"As far as how it runs, at idle, it’s kinda like a horse at gallop/“dahdun-dun, dahdub-dun” under power, it spoils quickly, with a hint of a stutter when DUMPED more throttle... so much so you can drift all 4 tires without much effort. So,overall RUNS well and power and it’s delivery seems fine(& is my only doubt on tune being the culprit for heat).
The stumbles when floored could be ignition and/or carburetor tuning. Sounds like it has power, but maybe could use some fine-tuning still. And yes, that could easily lead to cooler running.
Unfortunately it's never a guarantee, but it's an important first step in ruling stuff out.
Yours may end up like so many, that just never get theirs to run cool. But you won't know until you eliminate all the potential sources."
I think DirtDonk nailed it.
This sounds like a timing and fuel issue. My guess is you're running lean and slightly advanced. Lean = mean but it also adds a ton of heat. The stumbles sound like your tip-in could be lean also and your jets need to be changed to larger but I would investigate that carb further.
I know you said you weren't sure on the carb but anything less than a 650 on a built 351W could be your main culprit. There is no way you will be making 600hp on that carb and even a ported 650 will be stretched at that power level. The issue is, even if you open up the jets to max, the motor draws so much air (especially with a roller cam) that a small carb simply can't keep up. It'll be fine at idle, or even driving at part throttle but quick throttle inputs will result in stumbles. The old hot rodder formula is: VE = (displacement x rpm)/3,456
If you're running a 351 at 6000RPM you need a minimum of 609CFM. This doesn't take into consideration your aggressive cam however and overlap can result in much more carb flow required.
I'm running a similar setup to you with a bored and stroked 351W (now 427ci) with high compression, edelbrock performer heads, ZF trans, dual plane intake manifold (also something to consider on your tuning issues), and a 180 thermostat. I run the stock radiator, no shroud, no mechanical fan but two electric SPAL pullers (only one runs until I hit a threshold temperature and then the other kicks on), and a high flow water pump. The stock radiator is the original from 1969 and keeps on trucking without a single overheat problem and I run in the deserts around Los Angeles.
Now is when I try to sell you on switching to fuel injection and be rid of all these issues but that's for another time. ;D
Basically, your radiator sounds fine but your tune is off.
Jon
