507OLDS

When I installed the hood on my 72,I removed the 2" rubber stopper,on the top of the cowl,and it fit real well,but I felt that it was needing more clearance,so I removed the upper cowl seal,that runs along the top of the cowl.It fits like a glove on my car.You also need to realize that this car does not sit outside,or get driven in the rain,and when I wash it,I know not to deliberately shoot the hose down the back of the hood.I'm not sure if it would matter or not,but I do not get any water under the hood.If there is any gap,or room for air,it can help get the underhood heat out.I did NOT do any grinding to the hood.

HWYSTR455

Yeah, this car will see weather, rain, hopefully not snow, but could happen. Plus without the OAI air filter setup, water is just going to shoot down the scoops. Don't think it's really going to booger anything up, other than maybe just puddle on the intake, maybe make water marks. Might get some moisture in the distributor cap, but limited.

Here's a couple shots of the hood again, one where the body shop did the screen, one where I made a plate for the retaining the washer hoses. You can see the rear underside of the hood, and where the washer hose routes.

I removed the rear center hood bumper, but didn't make a diff, so will probably put it back...

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Allan R

So the screening is just held on by some globs of glue?
Even if you were in downpour or light rain I don't think that's going to affect your fuel mixture. I'm sure that Olds anticipated that with this hood. A little added moisture to the combustion chambers might actuall help burn off some of the carbon deposits on the piston and valves.

HWYSTR455

Yes, the screen is held on by gobs of what I believe the body guy said is 'Marine Tech', but would have to double check that. Believe that's what he said is 'common practice' with these hoods.

Anyone know how the factory ones are held in place? Curious.

As for water in the mixture, yes, some is actually beneficial, and there are still companies that make water injection systems. Many add methenol, and it helps combat detonation, as well as clean carbon deposits in the combustion chamber.

Thing is though, with the OAI filter setup, there's only so much air it can injest, and the scoops at speed actually are a higher pressure area than if it doesn't have the OAI air cleaner setup. In an extreme case, it can actually lift the hood and cause stress fractures, especially around the hinges and latch. Honestly, it would be better if I block it off entirely if I don't use an OAI cleaner setup.

I'll make a determination as to what I'm going to do once the car is closer to being done. I'm leaning towards installing an OAI cleaner setup though. Just seems the right thing to do!

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Allan R

Yes, the factory hoods were metal lined so the mesh was held in place with tac welds

Really good info to absorb. Hadn't thought of that at all. The unit that sits on the air intake is currently running about 429 at Thorntons. Too late I found out they had a Christmas sale on them for 329.00 complete. So as a temporary 'redneck fix', have you thought about cutting some very porous foam, paint black and cut to fit back in the opening of the ram tunnels? That would allow some air flow, but not enough to create the lift you were describing. And it would keep bugs out of the scoops too. Maybe that's a dumb idea, but it just might work till you have a permanent solution.

HWYSTR455

Dang! $329 is a great price! Bummer I missed that! Oh well, I budgeted for the full price, so will just have to bite the bullet.

Yeah, I thought about it all, blocking it, etc, and it boils down to knowing I'll have to eventually do it 'right' anyway, so I figured why bother.

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boondocker

Could you enlighten me? ...how does the OAI breather assembly work, how does it keep out the elements? I was going to leave the FC hood raw without any stock paraphernal.

HWYSTR455

Well, the factory one doesn't reall keep the elements out completely, some water still ends up in the rear of the lower filter housing, and a drain goes out the back. The air filter keeps out debris from the engine, but it's still going to suck some water.

The top of the factory air cleaner opens by a soleniod, activated by vacuum switch. A big foam seal goes around the parimeter of the housing to seal against the hood when it's closed. (a pic says a thousand words).

Picture holding a glass in your hand and holding it out a window of a car doing 60, with the open end facing forward. Now turn the glass around.

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Allan R

Well HWYSTR455 said most of it. When the car is running at normal speeds it has vacuum right? When you tromp on the gas, what happens to vacuum? it goes way down... That's the principle of how the OAI works. Under normal conditions you get air coming in the snorkel like any other car (although the snorkel for the OAI cars was just a little bigger). The flapper that sits on top of the air cleaner stays closed and, as mentioned, doesn't draw air into the carb because of the foam seal around the hood intake/flapper block.

Now you pound the gas. So gas is now pouring through all 4 venturies of the carb. the solenoid that was referred to is mostly a vacuum switch. With the sudden drop in vacuum, the flapper is allowed to open and the engine gets 1.) normal air from the snorkel and 2.) air that is being rammed down the twin tunnels of the hood. The density of the air/fuel increases and you have that sudden increase in torque and power.

Here's a link that shows the assembly. You can see how it slopes to the front to drain moisture that comes in though the hood tunnels. It's what an OAI hood needs to function right. http://gawain.membrane.com/~thornton/images/OAIassy.jpg

GINCSC

I hate to dig up old treads But what springs did you end up using on the FC hood?

HWYSTR455

I use the OE springs, you just have to kind of push back at the same time as down when you're closing it, and you will be fine. After the springs break in some, it's a lot easier.

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Allan R

So now I have to ask, because I know why GINSC asked. Have you noticed any distortion in the hood using OE springs?

HWYSTR455

No, because once the hod goes down below a certain height, most of the tension is relieved off the hood. As I recall, the hood has reinforcements in the hinge area to prevent distortion, but would have to check to be for sure.

Here's a pic of how the hood lines up with the fender today, and keep in mind, this is a black car and sits outside just about year round.

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HWYSTR455

One final note on the FC hood, there was some out gassing after it was painted, and had to be touched up. Think I mentioned it on the build thread. But the body guy said that was somewhat common on hoods that don't sit for a while after manufacturing, and if he would have known it was made that recently, he would have had it under lights for a while before working on it. Might want to make that comment if you take it to a shop for painting.

I did work out the cowl lacing / weather strip. I used the foam one, and added one shim to the rear of the hood. Once the lacing/weather strip heat cycled a few times it relaxed, and the hood now rests where it should.

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Allan R

Lines up perfectly from front to back. How difficult was the rear cowl molding to get to fit?

HWYSTR455

The rear hood edge trim from what the body guy said was not a problem at all, I even warned him I had heard it was an issue, so he paid attention, and didn't run across any issues to even mention.

Yeah, it's been what, 3 years? So for what I do with the car the hood was a deal.

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Tony72Cutlass'S'

Hey Al,

Are you thinking of going with a fiberglass hood? I just cut and buffed the 'in-my-driveway' paintjob that i did 4 years ago and now am kind of itching for one, but dont want to pay the wild pricetag in CAD to get one up here..

Boy would it match that sweet bumper that i have waiting to go on the car

Allan R

Hey Tony,
The car looks really nice! No, I'm not going with an OAI hood. They're just waaay too much money for what it is, and you're right - to buy and ship to Canada from the US would put that hood close to $5K with it's related parts. Just not financially worth it, especially since it doesn't add that much value to the car.

Your Dad would be proud of what you've done to this car.

I see you're still on the hunt for those grill trim pieces around the hood? Check with Scott Winn (Oldspackrat), I'm sure he has some you could restore. BTW, 71 and 72 are not the same molding although they fit the same. The 72 has the raised lip around the edge, and the 71 had the raised portion in the middle.

Tony72Cutlass'S'

That's the problem! I had restored those old 4-4-2 grilles years ago and they came with 1971 grill surround mouldings. I have the trim pieces that go on the hood but they are for the 1972 year, so rather than have a mismatched set i just left them off for now until i find a nice set.