Fresh rebuilt AMC304, first start up and oil psi is too high

Hello everyone. Newbie here.
I'm currently doing a frame up rebuild on a 1979 CJ5. Has a 304, Ti76 and Dana 300. Had the engine completely rebuilt by a local machine shop. Both machinists there are in their 70s and one used to race AMC motors.
Motor was completely rebuilt. All bearings, seals, pistons, bored .30 over. mild comp cam. Edelbrock performer intake, complete Holley Sniper EFI system. I used Bulltear AMC oil pump kit + upgrades. Did the standard HD version for oil filter adapter and the HRC gears.
Started engine for the first time today. It has Lucas 20w50 break in oil in it. Was given to me by my engine builder. Carquest oil filter - 85258. They assembled the front cover and oil pump and I know they packed it with grease upon assembly to 'prime' it. It started right up and sounded great but my oil pressure is reading 100psi on the gauge I temporarily hooked up to monitor it. Nothing is leaking and the engine didn't sound strange. The gauges I'm using did come with an oil pressure sending unit so I don't know if it is a calibration issue. I'm going to call auto meter tomorrow.
Asking for some advice as to where I start? Pressure relief valve? Wrong oil filter? Bad gauge reading and need a different one?

Thanks in advance

Harold

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It could be that the pressure relief valve is stuck. There's a big nut on the oil filter adapter. Behind it there's a spring and plunger. Make sure the plunger moves freely and that it faces the right direction. The pointed end goes in first. I have heard that some of the aftermarket adapters had the hole drilled on the small side of the tolerance limit.

Bob
tufcj

It could be that the pressure relief valve is stuck. There's a big nut on the oil filter adapter. Behind it there's a spring and plunger. Make sure the plunger moves freely and that it faces the right direction. The pointed end goes in first. I have heard that some of the aftermarket adapters had the hole drilled on the small side of the tolerance limit.

Bob
tufcj

Thanks for the reply. I'm going to try that. Spoke to my engine builder this morning. He suggested that I try the sending unit for the gauge and a mechanical gauge first to ensure that the pressure is that high. Then open up the pressure relief valve. So I'm going to try all that and let you all know what results I get.

Harold

Thanks for the reply. I'm going to try that. Spoke to my engine builder this morning. He suggested that I try the sending unit for the gauge and a mechanical gauge first to ensure that the pressure is that high. Then open up the pressure relief valve. So I'm going to try all that and let you all know what results I get.

Harold

Just spoke to Autometer. Tech confirmed that NOT using the sending unit that comes with the gauge will cause it to peg to one side or the other. Will confirm pressure with mechanical gauge and if all good I'll install the included sending unit while this gauge is in use.

UPDATE. I'm happy to report that I put a mechanical gauge on my engine and got a healthy 55-60 psi oil pressure on start up when cold. So the issue was conflict between my gauge and the sending unit on the motor.
Next question is that I was going to install the included sending unit for my temporary gauges but it is way to large to fit in the tight factory location. What are you guys doing in that case? Remote hose to locate it elsewhere?

Harold

the fittings are 1/8" pipe thread. On AMC cars that had both a light and gauge (2 senders) they used a brass nipple and "T" fitting. You should be able to come up with something at a hardware store. The hex fitting in the block that the sender screws into is threaded, and can usually be clocked slightly for clearance.

Bob
tufcj

the fittings are 1/8" pipe thread. On AMC cars that had both a light and gauge (2 senders) they used a brass nipple and "T" fitting. You should be able to come up with something at a hardware store. The hex fitting in the block that the sender screws into is threaded, and can usually be clocked slightly for clearance.

Bob
tufcj

Thanks for the advice. I ended up hooking a mechanical gauge and had a healthy 55-60 psi on cold start up. Left the mechanical gauge on and did an engine break in. Warmed up the oil pressure drops to about 45psi and is about 30 psi at idle when warmed up. Engine runs great. Got my EFI set up and tuned and it idles beautifully at 700rpms.
Now to deal with my next issue....LOL. I bled out my brakes, hydraulic clutch, and power steering. All went well and is functioning as they should. But....after I shut my engine down, total run time on it of about 1-1.5 hours. I noticed a drip under it.
Investigated it and it was clean coolant. Dripping on driver's side rear of block. At first I thought it was the freeze plug right in front of the dipstick tube but have since realized it appears to be seeping from the head gasket. It only drips when under pressure. Stops as soon as it shuts off and pressure drops. I checked my oil and coolant and no evidence of cross contaminating. No evidence of burning coolant. Spoke to my engine builder. He told me not to panic and to run it through several more heat cycles and it will likely seal itself.

Any thoughts?

Harold

AMC V-8 heads are known to crack at the lower front and rear corners if not torqued correctly. There's a sharp point in the casting. Between cylinders has to be a gasket problem. I doubt a few heat cycles will do anything. It might take a re-torque of the head bolts to proper torque in the proper sequence. If that doesn't fix it, you'd have to remove the head to find the failure. I've had good results with the AC-Delco stop leak tablets, but I only use them as a last resort.

Bob
tufcj

AMC V-8 heads are known to crack at the lower front and rear corners if not torqued correctly. There's a sharp point in the casting. Between cylinders has to be a gasket problem. I doubt a few heat cycles will do anything. It might take a re-torque of the head bolts to proper torque in the proper sequence. If that doesn't fix it, you'd have to remove the head to find the failure. I've had good results with the AC-Delco stop leak tablets, but I only use them as a last resort.

Bob
tufcj