I think expecting "success stories" is pretty unreasonable. Nobody goes around saying "Yep, my junk didn't blow up today, works great!" If you're trying to make high horsepower with a stock block, the marginal cost increase with a girdle isn't really a deal breaker unless you one of the MANY people trying to do a lot more than they can actually afford to do. Which describes somewhere north of 50% of racers, if people are being completely honest. S/F....Ken M

ok the thermal expansion of steel and cast iron is about 10.3 x 10^-6 in/indegF and the thermal expansion of aluminum is about 21-24 10^-6 (in/indegF) so when figuring the thermal expansion assuming engine is built at room temp at 70 deg f and most racers run around 180 deg f so 110 degree difference. the cast iron of the block expands about .00103 and aluminum is about double that. so the difference in expansion is about .001 of an inch, also take this with a grain of salt as the growth goes in all unrestricted directions. without some serious thermal modeling and a good sampling of blocks to get real as cast dimensions from, i dont think anyone is going to spend the time to do this on a 50 year old block. with aluminum heads i've seen about .008-.010 thiousandths of thermal growth, this is measureable at your rockers when your lash is no longer as tight as you set it. but again combustion temps vs oil temps.

Sort of related info.....I have one of Jerry's girdle and cap kits on a twin turbo 493 built for a fun street truck. Originally built with a small hydraulic flat tappet cam and then dyno tested and made 723 HP/860 TQ at 7 psi. I think we did 4 or 5 pulls on the dyno. This was done a few years ago in August in south Florida. Ambient temp in the dyno room had to be over 100 degrees. I do not know off hand what the coolant temp was but I think it was less than 190 degrees, I'd have to check the data log. The engine had a Melling M63HV pump and the bearing clearances had been check by the machinist, again I'm not sure of those numbers but I know they were within the expected tolerance. When it was cold at idle there was about 60 psi oil pressure. As expected it dropped as everything warmed up. Once it was completely heat soaked, the oil pressure would drop to under 15 psi below 900 rpm. 900 or over it was fine. I had a rear main leak so I tore it down and found 2 lobes starting go bad and upgraded to a small hydraulic roller.. I had no issues with any fasteners, but again only 4-5 pulls. When originally assembled I did need to open some of the fastener holes in the girdle to let it drop easily over the studs. I attributed that to factory variances in the block and a tight tolerance of the girdle. Honestly, I expected to have to do some clearancing. At this time I switched to a Milodon billet oil pump 21814 with a 1/2" internal pick up and I use an old cast Milodon cover with a remote oil filter due to rack clearance. Milodon assured me this pump flows a lot more oil than the Melling. It did improve oil pressure after heat soak, but I still need to maintain 850-900 rpm for idle or the pressure does drop off a lot. This is telling me that the caps experience growth. How much ? I have no idea. I have to think than any aluminum main cap would do the same.