Before I bite the bullet and spend 750 bucks on a stock radiator I am asking for your opinions 1 last time. Mine is a 68 camaro convertible with a 427 and vintage air. I have tried a large aluminum radiator with just an EF, then I tried moving the fan to the front (made it blow) and adding a mechanical clutch fan, then I switched the clutch fan for a flex fan. No matter what I have tried the results are the same. On a hot day like now in California it runs at 215 and will always blow coolant out after running it for half hour or so. It takes about 3 quarts to fill it back. I have added some photos too.
Thank you as always!
Scott

 

A radiator (23" BB size) with 2 large, 1 1/4"-1 1/2" wide rows cool better with more but smaller cores. Cold Case makes the large 2 core versions that also have the 2 lower clips to use a stock fan shroud. I have their radiator but SB motor but their 23" size as my SB originally was an AC car which had the 23" radiator. 7 blade 18" fan with clutch. Runs 185 all day. Can hit 200 in stop/go traffic when its 100 degrees out but goes right back down to 185 once moving

BB motors do struggle, especially with EL fans that are simply not up to task. The high $ SPAHL brushless fans mounted in a matching shroud seem to be one if only solution. However, many use the 7-blade clutch fan with stock shroud without issue

Too much timing will make the motor run hot

Puking 3 qts though is definitely a overheat issue. You do want to keep coolant level at about 3" from neck as it needs roo, to expand

Regarding overflow tank, the 75 Nova one fits in PS fender and looks like it "belongs" there vs outboard tanks mounted elsewhere

 

Hi Vsj100, I was just wondering if you checked your thermostat operation and if you burped the air from the engine after you installed the new radiator. I don't have that monster 427 in my 68 but I did change my 2 core to a 3 core and never had any boil overs when I drove my 68 327 from the OC to Las Vegas during the hot summer. Summit racing has stock 3 and 4 core radiators that might be something to consider if you want to save a little $$. Socal67 I dig that Nova overflow tank you installed and your right it does look like a stock setup.

 

I finally bought an 18 inch fan with clutch. It went on today and lowered the temp to 190. Next week the stock shroud arrives. That should do it. The current shroud is what came with the ef. I opened it to match the fan diameter but the stock shroud should allow better air flow. Regarding burping coolant past the thermostat. I learned a great hack awhile back which is to drill a couple of 3/16" holes in the edge of the thermostat to allow the system to equalize without waiting for it to heat up. Works great.

 

Hi, glad you solved your overheating problem by using a larger fan/shroud combo, I never heard of that trick, but it sounds like its working great for your big block motor.