[ellwood]

I just fired up my engine last night and immeadiatly ran into an overheating situation. While Breaking in the cam at 1800 rpm the temp climbed close to 230 degrees in about 2 minutes. It is a 400 block with an Ohio Crankshaft rotating assy. (455 crank w/ 3" mains) SRP Pistons, H-Beam rods, 230 duraation Cam @.050. Edelbrock Aluminum heads 87cc. Edelbrock RPM intake, MSD ignition, Demon 850 w/ vacuum secondaries. Rodney Red 15" radiator w/ twin electric fans. Fans come on alright bu temp just keeps climbing. I'm @ 6000' Could timing affect the temp that much? Jetting? Plugs look good. I get the feeling it is just new and tight but on the other hand I don't want to fry it. Any suggestions?

[Tripower455]

They tend to run hot for the first hour or so. My 462 ran about the same temp when doing the cam break in. In addition to the radiator with a fan in front of it, I ran some hoses to a heater core immersed in a bucket of water, with the garden hose running, allowing it to overflow. The water in the bucket got hot very quickly, btw. You can also set the garden hose to spray on the radiator to help it cool better.

[george kujanski]

Make sure you don't have trapped air in the block and that the water pump is moving the coolant.

George

[David Jones]

Thermostat opening?

[ellwood]

Thanks for the replies guys. I did check the thermostat while it was still hot and it was opening just fine. The pump seems to be working well too. The coolant is flowing past the neck when I take the cap off. In addition, if I shut down the engine and run the electric fans on the radiator for a while then restart the engine it cools very quickly which makes me think the pump is working fine. I'll try retatrding the timing and check the jetting. Hey Tripower, what is your temp running now after break in?

[Tripower455]

Originally Posted by ellwood

Thanks for the replies guys. I did check the thermostat while it was still hot and it was opening just fine. The pump seems to be working well too. The coolant is flowing past the neck when I take the cap off. In addition, if I shut down the engine and run the electric fans on the radiator for a while then restart the engine it cools very quickly which makes me think the pump is working fine. I'll try retatrding the timing and check the jetting. Hey Tripower, what is your temp running now after break in?

Still too hot at prolonged idle, but around 180 or so (160 t stat) when cruising. I have an underdriven crank pulley, and probably not quite enough radiator for the engine.

[ellwood]

Retarding the timing seemed to help quite a bit. I've got about 20 minutes on the engine now and it has gone through about 4 gallons of gas. At this rate we're going to have to invade another middle east country. But it does sound mean.

[68lemans462]

I just broke in my new 455. I used an aluminum radiator and stock 7 blade fan/clutch. Temps NEVER got above 180. I believe that engines running "hot at first" is a myth. What is the clearance between your water pump impeller and divider plate? That is probably the problem. I'd also drill holes in your thermostat if you havent already. With that RR radiator, you should be trying hard to get the motor to heat up. Something is wrong.

[Formula8]

I'm at about the same point with my motor but mine maintained a water temp of 210-215 during my 20 min run in of the cam. However, my oil temps crept up to 240 degrees toward the end when I had to shut the party down. I went through the same routine the next day with no changes other than fresh oil and water temp maxed at 210 and the electrics could bring the water down to 185 but oil temps stayed at 210. I'm going to ditch my relays for a DC controller eventually to steady the water temps.

[Tripower455]

Originally Posted by 68lemans462

I just broke in my new 455. I used an aluminum radiator and stock 7 blade fan/clutch. Temps NEVER got above 180. I believe that engines running "hot at first" is a myth. What is the clearance between your water pump impeller and divider plate? That is probably the problem. I'd also drill holes in your thermostat if you havent already. With that RR radiator, you should be trying hard to get the motor to heat up. Something is wrong.

FWIW, Every rebuilt engine I've put together ran hot on the first run and then settled down after a while.

My current setup is running hot at idle, which I suspect is a function of fan speed coupled with not enough radiator capacity. 9.5:1 462, tripower, 6X heads I have a 15" Rodney Red, 7 blade clutch fan with good clutch, 160 degree thermostat, cast impeller pump with the divider almost touching and a repor AC car fan shroud. I have a March underdriven crank pulley, which I feel is a big part of the problem.

When sitting in traffic, the temp will creep up to 210-230, and will come down immediately as soon as I start driving again. Before I did the water pump mod, it would take a lot longer to cool down. If I drive the car for 5 minutes, it will stabilize at around 180, eventually coming down to 165 or so if I keep it moving.


I am going to put a larger crank pulley on it, and if that doesn't solve it, I'm gonna look into a thermostatically controlled pusher fan setup. I realize a puller is better, but I don't want to mess too much with the stock-ish looks of the engine compartment.

[ellwood]

It's starting to stablilze more but I still have not reinstalled the thermostat yet. It's holding at about 200 degrees at idle. I think the 10.25 : 1 compression may have something to do with it. My water pump divider to impeller clearance is at .0625". TIming at idle is 12 degrees BTDC I'm starting to think it is just going to be warm natured. Definitly the most powerful car I have ever owned though. I'll be shopping for slicks now.