quick update

I went back through the suggestions on here and saw that one member had suggested to run the engine without the risers on there and just extend the water from the manifolds over the side of the boat.

I did that and can see the water forming in the manifolds. It looks as if it is coming out of the exhaust valves. Or at least I can say, the water is forming from way down in the manifold towards the exhaust valves.

I watched this water form then dried it out by jamming a shop rag down there in case it was residual from the previous run with the risers on, but it formed again when I restarted the engine.

I need another beer.

Maybe try disconnecting water from manifolds and run it just long enough to get a peak inside there?
Pressurized leak check of the manifolds been done?
Is it possible these manifolds could have cracked internally due to freezing?
Do you have another set of manifolds to try?

Pressure test the mans, can be done attached

X2

surely rules out cam overlap. pressure test manifolds.

You have a leak.
There is no way that is reversion.
That much water in the oil from 20 minutes on the hose is not reversion. You have a water leak.
Like said pressure test the manifolds.
I personally think you have a leak somewhere inside the engine.
Possible bad block or head. I have seen this before.

yup, plan for today is to pressure test these stainless marine manifolds. I have a hard time thinking that both manifolds are leaking but that would be best case here I guess.

These manifolds have never had the chance to freeze with water in them, so I do not think that is the case.

If the manifolds test water tight, I am seriously thinking about getting a new engine. I missed last boating season working on this boat and boating season is getting ready to start here now and I am not willing to miss another one.

We live on a lake and so boating is our deal. This boat was not supposed to be a long term project. I have a 28 sleek craft enforcer that is going to be a project and is planned to get twin small blocks that I can use this motor in after going through it if I need to. I am not giving up on this motor, I have too much into it, but I really want to be on the water cruising in a few weeks with this boat.

If I end up purchasing a motor, I am thinking about this one:

https://www.michiganmotorz.com/377ci...ent-p-545.html

I am wondering if my exhaust will fit seeing as though the heads will obviously be different. Do all small block heads have the same outside dimensions?

I was thinking about the HT383, but the cam although quite small is 109 lobe separation which from what I know is to tight for water exhausts and this 377 has decent specs for what it is.

Any other suggestions for a nice, ready to go small block with good parts would be welcome. I am not interested in engines from ATK or Blueprint or places like that.

I don't get it. New block, new risers, eliminated risers. Head gasket and intake manifold gaskets basically replaced twice now. What is the history on the exh manifolds? Let us know after you pressure test. I'd pressure test the engine as well.

I have seen head studs that don't seal till a couple hours of at temperature running. I don't know if you are getting seepage there but could be the answer. I had it with one of my motors and my builder suggested running it for a day and it did go away.

Did your oil look like his from seepage? I honestly believe no sealant at all could cause this. Pressure test the whole works. Quick and easy and just need an ear and a beer.

Are you sure heads are not cracked?