The Stovebolt Site Forums The Shop Area The HiPo Shop radiator cap on stock radiator

Can I put a "pressure" cap on my original '49 radiator or will it let go and burst ? It had a slight tendancy to run alittle hot (highway or idleing) in the summer , and I just lived with it . 180 thermostat and it sometimes would get to 215-220 in summer then I'd shut it down . Now (winter driving) it stays cooler BUT I noticed the inside of the briether and valvecovers are milky-yellow . Should I put in a warmer thermostat AND a pressurized cap - Can't afford a new radiator yet and don't want to mess this one up , yet .

you're running a 350? if the shape of the neck will take a pressure cap [earlier zero pressure rads wouldn't] you might try a 7# and if you do have a 350, make sure you get to afford a new rad that can stand a 14# cap and then go to a 190 stat - you should likely also have a shroud

Bill

I am running a 350 , have a shroud with electric fan . I changed out the stock intake for an edelbrac performer about 2 months ago , inside of motor was clean then . I ran a 180 thrm. and switched it out for a cooler one for next summer . Now I'm guessing it is running too cool to burn off the moisture in the oil ?! causing the milkyness . I suppose the only way to make it work correctly is to buy a radiator that works correctly . I was hoping maybe for a quick fix in something as simple as a hotter thermostat and a pressure cap .

a thermostat sets the minimum temp it'll be, doesn't prevent it from getting as hot as it wants, and a 350 will easily get above 212, which is why they need a good system that can take a 14# cap, higher pressure allows higher temps .... if the temp is OK around town but climbs when you're idleing, the fan isn't pulling enough air thru the rad - if it gets hot at steady highway speeds the fan is most likely preventing enough air thru the rad then, need to check the fan cfm compared to what's needed with a 350

the milky oil is another side of the problem, but mostly the weather, it's simply a result of humidity condensing inside when the hot engine is shut down, only thing to do about it is avoid short trips, when it'll happen most, and change the oil more frequently .... you'll also get plugged pvc valves from that, which will make it worse

Bill

If your 350 is running around 215,dont worry about it.they tend to run on the hot side.Also if you are running a fan shroud there is no reason for an electric fan.I have to laugh at the strret rods set up with the fan about 6 inches from the radiator and yeah there is an electric fan.A good shroud would do twice as much good,as it makes the fan pull air thru the radiator.

I have the electric fan mounted onto the fan shroud , no fan on the waterpump . The fan is controlled by an adjustable temerature switch so hopefully it will turn off at highway speeds and on at slower speeds . I'm sure a new radiator with the proper cap would solve my problems , I just need to sell some stuff to make some cash . Anyone have any experiance with the aluminum ones on e-bay - going for less than $300.00 ? I know they don't look just right like a stocker would I'm not too concerned with originality .