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Old 10-21-2013, 01:34 PM
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Oh Low is Me! (and my oil pressure)

Hi All:
Finally got the ride of my dreams. 34 Ford three window coupe, Rat Rod style. Got it registered Friday and took if for its maiden cruise Sat. Has a 78 Nova 350 in it. Many mysteries in the engine as I bought it from the second owner and not the builder. Car sounds tough and runs rugged but after she warmed up my oil pressure guage dropped to -0- (a tear). When I rev it she comes back up but drops again at idle. Only thing I did prior to this was change the oil. I used 10/30 and probably should have went with a good synthetic with a higher grade? Any thoughts on wether this could be part of my problem? My first thought was to yank it out and put in a new crate where I know what I have but I love a challenge. 9Actually I'm too old for challenges and just want to ride. LOL I know there could me a million reasons for this but any suggestions on preliminary tests I could run before I make a yard orament out of the motor? Thanks all!

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Old 10-21-2013, 01:42 PM
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Test with a reliable mechanical pressure gauge. You can then change to a 20w50 but that will only mask the problem if your bearings are wore out.
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Old 10-21-2013, 01:49 PM
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Bill, this is exactly why I never buy anything that runs, unless it is bone-stock from the factory.
Things I can think of that will offer low oil pressure.....
1. Excessive clearance of rod and/or main bearings.
2. Oil pump relief valve stuck open.
3. Air leak at pump mounting on rear main cap.
4. Air leak between pump and pickup.
5. Pickup uncovered by failure of oil to return to pan. (gummed-up drain-back holes)
6. Holes drilled in front galley plug to oil timing chain.
7. Notch ground into big end of rod to oil underside of pistons to remove heat. (been there, done that, 1/2" wide, 0.012" deep. Suggested to me by Joe Mondello during a phone conversation with him concerning building a 455 Olds)
Other fellows will likely wade in with their suggestions, but I'm seeing an engine stand in your future.
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Old 10-21-2013, 01:52 PM
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Thanks

Thanks Rich.
I will give that a shot and see what I see. I was hoping for a faulty guage or sending unit (easy way out of course). I will let you know what I find.
I really appreciate your help!
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Old 10-21-2013, 02:17 PM
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I had this happen, caused pressure problems and excessive heat.
And a long time to find it.
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Old 10-21-2013, 02:35 PM
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Ouch!!

appreciate your reply!
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Old 10-21-2013, 04:59 PM
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The 350 SBC is notorious for low idle psi after getting worn in good.The synthetic oil will make it worse.What is the cold idle psi ? As said above,ck it with a known reliable mechanical guage.As a rule of thumb,you need a minmum of 10 psi per 1000 RPM.
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Old 10-21-2013, 05:11 PM
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Is it knocking or anything weird when the guage reads zilch?
Get a known good mechanical guage on it, like Joker said, skip the synthetic, if its quiet and runs fine, throw 20/50 in it and just enjoy it...save your pennies and if breaks you will be ready.
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Old 10-21-2013, 08:37 PM
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throw straight 40w in it.You have the simplist/cheapest engine around,no problem to fix or repair if required
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Old 10-22-2013, 07:28 AM
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Thanks for all your help guys! I feel a bit better. The cold idle PSI is at 40. No noise at all when the pressure drops. Top and bottom end are both quiet when pressure is down. I noticed last night also that I am down a quart on the stick (didnt comepensate for the filter). I am going to change the oil again with 20/50 (no synthetic) and drive it till I have to make a lawn ornament out of it. Its still cool and I can always sit in the driveway and make engine noises!
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Old 10-22-2013, 08:23 AM
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Since you've got good cold idle pressure, I doubt the gauge is bad or wrong. I'd guess it's worn bearings, and once the oil gets warm it simply drops pressure. Any other issues would probably show up hot or cold. I'd follow the advice of getting a heavy straight weight oil, and run it until that doesn't work, or the engine finally drops dead. Then swap in your new engine.
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Old 10-22-2013, 10:12 AM
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As many have mentioned, you could check it with a reliable oil pressure gauge. You could also just use a heavier weight oil in it, but also as others mentioned this will only mask the problem. My advice would be since you aren't sure what parts are really in the motor then I would take it out, tear it down, and freshin it up. Have the crank and rods turned and resurfaced, you can likely get away with just honing and using the same pistons (assuming you are happy with them). You could change out to a cam that you want. If everything is still in good condition then you could likely get away with only spending around $1000-1500. Then you would have the engine that you want and that you know about, not to mention it would be fresh.
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Old 10-23-2013, 08:24 AM
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Bill34, Replace the distributor if all else failed. I had low oil pressure and turned out to be a bad dist. I did not get a good seal to lube the lifters. This happen twice. It happen to my 307 sbc and my 406 sbc.
[IMG][/IMG]
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