[Half-Inch Stud]

The 3/4 groove bearing sounds to me as a risk-free prospect. HAd close discussions with P-Dude over a year ago about this bearing modification, and would recommend these lowers for the 400 and 455 motors that see regular high HP stress.

The ungrooved lowers will survive for years in a motor that has less than or similar to 1HP/CID, and stays cool during the high HP activity. The high RPM activity has the ability to cause dramatically quick journal heating.

Today's Pontiac Engine designers/builders do not want to take the chance of hot journals. Us regular folk keep pounding the spit out of our PMDs with no regard to aging/fatigue of the hard parts. Then add the NOS, Blown, and high RPM folks running the higher stress on the rod journals causes pause to seriously consider grooved mains and cross-drill cranks as the secondary means of cooling the rod journals.

I do not look favorably on the folks running the combination of Deep pan & Dry sump & crank scrapers. Because the Primary journal cooling system is gone and Rod journal temperature rise sharply in all cases.

There are combinations of these taffy-rope reduction efforts (like I run a deep pan with factory windage, and full-groove mains) that keep some sort of Primary journal cooling in effect.

"But do these mods help?": YES.

H.I. Stud