Boss 9 OE oil drainbacks

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JBR-3 wrote:In the OE Boss blocks, do the oil drainback passages essentially run through the coolant area into the valley,
or down into the crankcase ?

Also, my understanding is that the flow capacity of the original drain-backs was marginal, is this correct ?

The OEM Boss 429 block oil drain-backs which I have seen are at a different location at the deck surface than a normal 385 series block. They go down to the crankcase in the rear and front cover area in the front.

I was told there are other versions of oil drain-backs in a Boss 429 block but, I have not seen what those might be.

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they can drain back a lot,there is no issue returning oil on a BOSS

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