What would be an acceptable engine temperture range for a mildly modified smallblock with aluminum heads with the outside air temperture about 85 - 90 degrees. Mine seems to be running at about 210 degrees. Is that a little high? I'm using a 160 degree thermostat and the stock fan w/ the fan clutch.

 

So what is the normal temperture operating range for most smallblock C3's

 

So what is mildly modified?
Overbore? Cam & heads?

 

210 is not going to hurt but you can do better. Depending on what you want and your cooling system you can put that temp anywhere. Is this 210 at idle or driving down the road ?
Have you checked the temp with a gun ? Have you done any testing to tax your system,cover the rad with a towel and see if the temp goes up,put a fan in front of car,run water down front of rad,is your stock fan clutch pulling air ?

 

SB Chevy engines were designed to run at about 180*F. That is the point for best performance, durability, reliability, and economy (combined). If you leave it running at 210*, you should probably use synthetic oil, as it resists the effect of heating better than organic oil.

Your engine's operating temps are dependent on the cooling efficiency of your coolant system and the thermostat you have in the car. Your stat could be defective, causing the temps to be elevated; but it's more likely that the cooling efficiency of your system is not as good as it should be. Change the stat out first. If that fixes the heating problem, so be it. If it does not, your cooling system isn't "up to par". The most likely culprits are: limed-up fins in the radiator reducing cooling capacity; fan not shrouded properly and air flow limited as a result; poor coolant circulation due to pump problem; collapsing pump inlet (suction) hose causing restricted flow.

Even though the engine is 'modded', normal driving loads are no higher with the upgraded motor than previously encountered. The engine only makes more heat than before when it is seeing more load (WOT, etc.), so the cooling efficiency of the coolant system should work the same until heavy loads are encountered.

 

Id say you are borderline. If it were mine , id want to get it down a bit . A low cost solution would be to give the cooling system a good clean and flush opening the block drains, then use 10% antifreeze to 90% distilled water for summer use (adjust as necessary for winter if youre in a cold climate ) along with a bottle of Redlines Water Wetter. This has an immediate effect on virtually all who have tried it .

The next time youre in need of a replacement Water Pump, take a look at a high-flow Stewart level 3 Pump which made a big difference in my temps. When you need a replacement radiator, pop for a DeWitt aluminum which has gobs of capacity over the factory one.

 

yes sir ! look here first. been there. you would be very surprised what the inside of a 30+ year old radiator looks like.

 

of course we are assuming there are no timing issues....

 

Items to consider:

1. 210-degrees F on occasion is fine, but if sustained it indicates that something is up (timing advance issues, clogged radiator, improperly functioning thermostat, poor performing water pump, etc.)

2. Water is the best coolant. However, water has no rust protection and/or lubrication additives that anti-freeze affords. Adding a bottle of Water Wetter helps, but is not the magic answer.

3. What condition is your radiator? Are the flow tubes plugged, bent, or such? Are the external cooling fins clogged or bent? Is it a 2-core, 3-core, 4-core design or what?

4. Being that my musclecars are only driven in the summer (no cold start-up issues), I usually do not even run a thermostat.

5. Upgrading to an aftermarket water pump (especially an aluminum pump) not only delivers more water volume, but generates improved block pressure ... all of which helps keep the engine cooler.

6. If you are using a 400 small-block Chevy, they have "siamese bores" that are noted for running hotter than traditional small blocks.

 

Typically, if your coolant temp is much higher than what your thermostat is rated for, something is wrong. (Not neccassarily wrong from stock, many cars came from the factory with insufficient cooling systems.) You should be running a 180* thermostat, and not be seeing engine temps above 190*.


Scott

 

Don't want to highjack this thread but it seems to fit along with what I'm having trouble with.

I have a lightly modified 350 in mine. Stock bottom end, with cam, aluminum heads, aluminum intake and Holley SA 670 Carb. I have an aluminum radiator with dual flex-a-lite electric fans. I have a 180 degree thermostat, but when I run down the highway at around 3,500 + rpm, driving around town with the AC on, or both, my temps will creep upwards continuously. I will see 210 almost immediately and have seen as much as 240 in 90 + degrees, on the highway with the AC on. I find the AC to be the main culprit as far as increasing temps go. Certainly not ideal and also needs addressing. My first thought is adjust the water/antifreeze mix. I've tried a high flow pump but still had the same problem.

How do I stop this thing getting so hot when running on the highway and/or with the AC on??

 

Since you don't want to hijack this thread, why not start a thread of your own...

