yes its a good idea. If your temp sensor is located at the back of the intake this modification will make a huge change in your temperature gauge reading.

I run PCV on all mine now, even my 454's in my Gibson, keeps top of engine much cleaner...I figured if merc did it on the 500HP and most all newer engines.....

I would assume they take a hotter reading at the back of the intake? I have mine installed at the back of the intakes on 598ci 10-71 blower motors, and have wondered if they would read less if I took a reading at the t-stat housing? Going to shoot both areas with a temp gun over the weekend to check the difference. What reading should you use as reference on your gauge?

Ezstriper, I think I have about the same setup as you. '94 253 Convincor, 502 with M-3 procharger. My water temp never moves off 100-110. Is the consensus say this is ok. I've talked to a couple motorheads who think I'm holding back a lot of power not getting that block up to temp. I've planned on putting in a restrictor plate but now I'm second guessing myself.

I just installed Teague crossovers and thermostat housings(no bypass) on my built sbc's and am only reaching about 100degrees as well. I called teague to see if I needed a bypass/thermostat set up instead. The reply from the tech support is that theu want the motors running between 100-110 degrees, that is optimal for a performance marine set up. I cant find a single reason to second guess the guys at teague.

Did your manifold already have the bosses for the rear water ports? I wanted to do this, but the manifold I am thinking about running does not have the rear ports or even bosses for them. In fact, it has a reinforcing rib on each side. I was wondering how I would be able to drill and tap these areas without a boss - grind down the ribs and just drill straight through them, or maybe weld some aluminum in this area and build up my own boss? I would be a little bit worried about cracks in this area.

Ask those motor heads if they'll buy you pistons and valves if you install the warm stats, and detonate it with your procharger. Even if u gained 10hp from getting the block hotter, .5mph ain't worth the risk of melting it

If you want more power, raising the block temp isn't the answer . For the guy who runs a 9.80 in the 1/4 and is looking for 9.70's , maybe .

Adding a restrictor plate will do almost nothing for temp, but will increase your water psi

I agree. Too be far though, the "motorheads" I was referring to were car guys so maybe in their case its a bit different.
Water PSI was one of my concerns with the restrictors. Glad you're easing my mind about all this. I wasn't looking forward to ripping my procharger apart to try and get to the t stat.

I have a Stainless Marine crossover with bypass and Stewart 160 thermostat and I run right at 150 Gauge temp, it climbs to 180 after coming down to idle after running real hard and then settles down to 150 after a minute. I run in real cold water, once I was in 34 degree water boat didn't get over 130 running hard. Maybe your thermostat isn't closing or the gauge is off. It shouldn't work any differently than with a circ pump. If the thermostat is closed no water should circulate through the motor except what goes through the bypass holes in the thermostat.

Do you or halffast have any pictures of your manifolds where you tapped into the water ports? Trying to figure out if this is possible on a manifold without the rear water port bosses.