Its a worthy thread!!! The old ones are the good ones!
Chevy 350 Max operating temp (1 Viewer)
- Thread starter Azrocks
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Interesting, you should not be overheating until your up to or over 240, most cases 260.
I have dual electric fans and the first fan kicks on at 195/200 and the second fan kicks on at 220. Red line is at 260.
GM/Chevy V8's traditionally run at between 195 and 220 which I beleive is considered normal!
Back from the dead again...
All this talk of temps but no mention of where the temps are being measured. In the head, intake manifold or somewhere else? I assume in older SBCs we are talking about the stock location in the right front head.
I know that each rig will manifest different temps and this has to be taken in to account but the wild variations in what is deemed "normal" or acceptable is interesting.
All this talk of temps but no mention of where the temps are being measured. In the head, intake manifold or somewhere else? I assume in older SBCs we are talking about the stock location in the right front head.
I know that each rig will manifest different temps and this has to be taken in to account but the wild variations in what is deemed "normal" or acceptable is interesting.
That being said, what should the temp range be for a carbureted sbc 350 with the temp sensor in the intake manifold?
ChaseTruck
--
Just for comparison, since it's my Blazer, but maybe pertinent re sensor location:
'84 block w/ Vortec heads and aluminum intake, 195°F T-stat (Napa); two (yes, two, and I don't remember why...
) aftermarket temp gauges, aluminum radiator, stock fan blade on a partshouse HD clutch, stock shroud.The gauge with the sensor in the intake manifold next to the T-stat housing reads 195°F to 200°F, max I've ever seen there was 205°F pushing it on long highway climbs. The gauge with the sensor in the head typically sits at 205°F, haven't seen more than 210°F on this one.
No idea whether/how the gauges were calibrated (AutoMeter, right out of the box), patterns are very consistent (head reads ~10°F higher than intake); this was with a 4-barrel Q-jet, and remained the same after switching to TBI. Going from headers back to manifolds seems to have reduced temps under the hood, but not the motor temps. Lots of space around that motor under the hood though, so, heat can dissipate easily
350 carbureted. 190/105 all day
Assuming a Gen 1 SBC, normal operating temp range? 185°-210° assuming a 195° thermostat and temp sensor in the intake manifold. On hard runs where you are pushing the motor you might see 220-230. If your temp sensor is in the head, you can expect readings 20° hotter (or more) on a hard run. While sitting at idle, the sensor in the head (between 1 and 3) will read slightly warmer than the intake manifold position, but will easily spike 20-25° when you put your foot in it.
I've seen 250 in mine (temp sensor in the head) climbing some fairly serious grades, at highway speed, ambient temps of 110. Temps come down fairly quickly though on the down grade.
Last edited:
Bringing this thread back from the dead. Here is a riddle for you. Have a 383 SBC with the MSD Atomic EFI system. Has two temp readings, the stock L-H gauge and the MSD Digital gauge. Both take the temps from the block with the stock on the driver's side and the MSD on the passenger side. Upon start up and initial warm up I see normal readings, hovering around the L on the stock gauge where as the MSD gauge creeps up to 245-250 and then drops right down and it operates at normal temperature afterwards. I thought maybe I had an air pocket in the coolant system so I burped it and it is still happening, so I bought a new 180 Thermostat because maybe the current one is sticking. Waiting to change it. Opinions, does the engine initially run hot. It drops down afterwards so I know that the thermostat opens up and circulates the coolant
Suggestions
Suggestions
Downey
SILVER Star
Adding my 2 cents to this relic thread:
(1) Water boils near 240 degrees, but antifreeze does not.
(2) GM had a V6 engine in the past that was kept above 240 degrees since the smog device required that temp, possibly trying to burn off some emissions before they become emissions?????
(1) Water boils near 240 degrees, but antifreeze does not.
(2) GM had a V6 engine in the past that was kept above 240 degrees since the smog device required that temp, possibly trying to burn off some emissions before they become emissions?????
reddingcruiser
Practicing for retirement
GM FSM sets the norm for the water temp based on what the engineering folks wanted to get out of the motor (see@Downey comments). Old school folks are comfortable at 180 - 210, most folks are good at up to 220. The question is whether that is a ' controlled' temperature or borderline under optimal conditions.
Downey
SILVER Star
Actually I made a typo above, I meant 220 degrees, not 240 degrees. With todays higher quality metals and lubricants the higher temps are not as much of a trauma as they use to be.
Once again this ol thread...
I got an old carburated 89' 350, all stock, fan, radiator, even thermostat (180f), radiator cap is 9lbs.
