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10-22-2021, 05:26 PM | #1 |
Member
Join Date: Jul 2021
Location: Minnesota
Posts: 31
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8CM high oil pressure?
I fired my Flathead for my 50 merc up today for the first time. For some reason I’m getting 50-60psi of oil pressure at idle. Revving it up will move it to about 70, maybe 75. I’m thinking there is something goofy.
I plastigauged all the rod and main bearings when I assembled the engine, they all checked out at around .002-.0025. Cam bearings I couldn’t check cause I don’t have a bore gauge, they felt a hair tight, but I could still spin it by hand without too much effort. Oil pump is a new Melling M-19 from speedway. I had done the 95% oil mod, and had 1/2”(AN8) hoses and fittings going to a k&n spin on filter. I removed the lines and internal plug, it’s reverted back to stock oiling now, and if anything that made the pressure go up a few pounds. I’m confused. Any ideas? |
10-22-2021, 05:43 PM | #2 |
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Join Date: Sep 2011
Location: Christchurch New Zealand
Posts: 1,610
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Re: 8CM high oil pressure?
What weight oil are you running? After a new build some rin in oil or at least a lighter weight oil. That pressure considering a rebuild with a high volume oil pump is up there but in my opinion seems ok. Oil also would not have reached an operating run temp, will give a slight pressure drop off.
Phil NZ |
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10-22-2021, 05:45 PM | #3 |
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Join Date: Jul 2021
Location: Minnesota
Posts: 31
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Re: 8CM high oil pressure?
Running 10w30, forgot to say. The M-19 is standard volume.
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10-22-2021, 05:54 PM | #4 |
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Join Date: May 2010
Location: Coral Springs FL
Posts: 10,919
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Re: 8CM high oil pressure?
50MercMetalHead: What is the oil pressure after the engine is at operating temperature both at idle and "on the road"?
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10-22-2021, 05:58 PM | #5 |
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Join Date: Jul 2021
Location: Minnesota
Posts: 31
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Re: 8CM high oil pressure?
I haven’t run it up to temp yet. I was going for a few laps up and down the driveway but I had to stop and fix something on my exhaust. I will let you know once I can get it up to temp. I did notice just now before I had to stop, it had dropped to about 40 for a moment, before going back up to 55.
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10-22-2021, 05:59 PM | #6 |
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Location: upstate SC
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Re: 8CM high oil pressure?
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10-22-2021, 06:27 PM | #7 |
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Join Date: Jul 2021
Location: Minnesota
Posts: 31
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8CM high oil pressure?
I get the same reading on 2 different mechanical gauges. For a moment I thought that may have been the problem, but the gauge is fine.
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10-22-2021, 06:38 PM | #8 |
Senior Member
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 10,302
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Re: 8CM high oil pressure?
Sounds like someone shimmed or stretched the relief spring.
I'd replace it. |
10-22-2021, 07:27 PM | #9 |
Member
Join Date: Jul 2021
Location: Minnesota
Posts: 31
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Re: 8CM high oil pressure?
Ok, I’m having temp gauge issues, but I’m positive that got it up to temp (no way it wouldn’t be up to temp with 180° stats and no heater cores), I drove it probably 4-5 miles, it was running for probably 30-45 minutes. It runs really good btw. I’m seeing somewhat more expectable pressure now. 20-25 at idle, and 60 at cruising rpm.
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10-22-2021, 08:09 PM | #10 |
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Join Date: Jan 2021
Location: Slightly left of Vernon, BC
Posts: 155
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Re: 8CM high oil pressure?
I have had my '49 F-47 for about a year with a C1BA and from the time I first started it, with a good mechanical gauge screwed right into the engine block, I get 50 PSI at start up and doesn't really drop much after it warms up. Haven't been able to drive it yet,it may drop after it runs for a while.
cheers
__________________
1949 Ford F-47 with a '51 8BA Flatty, GM TBI fuel injection system, and a grey shop cat, Spot. |
10-22-2021, 09:25 PM | #11 |
Senior Member
Join Date: May 2010
Location: Coral Springs FL
Posts: 10,919
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Re: 8CM high oil pressure?
Sounds like things are getting better. Keep driving it.
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10-23-2021, 05:00 AM | #12 |
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Join Date: Sep 2013
Location: Dighton, Mass
Posts: 1,230
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Re: 8CM high oil pressure?
Looks like a healthy engine in my book thats exacty what mine runs at now 7,000 miles
no changes. |
10-23-2021, 03:07 PM | #13 |
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Join Date: Jan 2011
Location: Central Ohio
Posts: 5,062
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Re: 8CM high oil pressure?
I don't see anything wrong with it . . . just drive it as is!
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10-23-2021, 06:33 PM | #14 |
Member
Join Date: Jul 2021
Location: Minnesota
Posts: 31
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Re: 8CM high oil pressure?
Well I put about 50miles on the car today, just cruising in town so a few hours of driving. Seeing 22-25psi at idle, 40-50 at cruising rpm, and about 70 when I really get on it. I’m happy with those pressures, and it runs great, so I think all is good. I appreciate the help guys. Felt great to drive it again.
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