Bought a couple 350 motors from a guy awhile back to build for projects. PO didn’t really know much about motors they had sit in the shop for years. Both were truck motors 4 bolt mains. Took one apart today to maybe rebuild turns out it’s a 350 bored 60 over with a gm 400 crank the mains have been turned to standard bearings for the 350 block the rods are 10 under. The mains all look really good hardly any bearing wear. Looks like rods have been resized four of them bearings fit nice and tight. The other four are loose in the rod they haven’t spun but not tight. Crank not scored will polish up ok. Checked all the bearings there federal mogul all 10 under and same numbers. All matching If I put the loose bearing in the tight rods there loose also. I even put the tight bearings in a loose rod put on the crank with plastigage it presses out nice and even and in spec. Kinda crazy I know Another thing if you set the nice fitting bearings half’s on the crank they sit down on the journal like they should. If you set the other ones on they don’t want to go on you can push them on but it flex’s them to sit on the journal. Any ideas. Thanks all.
Personally , I think the P.O got the rod caps mixed up So get ALL the rods resized and install new bearings. [and get the crank rod journals measured as well] Don't turn a $100 job into a $1000 job
Bad set of bearings,,,,,,buy a new set . That was probably what was wrong to start with after original rebuild. They had some problems and didn’t know what to do . Just pulled it and it sat in the corner for years,,,,,waiting on you . I know this sounds far fetched,,,,but it does happen . I bought a machine once that would not run no matter what,,,,,,,it had zero compression. But it looked great,,,,was in great condition,,,,,and I thought I could fix it . I pulled the covers,,,,,and the adjustable rockers had all backed off , They had at some point in time adjusted the valves and didn’t lock nuts back down . I put the adjusters back in ,,,,,tightened them up,,,,,,,it fired right up and I used it for years ! Mic the rods and bearings,,,,,you might get lucky . Tommy
Yea I would try another set of bearings too. I bought a 389 Pontiac years back cheap, the guy rebuilt it and could not get the lifters to pump up, he gave up on it and bought a used one for his car. I started pulling it apart to redo and noticed the lifter oil galley plugs were missing in the front of the engine behind the cam gear, tapped in 2 plugs and the motor ran great in my 66.
Thanks guys sounds like the crank and rods get a trip to machine shop. I’ve seen some strange things over the years usually spun bearings or messed up piston flat cam. But this is 8 loose in the rods and 8 nice and tight in the rods. And on random journals no pattern.
Yes get it to the shop. It does sound like the bearings got messed up but if the shop torques the rods and bore check them as well as confirm there not mixed up and the crank Mics up ok the only thing left is the bearings. Sent from my iPad using The H.A.M.B. mobile app
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