distantthunder

All,

Mark IV 454 Mags in Formula 292 SR1. Merlin Heads, Edelbrock Performer RPM Air Gap, HP500 Carbs, Gil Offshore Exhaust.

Installed Hardin Marine Crossovers with Bypass over the off season and stuck a #8 Exhaust Valve on the starboard engine. I pulled heads and sent them off to be cleaned, fixed, new springs, etc. then I reinstalled last week. Upon reinstallation, I added -4 AN Lines from the rear water cross over ports to dump back into the water log on the bottom of the manifolds. I also drilled 3 - 3/16" holes in the t-stats and stuffed a brass plug with a 3/8 hole drilled into the bypass hose and added water pressure gauges tapped from the port side block drain.

Ran great for two hours but then I stuck another exhaust valve but on #6 on the starboard engine. Water pressure was 1 - 2 PSI at idle then 12.5 PSI at WOT. During the two hour ride, the engines were checked 6 times for any abnormalities and none were found. One thing I did notice, the temperatures on the crossover were ice cold on the side of the pipe going to the odd banks and then pretty hot on the even side. I ran this exhaust water crossover on my previous engine and do not remember having this issue. The water temperature gauges on both engines (installed under t-stat housing on manifold) showed ~110-120F while running but when I would shut the engine off, it would climb up to ~170F then if I fire up the engine again, it would quickly settle back down to ~110-120F. The river water temps are around 55F currently.

Based on the information above, does anyone have any recommendations? Aside from putting the stock Merc water system back on, any changes or things I should check? The two crossover kits were expensive and the stock stuff is no longer available to me so I would like to make this system work somehow as others are running this kit with no issue. The portside engine has run fine (no stuck valves) 8 hours since the upgrades (idling back to the dock after the starboard side goes down).

These were supposed to be simple modifications that I wanted but have turned into a huge pain in the butt, wallet, and my back. Look forward to everyone's input.

Donzi1979

iTrader: (1)

I can tell you I fought the same cross over for 2 seasons and couldn't get water temp up to even with what the T stat was rated for (140) and not sure why tried the the 3 holes in t stat and the bushing in the bypass too. When the water was in the 60s here I couldn't get any water temp but PSI was good. I just couldn't get it to where I was happy, and went back to re-circulation pumps and the factory style T-stat housings with the t balls (factory HP500 set up). I tried the later style t stat housing with only two water hoses for the exhaust and water PSI was too high. Probably not what you wanted to hear.

Water pressure too high after adding back rec pump

distantthunder

Thanks Donzi, I have been hearing that a lot lately. I had good experience with the crossover setup on my old engine in the 223 i had (Gen VI 454) but this is killing me, definitely has set a mood for the 2018 season so far. The machine shop feels that a jetting issue/combustion issue on that cylinder could have caused it but that doesn't explain the uneven temperatures around the entire engine. I am hoping someone chimes in that was able to get theirs to work before I dump more money into new circulating pumps and housings.

Donzi1979

iTrader: (1)

I hear you loud and clear seems like a stupid money especially X2 for you to get it to work. I blew over grand jacking with this and which is stupid if there is not performance gains to be had. I guess the Merc engineers knew something when they set up the factory stuff. I remember some threads last year about valve guide clearance issues and being too tight and the crossovers keeping the motor cold thus hanging valves open. That's why I tried to get some heat in the motor, plus oil temp raises much earlier.

dunnitagain

Put the Circulator Pumps back on, the Crossover deal is overrated.

articfriends

iTrader: (1)

what size jets are in the carb, how did the plug in cyl that stuck look?

Full Force

iTrader: (5)

guides on the edge of too tight to have that cold of temps, also ditch the bypass hose forcing all water through engine and out exhaust for better flow... I run .0020 guide clearance for this reason.

convincor

Besides ditcting the bypass, did you change anything else? Mod t-stat? Running a pressure relief?
And where are your temps running?

distantthunder

Full Force

iTrader: (5)