The Great Pumpkin - '71 Duster

Well, I managed to get the bearing measurements done. I finally figured out the dial bore gauge and now I have a decent feel for it. Not sure why I was fussing over it so much, it wasn't that big of a deal. Sometimes you have to fight through your trepidations and just do it because once I started, things just came naturally and I just knew what to do. I actually had a rhythm going.

I believe the one thing that might have contributed to my missteps was disorganization. Maybe I was doing a couple things at once, there was probably a bunch of stuff cluttering up the bench etc. There really is a benefit to being neat and organized because there are so many things that can and will trip you up. Why make it hard on yourself and introduce more possibilities for error?

So I cleared off the bench and put some new clean paper down. I took the crank and bearings out of the block and washed everything again with hot soapy water, then rinsed with clean water and air dried. Yep, wash, rinse repeat.

So now I got everything all clean and lined up on the bench on new paper. All the other crap was cleaned up and I was in the zone - no wife or kids around, just me, the dial gauge and my bearings.

The procedure is to do each journal individually. Step one is to mic the main journal and lock the micrometer to wherever it's set. Most of the readings I got were either 2.500" or 2.4995". Then, the locked mic gets clamped into the vice to 'zero' the dial gauge. If you've never used a dial bore gauge before, it has a spring-loaded plunger that accounts for any variation from a known spec. So you find the right-length adapter (2.500" in this case for the mains) screw it down to the gauge end and put it into the locked micrometer. It should fit without the dial moving at all or at least very little. Once you see that the gauge is not moving while inside the mic jaws, the gauge is set.

Now, you move over to the block. I installed the studs finger tight (per the ARP instructions) slathered some moly lube on the threads and torqued 'em down to 110 ft lbs in three equal steps - 36, 73, 110. Then the 'zeroed' dial gauge is inserted into the main bore to check the clearance which in my case is .0025". With the gauge inserted (make sure it's not in the bearing groove or oil hole) it is rocked back and forth. You watch the dial face to see how much the pointer moves. It will reach a certain point then will change direction and go back to where the dial was initially set. That is your measurement. To keep the thing steady, you put a finger behind the plunger section. This really helps because the adapter can slide around and even the slight pressure from your finger will just keep it that much more steady and solid.

I basically found everything was dead nuts, probably the most variance was .0005" one way or the other. So again, the machine shop nailed the job and everything looks good to go. And honestly, any variation was probably from my amateur measurements and cheapo off-shore dial gauge. Close enough for horseshoes and grenades I guess.

So next the crank goes in for good and the caps torqued down for the final time. The rear main seal is in. I checked the little cap plug that goes underneath the #5 cap and it's in there 'cause I never took it out.

One thing I do have to take care of though is to install the rear freeze plugs before the crank goes back in. To get this done, I unfortunately have to take the block off the stand to get enough access. I knew I would have to do it this way since I painted the block before putting the plugs in. What I probably should have done was put the rear ones in before painting since you don't really see the back of the block but we all know I ain't too swift. Oh well.

But hey, I learned something today and I was happy that I forced myself to do it. Felt like one of those rite-of-passage things. I will always know how to do this now.

Sorry, no pics again, was just focusing on doing the job, didn't even think about it.

More to come.