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Discussion Starter · #1 ·
I picked up a used but rebuilt 390 recently, done .90 over with c3ae6090c heads, hv oil pump, performer intake, stock cam. After running it that way for a while without any problems, I installed a hydraulic roller cam that i had pulled out from my previous 390, so I know it worked well and I didn't expect any issues from it. Running it without the valve covers, the drivers side is getting way more oil than the passenger side. So much that the valve cover leaks and the exhaust pipe on that side smokes a lot. I have no idea how this came about just from the cam swap, I have some shims under the rocker shafts on both sides because the pushrods were off, though on my last 390 with this cam that caused no issues. My only thought is that when it was rebuilt they used a non-matching pair of head gaskets, one with a restricted oil feed hole and one without, perhaps I just haven't noticed this until now or the cam made it worse somehow. Oil pressure is still good, 70psi cold at idle and always runs 60psi around 1500rpm. I think I'll proceed with changing the head gaskets, i probably should have done that in the first place just being that the engine was used and I don't know much more about the rebuild, If anyone has some ideas on this I'd appreciate it. Thanks
 

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No really good ideas beyond checking for drain back. The FE usually has feed problems what with the oil needing to get around a head bolt, then through a transfer passage in the head‘s deck to a rocker shaft boss mounting bolt. Not as bad as the Y block but no picnic either. The sheet metal guide is an important at of the drain back process as well, and the rocker shafts should be plugged on their ends otherwise oil leaks out the ends. The shims you reference may be leaking or bleeding oil before it enters the rocker shaft.

Bogie
 

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Discussion Starter · #3 ·
I replaced the head gaskets last night, nothing seemed off with them. I ran the oil pump without the heads to see that both sides we’re getting equal oil, they were. I also replaced the rocker shaft assemblies with some spares after still seeing one gush oil when priming, that seemed to do the trick. One was still getting a little more oil i think, but I’ll check under the valve covers later today. Curious issue
 
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