When I first got my car it overheated a lot. The engine is a carbed 350 bored over by 60 thou (yes, I know that's a lot for that block). I got an air dam and of course that helped a lot. I was then able to put in a thermostat (170 I think?). In the winter its fine but in the summer (80-90*) or on long hills (65-70* ambient temp) it creeps up until the coolant boils. The fans keep the coolant from boiling so its tolerable but I've been told that there's no reason I should need the fans if I'm driving 75 mph. I've flushed the coolant and replaced it with a 50/50 mix. I'm now wondering if I could have a partially blocked radiator. As far as I know its the stock radiator from when there was a 305 in it (91 RS) so it's been there for a while. Is it possible to have a radiator that is half blocked or perhaps very restricted rather than completely blocked? If so how can I tell and what can I do about it?

I have a 91 Camaro RS that I put a TPI 350 with a TH350 transmission, and I've noticed it needs the cooling fans running when moving down the interstate. I recently acquired an 89 Formula with a stock TPI and that radiator is WAY larger than my 91 RS's radiator. I would say that it's just not enough radiator for your combo. Try some water wetter, that helped me out quite a bit a few summers ago.

In my case its a 700r4. The thing is that while it's the stock radiator its also not by any means a strip engine. It runs with old heads on low enough compression to take low end pump gas (and putting in higher octane gas has no effect). It seems that there's nothing about this engine which would produce an unusual ammount of heat that the stock setup shouldn't be able to take. If it matters any there are headers rather than the stock manifolds although I don't know what type.

Anyone?

You know you can pull the radiator and super flush it with a garden hose once you safely dispose of all the coolant; that won't really tell you exactly what you are asking but it'll probably help you sleep easy.

just wait for it to warm up, and actally feel the radiator. If the bottom is colder then the top, its clogged. What we use at the shop to un-clog heater cores, is wheel acid/cleaner. Toss some in there, let it sit for a hour, then flush it out.

Captain obvious here: Can you see any crusty calcium build-up when you look in through the cap? Even a little coupled with your mods and current problems would warrant re-coring or replacement.

I don't see any calcium buildup and I did flush the radiator over the summer. What I was wondering is if half of it could clog? That would still allow it to flow and partly cool but it just wouldn't work as well.
86camaro383- Do you know what kind of acid wheel acid is? I can probably get it from the chem lab where I go to school.

HI, TOP RAD MAN HERE. IF YOU HAVE MORE THAN 80,000 MILES ON THAT RADIATOR IT IS PROBABLY NEEDING RODDED OUT BASED ON THE AGE. ALUMINUM RADIATORS DO NOT NECESSARILY SHOW CALCIUM BUILD UP ON THE TUBE ENDS LIKE THE OLD COPPER/BRASS ONES DID. COPPER/BRASS RADIATORS BUILT UP DEPOSITS ON THE TUBE ENDS YOU COULD SEE BECAUSE OF THE DISSIMILAR METALS IN CONTACT WITH EACH OTHER WHERE THE TUBES GO THROUGH THE HEADER PLATE THAT THE TANK SITS ONTO. EACH BRASS TUBE HAS A RIBBON OF SOLDER AROUND IT THAT WOULD BE LEAD/TIN. THE ALUMINUM RADIATOR IS VACUBRAZED AND THUS IS ALL AN ALLOY OF THE SAME METAL. I SUGGEST YOU EITHER TAKE IT TO A REPUTABLE SHOP IF YOU CAN FIND ONE AND HAVE IT RODDED OUT. THEY WILL PROBABLY WANT TO SELL YOU NEW TANKS WHILE IT IS APART. THE FILL TANK SHOULD RUN NO MORE THAN $32.00 TOPS AND THE INLET ABOUT $28.00. LABOR SHOULDN'T BE MORE THAN $65.00. THIS IS A TOTAL OF $125.00. A NEW REPLACEMENT WILL RUN YOU ABOUT $140.00 SO YOU HAVE TO DECIDE. REMEMBER HOWEVER THAT ALL RADIATORS ARE NOT CREATED EQUAL SO YOU MAY WANT TO KEEP THE QUALITY OF YOU ORIGINAL CORE IN PLACE IF THE REPLACEMENT APPEARS NARROWER THAN THE OEM. IF, HOWEVER YOUR PLASTIC TANKS (ACTUALLY NYLON) ARE IN GOOD SHAPE THOUGH, YOU WILL ONLY HAVE THE LABOR AND GASKETS TO WORRY ABOUT AND THAT WOULD BE AROUND $77.50 TOTAL JOB. THE BIGGEST HURDLE WILL BE FINDING A RADIATOR SHOP THATS WORTH A DARN! THERE AREN'T ALOT OF THEM. IF THEY DON'T STOCK THE TANKS AND GASKETS CHECK ELSEWHERE. THEY ARE NOT A VERY AGGRESSIVE SHOP.(HAVE BEEN IN THE RADIATOR BUSINESS SINCE 1981) GOOD LUCK....TOPRADMAN