I know that this topic has been written about several times, and I have read the posts. There is a ton of great information in there. However, I have not seen any pictures of a 455 automatic crank in order to compare it to my current crank and to help clear up some of my confusion. The first picture (darker picture) is of a 70 455 crank that I have on a shelf and was allegedly pulled from the original block (which was cracked). It was on a 3 speed manual transmission car. The second crank is in 1970 455 motor that I am hoping to install into the car along with the original 3 speed. The depth of the recess of both cranks appears identical (to the bottom of the hole) and the diameter and depth of the initial recess appears identical. The difference appears to be the diameter of the recess (or section) where the pilot busing would ride. I don't have a measuring device at home that will allow me to get inside and measure the diameter of that recess but will likely need to. My question is whether the second picture appears to be "automatic" crank, and if so, shouldn't the depth of the hole be different than the manual trans crank? Any observations are greatly appreciated.

 

MT on the left, AT on the right.

 

Thanks, Joe. So, do you agree that it looks like second crank has been drilled, but that the dimensions are different than a typical manual crank? My crank definitely has recess where a pilot bushing would ride.

 

The second crank looks like an AT crank that got a clearance hole drilled to use a conversion pilot bearing without having to trim the input shaft.

 

Thanks. I was guessing the same thing after seeing your picture. The engine builder and I didn't compare it to anything but both assumed it was already set for a manual. It wasn't until I got the motor back that I looked closely at the dimensions.

 

The second one looks like a chevy pilot bearing would fit it ,in the depth of the hole looks like deep but hole diameter look small oldsmobile had larger outside diameter hole but center diameter hole was same for all GM tranys to fit , some engine shops just drill to fit common gm pilot bearing olds drilled the crank with outer hole larger to fit oldsmobile bearing .

 

The dimensions or drilling the crank are in the Mondello tech manual. It is a machine shop job.

The correct bearing is a BCA7109.

The conversion bearings are junk. I had one fail on me.

You need to get this right or you will have shifting problems.

 

Thanks, everyone. I was able to measure the depth of the second recess where a pilot bearing would ride and it is approximately .70 inches. So, it should have plenty of room to hold a bushing or bearing. I am hopefully getting my hands on an inside diameter measurement tool today. I am hoping that a common Chevy bearing will work. Fingers crossed!

On another note, I don't post much, but this site is awesome. Thanks for sharing all your insights. I have gotten a ton of good intel. I have been working on my 70 442 (black with gold stripes) and a Hurst 3 speed manual soon for many years now. It has been ground-up rebuild with body off. Just saw it in the paint booth last night. they are getting ready to spray the stripes. Getting excited to finally have it on the road over the next several months. Will share pictures

 

Comparing these two cranks to the image Joe posted of the MT above, are these cranks ready to go for MT? (One came out of a '75 full size and the other from a '69)

 

Yup, both look correct for MT. Here's the diagram.

 

Well that's certainly a pleasant surprise! Thanks for the info, Joe