Chevy 350 Small Block Build - Part 3 My First Engine Build

Checking the main bearing clearance can be done one of two ways. First, you can assemble the main bearings in the block without the crank, torque the caps down, and then use an inside micrometer to determine the ID of the bearings. Then, by using an outside mike and measuring each journal, you simply do the math. A much simpler way is to use Plastigage. This thin, plastic-like material is designed to be placed between the crank and bearing. Once torqued down, the Plastigage is measured and its width determines what the clearance between the crank journal and bearing is.

And finally the cast-iron arm was carefully placed into the block. Note that there is no grease or lubricant used at this point.

One of the other items that Pat picked up from PAW was a complete engine fastener kit from Milodon. One of the components was a set of main bearing cap studs designed to be used especially with Milodon's trick windage tray. As with any fastener, a good lubricant should be used prior to installation.

One area that Patrick got the benefit of better tools and techniques was in checking the crank's endplay. A dial indicator and magnetic stand made quick and accurate pickings of this spec. However, a feeler gauge stuffed between the thrust bearing and the crank's fifth journal does the job just fine.

Patrick's next step was to undo all of the main caps and lubricate all of the bearings. This required removing the crankshaft one more time.

A good torque wrench is an engine builder's most trusted friend. If the book says torque the bolts to 65 and use oil as a lubricant, do it!

Don't we wish more things in life had such easy directions? How could you go wrong with an arrow on top of the piston telling you what way to point it in the bore? Well, believe it or not, you can install them just the way they tell you and still be wrong. That's because they have to coordinate with the connecting rod. And since a piston can go on a rod either way, you have to make sure they are aligned properly. In Patrick's case, PAW had marked each piston/rod combo with an L or R, indicating what side of the engine it needed to go in.

Note the absence of rings. Subsequently, no ring compressor was needed to get the pistons in their bores. It is important to keep the rod bolts from scoring the cylinder walls or crank journal. Therefore, caution is the best thing here.

Checking the rod bearing clearance is an important part of building a reliable engine. As with the crank, the bearing was installed dry and the piston/rod was installed in the block and torqued down.

Again, Plastigage is used on the crank's rod journal. The cap is tightened to its correct torque spec and the squished Plastigage is measured. Voila, our rod bearing clearance was dead on.

With bearing clearances checked, Patrick moved on to making sure that the rings would fit perfectly in the freshly bored cylinder walls. Using another special tool (which only made the job easier), each ring was squared in the bore and the end gap was measured with a standard feeler gauge.