Greetings from Downunder,
I'm looking at purchasing hood insulation (for my '74 coupe L-82 350)from feebay.
http://cgi.ebay.com/ebaymotors/ws/eB...3AIT&viewitem=

The description says
"NEW reproduction under Hood Insulation for 68-75 Chevrolet Vette models with Cowl Induction".

Dumb question time,
What is Cowl Induction???
Is it the air intake at the rear of the hood????

Also has anyone bought one of these ??
If so how do they look ???
MANY THANX for your time and patience.

GAV

 

Yes, it is the air entry system at the rear of the hood. The "cowl" is the area where the windshield wipers reside. Sorry, I don't know about the insulation quality.

 

Not sure if you're looking for the short answer or its history. The air cleaner assembly consisted of a base and a top using an A348C air filter. A single snorkel extends from the base toward the front on the driver’s side for smallblocks while the snorkel for big blocks flips to the passenger’s side. The basic notion of forcing cold air into a carburetor was used to improve performance compromised by fuel economy requirements and emission standards.

Cold Air Induction was introduced in 1967 with the L88 and saw service through 1969 with both the L88 and ZL1. Briefly retired from 1970-72, cold air induction was resurrected in 1973 to improve performance while emission control and fuel economy measures had begun to glut those measures used in the past to boost performance. Once introduced in 1973, cold air induction would find its way into all future air intake applications, eventually modulated by Mass Air Flow.

In 1973, the air intake used a new design for cold air induction but without the obvious indication (hood bulge) of what lie under the hood as in 1968-69. As a result, the “carb-air induction” required a new hood, featuring a functional grille centered at the base of the windshield. Inside, the air cleaner used a round rubber seal, which fits into a flange that surrounds the dual snorkel air cleaner assembly. Once the hood is closed, it mates to the hood creating a seal that draws cold air in through the grille at the back of the hood. Upon hard acceleration, a vacuum operated solenoid opens a flap that covers the hood grille from the underside, drawing cold air from cowl area. When the vent opens, the rush of forced air sends an adrenaline message to occupants to hang on, especially for LS4 passengers.

 

He says it will fit 68-75 hoods and even the 4dr corvette

If I were you go to one of the vendors and purchase from them. Docrebuild, Ecklers, etc. Its only about $10 more. They specifically state 73-75 not a large range like the one you mention.

I suspect you would be disappointed with the ebay one. He does not state size, thickness, etc.
Like a glove where the seller says "fits all". Sometimes they dont.

 

Now that's good for a laugh Tom

Shows that horribly inaccurate marketing hyperbole was alive and well- even back then.

 

I would suggest that you get the proper insulator mat for 1973-75. They vary in quality and fit. I opted for the more expensive molded/contoured version. Others are not molded and basically do not hang very nicely.

 

Thanks everyone,
I'll do some more searching(Does it ever END ???)
and see what I can come up with. I will keep ypu informed of my findings.
Thanx again

GAV

 

Take a look here:
http://www.corvetteforum.net/c3/vette73/cowlintake.htm

 

Paul, can you save me many hours of searching, tell me where you got that insulator in a PM?
I have made my own air box, and yours looks like it would fit my 69 hood perfectly. TIA, Tank

 

PM sent this morning.

 

I actually wrote that for a chapter that has yet to be published! Good stuff huh?

 

I'm not sure what that means. I removed the WOT valve but believe me that cowl vent sucks cold air even at idle. You can hear it.

 

bout how long did that take to remove that valve? my throttle dosent reach the kick down so mine is always closed, is it just unbolt and done?

Miles

 

About five minutes. Just tuck away the wiring for the solenoid neatly in case you want to use it again. The parts are hard to find so do not discard.

 

Let me take my foot out my mouth. :o

In all seriousness Tom, there are some incorrect/inaccurate statements in the text.

PM sent

 

Upon hard acceleration, a vacuum operated solenoid opens a flap that covers the hood grille from the underside, drawing cold air from cowl area.

I have a '73 with this cowl induction hood. Can anyone show a pic of where this vacuum operated solenoid is? I see nothing that operates anyting on my car. Also on the forward driver's side of the hood is a hole about 3/4" dia that has a hole plug in it. Is this a drain hole? Why is it plugged?

Also to Paul67. I purchased the hood blanket and received it yesterday along with a retainer kit. The retainers get glued to the inside of the hood. If you glued your retainers to the hood what adhesive did you use? The adhesive has to withstand the temperatures of the engine compartment.

 

There isn't one. It's electrically operated. That's part of the note I sent to Tom. It should be at the rear of the duct under a black plastic cover.

 

My 1974 still had the retainers from the factory and they were in very good condition so I just re-used them. Here is the old, ratty insulator.

On the adhesive, surely some product line like BullDog would have what you need. But I will check the AIM later today. Sometimes it specifies fasteners/adhesives/etc.

 

Here is the electrical solenoid, flapper, and associated rubber gasket/sealer.

 

Thanks for the response Paul. I'll check into that Bulldog thing. Somehow I don't think I have an operating cowl vent. I don't see any wires going from the carb, throttle cable or anywhere else that snakes over to the hood. If it's electrically operated or vacuum operated there must be a wire/hose to the hood somewhere. I wonder if water intrusion is an issue if the flap is missing and it's open all the time. That's why I'm wondering if the hole in the underside of the hood at the front driver side with a plug in it is a drain.