Technical Opinions on th350 tailshaft position in 53 bel air

About to start modifying my transmission cross member for a proper mount. Currently it has a 1/4" plate bolted in place of the mount that then bolts to the original closed drive power glide mount. Always felt like the rear of the trans was an inch or two too high. And intend to correct in the process of modifying the cross member. For guys that run an sbc in a 49-54 Chevy car what do you think? I know the body of my gennie style shifter stick out of the tunnel a good bit and body of the trans comes to less than an inch in spots to the tunnel

 

Put an angle finder on it and set it up 3 degrees down

 

Ok this is a reading on the plane of the car itself

 

And here's the reading off the engine

 

So I'd guess that means my tailshaft is 7° too high?

 

Use the Tremec app to calculate your drive line angles and you'll know where you're at.

The angles between the driveshaft and the trans and the driveshaft and the rear end are what you want to know.

You need to do all measurements with the rear end at ride height (jack stands under the axle).

 

Just check your angles at the engine and pinion body makes no difference.

 

Before I open my mouth with a super simple way I need to ask to be sure. It has a V8 now?

 

At the same car position the pinion is at 86°. Couldn't get a screenshot because that end of the car is too low to check angle And take a screenshot lol

 

Yep. Cliche 350/350 short tail

 

So that’s 4 degrees up.

 

Level car at rocker panels.
Remove carburetor.
Put a small level on carb pad of intake.
Raise/lower trans until level on intake reads level.

 

Check the crankshaft centerline to the pinion center line in relationship to the driveshaft angle. You should never have a level on the frame of the car.

 

Eh kinda stuck doing it with the car at current position. Otherwise I can't work on it lol.

 

Need car angle for reference. Car is on car ramps on a slight slope

 

Is the rear end axel tubes on jack stands or is axel drooping?

 

Exactly how it is sitting

 

Then do what Saltflats said.

 

Well you will want the pinion center line at ride height, the crank center line wont change.
Thinking out loud I wouldn't tackle that project until the car was properly supported.

 

It's a tackle as it is or don't tackle at all kind of deal

 

And suspension is at normal position

 

Then just use the crankshaft center line to pinion center line.

 

Did the mount in that spot on a 54 years ago.set the mount on the cross member.. plated the top of the crossmember. Used a single bolt mount. Set carb level. Set the rear at zero. Drove like a dream.no issues.

 

Was my original plan before I actually stabbed the engine and trans in. Unfortunately with mounts slid all the way back the mount mounting holes on trans are a couple inches too far forward

 

This is how to do it. Angle 1 and angle 2 should be equal, or as close to equal as possible. 2 to 3 degrees is good. It has no relationship at all with the cars frame or body. Only the angles between transmission/driveshaft and driveshaft/pinion matter.

 

I’ll clearify why I said to level the car. This car does not have mods that require special needs. Stock these cars were level. Just base line referance points needed on this one.

 

Only alteration to anything drive line related besides obvious eng/trans/rear end swap is I lowered the rear 3"

 

That would change the angles if it was lowered after the driveline was set up.
If you are leaving the suspension height as it is now, just follow the diagram above and it will be right.

 

My guess is that you have a "smart phone", here is the link to Tremech's app that should be helpful to you. I've used it on every engine swap I have done.
https://www.tremec.com/menu/tremec-toolbox-app/

 

Really doesn't matter what angle the body sits at, but you want to take measurements with the car sitting static as it would be on the pavement. So if the car is jacked up on those ramps now, then you need to get the same height under the rear tires before checking engine angle, or trans angle.
I prefer using the carb base on the intake manifold to check angles front to rear, and side to side. Then build the trans crossmember to ensure the engine angle is close to flat at the carb base. A number of intake manifolds have angled carb bases to situate the engine 3-5 degrees down at the rear when the carb base is level. So the carb base is the best place to check level.
Whatever the trans angle ends up at will dictate the pinion angle as the two have to cancel each other if you want to avoid induced vibrations caused by mismatched angles.