Acceptable Oil Pressure

[gus91326]

Guys:

So I have a about 1300 miles on my rebuilt 6. To refresh your memory, it's a 200 with a CI head ,Yella Terra Rockers (I plugged the oil port for the stock rockers), HSC flat top pistons, stock crank and stock forged rods. I have a Clay Smith 264/274 cam and used a new Melling pump when the motor was built.

Break in went well and the engine runs great. During break in miles I noted that cold the engine would show just under 50 PSI. When warm, at idle it would show about 20-25 PSI and at 2000 RPM and up it would show 35-40 PSI.

I changed the oil at 500 miles (10w-40 Mobil 1 and ZDDP additive). I'm seeing the same pressures. I've read that lower pressures just mean that the oil is circulating easily through the motor and is fine. Is this acceptable?

Thanks!

 

[rbohm]

the rule of thumb is a minimum pressure of 15-20psi, and ten psi per thousand rpm above idle. so your pressure numbers are spot on. remember these are hot numbers, cold number will be a bit higher.

 

[B RON CO]

Hi, Maybe a little early for synthetic oil, but the pressure seems good. You should always see higher pressure when cold and less pressure after it warms up. Hot oil is thinner than cold oil. Good luck

 

[Econoline]

From everything I've read 500 miles is to early to switch to synthetic. The theory is that the rings may take up to 1000 miles or more to completely seat. But if you have moly faced rings and the machinist did his job, you ran it in well it may not be an issue at all. Doesn't hurt to wait until 2K+ though.

 

[gus91326]

Thanks so much for the responses- we did do moly rings. I confirmed with the machinist on the oil and he said the switch to synthetic was fine as long as zinc was added. Thanks again!