Hi all,

I've got a lot of stuff going on with my '69 4-speed convertible currently, and here's yet another thing that I'm starting to think about in preparation for re-paint later this year. That said....

Last year, I purchased a period-correct big block hood for my '69 to replace the OEM hood. Although I like the stock hoods that come with the base and L46 cars, I think the '427' hood on the 68-69 (non-L88) big block cars look beefy and bad@ss. Plus, I need the extra clearance for the Eddy RPM Air Gap that I'll be using on my 383 stroker I'm building (I do have the original engine that the car was born with, but storing that away).

I already knew this going into it, but the air inlets (or more accurately, air 'outlets' or vents) on the non-L88 BB hoods are non-functional. Has anyone here actually cut holes out and made them functional, and if so, does it make any difference in controlling engine bay heat and engine cooling, in general? Frankly, I never quite understood why Chevrolet made a hood with non-functional vents. It looks cool, but when you look into the air vents and can't see through to the engine bay, it seems kind of lame.

It's obvious that Chevrolet wanted them to look like air vents, but if they're not functional, and only cosmetic, then why have them there in the first place? That's just cheesy. I have few complaints about these early C3s, but that is one of them.

I love the design of the hood, but don't like the fact that these things a fake, as I believe everything should have a functional purpose (not talking about obvious cosmetic pieces that are designed only for aesthetics - chrome trim - bumpers, hood/fender emblems,etc etc).

I'd love to hear thoughts from early chrome bumper C3 Corvette owners who have done this, and what parts you used. Also, include pics please!

I thought I once saw a similar thread on this topic months back, but cannot seem to find it now....

 

keep in mind you may not be able to use the factory big block hood with the rpm air gap. you may want to consider going directly to an L88 style hood for the needed clearance

*****

 

Understood. I anticipated that and bought a 2" drop base that works with the electric choke on the Eddy AVS2 carb I'll be using, along with a slimmer 2" air filter (instead of the 3"). It'll be close, but it should fit nicely. Besides, the L88 hood is a bit too radical for me. I prefer the more subtle 'hump' of the factory (non-L88) BB hood.

 

You'd need to fashion something to direct water from flowing onto the forward half of the engine. The hood provides air cleaner clearance for the big blocks and LT-1s; that Chevrolet put fake vents there is par for the course since they'd been doing it since the '56 Corvette.

 

Or how about fabricating plugs to cover the openings when washing the car? When this 'vette is done, it's likely never again going to see another drop of water that doesn't come out of a hose.

If I do this, I'd plan to put in automotive-grade screen mesh to cover the openings, and I guess at that point, I could just use (and re-use) a couple of plastic grocery bags to cover the openings with the screen backing to prevent them from falling through.

 

My 2017 Camaro SS has functional hood vents that dump water right behind the radiator, so nothing really gets on the motor, in the rain (gasp!) or while washing. And I've had it in some monsoons.
Maybe you could fashion a simple channel out of aluminum to bring any water forward so it dumps in front of the motor?

 

Non functional vents, scoops, etc, have been a standard feature of automobile styling since at least 1948, when Buick added their famous "port holes" to the Roadmaster's front fenders.

I don't know that opening the big block's hood "vents" would offer much, if any improvement in cooling. First off, the openings wouldn't be very big, at most you might have two 1"x3" openings? It's also possible that like a Camaro cowl induction hood, or a Trans Am rear facing shaker scoop, the areo effect caused by the vents being sunken and rearward facing may actually cause air to be drawn in to the engine compartment, instead of scavenging air out?

It's easy to say a car will never be driven in the rain, but unless you never take it out of the garage, there's always to chance of getting caught in a shower. The Corvette's distributor, and most of it's other electrical components are located in the rear of the engine compartment, so water dropping into the engine compartment that far up shouldn't be a major issue. Though the fan would likely cause rain water to be blown around the engine compartment.

If you wanted to open those vents to aid in cooling, I think I would fabricate some kind of under hood duct work that started near the fan, and ended at the vents, forcing air to exit through the vents.

 

I love this idea! There must be someone on the forum who has done something like this. Why re-invent the wheel if this has been designed. It's a splendid concept.

