water in cylinders

back two spark plugs?

Brad,
Get back to her as soon as you can to check those back cylinders again. It's hard to imagine that if you winterized properly, draining all the water from the HM manifolds, (or whatever kind for that matter) that both would crack, but if you have water back in the cylinders that could indeed be the cause as hinted above. (Where've you been, Mack?)
If you have a manifold leak, it could indeed run fine all day, with only a small amount of water leaking down not presenting a noticable problem as it blew it out, but then after sitting for several days, water could continue to leak out at a slow pace and flow mostly towards and settle in the back cylinders on decline. I had my 69 Mustang ingest half of Lake Norman two years ago when another operator attempted to start it and said it sounded like it misfired and preceeded to fill all 8 cylinders, and we NEVER found the cause, or evidence of it anyway. It's been fine ever since. Don't know if anyone remembers the thread, but it was suggested that it somehow spun backwards for a second while attempting to start and sucked water back up??   Never made sense to me, but we checked everything and then took it to some pros who also found nothing after performing every vital stat test known to man. Anyway, check to see if the water crept back in and let's go from there.

If the exhausts are leaking water, (which probably leak in after shut down, while running, exhaust helps to push it back) look on the heads under the manifold where it touches the head and see if you see any signs of water/rust trails coming out between the gasket and the head.

the gasket between the manifold and engine can't cause a problem, the gasket between the riser and manifold can depending on the type/style they are. Check the intake bolts and make sure they are all tight.

The H/M aluminum exhaust manifolds do have a tendency to corrode or burn through. Have a friend with a 70 Barracuda with the H/M 302 with water getting into the rear cylinders. After lots of testing and new gaskets he finally found holes in the risers. Both sides and in the same spot. There is a section in the riser that is very thin walled. They would leak back after shut down. Welding was a problem because there wasn't much aluminum left in the area.

Jbear needs some elbows like those for his manifolds, if you can't fix them and the risers are good maybe you can work something out with john.

Ok so I don't totaly know who it works is there two chambers inside the manifolds, one with exhaust and one with water and the one with water has rusted through to the exhaust?

Is this what it looks like kind of?

That pic is just one I grabbed off of someone's post, I have not had mine off yet. I guess I will have to do that sometime. Is there anything that I should know when I take them off should I go a head and get some new gaskets before I take them off, do you suggest any certain type or companies to buy parts from.

Where or how should I get them pressure tested?

Thanks for everyones help!