Holy sh#t, I just remembered something else. Water pressure. At an idle , its at 5 lbs, but goes up rapidly as rpms come up. Like 10 lbs every 1000 rpm. So at 3500 prm, there is 35lbs water pressure. My gauge only goes to 35 or 40 lbs so I dont know what happens after that. If I take the stat out, its always between 5 and 15 lbs of water pressure. The water pressure censor is in the top of the intake manifold next to the thermostat. Could this high pressure be effecting the temp?

Yes. Some people have a problem with crossovers and high water pressure. It can lead to blown intake and head gaskets and water in your engine. Serious problem!!! I've never had that problen but the bypass on my crossovers is pretty big. You can get a pressure relief valve but that won't help your water temps any and may make it worse. Maybe it's the design of your crossover doesn't work well with a thermostat. If your set up works well with out a thermostat, you could just install an oil thermostat to keep oil temps up and leave the water therm. out. Could you post a picture of your set up?

if this thing has a full cross over, it doesn't have a traditional water pump, right ? if it doesn't have a traditional water pump, then it is going to need a blanking sleeve with a big hole or he is going to see the big pressures he is seeing. i admit that i could be completely wrong here because a lot of people do a lot of , what i consider to be weird things, but for me there are only two systems... the ones with the full crossover and no water pump and a blanking plate sized to control the water flow to achieve the thermal balance you need, or the non crossovr ones that do have a water pump and , as such the correct bypass and THOSE need a conventional unmodified thermostat.

everything else is something else. if understand this particular configuration correctly, it has a full crossover and no water pump. for me, that answer is simple... a blanking plate w/ a 1" hole more or less. its not efi so temp whileimportant for all the usual reason is not critical to function...

Stevexm, they do make crossovers for use with a thermostat. They have a bypass to allow water to the exhaust manifolds when the thermostat is closed. Don't try to run a termostat with a crossover without a bypass! With out the bypass you would cook your exhaust. You also need the proper matching thermostat housing. It has connections for 3 hoses, 1 for each exhaust manifold and 1 for the hose to the crossover. Take a look at the Stainless Marine or CP Performance catalog online.

so what configuration does this guy actually have ? seems to me that if its one of the two i mentioned or the one you identify , then the answer should be self evident... there really is no mixum and matchum ... each configuration demands its own cut and dried answer...

and if his system has a true bypass then he shouldn't be seeing the pressure spikes...

Steve- I have a "true" crossover system. Including a bypass hose. Have a sea pump and no circulator pump twith a stat and 2 small holes drilled in it.

Sounds like what I use. Mine works perfect. Can you take a picture? Maybe we could see somthing?

he's right. with that confuration you should'n see hi water pressure and the system should work ( with the exception of the holes in the tstat which could easily screw things up but who knows ) is it possible that this thing has lost a head gasket into a water gallery which is both causing the pressure and the wild temp fluctuations ? the cooling arrangement seems pretty straight forward and i would expect it to work... logic suggests you may be looking in the wrong place...

steve- I dont know man. The oil in the pan is fine , not milky. Engine runs great, idles great, no fouled plugs...........I need to do some testing and by process of elimination, make sure I not getting any false readings on my gauges. I really appreciate your input. I will keep you up to date....Kevin

why not just take the t-stats out? especially if its a carb motor... what temps does it run without them?