I recently put together a street/strip 350 crate motor (.060" over, flat tops) 284/292 .488" cam, Hedman shorties, Dynomax 3" pipe to flowmaster 80 series. Built the TH350 too, used 2200 stall. Edlebrock intake/Holley 600CFM VS. Runs real strong and fast. New water pump, stock 92 Z28 pump & serpentine setup, it's spinning counterclocking as it should, I hope they gave me the right one, it looked just like the old 305 motor pump.

Here's the dumb part, I used the existing 305 old '92 Camaro radiator. I was told it was good. I also used a new 160 stat and hoses. Using stock electric fan (wired to ignition with relay), 92 camaro RS.

When I first attempted to fill the radiator, it seemed to have a pin hole leak. Figured it was good enough for the 20 minute cam break in anyway so I continued. Well I only made 7 minutes before I hit 240 degrees so I shut it down. Oddly, the radiator "sealed itself", the pinhole leak had stopped for good.

The flow at the top of the radiator was excellent. I figured the motor overheated because the radiator wasn't completely full and it was a hot day (but 7 minutes is kinda ridiculous).

I have since replaced the 160 stat with another new one, and then even removed it. The result is the same, just a mere trickle of coolant coming to the top raditor hose. Obviously, the radiator or engine block got jammed, or the water pump is the wrong impeller type. But I did get good pump action for a few minutes, so I think the pump is good.

I hope the motor isn't too damaged from local hot-spots, as I drove it a little bit before I realized what was happening, the new gauge never really passing 220. It is using mixed heads 624 (worst) and 993 castings, both with prior metal repairs, but both machined perfectly. And the motor still runs awesome, but not for long on only air-cooling.

Is it plausible that the deposits in the old radiator moved/shifted therefore clogging the radiator? possibly clogging somewhat my new block?

I plan on buying a new cheapo radiator for $116. I suppose they make something I can put in with the water to possibly "clear" any deposits in my freshly built block.

Thanks in advance.

 

Update: Replaced the radiator, car runs cooler and does not hit 230+ anymore. 220 is pretty much max. Different antifreeze mixtures aren't helping much either.

Car runs at 180 at night, 220 in the day, and this is cruising temps with air dam. I was hoping for better temps because one of my heads is the weak 624 casting prone to cracking.

Well it is a 400hp motor that will snap the car in half, so I suppose the only was to lower the temp further is to run 2 fans instead of the stock single setup.

 

Id get appropriate heads before running a new engine..
Is the compression identical on both sides?

 

Yes the compression is the same on both sides, and both are 76cc heads. The 993 flows better on the exhaust I believe, as internet specs say, plus the header on that side is white, the 624 side is still pretty black.

I tried getting new heads for the motor, every place I tried the heads were junk and machined horribly. These mixed castings actually came with the block as a long-block assembly, and had excellent machining with brand new valves/seals. I found a bent pushrod, stuck rocker, and oil-soaked head gaskets.

So I bought all new valve-train parts from Crane, and used Fel-Pro 1003 (.038" thick) head gaskets that I know I installed correctly. Used ARP bolts for the heads. I checked the block and heads for straightness and they were perfect.

I'm going to put the TH350 tranny on a cooler by itself hoping that will cool down the motor some more. I have my temp gauge attached to the driver side (as hot water leaves thermostat) of the Edlebrock manifold. I was told this reads higher than reading from the cylinder heads, although I remain skeptical on that.

Also my Edlebrock intake didn't come with rectangular exhaust block-offs, so I left them off when I installed the intake. Could this cause the motor to run unusally hot?

Also I'm told .060" over motors run a little hot anyway, but I certainly don't like the temps.

 

Ok here is my best attempt. First off the 2 different colors of headers should tell you that the white header has burned off the paint, while the other side has not. So your fuel mixture might be off a little, if thats from the different heads I dont know.

Removing the tranny cooler from the radiator will not significantly change the way the the radiator cools the engine, by adding a stand alone you basically just cool your tranny better from the upgrade.

Going .060 over will tend to make the engine run slightly hotter as you have less cylinder wall thickness.

Now its time for "Honest time". Im not trying to burst your bubble and dont take this as a dig at you (just an FYI). I have a hard time thinking you have 400hp on a 350 with 8.5:1 compression, stock iron heads, and a cam thats not the right size. In order to make some power you need more than 8.5:1 compression unless your planning on forced induction. Also I think your cam is a little too big, I tried to find your cam on Cranes website but could only find one that was very simular. Yours is a 284/292 and the one I found was a 284/290, just slightly smaller. This cam has a duration of 228/234 @.050. With only having 8.5:1 and a cam that size, you will have some overlap which bleeds off cylinder pressure. This allows people to run higher compression, but yours is already low, and i think your losing some more to overlap. ( I did a quick DD2000 on your motor, and I know the program isnt perfect but its a good indicator, see the pic added)

