Just rebuilt a 94 1.6 16 valve,blue printed,lined board,and new parts.When the engine reaches op. temp the pressure at 4k only reaches 38-40 psi.It has a new oil pump and I'm running 10w30 oil,would adding another washer to the oil pump pressure relief valve work?Has any one done this?

Maybe, maybe not, but I doubt it - what's the pressure at a cold start like?

The pressure relief valve shouldn't start to lift until you get up around 55psi, and since the oil pump is new, a leaking relief valve or a weak spring should be low down on the list of probable causes - excessive bearing clearance is, at least in my mind, a lot higher on the list.

You said lined bored & new parts ...

1 - Why did you need to line bore?
2 - Which bearings did you line bore?  the mains bearings?  If yes - where did you get the new main bearings from?
3 - Is the crank new?  If no - what condition were the journals in?  Did you grind it undersize?
4 - Did you plastigage the bearings (or measure the clearance in any way)?

I had it line board because it had high spots due to my friend scraping the surface replacing the bearings at one time.
It was the main bearing caps that were board.The bearings were from the Hawk rebuild kit sold by Low range.
The crank was used and got reground and bearings matched to it 10 under.
The machine shop did all the oil clearance checks of all the rod and main bearings before giving me back my motor.
The oil pump is after market and could be a dud too,I do have another one in the box(a new one)I can throw in also.

Some thing doesn't sound quite right - what had high spots due to your friend scraping which surface?

Assuming that you have the original main bearing caps and the inner bore is undamaged (no spun bearings), I don't see a need to line bore the main bearings - you're boring the inside of the bearing caps larger, at the same time as you're grinding the crank journals smaller, it wouldn't take much to get more clearance than you need - especially given the fact that Suzuki does not necessarily use the same diameter bore on all of the bearings - on the 1.6 it's possible to have three different bore diameters and Suzuki supplies five different thicknesses of bearings.

I can think of maybe a dozen different questions - but they all come back to one thing - the machine shop did all the oil clearance checks of the rod & main bearings - what were the clearances like?

Suzuki specifies 0.0006~0.0014 inch for the mains with a limit of 0.0023 and 0.0008~0.0019 inch for the rods with a limit of 0.0031.

Just got done pulling all the main and rod bearings doing the plastigauge oil clearance test.All the bearings are within the standard area(almost too tight)The line bore was to make all the main bearings the same size to match the crank.The o ring at the oil pick up is new and I didn't see any holes in it either.I had another new oil pump so I installed it too so I'll see what happens next.

Suzuki specifies 0.0006~0.0014 inch for the mains with a limit of 0.0023 and 0.0008~0.0019 inch for the rods with a limit of 0.0031.

Are you sure that's not mm instead of inch, some of your numbers are a bit tight for an engine in thousandths
of an inch or you got to many zero's  .0006 is 6 ten thousandths, way too tight for rods or mains .001 to .002
would be about right in inches.

I'm just saying, I will go look it up to be sure but in my engine building, that's about where it should be

Wild  

|removethispart|@wildgoody - No harm in double checking - those figures are in inches and were taken from volume 2 of the SQ416/SQ420/SQ625 service manual.

Anyway - now that you've brought it up - let's assume that you and his machinist worked together and have similar experiences, and his block/caps have been lined bored and the crank reground with those (or similar) clearances/tolerances in mind - then the blue printed engine would be on "loose side" of Suzuki's standards and the oil pressure might well be lower than expected.

|removethispart|@zuk1988 - there should be a brass restrictor (sort of like a carburettor jet) in the cylinder head - it controls the flow of oil to the head - is it in place?

Got it running again and it still has the same pressure.Talked to the machine shop and he couldn't remember any thing about the oil restickter in the cyl head or if it was installed,would that cause a 10-15 psi drop?Thanks for the input guys.

I don't recall an oil restricter in the head, the cam and the bearings should block
the oil enough to not have a drop, is there any way you have a loose cam cap?

Wild

I have another cyl head laying around and found were it was,it's threaded into the hole that feeds oil to the head.The hole is very small and would increase pressure to the lower engine block as far as I see.

I have a 16V head here that I was working on, port cleanup and stainless
valves, I'll have to go out and take a look, I don't remember the 8V head
having one, just a small hole for oil to the cam

Wild

It's there on the 8V also - same part on both engines - just look down that same hole

The machine shop said it was never removed so I don't know what else it could be,worn cam or the bearings looser than Suzuki specs 

You might want to check the relief plunger in the oil pump,
just make sure it's not stuck, or that the spring is strong enough

Wild

I'll do that next,thanks.