Engine Build Pre-Assembly (crank straightness, crank measurements and main bearing oil clearances)

 

Before I put the engine together for the final assembly there are some critical measurements and clearance checks that need to be completed in any motor to ensure that this engine will have a long life.  In the next few entries I will be going through these checks and I will try and explain the best I can.

 

Here is the Crankshaft.  I cleaned it up with some brake cleaner.

 

The first thing that I checked is the straightness of the crankshaft.  To do this I installed the #1 and #5 main journal bearings with some lube, I then set the crankshaft into the block carefully (it's heavy!).  I then install the main caps on #1 and #5 and torqued them to spec.

To check the straightness of the crankshaft, I used my magnetic base with a dial indicator setup on the #3 journal.  I zeroed the dial and then rotated the crankshaft a few times and see if the dial reads anything.  I then moved the dial indicator to the front snout of the crankshaft did the same thing.  I then took the #5 main cap off and put the dial indicator on the rear main seal surface.  everything checked out perfect, which means the crankshaft is perfectly straight. 

Here is a picture of the main caps with their bearing halfs installed. 

I then installed the rest of the main bearings in the block.  I then lubed the bearings up, set the crank back into the block.  I installed all the main caps and torqued them to spec and then spun the crank by hand making sure it spun with ease.

Every time I torqued any bolts down I coated the threads and washer faces with ARP lube.  This is used provide accurate torque readings each time.

The main caps were then taken off and the crank was then removed again.  The lube on all the bearing surfaces was then all wiped clean and the main caps are reinstalled without the crankshaft and torqued to spec again.

I then took my 2"-3" micrometer and measured every journal on the crankshaft and recorded the readings I got.  These readings will be used later. 

The next check I did required using a dial bore gauge.  I had never used a dial bore gauge before, so it definitely took me a little while to get the hang of this tool.  I'm not going to go into much detail on how to use this tool, but if you are wondering how to use it I found a lot of helpful youtube videos on how to use one.  I was using it to check oil clearances.  so what I did was take each journal measurement from the crankshaft and set zero on the dial bore gauge to that measurement.  Then when I put the dial bore gauge into each main bore in the block and took the reading it read the difference between the crank and the block, giving me my oil clearances

I then repeated this for each main bore and recorded each reading

All the main oil clearances on #1-4 bores came in between .0025" - .0028" and the #5 bore came in at .0032".  It is normal for the #5 main oil clearance to run a little looser.  I would like to note that all these measurements I did were double and triple checked each time.  I am happy with all the measurements I got so far and are right on spec for my engine.

Just as a added insurance, I decided to check all the main oil clearances with Plastigauge.  Plastigauge is a little strip of plastic that is put on each crank journal, then the caps are torqued down on top of it.  When the caps are torqued down it squishes the plastic.  The caps are then removed and the squished plastic is then compared to a clearance chart, giving a clearance measurement.  This method is less accurate but still works.

The thin strip of plasticgauge is hard to see in the picture below unless you look closely

In the picture below, I am comparing the squished plastigauge to the comparison chart found on the plastigauge package.  All my plastigauge readings came in at around .002" give or take a bit.  So as this is a less accurate method of measuring clearances I am happy with those results.

In the picture below it shows my white board that I mounted to my garage wall.  I bought this from walmart and find it to be a great investment, it comes in very handy for recording all my results as I go.