I have a crossover with a bypass with a 140* thermostat with 2- 3/16 holes in it. I also have the back of the intake manifold taped for a #4 fitting and a hose run to the thermostat housing. AFR 315 heads with .00018 valve guides. All four corners of the engine stay very even. Works for me.

I`ve thought running the water thru the headers first then into the block but then I`d need 2 stage water pumps

So I can get temp with crossovers that's all I wanted to know really, I will work on this.

Do you have h2o pressure relief valves Tim?

do you mean .0018.?

Tim, first I would say that ideally Mike is correct in suggesting going back to the recirculating set up, with that said if you elect not to do that you might look into restrictors in place of the t-stat, they sell them in different sizes so you can adjust the out flow of water from the block, a few down sides to this is that you will have to watch your water pressures at WOT, and as the lake water gets warmer you may need to change to a larger size hole to reduce the heat, I'm not condoning this approach but it is another option that you can research.

This is how mine is set up , N/A 540's 700hp water temp stays 140-150 & oil temp 200, gets to operating temp in less the 10 min
I used to run crossovers , but got tired of playing with different t stat set ups to keep it dialled in

I tried to run stats (with the cross over only no hose between) on an NA engine, drilled the holes ect ect I could never get the temp regulated, if I drilled the holes to keep the temp at 140 at WOT then at cruise the temp was super cold (wouldnt even read)

On the other side if I drilled the holes on the stat to be at 140 at cruise, then at WOT the engine would get super hot

Crossover with the thermostat hose

THen I tried the crossover with the tube between the cross over and the thermostat, that didnt seem to work well either, so the circ pumps went back on

Just my experience in Lake saint clair, now on the blower engines that I have the crossover seems to work just fine (but everything on this engine is cast iron)

Too early, yes

Just curious why there is no talk of switching to a closed cooling setup? I run closed cooling on my scarab and love the stable consistent temperatures!

I am guessing it's a cost thing?