tolerance stacking

Well, the saga goes on.
Yesterday I was able to borrow the machinists height checker dial gauge and measured the piston stick-out above the block. Due to tolerance stacking, in order, the pistons were 010, 013, 014, 014, 0155, 014 sticking out of the deck. Those numbers were supposed to be 010. The reason I think they got off was the crank was ground 10/10 which meant they had to follow the casting which could have been off from OEM. So 2-3 thousandths there and maybe a piston was cast a little off and then maybe a bearing shell was off and maybe the rod wasn’t perfectly ground. When you add up the 4-5 different possible places to have a critical dimension, then you can end up with that much error. The 010 out of the block is what I want to end up with so that combined with the measured 049 headgasket that supposedly will compress to 046… I’m gonna be pushing the compression!

So today I pulled all but the #1 piston, marked bearings to make sure they went back exactly in the same spot, and pulled the rings BACK off the pistons and took them back to the machine shop to be re-cut to alleviate the 0055 too much stickout. Will see on Monday what it ends up with.

cam timing and nerd speak

So I got out the degree wheel and the dial caliper after spending a lots of hours wrapping my brain around degreeing the cam.
I needed a way to reach WAY down into bore to get to lifter and accurately measure valve lift. A lot of people mention using a pushrod but it woulda been flopping around and just not as accurate as I wanted.
I grabbed a handful of the old lifters and welded them together. That way there would be limited rocking, I would be assured of a solid contact and hands-free operation. I used 3 of them and welded together in a stack with bottoms at both ends for a flat measuring surface. First try worked for a bit then weld broke cause I had to grind smooth to fit in lifter bore. Next try will be perm as I ground 3 vertical deep grooves for weld to grab so I could grind smooth but still have a good weld.


I set it all up and got it dialed in with TDC zero and all (BTW-due to some tolerance stacking and an error in initial bearing size the piston instead of zero deck is proud about 7 thousandths…)
I had a heck of a time making sense of the results-it was telling me I was 166 degrees centerline (54 degrees retarded) or something equally weird (116.5/216.5)... This went on for a while till I realized I was measuring exhaust lifter instead of intake-DOH!
Once I fixed that (swapping holes is what broke initial lifter extension) I initially measured around a 125 centerline (80.5/169). Cam is ground to be a 112 and factory set –8 retarded. I wanted something more like 109(3 advanced) and I ended up with 63.5 at 050 before max lift and 154 at .050 after max lift to give me a 108.75 centerline.

This changes things too depending on headgasket-I could be looking at 9.93SCR/7.85DCR and 0.044 quench with cam at 112(straight up) advancing 3.25 degrees will give me 9.93SCR/8.05DCR 0.044 quench. If headgasket turns out to be the 0.041 instead of the 0.051 I’m gonna be running expensive gas at 10.15/8.23 with 0.034 quench.  Hmmm…

slowly

got the last piston ring in, getting ready to degree cam.

installed 1 of the new mile marker 104 hubs

back on track-getting my bearings

Long story short, I was able to pick up the correct bearings for the new motor today. Wrong ones came with order, corrected-new ones were previously used/installed. 3rd set came today and was installed. Mains ended up ranging between 0.002-0.0025” except rear main which was 0.003” machinist did a zero deck which was tested with the std bearings instead of the 10/10 bearings... so with my dial gauge i read a piston standing 0.0075 proud of the block.. hmmmm... good thing i didnt order the 043 gasket and have the 052 felpro.. hmmm...
Rods were 0.002 and all was installed just fine. Except I used the ring filer 5 too many turns and took one moly top ring from 0.017 to 0.031 which is almost 0.009 too much. So now I have to find a SINGLE moly top ring …. Argggg…
Whatever. Got my new 104 locking hubs. They are the 3/4turn stainless version instead of oldschool 1/4turn.