horsepower1

I agree with Mike. At this point you need to go through a process of elimination. Gauge first, then go back to filter-only on the engine. This will tell you a lot.

activator40

I had a problem similar to yours many years ago.. I will let you in on my secret.believe it or not but there is a gasket that goes under the oil filter bracket and its not shown on the parts diagram.i repeat...it is not shown on the parts diagram..it took me some time to find it and mercury DOES MAKE IT.IT goes between the block and the filter bracket..oil will bypass the mains and create a loss of pressure if it isn't used.I am not saying this is your issue I am only sharing this..hope it helps.

Full Force

iTrader: (5)

He would have a huge leak to bilge then..

SB

iTrader: (1)

You talking the gasket under the block mounted oil filter adapter ?
See pic:
Link:http://www.jegs.com/i/Chevrolet-Perf...oductId=763945
and pic:

mike tkach

iTrader: (3)

i have never seen or used that gasket on any chevy v8 and imo that is not the issue.

SB

iTrader: (1)

Correct. They don't come with them from GM. It does with the GM Performance one, though, as you can see, for some reason.

Just trying to figure out what gasket he's talking about because, other than that and the one for the oil line adapter to block housing (#8) the the only other one where he's talking about is the one that sits between the center screw on fitting and the 'cup' of the oil line adapter. If this was missing, there would be a massive external oil leak. #5.6.7,8 in pic.

His wording is not too clear to me.

mike tkach

iTrader: (3)

maybe he means #6.

Zone 5

A larger line/less restriction is only going to give you more flow if the pump can increase the flow to match the line. If a pump is rated at X gph thats all it is going to put out. Likewise, if you increase the size of the line, and the flow stays the same, the pressure will decrease, not increase. Think of it as a water hose free flowing. Then hold your finger over 1/2 of it and the pressure will increase because the opening is smaller.

Now, with that being said, if the flow increases say from a change to a higher volume pump, when that flow hits the bearing clearnce that has remained the same, the oil pressure on the gauge "should" increase. and based on the OP's clearance which I agree is tighter than I would use on a marine engine, he should have good pressure numbers.

Zone 5

I have had #6 leak, and make a mess, but I don't remember it haven't an affect on pressure.

mike tkach

iTrader: (3)

^^^^^^^^^^^^^^^^^^i have said it a hundred times,pressure is caused by resistance of flow,so yes,the larger oil line will be less restrictive to flow.i feel that mercury put to small of diameter oil lines on some of their engines.