Could be wrong too. i speed read and skip a bunch sometimes.

SB,

We've established it's a VP 8.1. And we all know that's a Merc 496 by another name.

Thanks. Brad.

Double checking there isn’t an o ring or gasket for the oil passage on the rear cap to block joint.

can you post a pic of the rear main cap

Crankshaft Main Bearing oil clearance.

1- .002

2- .0015

3- .0015

4- .0014

5- .0019

All within spec

Both heads are on. Found 2 bent push rods from the old heads. Can I just replace the bent 2 or do I need to replace the whole set and more? Thanks

ha e you determined why the 2 bent?

You have rockers that are non-adjustable. The adjustment is in the pushrod length.

I would source a an adjustable length pushrod, and see what you need for optimal rocker contact on your valve stems.

Then buy the appropriate sized set of pushrods.

How did you measure the main bearing clearances? Very tight for a marine BBC.

That's spec? Seems tight to me, my rods aren't that tight.
I thought at least 0.001"/in

In another life I built a lot of engines. Sometime in the beginning had a problem with one in particular that was eating main bearings. After a couple of failures I finally figured out that the machine shop I was using at the time didn't know wtf they were doing. They managed to align hone the blocks so they were small at roughly 60 deg before & after vertical. Wasn't until I had my own align hone that I saw how easy it was for that to happen. Had never run into it before, always just measured vertically. That was a real wakeup.

So - here is what I came up with - all measurements with a dial bore gauge that can read tenths, same with the mike. Measure journal in 3 places (find smallest dimension) Record all and take an average.

Measure crank in at least 3 places, check for taper, out of round. On an engine with some hours on it this is somewhat normal. Record largest & smallest dimension and take an average.

Subtract largest crank measurement from smallest journal measurement. This is the one that will get you in trouble the fastest. Actually printed out a form and kept it each engines file.