The Stovebolt Site Forums The Shop Area Engine Shop Does the 216/235 sit flat in the frame?

My '51 3600 does not have the original crossmember for the rear motor mounts. It was replaced with a cludged crossmember for an automatic transmission. I am putting a 235 with an SM420 back into the truck. The prop shaft is two-piece, open style (no torque tube). I will have to fab up a new rear motor mount crossmember, so I'll set up the motor and bell housing in the frame to get my dimensions. Looking at the intake manifold, and going by what I've read elsewhere on this and other web sites, the carb base should sit at zero degrees. So, am I correct that my 235 should sit flat (parallel to) the frame?

Going a bit further so I don't cause a separate issue, do the motor and trans then create a flat, straight line to the inermediate prop shaft support? I'm using a Dana 60 rear end, so the diff is off-center. The universals in the rear half of the prop shaft will be loaded up both vertically and horizontally, but if the front half of the shaft is flat and straight, should I be concerned about the unloaded universal at the transmission output?

I can’t answer your second question but the engine definitely sits at a slight angle, lower in the back but the manifold corrects this and places the carb so it will sit level. Take another look at the manifold and you will see this.

Rear tilts down, generally 5-8 degrees.

I would look for a rear crosmember from a junk truck there should be a few around and should be salvageable even on a rustbucket

Yeah I'm with KEVINSKI, put wanted ad out for original crossmember!

If you set the engine on the front motor mount and level the carb base, the angle of the crankshaft will self-correct. There is a slight downward angle to the crank and the trans output shaft. If a U joint does not have a slight offset the needle bearings will not rotate on the cross. I believe there is a good article somewhere in the tech tips section of the forum on setting up driveline angles.
Jerry

I thank you all for you input. This is my first build and I'm probably over-thinking the situation, but I want to be sure I'm making the right decisions.

I've looked at my 235 motor six ways to Sunday and for the life of me I don't see an angle to the intake manifold on this motor. Photos of other 235's I've looked at definitely show an angle. The junk 250 I took out of my truck showed a discernable angle to the carb base. I just might not be seeing it without a carburetor sitting on it.

I'd love to have an original crossmember to put back into the frame. Unfortunately, the local wrecking yard where I've taken a couple parts off of a pre-'54 3600 won't let you part out the frame.

So based on the input I've received, and what I've read elsewhere, I've attached a drawing to illustrate what I'm going for. The motor and trans pointed down at the rear (let's say 4 degrees). The prop shaft is then flat through the carrier bearing. The drive shaft then angles down (same 4 degrees) to the differential, which is angled up (again, 4 degrees). The sum of all three universal angles is zero. Since the differential is off-set from the centerline of the truck, the universals at both ends of the drive shaft are at a slight horizontal angle, loading up the universal at the diff and also totalling zero. Does this look correct to you guys?

Don't try to eyeball the angle of the carb flange. Put a carpenter's level on the manifold and shim the engine cradle until the bubble centers, then stand the level up at the back of the bellhousing and see how far off plumb the bubble is.
Jerry

I will do that. I hope to have the motor buttoned up soon. Thank you!

I built a spacer for the steady bearing to make the driveshaft match the slope of the crankshaft. So it's like a simple extension of the crankshaft.

Gord, did you read Jerry's post above?
That's true, although with a stock bushing type u-joint, I'm not sure it matters that much.

Here's what Spicer says about it:

https://www.stovebolt.com/techtips/driveline/setup/index.html

Thanks, Grigg!

Unless the joint flexes a little, the lube doesn't circulate and the bearing runs dry from having the same point of contact all the time.
Jerry

My setup is like figure 10 on page 14 of the manual: https://www.stovebolt.com/techtips/driveline/setup/DSIG-3311.pdf

I find it interesting that the diagram in the Spicer shows the motor and trans sitting flat.

You guys with 1954 and later trucks seem to have an easier time of it. The later style bell housing with the angled rear motor mounts, and a one piece drive shaft, looks to me to be a better set up.

From the Tech Tip:
Rule #1 -- Universal joint operating angles at each end of a driveshaft should always be at least 1 degree.

Figure 10 may show the angle of the shaft at the transmission output as zero, but it's not labeled as such. See Rule #1.

Perhaps I'm commenting on the obvious. If so please forgive me but driveshafts don't spin at a constant velocity unless they have CV joints at each end. With a cross-type u-joint the variation in angular velocity within a given revolution increases as the driveshaft angle increases. Because of this even with all angles cancelling to zero, a steep driveshaft angle will create a noticeable vibration. So, careful placement of the rear crossmember is paramount irrespective of the carb flange. You may have to set the engine off center to match the rear axle to get horizontal angles correct.

As Spicer's tech tip says, U-joint angles need to be >1 degree to spread grease but they must be equal on both ends within 1 degree for trucks, 1/2 degree for motorhomes or they will vibrate, according to the book. I suppose motorhome drivers have less tolerance for vibration. To get the angles correct on my truck with an auxiliary trans I had to shim the front motor mount with front-end shims and with various washers on either end of the auxiliary. Now when the truck is loaded, the driveshaft is 1 degree off straight, main box through the auxiliary and same between the auxiliary and the rear axle. It does not vibrate even at 3,000 + RPM. You may have to change the shims between the rear axle and springs rather than shim the front motor mount. I wanted to avoid shimming the axle because I wanted the auxiliary springs to hit the perches correctly. You might also want to shim the carrier bearing. I have no idea if my carb flanges are level nor do I care. It's all about the u-joint angles.

Brian, If you set up the angles per your graph paper drawing you'll be fine. I looks like it came out of the Spicer book.

The three angles should add up to zero.

https://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

A quick update to my situation. First, the local wrecking yard with a truck I've been getting a few parts from allowed me to remove the crossmember that my truck is missing. I had to use a battery powered reciprocating saw and hand tools (no grinders allowed) but I was able to get the crossmember removed (the transmission was already gone which made things easier to access). So that takes all of the guess work out of how my motor and trans will sit in the frame. Second, I took a long look at the intake/exhaust manifold from the junk truck's 216. I showed it to my son and he agreed that there is no slope to the intake manifold (unlike the one on my cracked 250 which has an obvious slope). Then I saw what I have been missing all this time. The base where the carburetor mounts is machined at an angle! I never saw that on my motor because the Bakelite carb riser was in place (and the hole was stuffed full of paper towels to keep dirt/debris out). I'm not going crazy and everything is now right with the world! Thanks again to everyone for your input.

Its amazing how getting the original parts makes life easy. I glad it worked out for you.

I'm working out the details of how to set a manifold up and mill the one barrel flange away- - - -to replace it with a 4-bolt flange for a Rochester 2 barrel for a 265 V8. I'm going to have to mill all the way down to the front/rear tube and replace the plenum under the carb with one that won't restrict gas flow like an adapter would. Getting that done without also creating an exhaust gas leak from the heat riser chamber might be interesting!
Jerry