Motor and transmission angles

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suicide33plymouth

Well-known member
Joined
Feb 25, 2013
Messages
48
So I have my motor and trans set at a certain look that I desire but the carb isn't level and the trans is at about 2 1/2 degrees but I like the look of the motor sitting where it is . So the question is what problems will I have if I let it sit right where it is and make the motor mounts? The motor is at about a 1 1/2 to 2 degrees angle nose down and not level to the frame .
 
So I have my motor and trans set at a certain look that I desire but the carb isn't level and the trans is at about 2 1/2 degrees but I like the look of the motor sitting where it is . So the question is what problems will I have if I let it sit right where it is and make the motor mounts? The motor is at about a 1 1/2 to 2 degrees angle nose down and not level to the frame .


if it's not pretty close to where it should be, you'll experience a pinion angle vibration that will not go away until you get the pinion angle back to correct...
A good clue is getting the angle right by getting the carburetor level...some can be corrected by changing angles at the rear end with wedges under the springs or actually re-welding the angle at the spring saddle to axle connect point.
 
Small foot

my understanding is if the pinion angle is at 2 1/2 down I can just put the pinion angle of the rear end at 2 1/2 up making them basically parallel right and there won't be any vibrations . I have a triangulated four link in the rear that is tacked in that I can adjust the angle pretty easy at this stage
 
I altered mine some too and was able to bring the vibration out at the rear end. It may take several tries. Not sure if all brands do the same but
chevy drivetrains are easiest if you try to get the manifold mounting surface for the carb level to start with.
 
Boat carb wedges

There are Carb mount wedges that are used on inboard engines to level the carb, The key to drive lines is to have the crank centerline and pinion parellel . an some trucks vans used to have the engines offset side to side
The Dana spicer webside has a lot of info. My link didn't work

google boat carb wedge and lots of hits for various carbs and wedge angles.
 
A few degrees might be OK, but if you're running a automatic especially you don't want too severe of an angle or the fluid will all be at the end of the pan, away from the pickup. Not as critical on the engine oil pan as it is deeper.
 
Where is the motor positioned? 1.5° down at the front, or 2.5° down at the back? It can't be both.

Ignore the intake/carb flange and measure at the pan rail or starter pad. (These surfaces are parallel to the crankshaft.) What do you have?

The rule-of-thumb for universal joints is opposite and equal. Pinion and crankshaft parallel to each other, though offset may factor and require some "adjustments".

I have this on file (below) and believe TIMOTHALE was referring to the same document...

Damn! It's too big to load here. I'll find the link...



EDIT:
Here it is...

http://media.spicerparts.com/cfs/fi...token=eyJhdXRoVG9rZW4iOiIifQ==&store=original

.
 
Last edited:
This is all good advice, but I want to underline one thing Dr. Crank said, 'Ignore the intake / carb flange angle', as it is usually 3 to 4 degrees off crankshaft level. Don't measure your motor, transmission angle where it's easy, [the carb base] measure where it's hard to get at like the pan flange.
While I'm whining about finding a nice place to measure from, I should say, some rear-ends have no visible surface that is parallel to the pinion shaft. You may have to take the driveshaft off and measure from the yoke.
Good luck.
 
Dr crankinstein

When I put the angle finder on the flat surface of the carb the angle of the carb is at about 2 1/2 degrees tilted forward front of the motor down im not saying the front of the motor is down I'm saying the angle of the carb is nose down. And when I put the angle finder on the out put shaft of the transmission it's at about 2 1/2 degrees . So if I do put the carb angle level it will put the carb at 0 degrees and basically add 2 1/2 degrees to the output shaft making it 5 degrees and making everything look tilted down towards the back if you know what I mean . It's a 460 with a c6 trans. My question basically was would it effect any thing if the carb wasn't level to the frame but the trans out put shaft angle and the rear end angle were opposite and equal which would be 2 1/2 out put shaft and 2 1/2 opposite angle rear end? Thanks for the advice guys
 
Thanks for clarifying. 2 1/2° down at the output and 2 1/2° up at the pinion is good.

I would take TIMOTHALE's advice and wedge the carb to level... which begs the question, what did the 460 come out of? (5° at the carb flange seems excessive. [S)

.
 
3 degrees down 3 degrees up is my formula, and has always worked perfectly. Like the other fellas here, I am wondering how you are coming up with such an extreme difference at the carb surface... [S
 
Measuring the carb and then the out put shaft

Yeah seriously that's why I was asking it's like the carb is kicked at an angle stock by a decent amount if I would put it level it makes the valve covers look angled downward towards the back and it's all stock out of a 1986 Ford F-250 that came factory with heavy duty springs in the back 1 ton I believe and the factory c6 with out overdrive
 
It's supposed to be lower in the back, that's so the oil will drain back to the pan better. The oil drains are at the ends of the heads. If the valve covers were level the oil could puddle in the heads starving the bottom end.
 
It's supposed to be lower in the back, that's so the oil will drain back to the pan better. The oil drains are at the ends of the heads. If the valve covers were level the oil could puddle in the heads starving the bottom end.

Exactly. The valve covers are parallel with the crank centerline, so they will also sit on the same 3 degree downward angle when the carb is level. That's how it's supposed to be.
 
carb leveling

When I was an engineer at Ford one of my buddies raced a 427 Cobra. ( he still races it, is the retired head of Ford racing SVO) one of the intake manifolds he used had too much angle. the cobra engine sat with the crank level . the wedges leveled the carbs but took some fiddling to get the linkage right again since the carbbs were then at different heights. .
 
Factory intakes should be level at the carb base, then the engine angle will be correct. Aftermarket intakes may vary due to their universal design to fit many applications. As long as you have enough rear drop that the oil runs to the back of the heads when it drips off the rockers, you should be OK. Then just measure the amount of rearward drop and set your pinion upward that much as a starting point. You might still have to shim the pinion up or down if you run into a vibration problem.
 

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