Originally Posted by coolracing
Correct me if im wrong but I beleive that was a grumpy jenkins combo that required main bearing spacers. I still have a set of spacers new in the box for a 400 chevy block when putting a 327 crankshaft in it!
I don't know who started it but i've ran them forever. I have 2 GM 400 blks. 1 in my car 377" and 1 on the engine stand 406". I run the 350 crank mains because it's smaller and less friction VS the 400 mains. Another big advantage is that the bearing spacers have a full grove on the top spacer. I drill an extra hole at 45 degres on the 350 top bearing to get extra oil to the mains. I've done this for over 20 yrs and have never lost a main bearing in a 400 blk.
Zip.