 

C'mon. Someone on the forum must have done something like this already...

 

The hood vents would be in front of the engine and would let the radiator heat out but not he exhaust manifold heat out. There are plenty of pics of vents from the newer camaros grafted onto the hood to vent it. I got some 396 vents from a 66 to vent my header heat, and they work but I wanted the big 69 camaro vents to vent a lot of heat but there isnt enough room to fit them on the sides. Im still using the cold air intake so it wouldnt work in the center.

for engine cooling we all know turning on the heater can vent enough heat to help cool an overheating engine. I wanted to add to small radiators with fans forcing the air though them and out he side vents. I thinmk it would cool event he hottest motors. A lot of the super cars run multiple radiators to do this

 

That's a detail on your car I hadn't noticed before... nice and clean installation!

 

Thanks.
No one has brought them up at any of the shows ive been too. Just small enough to go unnoticed

 

I have always wanted to try and force the air out through the vents on the lower section of the fenders behind the wheels. I refer to them as "Gill vents" and if you forced more of the air flowing through the engine compartment out through the vents it might help the engine stay cooler. On my 1968 they are wide open and with a small box you could move the air out of them versus forcing the Hot air to go under the vehicle.

I toyed with the idea of putting an oil cooler in front of the gill vents inside the engine bay and using a fan to push the air out when the oil warms up. The gill vents are not used very much but do help air flow inside the engine compartment.

 

I run a RPM Air gap with my factory SB 70 hood with the stock drop base air cleaner and a three inch filter. It's extremely tight but it fits. He should be fine with a BB hood.

 

I'm trying to do everything possible to draw out as much of the heat trapped under the hood.
Several years ago, I drove home from a car show, was stuck in bumper-to-bumper traffic for close to two hours when the outside temp was 112 degrees.
When I finally made it home, I opened the hood and found everything under the hood was too hot to even touch.
Some of the things I'm in the process of doing is, removing everything blocking the movement of air flow around the side gill fender vents.
The charcoal canister, and the wiper washer tank have been removed from the driver's side.
The oem ac will be replaced with a Viintage Air system which will open the passenger side vent.
I'm going with an DeWitts radiator and dual spal fan set up which removes the lower portion of the oem fan shroud allowing additional air to be forced up from behind the radiator.
I am also installing an oem chin spoiler extension to help.
My oem 73 hood has been replaced with a tall L88 hood for the additional clearance needed for my 496, intake, spacer and carb set up.
The top of the hood will be opened up and I'm adding a hood vent that will draw in ambient air at speed and allow heat to vent out at slow speed and when stopped in traffic or parked.
I'm also leaving the rear of the hood open which will draw in ambient air and allow heat to escape.
This is not a picture of my car, but a picture of the vent I'm installing.

 

OldCarBum,
That vent seems like it was made just for that spot. What is it from?

Rick

 

It’s specifically made for C3 Corvettes.
It’s a really stout yet ultra lightweight piece.
Give them a call, they are great to work with.

 

downside is that during torrential downpours, the rain water drains onto the alternator belt, alternator stops charging, windshield wipers flapping, defroster blowing, etc. never bothered to make a rain shield. or rain drain catchment diverter do-hickey, just do a better job of checking the weather report. heat is definitely coming out of those vents. 540 big block. you'll burn yourself touching the vents after driving. if I had to do it over, I would've integrated the functional vent style with the hood faux vent style better, swoopier. I was desperately just trying to vent under-hood heat.

ETA: video is a boring errand run, no banzai burnouts, no engine revs, nothing, just driving to the post office on the freeway. nothing exciting, boring all the way to the end. so don't waste 10 minutes of your life watching it to the end.

 

Wow. How did you shape the screen on the backside? That looks REALLY clean -looks like something you would buy from a vendor that was already formed.

 

how did I shape the screen? can't remember, 10yrs ago, but nothing sophisticated, stone-age tech, probably just the odd piece of wood, the big 8" jawed vise, and a honkin' rubber mallet. IIRC, the oval pieces started off as 5" SS exhaust tubing.