oil pump and pressure

[tn2]

has anyone used the melling 10555 oil pump much been trying to use it some but having a little oil pressure change as the rpm increase center of corner 55 to 60 lbs then by the time u get to next corner it is slowly dropping to 40 to 45 once u let off it goes back up. iv been building these engines for twenty years never had this problem with out a ring problem or something. the engine is fresh only two races on it everything checks good just looking for advice.thanks in advance

[twisterf5]

has anyone used the melling 10555 oil pump much been trying to use it some but having a little oil pressure change as the rpm increase center of corner 55 to 60 lbs then by the time u get to next corner it is slowly dropping to 40 to 45 once u let off it goes back up. iv been building these engines for twenty years never had this problem with out a ring problem or something. the engine is fresh only two races on it everything checks good just looking for advice.thanks in advance

seems more like a restriction or pick up to close to bottom of the pan.

[tn2]

all returs have been opened up no plugs in lifter vally 10 quarts of oil did leak down on engine all cylenders withen 3%

[tn2]

pick up 1/2 off bottom

[dirty white boy]

weak by pass spring...

[twisterf5]

pick up 1/2 off bottom

is that before pan gasket that would be the max i would ever use. what pan and what filter is bypass plugged off. do you have oil restrictors in the top end. if not with the pump that high it could be pumping it all up top and sucking air.back it down and give it a second to drain and you pressure comes back up. thats what it sounds like to me.

[tn2]

no with gasket it is 1/2 inch it does have restrictors the pan is an 8 quort canton pan with wix filter bypass in the filter adapter is pluged and we normaly run 9 qts oil we added 1 this past weekend didn't change any.

[twisterf5]

no with gasket it is 1/2 inch it does have restrictors the pan is an 8 quort canton pan with wix filter bypass in the filter adapter is pluged and we normaly run 9 qts oil we added 1 this past weekend didn't change any.

the only other thing i can think of is the rear cam bearing not knocked in enough. i have had that happen once.

[tn2]

I always knock it in ill the hole lines up with the groove in the housing and I can not see the walls of the groove then I know im centered.

[tn2]

I keep suspecting something with the pump has any body used them oil pump testers any I ordered one today to see what I can learn from it but I will take all the advice I can get iv been doing this stuff for along time but I know im not the smartest person and I will admit that but ur never to old to learn so all the advice I will listen to. thanks for all the info keep it coming.

[18gotrdone]

Have been using that pump and only time i had a problem was when the wix filter was coming apart! We was running alky. But it was doing the same thing so check it out good...

[tn2]

ok we don't run alky but I will check thanks

[fast_crew]

I would try a qt less instead of an extra, you maybe whipping the oil up causing foaming. I put stand pipes in the center valley drains then open up the rear drains around the dizzy, lower the front drains, no restrictors, HV/std. pressure pump w/3/8 pick up clearance and 7 qts. Never had a problem.