[G.M.]

Originally Posted by Kevin Marsh

Hello all, I could use your help. I wrapped up the restoration on a 34 pickup a little over a year ago. The owner participated in a couple parades last summer, and each time the engine overheated and coolant boiled over.
The engine is a fresh rebuild by a very experienced flathead specialist, the radiator also received a new modern style core, new water pumps with the improved impellor design and the stock four blade fan. Total miles driven so far are 45, and on the open road the engine runs between 170 and 180 degrees.
I realize the engine will run cooler with more miles driven and a sufficient break in period, but for now I need to do something to aid during the extreme conditions during parades as I know he will be doing more of those this summer.
I have tried to research the thermostats made by Bob Shewman that fit into the upper hoses, that have been discussed in several forums. The majority of the posts relate to bringing the engine temperature up, because the vehicle run too cool and never quite get to operating temperature. I am wondering about their effectiveness in maintaining the temperature during slow driving conditions such as a parade.
Ideally, the thermostat should allow sufficient time for the water in the radiator to cool before it cycles back into the motor. From what I have read about the Shewman thermostats they have bypass holes to prevent a surge of pressure when they reach temperature and open. Will that limit the amount of cooling efficiency of the radiator?
I would appreciate any feedback from those who my have encountered a similar situation, or have experience with these thermostats. I found an email contact for Bob Shewman ([email protected]) and have sent him an inquiry as well with no response back, so I am wondering if that is no longer a valid contact. If anyone has his current information I would appreciate that as well.
Thank you for your assistance.

Kevin. I just called Bob Shewman and he never got you email, said he checks several times a day. Call him at 1-610-933-6637. As long as the engine runs in the 160 range your OK. Thermostats have nothing to do with cooling, just make the engine run hotter. It looks like you have no problem driving at traveling speeds. This is not a parade vehicle in the summer the stock fan just don't produce enough air. Going down the road cooling air is produced by forward motion and in a parade there is not much of that. A shroud and a 6 bladed fan will do the trick, I'm not into electric fans so I can't help in that area. Getting the front of the fan about a 1/2" from the radiator helps some but not enough for parades. I have a 39 P/U with Skips high flow pumps, Bob Shewman's 180 degree stats in the hoses an industrial 6 blade fan, a shroud and Skips 3 lb overflow valve. This truck ran in the flea market at a National Ford V/8 show in Maryland in 2006 at a fast idle for over 2 hours and never got over 180. This was on a day that was over 100 degrees outside. If I raced it a little the temperature came down a little. You need a 4 lb pressure cap that seats down in the bottom of the filler neck and seals or Skips 3 lb check valve the go's on the bottom of the over flow tube. What the pressure cap or 3 lb valve does is closes off the over flow tube so water backing up in the top radiator tank don't back up in the tank do to the restriction of the 144 tubes and free flow out the over flow tube. Now you are also low on water. The cap or valve allows the radiator to remain filled to the top for maybe a year or more with out refilling. These caps and valve also let the pumps push the water through the radiator. Three things make for better cooling, more water in the system, more water forced through the radiator and more air through the radiator. This is all pretty well proven by your problem. G.M.