Engine rebuild (piston) question

biggerred

Member
I've rebuilt several M,SM,400 engines over
the years, but on my first C153 from a 504.
I did the usual: crank and piston rods to
the machine shop etc. I bought the
appropriate main and rod bearings per the
machinest. Here's the question. With the
notches in their slots, on the cap, the
bearing is flush on one side, protruding on
the other. On the rod, with the notched
side flush, the apposing side is recessed.
Kind of a male female situation. When
bolted together, it closes up nicely. No
gaps, no drag. Every other engine I've ever
done, the inserts were flush on each side.
Anyone else ever seen this? (Couldn't get a
shot of the rod)
 
Here's a pic
a229595.jpg
 
That is very normal, it is crush. The cleanliness of both is critical, and the shell is compressed into the cap and the other shell into the ron. Mains are the same. This tension provides a resistance to rotation, and eliminates any motion. Jimm
 
The bearing inserts should always protrude a little for bearing crush on all engines I have ever worked on. If they protrude too much the cap will not readily tighten down.
 
Looking at it,it made sense that it formed a lock of sorts. What really got my attention on this one was that it was somewhat out of line with the"joint".
 
I have torqued these down, and took the caps back off to check the alignment and this is how it looks after torquing
 
Everyone here is correct about the crush, just wanted to add the crush is to prevent the insert from spinning inside the rod bore when the cap is installed on the rod. Otherwise the insert could spin easily and damage everything. The crush helps push the insert's locating lugs tight into the rod and rod cap.
 
was just wondering because that looks like too much brg. protruding from the cap. what does the rod end look like with the brg installed? yes i know about crush but this picture looks odd.
 

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