High oil pressure?

[carl hinkson]

Originally Posted by Ed Wright

"Many smart engine builders use HV pumps so as to have enough volume later in life of the engine as clearances begin to get larger from wear."

What actually happens is the pump bypass stays open, peeing un-needed oil right back into the pan.

.

On a EOM or Mellings pump when the oil is bypassed and peeing back to the pan how does this happen as there is no orface in the pump cover to do this.

That being said on those HV pumps years ago we use to drill another bypass hole in the cover and bleed off the extra oil pressure when the oil was cold but when we did this we never saw pressure go over on the average 72 pounds.

Since Melling has come out with the 10% more volume pumps years ago we have never used a 25% higher volume pump.

That intersting pumping pans dry as where are you going to put 5 quarts of oil in that engines when the pan is dry.

[Charles Rainey]

I wasnt going to post on this subject any more until Carl posted, but I thought why not just one more. Carl is correct, the SBC does not bypass too the pan. It bypasses within itself, that is one reason you dont want the bypass valve to continually open. It by passes withion itself and builds heat. I, just like Carl, have drilled my on relief hole in the pump so that it will bleed back to the pump. Smokey unit showed me that several, several years ago. The reason, from what I understand, that Melling and other companies came out with HV pumps was to move more oil at the low rpm ban. If you go thru their catalog, you will notice that their HV pump does not make as much pressure. They have a pump called HP to do that. Several years ago, I mounted a remote oil filter with a flow meter mounted in the line. I changed the pumps from standard to HP to HV to Select. If the clearances were ok, There was no more oil going thru the engine, UNLESS you change the pressure. If you up the pressure, then it did flow more oil. It only had more capacity to do so if need. The pulsations WAS slightly lower on the HV. I, just as Carl, now use the 10% HV. Oh yes ED, I, like you, have been doing this since the early 60's. And I think I am too old to see something new, but damn I learn something every time I fire the dyno every day. So Ed, you and I are on the right path to still learn. If you learn something new today, call me. I dont want to miss out on anything. I have to keep notes now though. Book is getting full. I crashed my PC other day and I thought I was really screwed, cause my notes was on it. Then my grandson said, dont worry pops, I backed it up in the sky. So guess he has a direct line to the man upstairs or something like that. I told him to write him a letter and get my notes back. He said I would have them this week end. Now that is service my man.
charles

[Ed Wright]

Yes, I mis-spoke about the bypass. I was trying to get my point across. That, there is no need for a high volume oil pump in a SBC. Cleveland Fords? probably so. Why more oil at idle? absolutely no reason. If somebody has better bearing life with 10% or more pump volume, they need to seriously take a look at what they are doing. The old "big block-style" +25% pumps? Are you kidding??
A few of my old roundy-round customers seemed to worry about their oil pressure dropping to 15 psi at idle after running 25 to 35 laps WOT in Oklahoma summer heat (no oil coolers). Thought they needed high volume pumps to "cure" that. They just didn't know better, but you still have to waste time trying to explain something that was evidently over their heads. GM says 10 psi per 1000 RPM, I have found that to be VERY safe, to say the least. All this was before synthetic oil, btw.