I am rebuilding my 455 and I'm wondering if I should shim the stock Melling M22FHV oil pump. The engine has never had high oil pressure (around 52lbs max warm) and I had 430 1/4 mile runs on the engine when I cracked a C head and decided to rebuild. My old clearances were .0032 Rods and .0045 mains. The rebuild clearances should be .003rods and .00325mains.I am restricted on #1 thru #4 cam bearings at the mains and I did not drill the oil holes on the main bearings. I don't want to go crazy with pressure but 52lbs @ 6000rpm made me nervous even though the bearings all looked good when we disassembled it. I run Brad Penn 20w50 race oil and have had no problems at all until the head craked in the intake runner under the valve!

 

No. The loose clearances caused the lower pressure. Wide rod side clearances and light viscosity oil also lower pressure. The 22HV pump should be fine as is.

 

Do not shim the oil pump. You should be fine.

 

I'd shim it a little, about .150, then you can use thinner oil, more Hp.
Jmo

 

You want volume on those 3" main bearings,so don't be as concerned about oil pressure,but more concern with volume.Your looser clearances have allowed for that,and the fact that you bearings & crank look fine,is a good sign that everything down there is set pretty good.You would find that if you ran a thinner oil,your pressure numbers will drop.I run 20/50 as well.If I don't,I won't have any pressure at idle.She's loose,but this was all expected when it was being built.

 

Thanks for all your help Guys! Chas.

 

I'm with Mark on this one...... .150 should be just right.

 

Thanks for your help, by the way how did you post that nice picture of your car? I have tried but failed many times.

Chas.

 

I'm not computer savy.I just got lucky once.Big Jerr made me a picture for my sig line,about 2 years ago,and I haven't been able to get it up yet.

 

The .150 just answered one of my questions, too.