Heres a question for the collective wisdom of the HAMB. The vehicle is a 1948 Plymouth Special Deluxe. The engine is a 355 SBC (Please no flaming for the SBC in a Mopar). Champion 340B aluminum radiator (claimed to be good for 600 or so HP), large electric puller fan, 180 degree T-stat. The engine temperature stays around 180 degrees if its idling or just cruising along at 35 or 45 MPH. If I get on the highway and get up to 55 MPH, the temperature will get up to about 200 degrees. If I ascend a mild grade, the temperature will get up to 205 or 210. It has never boiled over, or exceeded 210 degrees. I verified the accuracy of the aftermarket temperature gauge with a laser IR handheld unit, and it seems to be right on the money. I fabricated a radiator seal atop the radiator, much like the original, and fashioned an air scoop below the radiator to force more air in front of the radiator. Perhaps Im just paranoid, but I dont like to see the engine temperature get that high. And I havent tried a run on the interstate yet, so I dont know what the results of that will be. Am I being overly cautious? The car runs great but I get a bit edgy when I see that temperature gauge on the rise. My next step will be to flush the radiator, refill with distilled water, water pump lube and Water Wetter, and see what happens then. Thank you for any and all replies.
Yup, 220 is fine, 230 is cause for concern but it won't hurt anything. The car probably just needs a bigger radiator if you want it to cool really well, or maybe a change in gearing if the engine is revving a lot at highway speeds. Also make sure the timing is correct, etc. I wouldn't mess with the snake oil in the cooling system, just run 50-50 antifreeze/water (or a bit more if you leave the car out where it gets really really cold in winter).
Drill a few 1/8 holes aroudnd the outside of your T stat. They should not run warmer on the road than the do in town. But like has been said it is not running too hot.
Where are you getting your temp reading? I seems to me that if you pick up the temp in the cyl. head the temp seems to vary according to how you are running, IE. going up a hill the engine works harder so it is hotter in the heads. If you pick up the temp in the intake manifold it seems steadier.
The sensing bulb for the gauge is located in the intake manifold. And I did not realize that 220 degrees or so is still OK for the engine, although now that I think about it, my 2003 Chevy Express with a 6.0 Liter engine runs at about 210 degrees most of the time. Maybe I was worried for nothing.
try shutting off your fan at speed. It may actually be blocking the air from flowing through when you at higher speeds.
Make sure your vacuum advance is working properly. I had the same problem, the vacuum advance was frozen. My car ran at 210 on the freeway but 180 in town. Popped in a new distributor and the temp dropped to 160. I may have to switch my thermostat for a 180.
Does it hesitate at all as if it's starving for fuel? If so, check the capacity of your fuel pump. Last resort, just thought I'd mention it.
Hey gang, thanks to all for the responses. Well, yesterday I decided to retard the timing a little, due to some slight pinging while driving up the nearby hill to the house. So I turned the distributor clockwise just a bit and went for a drive. The pinging stopped, and the temperature didn't get above 200 degrees, even after driving up the hill. Unfortunately, I can't use a timing light on it because the timing pointer is impossible to see under the water pump (short pump). When we first fired the engine, the distributor had a "sweet spot" where the engine seemed to run the best, and we left it there. But evidently the timing was advanced just a little too far and the engine wasn't happy. So far, I'm more comfortable with the temperature (even though I know now that it wasn't really an issue), and the pinging seems to have gone away.
Take it easy...your temps are nothing to worry about at all...take out the temperature gauge and put an idiot light in its place....as long as it doesn't boil over...you're good to go....chances are that the idiot light will never come on at all....stop watching the gauges and enjoy the road !! P.S. yes, you are paranoid !!!
Well, even though I was probably over reacting to the engine temperature on my SBC, I was still pursuing my quest to get the temperature down a little more. I replaced the electric fan and shroud ***embly with a higher capacity unit from Flex-A-Lite, added Water-Wetter, and blocked off the byp*** hose I had connected to the heater ports on the engine. I had the car out for a spin today, and the highest temperature reading I got was 190 degrees at the top of a steep grade. Previously, driving the same route, the temperature hit 215 degrees. I'm not entirely sure if any one thing made the difference, or if it was a collective sort of thing. It doesn't matter....I'm happy with how its performing now. Yeah, I know...I'm paranoid. I'm OK with that.
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