Don Terrill’s Speed-Talk

SBC with hydraulic roller street engine that has 70# oil pressure when cold 65# when hot. This is a brand new build rods are .002 -.0022 mains are .0026 -.0028. I know this is way too much can anyone tell me what color bypass spring would get this back to acceptable pressure. The pump is a HV55. Would also change pump if needed. This is with 15w40 would a 10 or 5w 30 help much? Thanks

65 psi when HOT, how HOT and at what rpm ? Mark H.

65lbs going down the road when at operating temp...... or 65psi at idle?

I’m old school.......65lbs going down the road at normal operating temp would be fine with me.

Wilson,
Your engine doesn't need 15W40 oil. Change to 5W20 or 5W30.

Sorry pressure is at idle in the driveway. I was going to switch at first oil change but might be sooner.

Wilson 1970 I want to hear the follow up on the difference in pressure when you change to a lighter weight oil I'm real curious about that. Mark H.

you installed a hv pump and you dont understand why the pressure is to high with your stated bearing clearance?

You may have bad oil pressure gauge? Bought brand new auto meter 4421 pro comp last year installed on new motor,fire engine oil pressure was good,gauge dropped back down to 50 lbs at idle shut it off and it's still there. Just checked,its still holding 50 lbs in the box! Didn't even do a return,just ordered another just like it. It would go up just wouldn't return pass 50lbs.

The gauge is an auto meter sport comp ll I am fairly comfortable that it is accurate.

I'd put in thinner or and live with it

I'm not a fan of high volume pumps in SBC's either. I have always used the z28 pumps with good results, but I put a pan and pump on a good friends car that I am lucky enough to be able to race too. We put a Melling Shark pump in it and I am pretty impressed with it's performance. Feels way better when priming it by hand and it holds 40psi idle hot and 70lbs wide open with 30w oil. Camshafts can change oil pressure also, my personal engine is exactly the same as it was before with no other change but the camshaft and the oil pressure is lower by 10lbs. I assume it has more clearance at the cam bearings and is allowing more oil to pass by. Many things can effect the psi on the gage.

wilson1970 wrote: ↑Thu Sep 20, 2018 4:01 pm SBC with hydraulic roller street engine that has 70# oil pressure when cold 65# when hot. This is a brand new build rods are .002 -.0022 mains are .0026 -.0028. I know this is way too much can anyone tell me what color bypass spring would get this back to acceptable pressure. The pump is a HV55. Would also change pump if needed. This is with 15w40 would a 10 or 5w 30 help much? Thanks

Thats what id expect with that pump, lighter oil will make the most difference at hot idle.
As has been asked- what 'oil' temp?
Wait till you have driven it and gotten the oil to full temp then reassess.

how much pressure do you have at higher rpm when hot? gen hv pumps have about 45 lbs hot with 30 weight at idle and whatever the spring pops off at speed assuming the volume of bypass oil is not overwhelming the port. i would put a std volume pump in it with the 70 lb spring. you will prob have around 30 psi hot at idle in gear. or try lighter oil

Thanks for the chart. I will change oil and re asses