Hello. My Name is Bill and I’m new to this site. The car I own is a 1965 Mustang 289 V8 Engine. I need some help from the engine wizards here. Let me tell you guys what’s going on. I recently rebuilt the engine it has a little over 500 mils on it. It and runs and idles perfect temp stays at 185 no knocking clicking or smocking.

Here is the problem it’s the oil pressure! It’s to high when the engine is cold the oil pressure is @65 engine warmed up the oil pressure is @60 down the fry @ 65 to 70 miles an hour the oil pressure is @ 75 to 80 pounds. I’m chopping at the bit thinking how long the oil filter can last before it will explode.

I have changed the oil pump thinking I was giving the wrong pump, changed the oil filter thinking it was clogged THIS I NEW WAS NOT IMPOSSIBLE... Also change to a mechanical gage it also reads 60to 80 pounds.

So guys tell me what I’m I missing???

This is not my first engine rebuild. What am I missing...?Damn,!

Thank you for any and all help in this topic..

Bill,

Bills Mustang

 

75 psi at 70mph is normal, generally its should be 10psi more per 1000rpm, at 70 with a c4 your probably at 3kish, which makes 75 right around normal.

 

MustangFTW,

Thank you for the speedy reply!! You have made an old man breath a little easier. You are right @ 3 k with a C4,,, 280:1 in the rear the oil pressure is @75 pounds.

What oil and weight are you using? Also are you adding ZDDP Plus Oil Additive? ..


Again I can’t thank you enough for the help.

Bills Mustang,

Bill

 

I use cheapest stuff :-D, some people like to add a zinc additive to the oil but it's not neccassary. I use 10w-30 but it depends on weather, i might switch to 5w-30 in the winter in MN.

Quick question, when you rebuilt the engine did you fully plug the oil galley holes behind the timing cover, or did you drill a small hole in the plugs?

 

MustangFTW,


Yes, I did plug the oil galley holes. They were plugged when I took the engine apart. Is this why I have high oil pressure? OR, again, hot or cold @ idle I’m @ 60 pounds. Is this normal..

Thanks again,

Bill

 

I would think you just have really tight clearances if you just rebuilt the engine.

I wouldn't sweat it as long as it isn't approching 90 psi. You didn't say what oil you are using, but you can probably use a 10w?? or even a 5w?? without concern. Try something lighter at your next oil change and see how it behaves.

 

I would say your oil pressure is fine. If you wanted to lower it you could pull the spring and get a lower pressure spring or cut a half coil off it but cutting wouldn't be my first choice.

Jim

 

some people drill small holes in them to oil the chain and distributor better but its not needed.

 

Which pump part number is it?

75psi on the freeway is NOT normal, even at 3k rpm. The standard pressure SBF pump is set to 60-65psi. My hand prepped high pressure pump only sees 40-45 on the highway and barely gets to 70psi at 6,500rpm.

If it's a standard pressure pump and it's actually producing 75psi at the low of an rpm, then you likely would have a jammed pump bypass AND too tight of an engine tolerance.