SB

Seen several bent connecting rods from water filled combustion chambers.

Tread lightly.

Baja Rooster

Ugg. Any way to determine if the rods are bent just by pulling the heads, or does it need to be a visual inspection?

Baja Rooster

Is it normal to have a slow spot when cranking or does that indicate something binding?

This is the motor, fwiw.
http://eagleenginesales.com/new-5025...gh-performance

MILD THUNDER

Water in cylinder can definitly cause a slow spot while cranking.

Was this engine straight from GM, or has it been touched by anyone?

Baja Rooster

Aftermarket.

http://eagleenginesales.com/new-5025...gh-performance


It was still holding 70+ psi oil pressure on the last run.

MILD THUNDER

Pretty sure eagle doesnt mill the heads, the block, do valve jobs, etc. They prob buy from GM, make a couple changes, and ship it out the door. So its straight from Eagle you are saying?

Baja Rooster

Bought it out of the swap shop with a reported 50 hours of run time, Can't say if it's been molested or not. I also had the heads off myself as I was going to get them flow tested for Rob to size a cam, but my flow tester took a month and still didn't get it done (that's a whole different story), so I bolted them back on for what little season I had left. I did not have them milled as I planned to pull them again this winter. Fel-Pro marine gaskets from Summit.

MILD THUNDER

A properly machined, and assembled high performance marine engine, should have equal deck heights, combustion chambers that have the same volume, valve stems that are equal length, etc. Things that can change that, are valve jobs, head milling, deck surface milling, head porting/chamber polishing/porting, and so on.

While you certainly have a header issue to focus on, and thats #1. I personally though, would never allow my engines, or buddy's engines, to vary as much as 20-25+PSI of cranking pressure from bank to bank. Its one thing if you have a slight loss of compression psi from cyl to cyl due to valve leakage or what not, but normally, when it's off that much bank to bank, I bet you'll find someone had their dirty little hands in there.

Get a machinist straight edge, and lay it across the valve stems. My guess, is you probably won't find equal length across them.

Baja Rooster

I had the highest recommended guy for this area who specializes in nothing but cylinder heads (why he was so busy), and he said they definitely needed work. The valve seats alone were .009 out of round. He was going to blueprint them. My concern now is if I have a bent rod or not.


Every primary tube of the header was completely full. I'm sure every cylinder on that side had water in it.

MILD THUNDER

Thats what caught my eye. That odd bank, which had the leaky header, had 160ish psi on all cylinders, except #5. The other bank, which had no water, had psi's of 180-185psi. Water in the all the odd banks cylinders, would make the numbers higher, not lower.

Sorry for getting off topic, which really has nothing to do with your leaking header issue. Its just things I notice when trying to look at the whole picture sometimes.