Crane actaually states this for your cam "Permance usage, good mid-range torque and HP, bracket racing; Street, Heavy, etc., auto trans w/3000+ converter, 10.0 to 11.5 compression ratio advised. Basic RPM 2800-6200"

Now to show I am not flaming you, but trying to help you from my experiences, I had this exact setup on my first v-8 (350, 8.5:1, 76cc heads, 236 dur @.050 cam) and I thought it was the cats ***. Not until I was informed of my low compression and overcamming did I realize I could optimize the engine a little better. I swapped the heads from 76cc to a set of 64cc fuelie heads, which bumped me to 9.8:1. I couldnt belive what a difference it made!! Then a while later I swapped in a smaller cam, and WOW!! The car felt so much faster, I never thought my car was ******* it off the line till I made those 2 changes.

Which leads me to what I have found out and others have known to be true for a some time. If you want to make power, get the best heads you can!!! Never skimp on heads, they should always be the biggest investment in your motor!

I think it was John Lingenfelter who said:

"Build a motor with the perfect cam and a poor set of heads and you will still wont make good power. Now build a motor with a good set of heads and a poor cam and you will make good power!

wow, sorry that was long. Honestly trying to give as much info as I can

 

Thanks for the info. But I did state I was running flat tops so the motor is 9:1 CR, not less. Search for 4002 on Crane's website you'll see the Bazer 284 cam I'm using. It has an LSA of 114, which is how I can pull 12-15in of vacuum at low idle (15 with A/C off) and makes a flatter HP curve than lower & lumpier LSA cams. This cam makes power from 2200-5500, valves float at 6000. Edlebrock performer manifold really only good to 5500, so it's a match. Using a 2200 stall on the TH350 tranny, I compromised a larger 2400 unit because of fuel economy. Crane recommends 9.5CR and a 2500+ stall with this cam, since I'll use Vortecs in the future (bumping my 9:1 even more), I don't think I picked the wrong cam.

The motor has crane's springs, lifters, pushrods, cloye's double-roller chain, Accel ignition throughout, Melling 55A high pressure oil pump, etc. My fuel mixture is right on, but the 624 head exhaust flow is almost 50% less than the 993's ability, so it just took more driving to turn that header white.

I don't have DD2000, but I've had plenty of 14, 13, and 12 second cars. This Camaro has a 2.73 non-posi rear. I made a series of full throttle runs the other night, I can assure you the 360 motor is making well over 300HP with these smogger heads. I'll prove it when I get a 1/4 run at my local track. Car craft mag did a test using the same exact cam and made almost 350HP with the stocker iron heads (I'll try to find the link). They used a nearly identical cam with Vortecs and made 386HP without even flat-top pistons that I have (I'll find this link).

Believe me, the heads were only used as a last resort (I tried to get better, I had the money). But the car really does rip the road, no trouble wasting people even with the lousy 2.73 gear and crap heads. Smokes the rubber from a dead stop and just keeps pulling really hard, no dead spots, loves to rev past 6000, I really have to watch the manual shifts. I love this cam and know many who do as well.

But the topic of this post was the motor over heating. Which has made the car undriveable. Today it hit 250 while running, all cooling components are new. Idling isn't really a problem. Driving, even at low speeds, is a serious temp issue.

I'm theorizing the part shop gave me the wrong water pump. One that has an impeller design for v-belt setup instead of serp. Serp spins counterclockwise, v-belt goes clockwise with motor. They look the same, but poor flow and cavitation results from using the wrong one. If it's not this, then I suspect the block, because I have too. I know 300-350HP motors run around 200 degrees, but 250 isn't right, and it will crack or warp something.

 

http://www.carcraft.com/techarticles/1057/

Here's a link to what Car Craft did in a 355 Small Block, stock HEI, with 8.37:1 compression (I have better than 9:1, and 360 cubes). The used the identical cam as me (cam #3) and got 343.6 lb-ft torque at 3900 RPM and 304.3 HP at 5200 RPM. Bigger is better, to a point, and they prove it.

Nonetheless my 360 motor is no doubt making more power because of the 5 extra cubes, the .015" thin head gaskets plus flat-top pistons (over 9:1CR), and Accel distributor, coil, & wires.

This cam is the cats meow even on smogger heads. The vortecs will up my HP to 390 and beyond , it's my next move. I already have a 125HP shot, so you can see why I gave my HP estimate as I did.

But the original topic of this post was how to keep this 360 motor cool. I have a Milodon high-flow water pump/stat on order, will install on Thursday and let you know if it helped, I sure hope it does, I love driving this car.

 

Its funny, my comments about your "400 hp motor" were in line. After you reply and tell me how I am wrong, you start adding all this extra info. "When I add my Vortec heads, my .015 head gasket, my nitrous...etc. So I really wasnt wrong saying your motor wasnt 400hp.

Good luck finding the solution to your cooling problem.

