Thread: low oil pressure, cam specs for 305?

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Pressure seems okay when warming up but drops when it is fully warmed up. I can't hear any knocking, no metal in the oil, and the oil pressure gauge is good. My problem is when I bought the motor the guy said it was a 350 with maybe 9k miles (said it was a crate motor, but I'm not so sure now). I finally looked up the numbers on the block and it turns out to be a 305. I really don't care about that part but I put a beefier cam in it (thinking it was a 350) and am wondering if I have too much lift for stock 305 valves, rocker arms, push rods etc. Any ideas? I'm going to cut open the oil filter tomorrow and see what's inside.

I put a Mellings cam with the following specs:

Cam Lift
INT. .298
EXH. .298

Valve lift
INT.447
EXH. .447

Lobe CTR
INT. 110
EXH. 118

Lash Hot
INT. HYD
EXH. HYD

SAE Duration
291 INT.
291 EXH.

.50 Duration
223 INT.
223 EXH.

SAE Timing
BTC 30

That's way more cam then a stock 350 could use....

My father in law used to race chevys and said it shouldn't be a problem... but I might be doing a cam swap again.

Is it a good chance the cam bearings are worn out now? Wouldn't I be able to hear any knocking or anything if it were the bearings?

Probably wouldn't be a problem....if it were a race engine, but it's just a wheezy little 305 with a long stroke and a peanut sized bore.... A stock 305 doesn't need near that much duration or lift.... Might want to check Comp Cams and download their Cam Quest program (it's free) then punch in the real information on your engine and see what they suggest....

A too big cam won't hurt cam bearings, if the valve springs haven't been in coil bind, or the valves haven't hit the pistons, a simple cam change would be in order. Guessing what the bearings look like would be just a guess...when you're changing cam and lifters, check the pushrods for straightness and all the other parts in the valve train for excessive wear...

If you want your new cam to last, make it a roller cam. Today's oil just isn't up to the task of lubricating flat tappet cams in a manner that will promote a long life!!!!!

Thanks for the response. I guess I'll just be swapping cams... That sure as hell beats pulling and overhauling the motor.

Thanks again.

Originally Posted by kelseydum

That sure as hell beats pulling and overhauling the motor.

You may be doing that also. Worn rod and main bearings contribute to low oil pressure.

I'm not trying to belittle you, but let this be a lesson to you. Never, never, never, never, never take anyone's word for the condition of a motor. Never. There are no honest people left on this rock. If you can't inspect and measure the individual parts for yourself, walk away.

The S.O.B who sold you this pig needs a blanket party.