My 3rd engine build and my most successful thus far, a 1971 350 with 3.0 flat tops, TA 310 cam, headers, qjet, TA intake and HEI, stock everything else aside from cleanup machine work. Stock bore. I live in iowa so most fuel is ethanol laced, and until recently had a 100 mile daily commute 5 days a week. I have a th350, so RPM at 70 was around 3,000. Below are pics after 45,000 miles, half of which are hard high rpm driving for long stretches of time, one a 5 hour spurt on a trip to Wisconsin. There was plenty of bearing material in the pan, shavings and chunks. Front rod bearings seem fine, rear bearings had pitting, moreso like the metal balled up and ripped off. Main bearings have little crush left and fall out of the caps. Front cam bearing is in perfect shape. Engine ran perfectly fine, had ok oil pressure (had more when fresh), has 5psi minimum after highway driving, has 40psi hot cruising at 3000 rpm. Didn't make a peep aside from sometimes cold start knock before oil pressure built up. What say yall? I'm gonna roll in new bearings and send it.
Kinda suprised/concerning to see that bearing wear @ 45k mi. Oil pressure/volume issue given it was the rears? Are mains/cam bearings towards the rear also more worn? I think I'd want to do something to try and address the problem besides just putting in new bearings.
As said above. Need to find root cause unless you just want to keep doing this over and over again. Devon
Tops of pistons and chambers look oily. I'd clean them off and get new valve seals. Mic the crank and if a little under std., maybe polish and get .001 bearings from Egge.
Crank isn't machine shop fresh, but nothing to be concerned with. Crank was cut .010/.010 before. Barely enough to catch a nail. As said, engine ran perfectly fine, made no noise.
Crank is already .010, plugs are a nice Tanish and dry. I think it was inhaling oil through the pcv at 3000-3500rpm.
I would say the motor needed the oil mods before driving 3500-4000 rpm I would have run Mobile 1 synthetic it takes the heat better. It should have 50 lbs at 3000 rpm if oiling was adequate.
Yes, and I used a pair of digital calipers. Not the most scientific but was .002 on the dot on rods and mains.
Also the underside of the intake valley pan (if that is the underside) is filthy with coked up oil. Also looks like one of the intake port sealing beads had oil getting in the port.
I'd do a light hone on the cylinders. My brother used to have a Pro Gas Vega and after every race season he would strip the motor down and use a sheet of 600 grit wet and dry sandpaper with a spray of WD40 and used a hone inside to spin it. Deglazed the cylinder with the light hone. Clean spots on the pistons are from running way too rich.
