383 rebuild - kinda whimpy on the dyno?
And now on to what I’m guessing is THE REAL PROBLEM... as I was carefully breaking down the bottom end (disassembling rod and main caps) for rear seal complete cleaning and replacement, I found that rod bearings 7 & 8 had spun during break-in. I’d like to be really upset, but this is exactly why I pulled it back out of the car to bench test it on a dyno.
Interesting that, when I tore down the core project block some time ago, this was the same two rods that had spun in the previous life of the block. I had the forged crankshaft rewelded and ground down and polished to .010-under on all journals. New -.010 bearings were supplied by the same builder outfit that had he crank sent out to be refurbished. I also meticulously cleaned all oil passages on the crank after I got it back from the machinist and before assembly.
I’m thinking it also explains why back-to-back dyno tests showed a pretty substantial decrease in HP and tq on subsequent pulls.
What a bummer.
And now on to what I’m guessing is THE REAL PROBLEM... as I was carefully breaking down the bottom end (disassembling rod and main caps) for rear seal complete cleaning and replacement, I found that rod bearings 7 & 8 had spun during break-in. I’d like to be really upset, but this is exactly why I pulled it back out of the car to bench test it on a dyno.
Interesting that, when I tore down the core project block some time ago, this was the same two rods that had spun in the previous life of the block. I had the forged crankshaft rewelded and ground down and polished to .010-under on all journals. New -.010 bearings were supplied by the same builder outfit that had he crank sent out to be refurbished. I also meticulously cleaned all oil passages on the crank after I got it back from the machinist and before assembly.
I’m thinking it also explains why back-to-back dyno tests showed a pretty substantial decrease in HP and tq on subsequent pulls.
What a bummer.