1970 455 Olds oil mods??? As I prepare to put the engine heads back on, I see on other forums, best to do some modification to the oil return port on the block from the heads. How critical is the concern regarding oil problems?

 

Stock build?

 

I think piston to bore clearance is more critical. Failing there gets you way more problems.

A stockish Melling HV with a pink spring generates 100psi cold with Brad Penn 15w--40. It calms down once warmed up. No oiling modifications beyond stock were used.

 

Hmmm I’ve never had anywhere near that amount of pressure in that scenario, 75# max.

 

I'll get a vid, if you want. I didn't believe it either LOL

 

What pressure do you get at idle when fully warmed? What RPM?
Thanks.

 

I believe you, it’s just a very scarce experience for me. I’ve seen 80 a couple times but mostly 75ish.

 

Hot (180⁰) idle is about 15-20psi. Max hot pressure is about 50-60.

 

Thank you.

 

Thank you so much, I really appreciate all the serious advice and comments. Took heads to a machine shop, They said they look perfect. Pistons and Cylinders show no wear, very light rust in 5 & 6. My guess is the owner 15 years ago had the engine built, and typical of jet boats, flooded couple cylinders with water and frustrated just parked it. My getting close to winter here in Montana, I plan on putting it back together, run it and keep my fingers crossed no issues.