Bbc 502 ,Melling 10778, bearing clearances?
Hi, bought melling 10778 oil pump for my 502 gen6 project, rod bearing clearances are 0.0031", mains 1-4=0.0023", 5=0.0035", plan is to polish the 1-4 main journals to get 0.003" clearance. should i go with Std volume pump/ blue spring, instead of my 10778 25% hi-volume pump? oil pan is stock 8qt.
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Jani,
You cannot polish that much off a crankshaft and still have it be straight and round. I would get a set of bearings that will give you an extra thousandth clearance and go with it. I have never had an issue using a regular Melling M77HV pump. How are you measuring the clearances ? |
I've used 10778, 10778c and M77HV.. For some reason I like the M77HV the best. Pressure seems to always be consistent and what I expect to see on a build. Seems idle pressure was better.
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Originally Posted by BillK
(Post 4735710)
Jani,
You cannot polish that much off a crankshaft and still have it be straight and round. I would get a set of bearings that will give you an extra thousandth clearance and go with it. I have never had an issue using a regular Melling M77HV pump. How are you measuring the clearances ? |
Originally Posted by Rookie
(Post 4735712)
I've used 10778, 10778c and M77HV.. For some reason I like the M77HV the best. Pressure seems to always be consistent and what I expect to see on a build. Seems idle pressure was better.
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My last engines I set mains up .0030-.0034 1-4 and rear was .0004 increased front to back, melting select HV with shimmed spring, 80 psi of pressure and ran flawless I was always told by marine guys more clearance and mire oil for endurance engines, I never had issues with them clearances
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Originally Posted by JaniH
(Post 4735732)
What kind of pressures you have? Spring colour? Bearing clearances? Oil?
Also, I am not an engine builder, this is what has worked for me. |
Originally Posted by Full Force
(Post 4735770)
My last engines I set mains up .0030-.0034 1-4 and rear was .0004 increased front to back, melting select HV with shimmed spring, 80 psi of pressure and ran flawless I was always told by marine guys more clearance and mire oil for endurance engines, I never had issues with them clearances
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What is stock 502ho/hp500, oil pump?
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Get a set of the HX bearings and only use one half. You will run you standards in the lower (cap) and the HX in the block. Will gain you .0005"
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