Extremely weird oil, pressure issues.

[GideonBowles]

I have a 462 that I just had built, originally a gen IV 454. So in other words, it is brand new. 
 

when cold my startup oil pressure usually is about 40 to 50, once or twice my gauge has read all the way up at 80, but it is pretty consistent at 40. As soon as I get to about 140 degrees water temperature, the oil pressure drops and flickers at what my best guess is 5psi. When driving it sticks about 25, but as soon as I let off the gas, it tanks all the way to zero and then slowly goes back up to about five. 
 

I am running 10W-30, with high zinc additive, which I’m going to try moving up to either 15-40 or 20-50

I am going to change gauges and see if my gauge is incorrect, as well as replacing my sending unit.

What worries me is I thought it was a gauge issue, drove it back to town and started hearing some pretty loud valve clicking which I’ve been needing readjust my valves already anyway but I’m worried that I may have [censored] my engine. 
 

Based on my symptoms, are there any other things anyone would suggest?

Thank you!

[jft69z]

First and foremost is get an accurate pressure reading. I prefer good quality, mechanical gauges for that.

I'd get the engine builder involved immediately too.

[cny first gen 71]

the engine builder would have been my first call.

[Michael Boyte]

I personally would not even attempt to start the engine again. Call a rollback and have it taken to the engine builder. Let the "professional" handle it. 

[Scott S.]

Sounds like the oil pump isn't up to par..... 

Any space/slop in the impellers will let the oil reverse flow at low RPMs. 

Sorry to hear about that. 

[72 Monte Carlo]

Get it to the engine builder first if they will honor their work. Have them readjust the valves to get rid of the lifter tick.

If not, then as suggested, get a mechanical oil pressure gauge to see what the oil pressure is actually doing at all times.

 

 

[riverdogs00]

Cold initial pressure is always higher, and then a little less as it warms. A good guideline is that it really only needs about 10lbs per 1k rpm. Totally agree on a good mechanical gauge to verify, ideally with the copper line.  It could also be a lifter bore that is out of spec, especially if you are hearing clattering. If its a new build, Id ask what the rod and main clearances were. If they are over .003 that could be it, but most any engine builder would see that and hopefully adjust.

 

jft69z hit it on the head.....

[riverdogs00]

another thought....if its a flat tappet cam and not broken in properly, you could have a bad lobe which would explain the clattering

[420ponies]

All good questions. Was it dyno'ed before install? What I mean is , was it started up and broken in on a run stand. With 10-30w that is a pretty low viscosity for a 468 in my opinion. Is that what the builder suggested? This means your bearing clearances are on the tighter side of things. I'm running .0023" bearing clearance on the crankshaft and running 10-40w right now (427 cu.in. 454 block,396 nodular iron crankshaft) and 80psi at 1,500rpm's ,and 40psi idling , at 180 degrees engine temp. ,drops to 25 psi in gear. I'm running a hydraulic roller cam. This is with a stewart warner mechanical gauge (copper line). I have the gauge package also, I just trust a good mechanical gauge. This mechanical gauge is coming off the port just ahead of the oil filter, not the one above the oil filter.That one is for the gauge package. If you are hearing clatter on the  cylinder heads, that's definitely a rocker arm. You could take off that valve cover  any see if there is any up movement on any of the rocker arms. Lots of information, Let's just hope it's something that can be taken care of. Sounds like not many miles on it yet. Your engine builder will help you. A good oil to use for the high Zinc  content is Driven oil or Valvoline Racing oil. I used 20-50w in my small block 355, that was almost .003" clearance (.0027-.003") on the crankshaft.

Edited January 5 by 420ponies
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[Chevy Dave]

80 psi is not normal for a stock Chevy big block. Do you have a non stock high pressure oil pump? 10w30 was a recommend oil for all of the Chevrolet V8s in the 60's and 70's according to the owners manuals.  5 psi at idle is to low. The gauge is not accurate, the bearing clearances are to large or you have a bad oil pump.