Hotrodder

L05 Chevy small block 93 model w/modified Vortec heads and ,500" lift cam
Stock oil pump.
Auto Meter electric gauge shows up to 100 psi of oil pressure on idle or when driving at low rpm's.
Stabilizes on app 75-80psi when rpm's goes up.

Should I change the oil pump?

sofakingdom

iTrader: (1)

If the oil filter hasn't been literally blown off the motor, the gauge is not telling the truth.

Verify with some other gauge.

Hotrodder

Ok, thanks.
I will.

sofakingdom

iTrader: (1)

Expect a new motor with typical stock clearances, everything right and working well, 10W-30 or similar oil, fully hot: 15 - 20 psi idle, 30 - 35 @ 3000 RPM for the "regular" pump (such as for truck or Caprice) like the M55 pump; 20 - 25 idle, 40 - 45 @ 3000 for the "stock" pump for F-body or Vette applications like the M55A pump

Hotrodder

Thanks for the inputs guys.
Very helpful as alway.
Forums like these are extremely valuable for guys like me.

Looks like the problem is solved. I found another sending unit in my spare parts bin (didn't know I had one!)
Now the pressure went up to app 50 psi at idle.

By the way, the oil I use is DynoCat Supreme Classic GT SAE 10W-40 recommeded by motor shop after I put on the modified Vortec heads, .5 lift cam and full roller rockers.

GeneralDisorder

iTrader: (1)

I think you are fine with those new readings.

My Vortec has 50 psi at hot idle, and over 75 (as high as either of my gauges go - likely it's closer to 100 when revved) on cold start. Verified with a mechanical gauge. Turns out the Melling shark tooth "standard pressure, standard volume" pump comes equipped with the high pressure spring, and the standard pressure spring in a bag...... thanks Melling for failing to deliver what I asked for! Of course I only realized this after I did startup, etc. The engine runs great, isn't in any distress, and makes 325 RWHP. I thought perhaps it would be an issue for the lifters but with 130lb beehives it's not experiencing any problems.

The issue is obviously that a LOT of people are building engines with $hit clearances and then complaining to Melling that their oil pressure is too low - resulting in Melling shipping all the pumps with high pressure springs to alleviate the "symptom" and the tech support phone calls and complaints that their pump doesn't make oil pressure and that's "why my engine threw a rod bearing", etc. The reality is that billy bob and his cousin skillet have bearing slapped a clapped out 70's truck block and the clearances are complete garbage resulting in low pressure with a stock pump. Put a high pressure pump spring in a blueprinted engine with perfect clearances and you get astronomically high oil pressure.

As to the oil filter exploding - might happen with cheap filters but it's ultra rare nowadays. We run WIX filters on all the Subaru's which have insanely high cold start oil pressure by design. They are never below 90 psi on cold start, and usually over 100 psi. Even when hot they are are 90 psi - bouncing off the relief valve - as soon as you crack the throttle. I run the Amsoil filters on my Vortec and they have REALLY thick cans which is obvious when you use a filter cutter on them. With modern engines often running much higher pressure I believe most, if not all, filter manufacturers of note have ensured their filters have an adequate burst rating far in excess of 100 psi. I can tell you for sure the Amsoil filters are more than capable.

I was initially running 10w40 premium protection Amsoil, but with the oil pressure so high and the clearance in this engine being tight as they are (.002" on every journal, new cam bearings, etc), and being a roller cam..... I switched it out to Signature Series 10w30 instead. Oil pressure is still nuts.

GD