Hi

I am running a mild build slant six (Offenhauser intake, Holley 390, Dutra Duals etc.) and I have been trying to run it with a 195 thermostat. However, it seems to run too hot.

Although the 195 is the standard Mopar thermostat I was wondering if something like a 180 would be better?

Right now I pulled out the thermostat and it runs at about 150.

Any ideas?

195° thermostats were used starting in '73 or so for emission control reasons (180° to 190° prior to that year). You may have better results with a 180° unit. I like the Stant SuperStat #45358.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks for the suggestion.

What is the Stant SuperStat #13358?

Is there an equivalent in Motorad or something from NAPA?

Stant is the brand name - superstat is the product line I suppose. I bought my last stant 13358 from napa actually.

"SuperStat" is Stant's premium thermostat range. They've got some design and build features that improve over ordinary thermostats in terms of precision/response time and durability (manufacturer's description here), but don't sweat it too hard. If you can't find it, a regular Stant or Robertshaw unit will be fine.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I've seen some stats that have a few hole drilled in them to bypass a bit of water. I supose this is to prevent overheating if the stat fails? Anyone have an oppinion on this?

Maybe it to aid in coolant filling. Lets the air out.

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

The small hole (or V-notch in the valve plate, or small hole with jiggle pin) is to bleed air out of the engine and pass it along to the radiator so it can eventually be expelled. Most all current-production thermostats have it, and the hole/notch/pin should be installed at the 12:00 position.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

That little hole is WAY too small to prevent the engine from overheating should the thermostat stick shut. It's purpose is to let out air, as you guessed.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

I wasn't referring to the factory hole in the stat. I was talking about people that drill additional holes in them. (6 or more 1/4")
I holding one of Napa's Superstats with the V notch. There is no hole for air bleeding. The stat has very little clearance around the notches for air bleeding. I personaly think that if one were to fill the cooling system with one of these stats installed, you should go take lunch half way through the filling process. I think I'll just drill a 3/16 hole on the top edge of the stat.
Also don't stats generaly fail in the closed position? Are there any that have some type of melt away protection?

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67Cuda,FAST EZEFI,340cu,CR=10.25,RollerCam&Rocker (XR268HR,#20-810-9)(#1622-16)(EddyRPM#60779,#7576), (MSD6AL,#6425) A904, GearVendorsOD, 8 1/4,3.55:1, ClassicAir

Someone on here made a set up that sounded to me like it was a T. If one thermostat failed, the hot water flowed through the other thermostat. Who was that, and can we get some pictures?

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Excuse me, does this smell like chloroform to you?

Murray makes one called a "failsafe" that is guaranteed to fail in the open position. And believe me, they will fail in the open position; usually within 5 minutes of first starting the engine. Other manufacturers may make variants that work better, but as few times as I've seen thermostats fail, I think it's probably overkill.

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Used to own:
'82 Dodge D150
Erson 270 Cam, O/S valves, mild port work, ~9.5:1 compression

Currently fighting with an '85 VW Cabriolet

My other passion

Seems like a lot of worrying going on about something that almost never happens, and can be prevented by installing a new top-quality thermostat every five years or so whether it needs it or not.

Drilling a bunch of holes in the thermostat flange defeats the purpose of having a thermostat.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Flushing and changing the coolant on a reasonable schedule will prevent quite a few cooling problems too. Using distilled water makes a difference as well. I always check thermostats before they are installed. The opening temps can vary quite a bit. Usually if they test good, they are good. I use the stant Superstats now too, but used to swear by Robertshaws, especially the high flow balanced version (which will not fit in a slant anyway). I have not seen any of them around lately. Opening up the notch in the poppet a little can help smooth out temperature cycling if that is an issue. Drilling holes is kind of a waste, they tend to clog, the notch is self cleaning.