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Help, please....I just had the 428 CJ rebuilt and the oil pressure seems very low. I have it on the dyno and the pressure is at maybe 10 psi at idle. At 2500 rpms it is at 24 psi and drops as the oil warms up. Everything is new including the oil pump. The temperature is good and stays steady. What gives? Shouldn't I be up higher at idle? I don't think changing to a high volume oil pump is the answer, is it?
Rule of thumb is 10 psi / 1,000 rpm. Did you check the clearance on the bearings? What weight oil are you using? What is the pressure when it is fully warmed up (around 200 degrees oil temp.)?
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I have heard the ten pounds per 1000rpm, but warmed up with 14 pounds (dropping) at 800 rpms, I am concerned. I would like to see a warm idle pressure twice that. Is that wrong? The engine builder has been called. The oil gauge is accurate. The engine is at dyno tester. I will have to check the filter, but I believe it is a regular ford street filter.
How much does your builder know about FE's. It sounds like one of my rebuilds from a builder that said he knew all about FE's but after 3 rebuild it was clear he was in the dark. I would pop the dist. out and hook up a drill to turn the oil pump and if you can see oil flowing out the front of the block down on your drill rod he forgot to install an oil plug by #5 cylinder.
Obviously, not enough. I will be having another machine shop do the rework. I plan to post this make a learning experience for everyone and I will post the issues up here on the forum.
Is your pressure gauge before or after the filter? If after, I would check carefully that you did not plumb the filter circuit backwards. If so, you may be pumping against the check-valve in the filter and seriously limiting flow and in-turn pressure. There have been several postings in the past on CC regarding this error - some repeated several times with resultant failures. Quick to check and may save more extensive work since you have limited run time on the motor.
Cobra Make, Engine: ERA 427 w/496 Side Oiler, roller, dual quads
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Quote:
Originally Posted by Coralsnake
...warmed up with 14 pounds (dropping) at 800 rpms, I am concerned. I would like to see a warm idle pressure twice that. Is that wrong?...
14 lbs or better at idle should be sufficient...10 is "theoretically OK", but I personally prefer more. 25-30 lbs at idle is more than you need, but can be done using heavier oil, which isn't always good because it takes so long to get pumped through the engine on startup.
A high volume pump will not fix your problem, but IMO anything but a stock rebuild should have one...they're cheap insurance.
Dan
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I think you have a problem…and suggest you do not cause further problems by running it until you find the source of trouble.
At 2500 rpms a fresh CJ engine should have at least 40 lbs and I would expect more. The CJ’s have a standard volume, high-pressure pump, limited to about 65 lbs. It should run at or near that pressure at cruise speed / operating temp. You have a clearance issue somewhere. A plug may be left out internally, or worse there is an assembly or machining error. I have seen several FE’s assembled with the cam bearings incorrectly installed and this will cause exactly the symptoms you describe.
I had the same problem. I had a Fram filter on at the time. I switched over to NAPA GOLD (made by WIX) problem gone! I even added a oil cooler which everyone said would my problem worse. Trust me. Go to NAPA tomorrow by a NAPA GOLD filter #1515. Do the swap and post back your results.
One more thing. If you are running roller rockers make sure you put rstrictors in the heads...this got me a couple PSI. Thanks to George Anderson.
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428 CJ with low oil pressure
I will be having another machine shop do the rework. I plan to post this make a learning experience for everyone and I will post the issues up here on the forum. 
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