i have a 69 rs/ss with a 355 that came with the car when i bought it. i haven't torn the enging down but it generally runs strong. all i know is it has hydraulic lifters and and a timing gear. the thing is that the oil pressure guage shows normal 35-40 psi on start up but gradually drops down after it gets hot after about 15-20 minutes, max. then it shows 0psi at idle, around 20psi at 2000rpm, and back up to 30-40psi at 3000rpm. (t-10 4 speed).
i've put a psi guage on it at a shop
(cold start) and it idled around 15-20psi but the car never ran that long. i was told not to worry about it from that shop because the psi raised with accelleration and there was no wrapping in the engine and to check for kinked lines, worned or clogged fitting. but, i was told by another shop to watch out, hold off from replacing the timing gear with a double roller, and that it may be my bearings or the engine might be bad. i've put a lot of money into this ride and basically don't have the kind of money and time to replace or rebuild. any suggestions?
i've replaced the oil from 10/30 to 20/50 and the symptoms returned after about 30minutes or so.