Took this 72 in on a trade, it came with a good running 406 stroker 550hp build. Seems to be built well, no smoke, knocks, or leaks except at base of dipstick but otherwise seems right. Driving in town, it runs 190 to 205 degrees in 60 degree weather. It has one big electric fan on back of the radiator and the engine fan, without the electric fans on you can add 10 degrees to that temp. I am not familiar with day to day driving habits of stroker motors but that seemed high. Do strokers typically run hotter? Should these temps concern me?

 

I really don't think those temps are overly hot. For comparison only, we have basically the same engine. 408CI, 550HP, 10.5 comp. Large Be Cool rad, 2 large electric fans set to come on at 165 degrees.


In the summer months my engine struggles to reach 190. I wouldn't be overly concerned with it running 200 in traffic.


Have you verified your gauge is accurate with a temp gun?

 

What radiator? It's going to be a tough job for a stock rad for a 350 to do a good job of cooling a warmed over 406, that's a lot more heat to try to shed.

 

What is the tstat rated for. If you have a 195 tstat in there it is running right where it should. I have a 408 striker in my Cobra with a 180 tstat. I runs all day at 180 while getting air through the radiator. Once it slows down or stops it climbs. I have one fan on at 190 and the other kicks on at 205. Rarely has the second fan come on. Once back moving it settles back in at 180-183. I do have a big radiator in it and have it all sealed up so all the air goes through the radiator. Make sure all your seals are there and are in good shape. You should run right around what the tstat is rated for.

 

hook up a mechanical temp gauge

 

It might need a pusher type fan since you already are using the mechanical fan. Also as HP goes up so does heat. You might need to install a 4 core big radiator or even an aftermarket aluminum.

Just wondering why you are calling it a 406 stroker motor? It probably is a 400 block with an overbore. No stroking involved.

 

Air temp plays a huge part in the engine temp, and from what you are saying at 60 degrees ambiant, I would bet when temps go up to 95 degrees you will have a problem. Invest in a good radiator.

I went with a Dewitt 1 1/4 inch twin tube deal, and run only one 16 inch Spal electric fan,....and no shroud. In 95 degree heat, stuck in traffic, the fan will kick on and maintain 195 degrees. Once under way, the air flow quickly drops the temps from there to 180, and after a short while, it's closer to 160, which is the T stat spec.

 

205 is a perfectly acceptable and normal temp. For comparison, the C4 Vettes, which used the same Gen I iron block and iron heads initially, were set up to have the cooling fans turn on at 230 and shut off when engine temp went below 217. My 406 runs 210 in traffic - perfectly normal.

Also, a 406 is not a "stroker." It's a plain ol' Chevy 400 small block with a .030 overbore (it actually comes out to 406.8 cubic inches, so many people call them 407's). It's a common performance platform for easy power and torque.

 

Man, im overwhelmed by the amount of responses and information, i cannot thank you guys enough! I have not dug deep enough to know which tstat the motor has but I am installing a 165 degree this weekend. I know the radiator is not stock but I do not see any names or designations on it so I may pull it and replace it. The vette has the factory guage and then has a sun aftermarket and both stay pretty close to each other in temp readings. When I use my laser therm on it, it corraborates the guage readings so Im pretty sure the temps are correct, Im in trouble when the weather heats up lol. As far as the motor itself, I can only go off of what the previous owner gave me information wise and from the paperwork the motor was originally a 245hp 350ci from the factory, when he rebuilt it he used a kit he purchased from summit racing and the kit he bought was a 406 stroker kit at 550hp. The motor was built by a race shop in mo. and according to the dyno sheet spit out 581hp according to what he gave me. The vette runs insanely strong even as rich as its running right now, but the temps concern has kept me from playing too much lol. I will start at the tstat and move through to radiator, ideally I would like the car to stay 180 to 200 but in really hot days not really cool days so my work begins. Again, I cannot thank you guys enough for the info, ill keep you posted.

 

My block is a 350, 4 bolt, clearanced for a 408 stroker. What I have sounds like you have.

 

I agree with some previous posters that 190-205 degrees is no big deal (I run a 195* thermostat in my engine), but before you spend money on a new radiator, have you checked the idle/low RPM timing curve to confirm that the timing is optimized? Insufficient advance will cause an engine to run a little hotter than it needs to be.

 

Keep in mind that a thermostat does not control or limit the maximum temperature that the engine runs at. A thermostat only controls the minimum temperature that the engine runs at. If the engine runs at 205, it will run at 205 with a 165 or with a 195 thermostat - both thermostats will be wide open below 205, so it makes no difference.

