i.e. the crank/trans shaft and pinion at or near parallel with the appropriate pinion/driveshaft operating angle. Not easily done in many applications.
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