PatriYacht

The exhaust flow for an iron GM head is about 200cfm at .6 lift. My Valako worked AFR's flow about 300cfm at .6 lift. My guess is that reversion is worse because the exhaust is flowing backwards easier as well. As far as solving these nagging problems, some people learn to do the work themselves, some people pay lots of money for the top notch builders and mechs. that stand behind their work, and others stick to stock Mercruiser power because of it's reputation for reliability. Good luck with fixing your problem.

articfriends

iTrader: (1)

I had same problem as patriyacht,my old 540 had a 228/234 at .050 cam ,merlin heads that flowed 10% better than gm iron heads,lightning headers with captains call and never had even a hint of reversion. I reworked the 540 with cam a few degrees bigger plus afr cnc'd heads that flowed 25-30% more (over 300 cfm on exhaust) and motor reverted so bad at idle it would stall within 30 seconds of idling. There is no way my motor went from running reversion free to sucking so much water it wouldn't even idle from a couple of degrees of cam timing,it was definately the high flowing heads that caused it. I WOULD NOT blame your blocks unless they are gen v's and have terrible leaks from oddball water passages. You need to pressure check the motors and find your leaks or idle them and immediately pull a manifold to check for water. As far as your copper head gaskets and o-ringed blocks,I always thought that set-up was for drag racing blower motors running 20 plus lbs of boost on alcohol usually without any water even in block,seems like I have heard they are leak prone but I might be wrong but I would not consider it under any circumstances in a n/a 700 hp marine application. This isn't a personal attack in anyway so please don't take it that way but between these 651 cams which put your tq peak too high and are limited in top end due to weight of valvetrain and lifters plus some of the other issues you are having-DOES YOUR MOTOR BUILDER KNOW WHAT HE"S DOING?? Smitty

Back4More

What are you seeing as far as oil and water temps?
I had a little milk on the sticks from running too cold up here on Lake Michigan.

Rebel_Heart

The water temp on Lake Ozark is now about 87 degrees. My oil temps are running a little on the cold side, but then again, I've never had it running long enough to get them up.

Just spoke with the engine builder. He had run an air compression test with 16lbs and did find the copper gaskets leaking. He said that they were definitely leaking. Now, he is looking for gaskets that will seal. He, also, said that there was a wire used with the copper gaskets that had to be considered when sealing it up? Does anyone have any suggestions? I asked whether this wire could come out, but evidentally that would entail quite a bit of work. I am looking for seals that would work. Thanks.

ScarabCV

Ditto on JC's comment. I have a naturally aspirated 496 (454 4.250 stroke) with aluminum Brodix BB-2's on it. First time started, engine was perfect, however on the first water test, I pulled the dipstick and not much of a change in level, but oil was chocolate milk. Went home pulled the thermostat out,put in a moroso restrictor in thermostat housing , changed oil, and started on hose... no water in oil, problem fixed, or so I thought..... next water test yielded yet another chocolate shake. Now I'm pi$$ed. Take it home, off comes the intake, and what do I see but clean water sitting on top of lifter galley splash pan. I immediately replaced intake gaskets and also heli-coiled all intake bolt holes in heads. Took the damn thing back to the lake and ran the snot out of it with no problems afterward. Seems the high water pressure took it's toll on intake gaskets near the back water passages, and all that was needed was a decrease in pressure, and some new gaskets. I would also highly recommend heli-coiling your intake bolt holes on heads, at least the ones directly surrounding the water crossovers and passages.

RBeyer

Had similar problems, I found studing with Cometic gaskets to be the resolve. The 3 layer gasket allows for some slippage between the block and heads thus eliminating the gasket problem. It worked for me.

Rebel_Heart

Cometic gaskets. Are they the best? Will they fit with the wire that was placed in the heads because of the copper gaskets used? I am not sure why a wire was placed in the first place, but as I understand it would be difficult to remove.

RBeyer

You say a wire? I guess you mean the motor is O-ringed. Good question. I still think this will fix it for you. Any other thoughts? Any builders?

articfriends

iTrader: (1)

The wires are called o-rings,the block or the heads (usually the block) has grooves machined into it to hold them in place. A regular gasket will probably never seal now unless block or heads are resurfaced flat. I talked to a tractor pull buddy of mine who o-rings his blocks and runs copper head gaskets (alcohol blower motors running 25-30 psi of boost) he also builds his own boat motors for them little "clown boats" that have v-drives and weigh 800-1200lbs plus the motor,he told me he would NEVER consider copper head gaskets and o-rings on a marine motor as blocks set-up like that usually are for very short duration pulls and when on alcohol usually don't even run any cooling system or water in them.
As far as head gaskets,any decent head gasket will be fine once you get block flat again,I run felpro marine gaskets with 10-12psi of boost on my blown 540 and have NEVER had a head gasket issue,Smitty

RBeyer

I have also been told not to use copper gaskets on a marine motor. I have heard that the Fel-Pro will work, however I took out two sets before the Cometics in one season. I have about 200 hours on the current set with no milk!!!