I have searched through a bunch of these on here and other forums and ruled out all of the common stuff. Here is my setup: 69 block, 882 heads, Edelbrock intake/600cfm carb, 268H cam, Griffin 2 row rad, serp belt setup. This was completely rebuilt from top to bottom about 600 miles ago. This engine will run at minimum of 220 at idle or down the road, it will stay close to 220 while driving. I have the electric fan hooked up to a switch and must have it on at idle or I will overheat

- System IS bled out
- 180 stat pops at 180 (tried 2 different ones)
- Correct rotation water pump (confirmed by part number)
- Base timing at 10 degrees
- Carb set to a bit on the rich side to rule out lean condition
- Single fan is blowing correct direction (pulling air thru rad)
- 20-25 degree temp drop across rad
- I thought "break in" may be part of it, but after 600 miles, the temp hasn't even started coming down a bit.

I may be missing something else here, so throw your ideas out there and I will respond.

 

Advance the timing.

I get SO tired of telling people this. I've yet to figure out why they don't LISTEN. Be the first!! Actually attack the problem at its roots (allow the engine to turn more of the heat from combustion into mechanical work, wasting less of it through the exhaust and cooling system) instead of worrying how good your Band-aids are.

EFFFFFF the "number" on your "mark" when you look at it with your "light". Advance it to where it starts to ping, then back it off til it quits. Won't be "right" that way necessarily, but should give you a REAL CLEAR picture of how far off your "number" is, from WHAT THE ENGINE WANTS.

 

DrDave88,

I had that problem on my daily driver car once (85 Chevy V8). I tried everything. Plenty of water flowing thru radiator, etc. But the only thing that fixed it was putting in a brand new radiator. A 3-row, even though it only needed a 2-row. Cured it. Apparently the heat transfer of the rad was ruined by too much use of "stopleak" or maybe just age. That's my suggestion, if all else fails! It only cost me $70 but that was about 10 years ago. Got it at Autozone. Good luck.

 

GTA, mine is brand new.

Sofa, thanks for the kind encouraging advice as always. I've messed with the timing and carb adjustment quite a bit. It's been adjusted by ear and by what "specs" say. There is no change to the temp.

 

Base timing is to far retarded for your set up, if you go out right now and put a timing light on the car as it sits and idles, what does it read?

At bare minimum it should read at least 30 degrees while at idle. What do you have?

10 degree before tdc that nothing more then a BONE STOCK engine would like, with your set up, the engine would respond better with 16-20 degrees of timing, base. About as much as it can take before it's to hard to start hot.

Then you need to have a vacuum can hooked up to add more timing during idle to help keep the engine cool. So your engine needs to have more then 30 degree of timing at idle to help keep temps under control.

Of course need to limit total mechanical timing to around 36-40 degrees

Get the timing sorted out and corrected not only will your engine produce more power/torque and make more fun to drive, it will help reduce temps.

Once the timing is sorted out then you can move on to other areas, if your just going to flat out refuse to do anything with the timing then don't bother doing anything else, it's just a waste of time and money.

I have several cars ( built many)with just 2 core radiators and blown big blocks and hot sbc that run really cool around 160-180 degrees, because the timing is sorted out, the idle mixture system on the carbs are good, jetting as well and have plenty of cfm pulling thru the radiator be electric fan or stock clutch fans and shrouds.

In fact the other day I ran my blower motor 15 miles down the road before I noticed I forgot to hook up the electric fan( I unhook my power wires off the battery when I park my rides, forgot to grab the power wire for the fan). Pulled over, hook the fan up to battery and took off. Never over heated. got warm but didn't over heat doing 45 mph down the road. And that thing probably puts out twice the power of your engine and I have no cooling issues.

One has told you about getting the timing taken care of and I am too, do this post up what you got for a new base number, total number, and what you have for vacuum advance. If all looks good and got solid numbers and you still have issues then more help can be given.


hope this helps

 

My first question is only one fan enough? I would find out somehow if more airflow changes things. My 4th gen camaro has 2 fans but both dont run all the time. Using a 160*F t-stat now and it barely gets hot enough to drive.

I would look for a pinched hose. Reads like u have eliminated most of the common issues. Well u can try a 160*F t-stat - wont hurt to try. I know on my corvette the fan shroud seal is crucial as the rad is tilted and only sees indirect airflow. That and the lower air dam (same on my 4th gen Z28) is a essential part for cooling when the car is moving. On my corvette it doesnt take to much shroud bypass leakage air to make it overheat - very common on the C3 vettes. So what im saying is look over your shroud seals for leak-by.

Worst case is sometimes the block has to much corrosion on the cyl wall jackets. It reads like your block is a new rebuild and maybe this was overlooked as blocks sitting in the boneyard have plenty of time to corrode inside. Check for this is to remove a block freeze plug and look w/flex shaft bore-scope. But as u can imagine this is a rare problem and something to test as last resort.

Hope this can help.