Seems to me that my experience with those high flow thermostats - Robert Shaw type in particular from Mr. Gasket - was that the 160º version worked fine (with the drilled ports added). But........... when I tried the same thing in a 180º version it was poor quality and failed. Back to the 160º and things worked OK, but I was hoping to get the warmer running temp for cooler weather. I think Charlie had a similar experience - the 180º version just wasn't a reliable part.

My engine with the mods you were talking about - bypass orifice, small pulley, more fan blades and so forth - seems to want to run about 100º over ambient (small T-bird radiator and the goofy 1" spacer behind the water pump). Rather than going all the way down to a 160º water temp in winter - the 180º would be preferable. 

 
 Steve Metzger       Tucson, Arizona

Took the car out and the temp gauge worked perfectly. Did not go high like the thermostat was stuck. I am sure the spring style thermostat was hitting the heater control valve extension. With the extension cut shorter the Robert Shaw Flow Cool thermostat fit. I should have looked a lot closer when I installed the Edelbrock manifold.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I went thru my stash and had a Robert Shaw FlowCooler style 160. I believe I removed it when I added the dual quads and the heater controller hit it. I removed the controllers extension and cut about 3/4” off it bringing it back to even with the thermostat hole in the manifold. I drilled 3 small holes in the circular crown of the thermostat housing. Replaced the coolant and ran the engine in drive with the radiator blocked with cardboard. I left the cap off and watched for movement of the water.

In drive idling, when my electronic digital thermometer aimed at the thermostat housing showed 162* there was movement of water across the radiator looking through the open cap. The temp gauge shows about 3/8” up the line and it never indicated that it stuck at all. Just went up from cold to whatever the run temp will be. I’ll know more when I drive it tomorrow.

Thanks to every one who responded. I am convinced the other style thermostat was hitting the heater valve.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

DLRacer - Yes - add a 1/8 hole or two to get water moving in the direction of the Radiator. As you may know, every time we hear of people with "hot spots" due to partially blocking the bypass - they typically have not provided another way for the water to move toward the t-stat / radiator. As someone mentioned, the little holes put in the commercial t-stats - is there for air passage, not for the viscosity of water. You need more of a passageway to create the altered waterflow arrangement..

 
 Steve Metzger       Tucson, Arizona

Typically a hole was added only to allow air to escape and not get an airlock upon start-up after a water pump change, or a rebuild of the engine.  Joe-JDC

JDC

Thanks Greenbird. I can see where they call the one I have “ventilated” and how it works with the water pressure from inside the intake allowing it to open and flow a slight amount of the hot water into the upper hose while the sensor on the thermostat heats up to properly actuate.

Are you saying I should add a 1/8” or so hole or two next to the poppet part or to the outer rim for extra flow? I can understand this as years ago I did this on other engines. Your ideas in the past are what solved my cooling problems.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Its been a while since I visited the Stewart Components site so I don't know what they currently offer for a "ventilated" high flow thermostat. In the past they drilled some free flow holes in their offerings so that the thermostat was not a total seal when closed - a controlled leak as it were. I know they were offering the "Robert Shaw" type of poppet but the other types should work too.
These two t-stats fit the same opening but have way different flow ratings. But even the large port variety has room for some "owner drilled" relief holes -1/8 or 5/32 drill bit? Rather than deadhead the cooling circuit it allows water flow toward the operating "pill" that then pulls the poppet open. When combined with the small orifice hole in the bypass plug - a fair amount of water can move. You may have to add one or more to make yours have a better "leak rate".

 
 Steve Metzger       Tucson, Arizona

55. I was 75 when I put mine in. I unbolted the seat and moved it back against the rear seat. My wife was in the back seat to hand me tools I’d set on the front seat. My radio was out getting converted to am/fm/blue tooth. I laid on my back with a milk crate next to the open door with a moving pad on it for more support.
She is always my helping hand since our kids moved away. She helps with all the brake bleeding both for the 8.8 I put in the rear and the Wilwood disc kit I put on the front. When our kids were real young she worked the floor jack when I put transmissions in our race car... stuck with me 54 year so far...

56 Vic, B'Ville 200 MPH Club Member, So Cal.

Yep, mine came from Tbird supplier, but the housing is plastic. I don't know if that's good or bad. Better it's in the engine compartment. 

Thanks for the tip. Fortunately, I've removed the seat for new upholstery, so I have more space to work in. I'm not a big guy, but I am claustrophobic. I don't like working underneath the car either, but I can't afford to pay someone else to do it. Even if I could, I have a problem paying for something I can do myself. If I screw up, I have only myself to blame, but my wife will say otherwise.