 

I have a 1980, last time I took it out for a long drive on a 80F day it stayed between 205 and 210F. It has a 195F thermostat. I am running two bottles of Water Wetter.

 

My first gut instinct is to say you are not getting enough cool air thru the radiator. With the A/C on, the condensor in front of the radiator is kicking out heat, (the better your A/C works, the more heat it's kicking out.) and that heat is being drawn thru the radiator, maybe? The problem on the highway is strange, most c3 'vettes have no problems if speed is kept above 25-35 mph or so. Perhaps the fan shrouding is not letting any air thru and the fans are not enough to keep up? Like, the air is kind of piling up against the fans? Bigger, or faster, fans, maybe? If you have an aluminum radiator, along with the rest of your situation as you have described it, I don't see how you should be having a problem. I'll bet the solution will turn out to be found because of something you haven't told us yet! Who knows, maybe you sucked up a big plastic trash bag and its covering up 3/4 of the radiator!!! Anyway, that's all I have for ya.


Scott


Scott

 

I just want to add that according to the Redline Tech, their Water Wetter product has the necessary rust inhibitors and water pump lubricant . In my BB , I run 90% distilled water with water wetter and 10% coolant with no thermostat down here in hot Florida.

 

Will a larger front spoiler under the bumper direct more air into the radiator? I'm talking about the little stock black plastic one, not the pace car type. I have a '79 bty and the spoiler is about 2 inchs high so I was wondering if a 4 or 6 inch high one would force more air up into the radiator.

 

Probably can't hurt, I'll tell you about something on my '80 by way of example. The '80-'82 'vettes have a chin spoiler that connects to the bottom of the radiator support, and kinda "scoops" air from under the nose and thru the radiator. I removed it one time, in order to replace it, (it was busted) and I drove it around one day without it. It did just fine at idle and at low speeds,(engine driven fan sucking air thru the radiator) but on the highway, it ran surprisingly hot! Sound familiar? Also, it can't hurt to make sure there is as little as possible in front of the radiator, like the vacuum lines going to the headlights, etc. Make sure the fins on the radiator are not clogged up with debris, (a good way to do this is to spray with a garden hose from the back of the rad, don't use to much force, or you will flatten the cooling fins) and speaking of the cooling fins, make sure there are none of them flattened over, keeping air from going in between them. I like to take a small flat tip screwdriver and VERY CAREFULLY straighten them out. Take note of the key phrase of that last sentence: VERY CAREFULLY!!!!!!!!!! Ever play the game Operation when you were a kid? That carefully. Ever try to juggle 3 raw eggs? That carefully. Ever make love to a porcupine? That carefully. I think you get my point by now.

While I am up on the soap box, let me add this for whatever it's worth. I am not a big fan of electric fans on C3 Corvettes. I installed a serpentine belt setup from an '87 'vette on my '80 and actually went to the trouble of finding a reverse direction fan so I could keep my engine driven radiator fan and shroud. Prior to this, I had an electric fan from a Lincoln Mark VIII on it. It looked cool, and worked OK as far as keeping coolant temp within limits, but due to the slanted radiator on our 'vettes, it blows the air down under the engine, and under hood temps were very high. Enough to melt spark plug wires and such. The engine driven fan blows air straight back and keeps the whole underhood temp situation under control. Not to mention The Electric fan conked out on me twice, and I said, "Why bother? Engine driven fan, come back here and do your thing!" Been pretty happy ever since. OK, hope this helps, see ya later.


Scott

 

My 1980 runs hotter in the summer on the highway also. Last summer on a 100F day it got over 240F.

 

Thanks for the info Scott. I have an aftermarket front bumper on my '79. It's an 80's style from ACI, so maybe I do need some type of chin spoiler that's larger than the stock '79 one. I'll look into that as mine only runs 210 while driving but does fine at idle and low speeds.

 

Ah-ha!! The plot thickens! See, we didn't know that before, it could have a bearing on things. If my mind's eye is seeing it right, the '68-'79 'vettes drew their cooling air mostly thru the front grill openings, while the '80-'82 has smaller grilles and draws most of it's air from under the bumper, using a scoop type chin spoiler. I'm not saying this is definitely the problem, but it's something to think about.

I have something else to check off the top of my head: Is the top of the radiator support sealed up against the hood with some sort of weatherstripping or foam rubber? Ya have to think like air, if ya know what I mean. You want to seal off as much as you can around the radiator, so the air coming in from in front of it has no choice but to go thru the radiator, instead of sneaking around it into the engine compartment. Sometimes little things like this can make a big difference.


Scott