Wednesday, June 3, 2015

Stage 4 - Big Ends, Pistons and Rods - 6hrs


Previous Build Sheet - 1mm oversized bore-->
After double checking ring gaps and cleaning the bores another couple of times, it was time to get serious and finish the bottom end.

I also had to figure out the big end clearance.

This is a sheet I created when I did the first build.
I have yet to complete a sheet for this current build

Using .0055" of stretch I am running about .038-.05mm of oil clearance on the big end.
I will slightly increase the stretch to ~.0065"





















































































I wanted to compare the three torque wrenches with a stretch gauge.  Interesting enough, they do vary by about 5ftlb.  After receiving some information from a professional engine builder I went on the path of testing the torque wrenches.

I was using the ARP chasing the stretch method, but I decided to try the below method.

http://www.performanceenginetech.com/connecting-rod-bolts-stretch-vs-torque/

"Depends on the type of fastener you are using. Word of advice though, when doing it by stretch, zero your stretch gauge on the bolt, remove the stretch gauge and then tighten the bolt to tension and angle and check the stretch. I usually start off at the lower torque spec and move my way up to get the desired stretch. On a 7/16 A1 rod bolt I aim for 0.0053-0.0057, providing your bolt yields the same, that will be spot on.

Don't place the stretch gauge on and tighten at the same time, this is what you'd call chasing the stretch and will always have inconsistent results"

I preloaded the opposing bolt to ~20ftlb and the zero'd the stretch gauge and torqued from
43->50->55ftlb to work out the desired torque for the given stretch of ~.0055"



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