 

You assumed it was a 8.5 CR motor, which it isn't (FYI, flat top pistons means 9:1CR with open chamber heads). I did end up using .015" when I assembled the block, because the .038" I originally bought I ditched after the first clay test, the earlier post is a typo, big deal, motor still would have been 9:1 with the big gaskets. Without the spray (which was on the car from day 1, making way over 400HP) the motor alone is making an honest 335HP I figure. My original post never stated I didn't have a power adder. If someone asks the HP of my car, I maintain 400 (rather than saying 335/450), race it and find out if in doubt.

As far as you being wrong, I have only pointed out what Car Craft and many others already know, I have not over-cammed my motor, another bumpstick (smaller or bigger) can not make it run better. The Vortecs will produce the 400HP without the wear-and-tear of the spray, so they are in my future, so what. They are in the VERY near future, but only if I can cool the motor at 335HP.

This is the COOLING section of the message boards. The ONLY reason I mentioned the motor's HP figure is because it's the only thing I can figure that's causing the overheating, to which NO one has given a useful reply to. Just moans about using proper heads on a new block & inaccurate HP figures; this doesn't help.

Honestly, with all brand new cooling components (many replaced twice) do you think I would even have a cooling problem if the motor alone was under 300HP? I'm pretty sure stock water pumps can deal with that.

 

The best thing I ever did when I put my V-8 in my old S-10 was to buy a Griffen aluminum radiator, and added 2 bottles of "40 below"($25/bottle from summit or jegs). I would pick one up instead of a smaller $116 one, in all seriousness it was the best $240 Ive spent upgrading anything. It ran 220 all the time, and after the radiator swap it would hit 190 and stop. I even drove it to the local Lowes parking lot and let it sit and idle for 30 minutes and it never went over 200!!! But the radiator w/o the "40 below" is only $180. Just a thought, I dont know your situation.

Dont take this personal(Lord knows I'm not), I sit here and laugh, friendly banter is fun, but FYI, flat top doesnt mean 9:1 automatically, Im sure you know there are true flattops, there are the ones with 2 vavle reliefs, and the ones with 4 valve reliefs. I was assuming a thicker head gasket, and 4 valve reliefs(bc thats what I used, lol) and if you havent had any deck work done, it is possible to be between 8.5-9:1. Not like 1/2 a point of compression is making a HUGE deal anyways.

 

I didn't know the Griffen was so cheap. Idling isn't much of a problem, and it's odd, because I can see the water pump isn't doing much at that RPM. Soon as I leave idle RPM, that's when the gauge ramps up (it's not the lower hose getting sucked flat either). If the Milodon water pump doesn't help, I'll have no other choice but to try better than stock radiator. I do plan on using the $25 40 below stuff (although I tried it, it hasn't helped so far, I still suspect water flow problem, highway speeds are devastating to the water temp, you can just watch it rise to 240 and above within minutes at 55MPH, slower speeds take longer, but do get there as well). Two bottles eh? Not that another $25 isn't worth it to me, but was 2 needed vs 1 bottle?

I meant flattop as true, without reliefs. And deck work has been done to the old 010/020 '67 block. I'm sure I'm just over 9, even considering the .060" bore. Gasket thickness only matters a couple tenths of a point. But I wanted as much CR as possible without going nuts (max HP on pump gas was a goal of mine). Even have a 3" Cowl hood, may help make a little power, but it doesn't seem to help the motor temp on the highway.

I just don't get it, you look on Edlebrock or Milodon websites about their high flow water pumps and you see 800+ HP street driven cars using them without problems on hot days. Seems unrealistic hype to sell pumps, but I know people with 800+ HP street cars, they just haven't revealed their cooling secrets to me yet.

 

I looked again and the price has gone up to $190 on the radiators, Griffen Radiators. I did use 2 bottles, I had actually driven to Summit in OH, and they said said it would work best if i used 2, dont know if they were tring to make and extra sale, or what, but it worked.

Have you ever thought of an electric water pump? I actually had a guy send me a Moroso electric water pump kit free with an Edelbrock Vic Jr water pump I bought!!!, but I havent used it. :hail:

 

Maybe it was free because it doesn't work well on the street? I've read on the net that electric pumps only provide like 5 lbs pressure to the block vs 30-40lbs pressure with high-flow belt-driven. Good for 1/4mile blasts only (1/4mile only people would want it I guess). And it's the pressure that actually cools the block. Common myth is when you take out the thermostat, the radiator can't cool fast enough. It's the lack of water pressure caused by removing the stat that overheats the motor.

Perhaps I'll try one $25 bottle first and leave some room for the second and see how that does, I'll get that Miloden pump today. I do know that 40 below stuff works better than the Prestone junk I have in there now.

Are you using the Vic Jr pump now? Just curious if it's in use with the engine temps you gave earlier. I think you meant you haven't tried the eletric.

 

I did my radiator swap when I had a stock water pump. I put on the Vic Jr way later. This was on my S-10 V8.