no oil to top end of my 2.8 V-6

I recently purchased a 86 SE, supposedly all it needed was a fuel line and brakes... Well after replacing the fuel pump, most of the engine electrical components and a bunch of tinkering it runs well. After a couple of minutes it begins to tick sounds like rockers ticking, upon further investigation I find that I am not getting oil to the top of the motor. I have 40 psi at the gauge in the car and just to make sure it was correct I hooked up a new gauge at the engine and got the same result 40 psi at idle. What would be the likely culprit??

The oil for the rockers travels up through the pushrods, but under minimal pressure. The pushrod oil passages may be loaded with sludge/dirt. Try removing them... you should be able to see right through the center of the rod. If not, clean them out, soak them in solvent and blow out the oil passage with compressed air.

If the pushrod bores are clean, you may have clogged or mismatched lifters, that is, lifters that were not intended for the 2.8.

Thanks for the info, since it sat for an extended period of time would it just be a good idea to replace the lifters and push rods. Also can you recommend a way to clean out any sludge etc without removing the engine?

thanks