Saturday, June 28, 2014

Engine Build Pre-Assembly (piston assembly)

 
 
Next job to do was assemble all the pistons with their connecting rods.  This job wasn't overly difficult, just tedious.  The pistons and connecting rods that I have are full-floating pin type, which means that the piston wrist pins are held in the rods and are not pressed in.  The wrist pin in my case is held in with spiral locks.
 
The picture below shows everything I used to assemble the #2 piston.

 

Each connecting rod has a flat side (below left picture), and a chamfered side (below right picture).  Before assembling each rod and piston I needed to make sure I had it in the right set up.  The chamfered side rests up against the crankshaft and the flat side butts up against the other connecting rod that it shares the journal with.  The Piston also needs to be in it's right position too.  In my case the intake valve relief needed to be set up as shown in the picture below.  I labeled the piston so I got it right.  The connecting rods NEED to be checked and double checked that they are correct, which I got one of them wrong (more on that later).





Here is a picture of the spiral locks.  These are a pain, but once I did a few they got easier.  Each one is stretched out to about 3/4".


I have a small pick set with tools that resemble something a dentist would have.  I found that these worked well for this job.  The first spiral lock is worked into the groove in the piston and slowly spiralled into the groove using my small pick.  Get the band aids ready......I cut my fingers several times.



The wrist pin is lubed up with some assembly lube that was supplied with my pistons.  I also put some in the connecting rod bore.


The wrist pin is slide in and then the spiral lock is installed on the other side.




Now, more on my mistake.  I don't mind admitting when I make a mistake.  Maybe someone reading this will learn from my mistake.  When I was putting the #2 piston and rod together, I didn't double check that I had the connecting rod in the right position.  I installed the piston and rod together and had both spiral locks installed.  I grabbed the assembled piston, and took it over to the block to check it.......it was wrong.  I had the rod in backwards with the flat side facing the crankshaft and the chamfered side facing towards where the #1 rod would be.  After I was done swearing, I started trying to work the spiral lock back out of the piston.  They are WAY harder to remove then install.  After about an hour I had it out.  I used two tiny flat head screwdrivers.  One to lift the end of the lock up and then the other to pry it out.  After I had the rod flipped over in the right position I installed a new lock back into the piston.  I searched the Internet about whether I should reuse the spiral lock that I had just removed and couldn't find a solid answer.  For the cost of a new lock ($0.97) I just put a new one in to be safe.

Here is a couple pictures of the finished products.







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