Motor running hot.

[blue69runner]

So here is the deal. Had a cracked head and got another one done at a shop. Put it back on the car. Have a new 26-inch radiator 3 core. 7 Blade fan. Shroud. Now the motor runs really hot. It did not ever get over 190 degrees while driving before but did get to 210 in stop and go traffic. At a loss for what to do now. Have a set of 440 source aluminum head coming hope this will fix the problem. Running 180 thermostat. This is a 383 motor with a purple cam and dome pistons. 9.8 to 1 compression. I did drive this car everywhere and felt grate. But now won't get too far from home. Any thought would be appreciated. Oh, this is only bored over 20 thou. Hope I don't have to buy another block and have it gone through. Thanks for any thoughts. Blue.

 

[Don67Satellite]

Did you burp the cooling system 100%, you could have air pockets.

One of these funnels is your friend.

 

[Ron H]

There can be some break in time with new-rebuilt motors, running hotter for a while. Might be a little of this with the new head. As posted, making sure there are no air pockets is a first go to. What ratio of coolant are you running? Among several things I did hunting down hotter temps was reducing coolant to around 30% researching higher ratio of anti-freeze retains heat. Added wetter as well. My car sits in a heated garage so a lower mix during winter storage isn’t an issue. Anyway, among the half-dozen things I did, got the desired results.

Is the new shroud to factory-like specs? Asking as some aftermarket shrouds can create hassles. And check the distance of the fan from the radiator. About the same distance as it was before?

 

[BigFlo]

Did you change the head and radiator at the same time? Or did you run the same radiator before and after the head change?

 

[Geoff 2]

Retarded ign timing & lean mixture. Both will cause hot running.

 

[PurpleBeeper]

Don’t freak out. First, work on cooling - 50/50 mixture, drill air bleed hole in thermostat, make sure there’s no air pockets. Maybe use some radiator flush (for the block mainly)?

 

[blue69runner]

All good suggestion. Have a USA radiator three core. The fan is as close to the rad. as I can get it. So, the head when putting it on seems to have been ok. Running a 50/50 mix of Preston antifreeze. I only have 5000 miles on this motor after rebuilding. The shroud is a factory one for the 26-inch radiator. Hope I answered all the questions. Blue

 

[Don Frelier]

If you have a shroud you don't want the fan too far inside.
1/3 of the blade inside is about correct.

 

[1967coronet]

So if I understand, the higher temps happened before the head swap ?
At the time it started running at a higher temp was there any other changes made under the hood previous ?
Is the system building pressure ? This could be a just a bad cap or thermostat.
I would swap those two for new ones to start with. Also pull the fan belt and give the pump a spin and see if all feels normal.

 

[beanhead]

Did the timing get moved? Late timing causes things to heat up quickly.

 

[PRHeads]

As mentioned, fan should not be more than 1/2 way into the shroud opening.

Also, the wp pulley should not be larger in diameter than the crank pulley.
If you’re having heating issues, having the wp pulley smaller than the crank pulley is what you want.

What is the timing at the typical part throttle cruise rpm?

Do you have, and are you running vacuum advance?

 

[blue69runner]

Running 12 degree before top dead center at 800 Rpm's. Total timing I am not sure of. Same distributor since rebuilding the engine with vacuum advance. No point ignition.

 

[Terry1213]

Don’t freak out. First, work on cooling - 50/50 mixture, drill air bleed hole in thermostat, make sure there’s no air pockets. Maybe use some radiator flush (for the block mainly)?

Do you know what the range is from the C to the H in degrees F?

 

[Ron H]

Do you know what the range is from the C to the H in degrees F?

View attachment 1737278

Agree, had to find this out with an infrared thermo. Yeah, just what IS the temp 1/2 way, etc.

 

[Ron H]

If running a 'new' head, heads, rebuilt motor, it will run hotter during break in..

 

[RJRENTON]

Don’t freak out. First, work on cooling - 50/50 mixture, drill air bleed hole in thermostat, make sure there’s no air pockets. Maybe use some radiator flush (for the block mainly)?

The perverbial 1/8" diameter hole in the T-stat mounting plate (near the valve disc) does nothing....once the t-stat opens for the first time ALL entrain air will pass thru the t-state and be purged. Where would the "air pockets" be?......it's possible that the head gasket is allowing combustion gases to weep into the coolant. Reducing the coolant concentration to 30/60% will allow better heat transfer because the specific heat of water is better than that of ethylene glycol, but the higher the glycol mix provides better corrosion protection. Who decided the coolant temps in excess of 200°F - 220°F are the end of the world???? With a 16# cap and 50/50 glycol/water mix raises the boiling point to ~ 265°F.....JMO.......
BOB RENTON

 

[Geoff 2]

Post # 13, C to H conversion. Do you mean C to Fah? Multiply C by 9/5 & then add 32= degrees Fah.

Agree with Bob, hole in stat does nothing. Holes in stats started because some performance water pumps eliminated the bypass. The fix was hole in the stat. Adding holes will not improve cooling & just delay warm up, needing the choke on longer....

 

[PurpleBeeper]

Do you know what the range is from the C to the H in degrees F?

View attachment 1737278

Yes….it varies with every car, sender and gauge. That “could” be running cold (seriously). All those gauges are worth is this…if you drive the car for 3-4 yrs, you will notice if it’s different. That’s it. You should invest in an infrared temperature gun from harbor freight for $25