I have my motor angle set up for zero degrees at the carb and zeroed side to side. My frame is also zeroed out. Is this good on the bubble or should I go down another 1/2 degree on at the rear of my motor? Thanks
you should have the carb mounting pad on the intake leveled side to side and front to back with the car at ride height. If it has any rake to it and you set it up with the frame level and the carb level, the motor will now be tilted down slightly. Could cause the oil to not run back to the sump in the oil pan and can cause carb float problems depending on how severe the angle is. Set the frame at ride height then level the carb.
Yes , what he said: you need the frame "rake" at where you want it for looks, then get the carb level. Then the pinion shaft angle needs to be same as crankshaft angle...or close as possible.
I added two new pics at the intake at ride height. I used shims to level from front to rear in one pic. In the second added blurry pic is the non level with out the shims. I am level side to side. I will need to shim the motor mounts to level the motor front to rear. I did not have to level rear to front. Am I good to go?
set the motor down 3 degrees to the back and the diff pinion 3 degrees up. Dont measure on the carb, measure on a pan rail or anything else that is parallel with the crank
QUOTE:"set the motor down 3 degrees to the back and the diff pinion 3 degrees up." Where are you guys coming up with a random 3 degrees? Some real early cars were nearly zero...meaning those engines had the oil sump and carb flange set to near zero.. And why would you measure the pan rail, rather than where the carb sits? The carb want's to be level, not the panrail. not making any sense here Example: if you choose 3 degrees up on pinion, and 3 down on engine, AND if the two are very close to each other, and heights differ a lot , then the U-joint working angle will be wrong(too severe of angle). If they are very far apart, the working angle decreases. "3 degrees" is the norm for the "optimum working angle of a needle type cross U-joint".(that keeps the grease flowing under the needles) That 3 has nothing to do with motor angle set to 3. The working angle comes "also" from height difference of pinion and crank, and distances Back to the real old cars again: Both the crank and the pinion would be near zero on some old cars, but because the height difference between crank and pinion, you can still get 3 degrees at the U-joints
To the OP; set the car chassis to the exact rake (or level , if that is what you want). next, move the motor until the carb is level, front to rear. next, set the pinion shaft angle the same as the engine crankshaft/trans output shaft angle. (in other words, if the back of engine is tilted down X degrees, the back of the pinion is also "down" the same degrees) Better way to see the angles is, if the "front" of the motor is "up" X degrees, then the "front" of the pinion is "up" the same degrees now run a string line or whatever, to be where the imaginary drive shaft center line will be. Now is when you measure the working angle of the U-joints. You are measuring the difference between driveshaft and engine crankshaft centerline. (and pinion). 3 is considered "optimum" as far as enough movement to lube the needles, but not enough severe angle to cause vibration. There are specs on the net for "U-joint angles". Those specs will say how severe of an angle is OK, and how much is not enough of an angle. I believe the "maximum" specs change a bit depending on driveshaft length. (this relates to vibration elimination in their charts) They will/should also have a spec on "mismatch" of angles of the two joints, but it's minimal
Now , When you have that all sorted, Remember..... Only drive on flat roads, Don't drive around corners as the centrifugal forces will hinder carb function. Only park your car on the flat when not in use. Don't even dream of driving up or down hills Now you are good to go.
1951 8BA Flathead w/C-4 transmission. Frame is at ride height. I get the pinion set up. I went back to my motor and looked at things again. If I do not shim the motor mounts, I will need to drop the rear of the motor down. But the transmission pan is sitting 5" from the floor now. The top of my motor mounts are flush with the top of the frame. If I measure at the oil pan rails, I am at 3 degrees but the intake/carb is also at 3 degrees and not at zero. All measurements are done on the same side of the motor. When I measure at the intake/carb, I get 3 degrees and can shim the motor mounts to zero it out with out dropping the rear of the motor, which would be the same thing as dropping the rear of the motor but easier and probably safer due to the clearance of the transmission. (sounds like My name Is Earl) Can shimming the motor mounts be done to gain zero degrees at the intake/carb?
Where I live (Missouri Ozarks), I'm pretty sure my car is never level on either axis for more that 10 seconds out of each minute and never continuously.
The key variable here is if your frame is at the actual ride height for when the car is on 4 wheels with the rake of how you want the frame to sit. Almost no real hot rod frames are perfectly level when finished. The frame needs to be at least close to the finished ride height or you measurements mean nothing.
If it helps, I have found that 1/8" nets you about 1° on an 8ba with the 39 trans I'm running. I put a washer from another biscuit mount setup under my mounts to shim them up when the raised mounts I put on weren't quite enough. I have not run this though.
--------------------------------------- Yes, 3 degrees is optimal u joint working angle. From the pics the shaft is not short. Correct, the u joint working angle is determined from the drive shaft not the frame. Keep the the trans output and pinion at the same but opposite angle at ride height. If you add the two angles together you want 0 (-2.5 + 2.5 = 0) No carb measurement mentioned here because it doesn't matter. (within reason) Use something that is in line with the crank. The carb is not one of those things. Intakes and carbs are not all the same.
If you want to be right on the gnat's ass you set the chassis at ride height/angle and then set your motor. Something to think about is that we took factory cars of all makes and models and raked 'em, dumped the front or the rear changed the tires and etc. We never changed the engine angle at all just modified 'em and drove 'em, no problems.
Carbs aren't that touchy. Set the engine in the frame so it fits and the driveshaft is right, not the carb. And if you are a real worry wart about the float, change to a Stromberg 97 as they are hinged from the side.
You might want to check the angle of the block without the intake , as later intakes have carbs angled to make up for greater angle of the engine , early blocks set almost parallel with frame rails . Set your ride height , pinion angle , tail shaft angle , then deal with your carb .
The 3 degrees has nothing to do with up or down of the engine but is the angle of the drive shaft as it relates to the rear differential u joint and the transmission u joint. You can use 2 degrees or 4 degrees and it doesn't make a whole lot of difference but they need to be the same. Set your frame at ride height and then set your rear end up 3 degrees and then set your engine to down 3 degrees. This angle will stay the same wither your going up a hill or have a fat chick in the back seat. The purpose of the 3 degrees is to assure proper lubrication of the u joints and to keep them in faze.
Spicer and Dana have good info, on achieving proper driveline inclination. It all begins, however, with a level carb base, measured at the intake.
I think the industry standard of 3 comes from the the fact that motors like the SBC have a crank angle of 3 when the carb is at 0. With that said I normally zero out the carb at loaded ride height, measure the trans output angle and set the rearend at the opposite ie 3-/3+ And I would invest in an actual degree finder, the analog one is maybe 10-15$ digital is my preference
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