Do you have a tolerance for clearance?

I finished the pre-build of the engine over the past weekend, and didn't take any pictures.  That's ok because I took it all apart again.

It is called a pre-build because this is when you double check the tolerances, clearances, and fit of the rotating assembly... the cam, crank, pistons.....

Goes like this - wash the block, crank, and cam with soap/water and pressure wash the whole thing, then quick get your compressor on it to dry it out.  This was the first time I had the pressure washer out since moving here, although the neighbors have made good use of it, and I got sidetracked cleaning a section of the driveway... now I have another project to add to my list because I have one clean section and 5 dirty ones.

First put some oil on cam bearings and carefully insert the heavy cubersome bastard making sure not to nick the bearings... spin it to see if spins freely - now take it out making sure not to nick the bearings and inspect for shiny wear spots.  Didn't have any, good, now put it back in again making sure not to nick the bearings.  by the way, this is done from the front of the engine into a blind hole the entire length of the block - and the rear hole had already been sealed so the last bearing was a bitch.

Then wipe out the main bearing saddles, check the main bearings - fit them in and align with the oil holes, light coat of oil on the bottom portion, lift in the HEAVY crankshaft, and fit the top main bearings and caps.  There is a little tolerance gauge called plastigage that is a piece of green thread.  You can see it below (this is the piston rod for those that can tell) and torque down the bolts to spec.  105ft/lbs for a 351W.

loosen it all back up and measure the gauge to see how squished it got.

 

Do this for each of the 4 main journals, and each of the 8 piston rods - Oh and you can't move/turn anything while you do this or you mess up the reading.  All of the tolerances checked out against the shop manual I got for this motor.  You know - the book with the greasy fingerprints and bad black/white photos circa 1969.

At the end of this process, you have the cam, crank and all 8 pistons installed and turning making sure that nothing touches.. then whack on the timing set onto the crank and cam and now check for endplay on both the cam and crank.  These are good too.

Did I mention the oil pump and checking to see if the crank counterweight misses the shaft?  The pickup screen and how much clearance there is to the bottom of the oil pan?  How much clearance there is when the piston is at the top of the cylinder?..... blah blah blah.  This took 4 days.

This weekend will begin the painting of the block and prepping for the real assembly.  I've got lot's of shiny parts to go on this thing and I can't wait to see how it looks.