SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: Rogers57x on December 22, 2020, 03:11:54 PM

Title: Driveshaft angle
Post by: Rogers57x on December 22, 2020, 03:11:54 PM
So I have a 1979 Rogers Dragstar the engine is a 489 stroker big chev has a 2 ft drive shaft  to the jet pump, right now the angle of the motor is about 2 degrees to the pump basically  about straight  on to the pump , the mounts look like  they were cut to lower the motor , I wish to raise the motor  up about 2and a half inches to clear my 10 quart oil pan and put my borla headers on ,will the driveshaft angle bind and put too much load on the u joints? Kinda like putting a 4 inch lift on a 4x4 truck and not changing the pinion angle any thoughts on this? The pic is what it is now ,without the 3 inch lift,Thanks
Title: Re: Driveshaft angle
Post by: Flusher on December 28, 2020, 05:03:55 PM
I seriously don't see 2" up happening, but one test is worth 1,000 theories.  Lift the engine with a cherry picker and see if you can get some 2" tube between the rail and the motor plates.  Then see how the drive shaft looks.

My micrometer eyeball is a little out of certification, but I think that isn't quite a 24" driveshaft.

If you wanted to crunch the numbers, you can get a really good idea by using .0175 per degree per inch.

That means that a 24" driveshaft, measured u-joint to u-joint, would be .420" higher at one end per degree.

.0175" * 24" * 1-degree = .420"

Or, a 2" change in height of a 24" driveshaft would equate to 4.76-degrees.

2" / .420" = 4.7619-degrees

You really need an 8" deep oil pan for a jet boat.

You will also get better performance from a lower center of gravity.
Title: Re: Driveshaft angle
Post by: Rogers57x on December 29, 2020, 02:37:54 PM
Thanks for the info flusher,  yes didn't think it would work  out thought I would ask though, I do have a milidon 10quart jet boat oil pan  it fits good just real close to the studs poking  thru from the intake but I can cut those, just got upswept borla headers with  mufflers  was hoping they would fit but I'll use my Bassett twisted thanks again flusher😎
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