These days my radiator cracked, after i got it fixed and put it back the temp gauge (original) showed me a little bit warmer and it fluctuates real bad, i would say between 180 and 210, it goes up and down all the time the first 10 minutes i start driving, after that it goes to 195 or 200 maybe, the middle mark on gauge, it seems like it want to pass the middle mark, before the rad got fixed it always ran on 180, even in hot days and after the rad fix is running warmer, i dont really know exact temperature im running since my gauge show min temp as 40 and max as 130 so i would say the middle mark is on 90.
Almost forgot, when i drive an hour or 2 on a hot day the temp goes up a little bit, i assume if i keep driving the temp will keep going up
My questions are, should i be worried about a inner crack in my engine? Maybe is my thermostat gettin sticky? Should i get the 160 or get the 180 as it is rn? What if i put a lower pressure rad cap? This may help going some degrees down on hot days?
I got an old carburated 89' 350, all stock, fan, radiator, even thermostat (180f), radiator cap is 9lbs.
These days my radiator cracked, after i got it fixed and put it back the temp gauge (original) showed me a little bit warmer and it fluctuates real bad, i would say between 180 and 210, it goes up and down all the time the first 10 minutes i start driving, after that it goes to 195 or 200 maybe, the middle mark on gauge, it seems like it want to pass the middle mark, before the rad got fixed it always ran on 180, even in hot days and after the rad fix is running warmer, i dont really know exact temperature im running since my gauge show min temp as 40 and max as 130 so i would say the middle mark is on 90.
Almost forgot, when i drive an hour or 2 on a hot day the temp goes up a little bit, i assume if i keep driving the temp will keep going up
My questions are, should i be worried about a inner crack in my engine? Maybe is my thermostat gettin sticky? Should i get the 160 or get the 180 as it is rn? What if i put a lower pressure rad cap? This may help going some degrees down on hot days?
Did you read this thread from the beginning? Lots of good info. I’ve been dealing with my SBC 305(w/carb). I put a new Champion radiator and Spal fan in and the fan relay kit from Champion Radiators dot com was recommended at 170-180 for on and off. Well that was a waste of money and I should have done all my homework. Cooler isn’t better as many hot rod/Chevy forums would have you believe.
You should double what thermostat was stock probably 185 or 195 and put that in. My late 70’s 305 calls for a 195. I’d suggest an aftermarket gage if you don’t have one in your intake. I ended up with an adjustable Dakota Digital fan controller currently coming on at 205 and off at 195. Based on hours reading I think 195-210 with spikes up to 220 are fine but I’m not an expert, I’ve just been reading a lot of forums.
My current struggle is trying to figure how much coolant should be moving in and out of the overflow bottle. Is it normal in cool temperatures(40ish) to expect the radiator to push fluid out? I’m going to find an incline and burp my system again.
Good luck with your troubleshooting, but it sounds like you cooling system is about right To this novice.
I am running a 96 350 built to 350 hp with earlier ram horn exhausts. I pretty sure the radiator is an original 64 tlc with a shroud. The fan is a mechanical 5 blade and no clutch. When newer, the motor ran cooler but the last couple of summers on the hottest days temps have creeped up to 200-215. At 215 I start getting vapor lock and have been working to insulate fuel supply but so far no luck in fully stopping it. Have to be really careful in slow traffic ... like getting caught on stopped traffic on the interstate. Thinking about changing radiator and fan but like the original look!
My mildly built 350 ran great, except trying to pull a hill. I had a electric fan that fit nicely in the stock fan. I could idle, crawl and cruise the highway no problem, until I needed to drive over the pass. Stock radiator that was rebuilt. Switched to a Taurus fan and life is good. I also followed the internets advice and found a Volvo relay that lowered the starting amps on the fan.
Great info here! Now I feel a little more "normal" 
. Just did a 24x Coil Near plug conversion on my RamJet 350. Had to run a electric fan now because of intake/maf clearance issues. With the mechanical fan before, never saw it over 195. Ran some trails in the sierras last week and got concerned when the temps got to 210-215 on some slow hot climbs. Temps would go down pretty fast after. ecm controlled 2 speed electric fan comes on at Lo 195/Hi 200. I guess its good!?
. Just did a 24x Coil Near plug conversion on my RamJet 350. Had to run a electric fan now because of intake/maf clearance issues. With the mechanical fan before, never saw it over 195. Ran some trails in the sierras last week and got concerned when the temps got to 210-215 on some slow hot climbs. Temps would go down pretty fast after. ecm controlled 2 speed electric fan comes on at Lo 195/Hi 200. I guess its good!?
