How to Rebuild a Corvette 454 Engine - Part 7 - Page 2

With the help of a friend I got the crank placed in the block. Of course we were very careful to set it evenly into the block and took care not hit the journals against anything during installation.

With the crankshaft in place it was time to break out the Plastigage. Plastigage is precision formed piece of wax that is placed between the crankshaft journal and bearing. The main bearing cap is then installed, torqued to specifications and removed. After the cap is remove the oil clearance can be determined based on the amount the Plastigage deformed or "squashed".

Plastigaging must be done with the journals and bearings dry, so that means don't spin the crank or you run the risk of damaging your bearings! The first step is to install and torque all of the main bearing caps except for the bearing you plan to Plastigage. A strip of Plastigage is then placed across the journal an the bearing cap is installed, torqued to spec (in 10 ft-lb increments), and then removed. Again, don't spin the crank or you'll have to start over since this will smear the Plastigage.

The Plastigage comes in a sleeve that doubles as a measuring tool and is used to come up with the oil clearance. Below you can see this bearing has an oil clearance of 0.002". I'm shooting for 0.0025" so this is just about where I want to be. After cleaning the Plastigage from the bearing and journal the main bearing cap was reinstalled and torqued, and the adjacent cap was removed and the process was repeated. I checked each of the main bearings and clearances ranged between 0.002" and 0.003". This is about as good as I could expect so I'll go ahead and complete final assembly of the main bearings.

After removing the crank one last time, the bearings were removed and the block and bearing mating surfaces were thoroughly cleaned with lacquer thinner. It's important these surfaces are clean and dry, any oil or grease on these areas can lead to a spun bearing sometime down the road. And yes, that was a bad pun :)

After a thorough cleaning the bearings were reinstalled. With the bearings cleaned and back in place I moved onto installing the rear main seal.

I installed the seal in accordance with Fel-Pro's directions and offset the seal parting lines 3/8" from the bearing cap and block parting line. I also applied a thin film of RTV black sealant to the ends of the seal and cap flange to help prevent any leaks. Lastly, I coated the seal lip with a thin layer of grease. The picture below is of the seal in the bearing cap.

Once the bearings and rear seal were in place I oiled the crankshaft journals and main bearings and installed the crankshaft. After torquing bearing caps one through four to specifications I aligned the thrust bearing by prying the crank back and forth a few times. This is necessary because the rear main bearing is flanged, doing this ensures the two bearing halves are aligned vertically.

So, this is it. The crankshaft is in and torqued to specs. You'll notice that I got rid of the stock main bearing cap screws and replaced them with studs. Studs allow for more accurate torquing and also lead to better main cap alignment. They are also considered by many to be stronger than the stock bolts.

Boy, this was a busy weekend, but it's not done yet. On to the piston installation! Similar to before I cleaned the bearing mating surfaces thoroughly with lacquer thinner before installing the connecting rod bearings.

Installation of the connecting rod bearings is pretty simple, similar to the main bearings the two halves can easily be pushed into place with finger pressure.

Continued on Page 3>>>>>>