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I just built a 408 stroker and my oil pressure flutters very quickly once it warms up. It goes from 38-44 very quickly. When cold it stays at 65. I’ve never had a fluttering problem before and was woundering what it could be or if it’s a concern. When cruising 1500-2000rpms oil pressure stays at a constant 50psi no fluttering. It only happens at idle. This is a freshly built motor with about 40 miles on it. Any thoughts? I’m using 10w-30 Right now with bearing clearences being .002 for mains and .0025 for rods. Has a mechanical gauge, also used my friends new gauge and did the same thing. Thank you
 

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I'm not sure I'd be concerned about a 6 psi swing with decent pressures like that.
 

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65 Fastback 289 4 spd, 65 convertible 5.0L 5 spd. 3.73 8.8
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I just built a 408 stroker and my oil pressure flutters very quickly once it warms up. It goes from 38-44 very quickly. When cold it stays at 65. I’ve never had a fluttering problem before and was woundering what it could be or if it’s a concern. When cruising 1500-2000rpms oil pressure stays at a constant 50psi no fluttering. It only happens at idle. This is a freshly built motor with about 40 miles on it. Any thoughts? I’m using 10w-30 Right now with bearing clearences being .002 for mains and .0025 for rods. Has a mechanical gauge, also used my friends new gauge and did the same thing. Thank you
I wouldn't worry about that, it has oil psi. What brand of oil pump? timing chain slack at idle?
 

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I wouldn't worry about that, it has oil psi. What brand of oil pump? timing chain slack at idle?
I believe it’s a stock oil pump, it’s been working great before I rebuilt the motor. And timing chain is brand new.
 

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It could be your gauge. I have an electrical oil pressure gauge in my white 66FB and it flutters at idle only. I have a mechanical gauge in the 66FB project I’m working on and it is pretty steady at idle and at speed.
 

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My 408 did the same thing. It's got about 3,000 miles on it now and seems to have leveled out. I broke it in with Brad Penn break in oil, then switched to the zinc added 10w40 oil.
 
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