Overheating during cam break in

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GoodTimeGarage

GoodTimeGarage

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Bedford, Indiana
i have a 72 duster with a 440 that i just swapped in. its a fresh rebuild, i tried 3 times to do my ca break-in. each time the car fires up just fine and after 3-7 min of running it starts to get hot. ive been shutting it down at the 210 degree mark. the first time it puked coolant out of the radiator, i did not have the cap on. so when i filled it back up i pulled on of the plugs on the 440 source waterpump housing for the heater hoses and used that as a way to make sure the air was being bled out as i filled it again. ive bypassed the heater hoses and installed the screw in plugs that came with the aluminum housing. the second time it started to get hot i let it cool and removed the thermostat. i was going to drill a hole in it but decided to just take it out for now. it ran a few minutes longer but still got hot fairly quick. i just want to make sure and noy pop the headgasket or something. i pulled the plugs and they all look fine, no discoloration and no coolant in the oil. i am running a smaller radiator but it is comparable in size to one out a big block newport a friend has. any suggestions would be much appreciated. im not new to this site, my old log in wouldnt work and i had to create a new one. thank you!


engine specs,
winnebago 440, stock forged crank
ported heads
fenderwell headers
comp cams xtreme energy .525 lift .262 duration (if i remember correctly)
milodon high volume oil pump
440 source alum water pump housing and pump pass. side drop
no thermostat as of this moment
radiator from 77 aspen
flex fan,no shroud.
 
13417413_10209735398132370_4297039905686285161_n.jpg


this was before i got everything hooked up.
 
hmmm, same cooling setup that both me and dad have and ours don't get hot, we do have 3 core champion radiators though. but 440 source pumps and flex fans with no shroud
when you checked the plugs were they lean, rich?
also where is the timing at, if it's too far retarted it will get hot quick
 
210 degrees temp during break'n is normal, now at 230 I'd start worrying a little. just a little.
 
it never got quite up to 230 degrees, timing is set at 10 degrees advance at idle, according to the timing tab. didnt have a box fan that worked but i thought of that and will add that next. spark plugs didnt give any signs of extreme lean or rich conditions and they werent wet. they did not appear to have any traces of coolant. its been roughly 8 years since ive done a cam break in, maybe im just being paranoid and need to let er rip?
 
fan is a good idea, also you can spray the radiator with a hose...., 10 at idle is very low, what's timing at break in rpm around 2500? or full advance?
 
You need to quit worrying about how much timing you have at idle. Your going to screw around and stick an exhaust valve. Set the total at 40*, put some more fuel in it and you should be peachy.

Slow timing is a new engine killer.
 
Straight water boils at 212. If you're fifty fifty with coolant boiling point is around 245. Leave cap off and garden hose ready to top up.
 
yeah, I think Id go for more timing at idle. 14 or 15. I have used one of those big squirrel cage fans that they use in houses for heating systems. Got it at an auction. Blows tons of air. Still my small block overheated during the break in. Sprayed water on rad, messy but it worked. It's hard to break in an engine, set the timing and carb all at the same time. I got it close and just went for a drive. Got broke in real nice. DON"T FORGET to check the oil level during the break in. Fresh engines, just machined and hot tanked will soak up alot of oil. {into the pores?? IDK} Good luck, I know 440's tend to run warm anyway.
 
Gotta blow air at the rad. Or at least spray water on it. The engine fan alone can't be making enough air flow to cool it down at higher temp. Engines run hot on break in as is already.
 
Lustle said:
Gotta blow air at the rad. Or at least spray water on it. The engine fan alone can't be making enough air flow to cool it down at higher temp. Engines run hot on break in as is already.
Click to expand...
you might try jacking the front end of the car up when you fill the rad., some times that will let traped air out during filling. I had a 406 vega that had to be done that way. I even had block side water plumbing, and a rear coolant crossover on it which all helped.
 
Lustle said:
Gotta blow air at the rad. Or at least spray water on it. The engine fan alone can't be making enough air flow to cool it down at higher temp. Engines run hot on break in as is already.
Click to expand...

Especially with a flex fan and no shroud.

This thing has all the ingredients for getting hot on the breakin.
1. No fan blowing on it.
2. A flex fan
3. no shroud
4. Low timing
5. Minimal radiator

I'm not saying all the above should be done, but almost any single one of them done would probably solve the heat problem.

Also go ahead and drill that thermostat and put it back in.
Why have to concern yourself with air in the coolant ever, let alone on a stationary engine on a breakin.
 
Last edited:
TrailBeast said:
Especially with a flex fan and no shroud.

This thing has all the ingredients for getting hot on the breakin.
1. No fan blowing on it.
2. A flex fan
3. no shroud
4. Low timing
5. Minimal radiator

I'm not saying all the above should be done, but almost any single one of them done would probably solve the heat problem.

Also go ahead and drill that thermostat and put it back in.
Why have to concern yourself with air in the coolant ever, let alone on a stationary engine on a breakin.
Click to expand...

I missed the flex fan part. The no shroud alone is a worry. The shroud is MORE important than the fan. Yes. Seriously. Flex fan doesn't help either. They are designed to not flow at high RPM. To save HP.

Ditch the flex fan (not just for break in, they are garbage anyways, ask the guys on here how many of them who know someone who lost a finger or more to one of them). Put on a solid fan, with fan clutch and appropriate shroud. You won't regret it at break in or after.
 
Ive been remodeling out bathroom and going to doctor visits with my expecting wife, so i havent gotten a chance to mess with the car lately. I did find a small coolant leak from the upper hose at high pressure, took care of that and also took the headers back out and wrapped sections of them where it was getting the floor hot and the brake master cylinder. the flex fan i used because it was what i had lying around for now. the clutch fan i had was too big and didnt fit in the space between the waterpump and radiator. when i find one that will fit ill swap it. hopefully this weekend i can try it again, i plan on getting some extra hands to help. going to re adjust timing. add several box fans, maybe mist thee radiator with the hose and see what happens. thank you all for the info!
 
I was setting timing on my buddy's Chevelle and the flex fan let go. (One blade tore off) Punched a big hole in his fancy hood and scared the piss out of me. I WILL NEVER USE ONE.....
 
Electric fans. Embrace the modern world of car technology.
 
Cam break in is done. no issues, used the water hose/fan combo and everything was smooth sailing. thanks for all the help. i will be changing the flex fan out as soon as i find a clutch fan that will fit between the water pump and radiator. i only used the flex fan because it was simply what i had laying around.
 
I Hate to be a dick but why would you risk an engine by putting on a flex fan for cam break-in, AND sticking with it two more times when it overheated on the first try?
You know the definition of insanity, right;doing the same thing over and over and expecting different results?
Thermostatic clutch fan. There is a special short shaft version available from Haydon,now. A member here talked them into producing them. Do a search.
 
my car, my dad's car, and 3 of my buddies run metal flex fans. we've never had a problem.

my uncle switched to electric fans when after years of running a flex fan he cut his finger pretty bad adjusting timing.
 
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