i have a 93 k1500 with a 98 350 vortech engine bored .30 over flat top pistons. i put new heads on it along with rings rod bearings and main ...

i have a 93 k1500 with a 98 350 vortech engine bored .30 over flat top pistons. i put new heads on it along with rings rod bearings and main bearings. i have about 400 miles on the motor about 50 miles ago i started to get a hard knock at start up than today i drove down the road and really got on it than it really started to knock hard...... i could feel it in the truck so i turned around backed in my driveway. motor was knocking really hard and fast. so i pulled oil pan off thought maybe a rod cap came loose everything seems tight i go have a little play in the rod bearings but dont think it would cause that much noise. could it be a piston or something? iam confused .......

It's hard to say without hearing it. Did you make sure you tightened the torque converter bolts? I would actually take the rod and main caps off to check the bearings before putting it back together. If it is a bearing problem it could save you some money so you do not grenade the whole thing. I assume there was no bearing material or trash in the pan when you got it off.

i rebuilt the motor in the truck so i did not touch torque converter bolts. and the pan was clean i thought i would find metal shavings but nothing....i know the rod bearings were 1 under and the mains were 1 under on top and std on bottom i bought a pack of std main bearings so i threw them in there. guess i better check all the bearings for play and go from there. the one rod bearing i did pull had a gold line wore in it!

I have never seen a bearing set be different sizes on the top and bottom. That could be your problem.