[63gmc4x4]

well my 351E is all in and running and driving, running great plenty of power , no smoke ,but I have a slight puffing noise, on drivers side so I decided to pull covers back off and verify valve lash when hot, started it for a minute with them off and found massive amount of blow by or appears to be blow by coming up from the holes where the pushrod come up on drivers side looks like a locomotive! so I turned it over by hand and the same thing you can even hear it from there, with the cover on you can still hear it slightly reset valve lash and verify pcv valve are not stuck, it also has new ventilation filter, I'm confused on this , runs so great , if I had a problem with on of the pistons or rings or head gasket I would think it would burn oil of have low power or even over heat any ideas? I think I'll just drive it and hope I dont blow out any seals I'm gonna change the oil to 20 50 and verify oil level now that it's been ran since 1998 any insight will be appreciated thank you