Lars

 

I like to run between 170 and 190 max.

I would be concerned in 90 degree temperatures. You may see higher temps.

I would swap to a direct fit aluminum ..

 

I am peaked by the timing response, the car in my opinion needs to be timed and I know the carb is off. I did speak with engine builder and he explained the "stroker" and why this motor was considered a stroker since he increased the stroke from the factory stroke, he did confirm it was a kit from white brothers racing, I thought it was summit. I just picked the car up first of the week so this is my first weekend to mess. Alot to absorb, Im used to them pretty much stock, this is the first motor modified to this degree that I have had in a corvette. I do believe after consideration I will re-time and reset my carb and test before I tear into the cooling system. Again guys, thanks a million for all the help, I will update as I wind through it.

 

It's either a 383 "stroker" or a 406. 383 is made from a 350 block, bored .030 over and adding a crankshaft with longer stroke (3.75 vs stock 3.48) - that's why it's called a "stroker". A 400 block with .030 overbore and stock stroke crank is a 406. You'd need to add a crank with at least 3.875" stroke to have a "stroker".

 

I've only seen two 4 inch stroker 350 blocks being built in my life. They come out to 408 ci. 4.030 X 4.00

the 4 inch stroke kinda ruins it from being a what I would call a performance build. For rod bolt clearance, you can only grind away so much before you are into the water jackets. So junk kits like skip white use smaller rods and rod bolts which are marginal for motors exceeding 500 hp levels. 4 inch stroker cranks are hard on the cylinder bores and stress the bottom of the block. I used billet main caps and ARP studs another fix is splayed main caps. It is just not a quality way to aquire more ci. Oh yeah you end up using short rod length which loads the cylinder walls and wares them out of round

 

I don't know what's greater here, your snobbery or your rudeness. Which of these two were you aiming for?

 

That is actually the truth about 4 inch stroker 350 blocks. One of them was blowing smoke out the pipes in about two years and the bores were so out of round the block went in the dumpster.

I'm actually just waiting for the Rolex 24 hours of Daytona to start!

 

To the original point:

More displacement is more fuel and more air, which explodes to create more power and, by definition, more heat. The Corvette is 'hot natured' and it would stand to reason that if the stock radiator did an adequate job when new, a 40-something year old radiator would have several demerits relative to heat removal.

The conversation is about "delta", not "absolute" being as the radiator is a very simple heat exchanger. So the issue really is the ability of the cooling system to dissipate heat in a 90 or 100 degree day. I personally run a 160* thermostat and have the biggest BeCool radiator I could stuff in the nose of my car. I have no issue maintaining 170 degrees in the very hottest of days...it will float up to 180 when I push it. My engine is a highly modified 350 that remains 350. No bore or stroke.

BTW, I'm running a new AutoMeter mechanical temperature gauge set in the top of the engine so I KNOW what the temp of the water leaving the engine is. I would not trust the stock gauge if this is an absolutely critical question in a modified engine. That is, of course, my opinion.

My thoughts, in summary:

If you maintain ~200* in 60* weather and you have a 190* thermostat, I'd say you're right as rain.

If you maintain ~200* in 60* weather and you have a 160* thermostat, I'd say you're going to be in a pickle when it gets up to 90*/100* being as your radiator (heat exchanger) is getting as much "delta" (temp in vs. temp out) as it can right now. As ambient increases, so will your engine temperature. Degree for degree, or something very close.

Off the subject:

There are many accuracies to what Mr. Gkull is saying. I'm considering a larger displacement build and am NOT considering a large stroke build for the very reasons he states (among others). A Dart SHP is a better way to get displacement with both a superior foundation as well as a shorter stroke, limiting exposure to the clearance issues that are accurately identified.

But I don't know what the hell that has to do with the issue of removing heat from an engine.

 

Thanks keith for the reply, i get everybodies opinions but for now have to work with what I have. I am working on getting the timing lined out and the carbs adjustment as precise as I can then I will run it again and see how the temps look. This car has a tilt nose front end which you would think would make it easier to access the radiator but not without removal. So, if Im going through that much hassle I am not reassembling it without a new radiator. Lots of recommendations (thank you all) on which radiator to go with, still studying it but in the meantime I did change over to a 160 degree thermostat and ordered a higher volume water pump since the one on it looked like a stock one. Thanks again to all for the great replies and great information, if I do smoke it ill have a good reason to redo it lol.