A good article by David Reher on oil issues and broken rods as it appeared in NHRA’s National Dragster.
This season, several of our racing friends have broken rods. The common factor I have seen in their pictures is a blackened crank or the big end of the rod, which indicates a bearing clearance or oiling problem to me.
Double click on the image to enlarge it for viewing – Roger
About Roger
Driver of our '57 Chev from 1972-2019, Vietnam veteran (A Troop, 3/17th Air Cavalry Scout helicopter Line Chief and later Cobra Periodic Inspection team leader), retired ASE rated automotive mechanic. Roger became involved in drag racing during his high school days and after his stint in the Army ran E & F/MP [Modified Production] here in Division 6 before switching to bracket racing when the '57 became obsolete for class racing. He often raced at Puyallup, Kent-Pacific Raceways, Bremerton, Portland & the original Mission, B.C. track.
We use Rotella T 15W-40 to break-in our engines, then switch to Brad-Penn 20W-50 after 15-20 runs.
On our 331, 350 & 406 we run .0025″-.0028″ bearing clearances on the rods & mains.