jim2527

Went to the Carlisle events event in Lakeland, FL today. About half the C3's were missing most of the seals around the radiator.

Seriously, across the top of the radiator surround was nothing but a big gap. It was easy to tell a lot of cars were over heating because they had aluminum radiators with dual electric fans...yet no seals.

Basic physics...air will take the path of least resistance....that big opening at the top is that path.

Seal it up people.

Bigdade

Do you have any photos of what it should look like? I think mine is missing some.But the car never heats up to much.

jb78L-82

Yes, the seals are important for maximum cooling but I have to tell you with my rebuilt L-82 355 (2014) with 425+ Gross HP using the same Dewitts aluminum radiator, 180 degree thermostat, and Stewart aluminum stage 2 water pump with the OEM stock mechanical fan that I had on the OEM L-82 for years before the rebuild WITH OEM RADIATOR SEALS FROM Oct 1977 build date, my engine NEVER goes above 180 degrees no matter what the outside temperature, idling all day long, moving slow in traffic, or high speed cruising....NEVER and the seals are marginal at best. The seals are vital to stock cooling system cars since the systems back then were marginal, being kind.....A quality aluminum radiator, high flow water pump, a FAN SHROUD with a mechanical fan, and a high flow thermostat have proven MUCH more valuable to me over the last 40 years to my 78 than the seals around the radiator...just my 35 years+ experience with my C3.

DUB

That is one of the things I look at when I get a new Corvette of that era in my shop. I ask the customer if it is getting hot and sometimes I get a yes and sometimes I get a no.

And on those that I get a no...I bet you know that they normally do not want to put any money into something that is not gong to help. Even though they are supposed to be there.

So I just shrug my shoulders and move on.

DUB

woodlawnmill

You are so right! My '72 LS-5 is STILL plagued with overheating problems. It was a loaded L-48 but converted to LS-5 ('73 rebuilt Corvette motor) Everything is 100% Corvette GM . New BB radiator,core support,fan shrouds,seals, fan blade,expansion tank (correct BB auto A/C ) removed license plate holder hoping for better air flow. Still runs hot. Going to re-curve the distributor and re set timing this spring. I did own an original '70 LS-5 auto no PS or PB manual windows NO a/c Astro Ventilation was WAY better the '70 never ran hot. On BB's EVERYTHING has to be right and even then they can overheat. hope this helps

SW

jim2527

The 'corvette forum club' was there, no joke, so I didn't want to inadvertently call anyone out.

What I did was turn out the lights in my garage and then place a flashlight in front of radiator. If you can see any light from the engine side odds are your missing seals.

Wrecked82

My 82 had an aluminum radiator replacement last year. No seals on top or sides. Only engine driven fan. Never goes over 195* in Houston heat in traffic.

cv67

Car guys are cheap, F em
How many times do we see a thread about the "cheapest way to" ??? These arent newbs they know better.
This hobby costs money wanna play you pay now or pay later. Go spend 15 at home depot to keep that engine alive I have no pity for pound foolish its common sense. Anyone who has owned one of these knows.

How many of you guys know of someone wiht a "big dyno sheet" but too cheap to buy a real driveshaft and tires..I know a lot of em.

lvmyvt76

don't forget the front spoilers, they help the shark to bottom feed

jb78L-82

YES! AND with a mechanical fan, air and full fan shroud is always being pulled through the radiator (not around the radiator, making the seals less important for an engine with a mechanical fan since the path of least resistance is THROUGH the radiator, not around it). If you have an automatic the stock mechanical fan setup is also ideal for running an automatic transmission cooler since it always is pulling air over through the trans fluid cooler as well...........

My 78 C3 with the chin spoiler PLUS the GM Spoiler extension from the 79 C3's with Heavy duty cooling (which also included an electric fan from the factory, which I do not have on my 78, in front of the radiator deep in the fan shroud). GM knew the factory stock base engine cooling was marginal.




This ^^^^^^^^^^^^^is how I cool my 355 L-82 and did cool my stock 78 L-82 4 speed. Neither engine ever got or goes above 180 degrees whether idling in traffic or at speed.....NEVER! and the radiator seals are original doing very little...............I am not a big fan of electric fans for various reasons on a C3 that kick on once the temperature is elevated. I prefer to keep the air constantly moving through the radiator and letting the thermostat control a constant 180/195 temp............despite the HP loss with the mechanical fan.

Bills17n72

resdoggie

I don't have seals. I have a 450+HP, 355" with a stock recored rad and original clutch fan. I don't overheat and temp stays around 195-200* on an 85* day (hot in my neck of the woods). Imo, overheating is caused by an incorrectly sized rad, all else working properly. Seals can help in certain situations but it is not the sole problem for overheating. Also, seals or not, the air will flow through the path of least resistance which will be through the radiator i.e. the low pressure area created by the fan behind the radiator, at least at lower speeds.

gavino

The spoiler and the foam seals are all very important.The 68 radiator was put on a steeper angle because of the length of the nose. As such without seals it was difficult to get air to flow into the radiator Also on 68s at least, there are two rubber flaps that open up at higher speeds to let in more air. If they are hard and not opening up completely that could be a problem.I think I read that some dealers would cut out some fiberglass to get more air to flow through. I have a 68 L71 and it never overheats. Remember the BB engine was supposed to run hot. Is the heat sending unit and temp gauge correctly reporting temps. Also on 68 BB there was no expansion tank so the radiator fill line was two inches below the top of the radiator. This served as the expansion tank. Also, don't forget that stock timing was done for hydrocarbon emissions not engine timing. I have a seven blade fan instead of the five blade as a modification. For 69 Chevy increased radiator size, installed an expansion tank and straightened up the radiator a bit by shortening the nose a little. Without all the seals in place your chance for success drops off dramatically.

jb78L-82

This explanation is correct^^^^^^^^^^^^^^.

As I stated previously, a modern aluminum 2/4 core radiator, a high flow thermostat, high volume stewart stage 2 water pump, chin spoiler (and extension even better!), seven blade+ mechanical GM fan, and lastly decent seals, I have never seen any SBC or BBC C2/C3 had any heat related issues as outlined....NONE...Any year as well....

69427

Good idea to get the timing a bit more optimized than what the original factory specs are.

Between bumping up the timing curve and a DeWitts radiator, my BB almost refuses to overheat. I run a 195* thermostat, have both the front side grills blocked off, and the center grill about 80% blocked (I do a lot of track days, and I'm trying to keep the engine bay and undercar airflow to a minimum. I've got a pace car front spoiler to help with the airflow, but I've also got the bottom openings half blocked off. It all works great even on hot days.

Decent timing and a decent radiator.

CrossedUp

... and don't forget the seal that goes between the lower valance and the bottom of the core support.

SteveG75

The spoiler extension is key. Added that to my '75 with 496 BBC and definitely helps keep it cool at speed. Dual Spals work for me at slow speeds.

MelWff

You need to tell people what year or add it to your profile in order to get exact information.

Bigdade

I can’t figure out what I’m looking at for the life of me.

C3 4ME

I factory repro pace car spoiler made all the difference in how cool my 79 runs. It runs 20 degrees cooler than ever after I installed it last spring.