I have a 1970 buick 350 High compression engine. Just back from machine shop new bearings etc. Installed a new TA high flow oil pump, primed pump and oil flowing good. Started and broke in cam, oil pressure was 70-80 psi cold but when it warmed up at idle it was 5-10 psi at 800 rpm. I nudged the rpm s up to 1000 and it was 25 psi. Could I have a relief valve sticking open and bypassing the oil? I am ready to remove and change it with a stock GM pump. Any suggestions.
I see you only have 12 posts so you are new to this site. Anyone who has been on this site for a while will tell you that the HVHP oil pump kits are a big waste of money and can actually do more harm than good. They put more pressure on the front of the cam and distributor drive gear. Good hot oil pressure in a Buick engine depends on 2 things, proper rod and main bearing clearances, and proper clearances inside the oil pump. The oil pump pocket is integral with the front timing cover and it can wear to the point where it needs to be replaced. If it is worn excessively, you will have excessive gear end clearance, and that will kill your hot oil pressure especially at idle. A stock pump set up in a good timing cover will give you all the oil pressure you need. All this has been discussed many times on this site. All you need to do is put "oil pump end clearance" into the search box, then open a bag of pop corn and start reading. Not knowing whether the shop you used had any Buick experience before makes it hard to say whether they used larger Chevy bearing clearances or not.
yes the hi volume pump isn't really the answer. also I always drill out the oil passage from oil pick up screen to oil pump to 1/2with the 5/8 melling pickup .use stock gears with booster plate and get ta gasket shim kit as clearance is the big issue as aluminum expands at different rates then the cast iron gears. and more clearance equals less oil pressure. chances are you need to tighten clearance on oil pump
You say new bearings but that's all. Was the short block rebuilt or did you just install new crank bearings? Were the cam bearings changed? The front cam bearing controls oil flow to the rest of the engine. If that bearing is worn you will never get good hot oil pressure. Only install grooved TA brand cam bearings as per their specific relocation instructions.
