AP700

I need some Help here since in Germany it is hard to find anybody who really is into Marine engines.
I have a Gen6 502 Mag MPI here. Did a hone and re-ring, nothing fancy.
It became a valve job, and Crane Golds with ARP conversion kit.
Long story short, I did let it run on engine stand, 2 cylinders are not firing. One has no spark, one has no fuel. Not that big of a problem.
I took the stainless manifolds off and spotted some water in them on both sides. not that it would fill a CYL up but there were puddles of water in both manifolds.
Cylinder without spark is dry, cylinder without fuel is wet with water. not filled, but wet. plug wet, bore cam showed wet around the exhaust valve. no puddle on piston.
I got this engine dissasembled so it is new to me and never ran.

Stainless Manifolds for Silent choice, engine and manifolds stay super cold. after 10 minutes of running risers are only hand warm. Engine pulls plenty of water out of a bucket. Engine stock, Crane golds 3/4 turn. (Maybe better 1/2?)

What can cause the water in my manifolds and the one wet cylinder?

1) one cylinder on each bank doesnt fire and causes reversion
2) Both manifolds are toast
3) Water comes from exhaust passage due to toast head gasket or intake gasket on both sides
4) only idle running on stand with a few revs causes reversion
5)cold Manifolds and risers are condensating

Okay, first get the 2 cylinders running.PERIOD. Have ordered cap, rotor, cables, plugs, injectors. But what could cause the water there? I'm terrified now. just built that thing...



Thanks
Philipp

AP700

Went to the engine and took some pictures with the bore cam. You see the wet cylinder. Piston is dry, around the exhaust valve it got wet.
have looked into the stainless risers ans manifolds. In the riser there is plenty of condensation i think. Took the cam down into the manifolds, in both manifolds are puddles of water. Where could this come from?
did it reverse from the 2 cylinders not firing? Could it be condension because of the cold manifolds and risers?

















Did compression test it. COLD, blades wide open. It had only 125 on each cyl. Battery was on the low side. Maybe it is reversing because 3/4 turn on the crane golds 1.7 is too much?

Any help is appreciated

Thanks
Philipp

TomZ

You can experience reversion if you have dead cylinders. Figure out why it's not firing first.

Compression readings - make sure the battery is strong/charged and then try again.

Wally

Did you change the cam? Unless its running really bad and popping or backfiring i doubt adjusting the rockers will change much. I usually did the rockers at 1/2 turn and then when you tighten the lock nut it moves it just a hair more...Ive heard people say anywhere from 1/2 to one full turn....ive never been comfortable going more the 3/4 personally...
Not having the cylinders fire on each side will cause issues because you don't have that exhaust pressure moving/trying to get out of the system. I'd fix the dead cyl's first then run it again.

AP700

Okay thank you guys! I will get the 2 dead cylinders running and go from there!

AP700

One has no spark, other has no fuel. Have ordered cap, rotor, cables and injectors.
I always ajdusted 3/4 turn, but later I read the adjustment advice from comp cams (have new comp cams lifters) and they say 1/2 turn.. don't know. Maybe I try 1/2.

Cam is original.

SB

Dead cylinders can/will draw water for sure.

AP700

Okay I just checked the injectors. The one on the no fuel cyl is stuck closed.

I will reply if all cylinders run and check then for water in the manifolds.

Thank you so much !

Philipp

Griff

It could just be your pic, but it looks like the engine is leaning forward. That will cause reversion.

AP700

It is the pic, but in fact the engine leans forward about 1/2 inch. I will check this and get it maybe leaned backwards about 1/2 inch, in the boat it will be leaned back just a little due to the squat the boat does. maybe it helps a little.

Thanks!