360 oil psi dropped all the sudden

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SAM67

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360 very low miles on it like maybe 2000. Changed the cam, heads, oil pan and pickup tube so I could put it in a car. Always carried 55 psi when warm. Made 2 passes and oil psi dropped to 18 at idle and goes to 45 when I rev it. Changed oil and filter. 10w40 with zinc additive mopar filter. Oil psi held at 65 then ran it Down road and back to 20 at idle. Any ideas? No noises from motor
 
It is normal. 10PSI for every 1000 RPM. You can try using a thicker oil like 20/50 if you are worried about it. This will probably increase your idle pressure by about 5psi.
Every car when it gets to operating temp, the oil pressure will drop a bit.
 
Well I thought it was that too, but now it's got a rattle down low when I step up on it, time to tear it apart, :(. Someone too me I coulda sucked the pan dry? Stock car pan from jegs, with mopar performance pickup and a stock replacement oil pump by mellings...? Ever heard of that happening?
 
It sounds to me like maybe the pick up tube is to close to the bottom of the pan.just a thought.......if the oil psi.was good before?....
 
1) get rid of mopar filter and install a wix,
*if that changes the OP
*change oil to Valvoline vr1 no additive required.
2) if 1 is NO Houston we have a problem pull the pan, is the oil pump seated properly?

above) assuming you have a good gauge.
 
Gauge is good... And the motor has been together like it is for a while, just never ran it hard. I got metal in the oil so ima take it apart and see what happened. Rebuild and install deep oil pan. High volume op be a good idea?
 
You say you used a stock replacement pan, I'm guessing you didn't put any kind of baffle in there? It is very possible you uncovered the oil pickup going down the drag strip and possibly rashed the bearings. This is why it's important to either weld in a home-made baffle when using a stock oil pan or go with an aftermarket deep-sump or baffled pan when racing.

EDIT: HV oil pump would be a good move esp. if you are rebuilding it with wider bearing clearances. Get one of the redesigned oil pump driveshafts as well since the stock ones are known to break the tip off when put under extra stress of HV pump/thick oil/high RPM.
 
I got a windage tray on it... Lol. I hope that's all I did. I hope I didn't scar the crank up too bad.
 
Agree with Mopekid3. Never use a non baffled pan in a car that you race (even street hot dogging). A windage tray isn't any thing like an acceleration baffle. A pan baffle keeps the oil in place (where the oil pump pickup can suck it up) under hard acceleration. I made the mistake yrs. ago of using a stock pan on a 360 and with stock radials had no problem but as soon as I put sticky tires on it the oil pressure would go way down on takeoff and naturally the bearings didn't last long. As for sucking the pan dry, that's an old wives tale that a lot of us used to believe until we ran across an article the Ramchargers produced way back in the 70's that proved the oil pickup is too restrictive to allow that to happen. In fact it showed the flow results of a stock vs. hv oil pump with a stock pickup and the hv pump didn't hardly pump any more cause the stock pickup is too restrictive.
 
Ok that makes sence and back when I ran it at the track in my truck I never had to worry about it do much because it was a rear sump set up?...
 
SAM67 said:
Ok that makes sence and back when I ran it at the track in my truck I never had to worry about it do much because it was a rear sump set up?...
Click to expand...

Yes you are correct, a rear sump pan makes this less of an issue not only because it is in the back but also because it is deeper and narrower than the center-sump car pans.

fishy68 made a great point about the oil pickup as well, be sure to get a bigger one if you're going with an HV pump and a higher-capacity pan is pretty necessary too at that point.
 
Op, did you build your engine yourself or did you buy it? I'm wondering about your bearing clearance. I've run my duster for years with a stock pan with no issues. I've even had numerous people tell me the car pulls the driver side wheel off the ground. I've never had an issue with oil pressure. With the clearance being not right you pressure may be ok till the oil thins when warm. Now that you have metal in the oil it sounds like your be pulling it apart. Keep us posted.
 
Have seen all to many spun rod bearing with a stock center sump pan, windage tray, and HV oil pump. Need a good high capacity pan w some kind of baffle to keep the pick up submerged in oil. I think the reason is under hard acceleration all the oil is forced to the rear of the pan and the pick up is left dry. I have had this happen to myself even. Hard acceleration at about 6500 RPM in one of my 340s the oil pressure dropped off and she started clattering like crazy. Shut it down immediately, But was already to late. 6500 w no oil is not good for things. Still ran OK but oil pressure dropped about 10 lbs. Ended up turning the crank and installing new bearings. Now run a 7 qt pan w some oiling mods. and have never had an issue.
 
Definantly starved the motor for oil, spun rod bearing, every bearing was shot and crank was too far gone. Wiped a cam lobe too. Got another crank, clevite p series bearings, hv oil pump, hardened shaft, and a 8 qt moroso oil pan and pick up, waitin on machine shop to finsh crank and block
 
Just to make something clear here. The reason why you don't over fill a crank case. If the crank is "dipping" down into the oil, It causes the oil to foam up. The the Oil pickup can't pick up the foam it needs pure oil. Not saying this was the cause but it's always something to consider when dealing with Oil pans and filling them up. And +1 to needing a Baffle in place.
 
..............If the crank is dipping down into the oil u have atleast a gallon over the full mark on the dip stick...infact i've never seen it...i have seen that with out a windage tray that the oil gets wrapped around the crank from the windage ....I have been racing for more than 30 years with a stock pan filled 1 qt over the full line and not 1ce have i had a problem big or sb mopar.....kim......
 
the hv pump in my old 340 never sucked the pan dry.

My guess is the old rod bolts stretched when you rev'd it up over 6k or so...let alone the cam wiped a lobe lord knows how bad and sent metal everywhere.jmo
 
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