49 chevy progress, Trans Position

rooster · July 11, 2005, 09:08:44 PM

Son got his engine set in today 305 350T, We have made a dropout crossmember for the trans mount. Not sure what to do next. Do we place a level where the carb bolts down, then have it tilt down a few degrees? Then check pinion angle? TIA

GPster · July 11, 2005, 09:55:31 PM

Back in the old days when intake manifolds where only made for carburetors we used to use a level on the carb flat both side-to-side and front-to-back. The carb base has a few degrees built into it to allow a back tilt of the crank when it's level. Set the car at the "rake" you want , level the carb base and then get your driveshaft angle at the pinion of the rearend. GPster

rooster · July 12, 2005, 05:00:39 PM

Heres what we came up with.
With a magnetic angle finder placed on the yoke of rearend 1/2deg-.
With a yoke placed in the trans we got 5 deg-.

Car sitting on level ground, eng resting on mounts, trans tailshaft supported by jack, bellhousing is maxed out for space on floor boards clearance. Also had greg stand on frontend to makeup for missing weight for front end.

GPster · July 12, 2005, 05:16:09 PM

The way I understand it the the pinion and the tailhousing angles should be the same . My first responce had to do with the level of the engine so that the carb was at the proper level to keep gas in the carb float bowl. If the angle at the tailhousing is 5 degrees than the pinion should be 5 degrees, then the difference in height between the pinion and tailhousing would give you the same angles at the universal front and back so that the universal joints so that the universals can work. I'm not smart enough to draw pictures. GPster

rooster · July 12, 2005, 05:39:49 PM

Quote from: "GPster"The way I understand it the the pinion and the tailhousing angles should be the same . My first responce had to do with the level of the engine so that the carb was at the proper level to keep gas in the carb float bowl. If the angle at the tailhousing is 5 degrees than the pinion should be 5 degrees, then the difference in height between the pinion and tailhousing would give you the same angles at the universal front and back so that the universal joints so that the universals can work. I'm not smart enough to draw pictures. GPster

With the driveline sitting in this position we placed the bottom half of the air cleaner over the carb, then a level for a stright edge on the cleaner, then placed the angle finder on top of that! The engine is leaning 2 deg- toward the rear. I think that part is ok.

Knot so sure about the other readings. I was thinking if you have 5- on tailshaft we would need 5+ on the rear. But that would point the hinnie up with the purches in the current location.

He plans to cut 1 1/2 coils out of front springs I guess this will also change things!

enjenjo · July 12, 2005, 06:40:35 PM

Here's a good article on driveline angles http://www.roddingroundtable.com/tech/articles/driveline.html

You just have to look around a bit.

FWIW, with the carb set level, most GM engines are angled 5 degrees down in the rear.

rooster · July 12, 2005, 07:18:45 PM

Quote from: "enjenjo"Here's a good article on driveline angles http://www.roddingroundtable.com/tech/articles/driveline.html

You just have to look around a bit.

FWIW, with the carb set level, most GM engines are angled 5 degrees down in the rear.

If I understand this right, I could add 2 2deg shims that would bring this very close, within a 1/2 degree! It dosent matter if there + or - just so there equal, both could be one end + and the other -, but just equal! Or both ends -, but equal.

thanks for the hookup

jaybee · July 12, 2005, 08:31:42 PM

If I understand you to be saying that the angles should be equal but opposite you're right on target. FWIW, a lot of guys set up the pinion angle to be just slightly down in front from equal. The pinion will rise slightly under power and then it will be just about perfect. Since it's fine either way that says to me that there is a slight (note slight) tolerance for unequal angles.

rooster · July 13, 2005, 01:24:33 AM

We just finished up the trans mount , now all the weight of the trans is in its proper place. There was no change in the angle though! Its at 5deg-.

The angle finder we are useing is not a persison instrument (harbor freight} but it does show the rearend pointing downward 1/2 to 1deg-.

I think when the front springs are cut ,1 1/2 Coils the reading will change again at the trans shaft. Hopefully the tapered shims will do the trick, if not we will move the pinion downward to match whatever degrees needed and weld in new perches.