Shimming an oil pump
#1
Shimming an oil pump
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!
#5
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.
#6
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!
Thanks for all your help Guys! Chas.
#8
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 your help, by the way how did you post that nice picture of your car? I have tried but failed many times.
Chas.
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January 27th, 2015 03:38 PM