mhood

I was showing my 72 vert with a 350 4barrel to a few guys last week. I've only had the car for a month or so and have been focused on the tranny leaks and front end issues. We all noticed that the air cleaner cover was on upside down (by previous owner).
Me and another guy remember doing this with our other GM cars 'back in the day'. Two other guys said its wrong and I should put it on right side up.
Car runs great and sounds great although its only getting 10 mpg.

citcapp

Put it on the correct way. Upside down it just letting hot air into the carb. You'll get better performance with it installed correctly

Lady72nRob71

Guys used to do that "to increase performance" by allowing more air into the carb, if the stock snorkel opening is the size of a golf ball (kinda like mine!)
As a bonus, you also get to hear the 4 barrel howl when you stomp it - music to my ears...

The down side, is that the engine will be ingesting lots of hot air - not a good thing. Of course my stock snorkel is pulling in from the hot engine bay anyway, so not sure which is better.

66ninetyeightls

Yeah lets get realistic. Unless you are talking about a high end model that has outside air ducted to the air cleaner housing every single factory air cleaner is sucking in hot engine bay air just through a smaller opening.

That's just an economical way of having an open air cleaner without spending money on an aftermarket unit.

joe_padavano

The reality is that there is virtually no difference in measurable performance. It SOUNDS louder, so the "butt dyno" says it's faster. Unfortunately, the butt dyno is rarely calibrated correctly.

Oldsguy

That's funny............butt dyno. I like it.

Boldsmobile

Id agree with Joe but also would add i dont understand why it takes in hotter air from the top as opposed to cooler air through the snorkel. Pat am i missing something?

cutlassjoe

We used to do that in high school. My mom had a 77' Newport with a 400 lean burn engine. It sounded cool, but that's about all it did....Thanks for triggering the memories.

joe_padavano

Not sure what your question is, exactly. The underhood temp is about the same at both locations. If the car is newer and has an outside air hose attached to the snorkel, then the question becomes one of which flow path is more restrictive. The inverted top will let in much hot air than cold air that could be drawn from the snorkel.

mmurphy77

Putting a taller Air Filter element will achieve the same affect without having to flip the lid provided the wing nut stud is long enough. I agree with others, though. Quadrajet 'howl' and a little more air in is pretty much the only changes it makes resulting in no performance gains.

442much

Yeah, the older I get, the faster I was. Must have measured the quickness via the "butt dyno" back then. If you lost, it felt more like the "butt gyno".

Boldsmobile

Joe, post above me from citcapp mentioned put it the correct way because he was letting hot air in. That implied putting it the right way would let cooler air in. I was curious where that cooler air was coming from.

I assume the inlet air temp was ~the same at both locations. Unless it had 68 like hose leading to snorkel. Thats why i was wondering why putting it the right way would let cooler air in, if its just a regular old snorkel.

stevengerard

in all reality for most of us it doesn't matter a bit - what would it affect 1 - 2 hp either way on the street? I on the other hand remember doing that to all my cars, the sound alone was worth it - if I didn't have OAI, I'd do it to my 442 all over again

OLD SKL 69

Probably only getting 10 mpg because your enjoying that "muscle car sound" every time you step on it!

z11375ss

I loved that as a kid. 69 Chevelle small block. Mom's car. Turn the corner and flip the lid. WAAAAAAAAA!!!!!! F'in A! Leave it if you like it, what's the diff?

442much

I remember doing that to my dad's 1968 Pontiac Grande Parisienne (Bonneville in the US). That 327 sounded pretty cool.

WhatIf

But I am reminded of this bizarre 1968 H/O road test where Doc Watson had the air cleaner lid flipped! I think the conclusion we had on this when we talked about it before was Doc flipped the lid to make it sound better for the cameras.

http://www.youtube.com/watch?v=NpmxaamNwhw

Lady72nRob71

About 15 years ago I bought a flat lid from a yard to put on my 86. The four barrel howled so loud that it vibrated something back towards the trunk.
It made bystanders look for sure!
Butt dyno said 50HP gain, but in reality, it was still the same ol' 307...

Lady now wears that lid as I try to figure out how to make her 4bbl open ALL the way...

mhood

Thanks for all the advice. I guess my take is that it doesn't really matter. I'm torn between how much I like the sound and the fact I would like to clean up the cover and put a Rocket 350 decal on. Maybe the decal will work with the lid upside down.
I do have a lead foot so that may account for the mileage

Lady72nRob71

Just find ya a flatter or smaller dia lid at a yard that the decal will fit on - thats what I did.

BlackGold

As was suggested. simply use a taller air filter element (paper, K&N, whatever) and keep the lid right-side-up so you can see the decal. The added benefit is that with the lid the right way, you're using its contours the way the engineers intended, probably creating less turbulence at the throat of the carb.

erke88

I have a 71 cutlass supreme with a 350 4bbl. It also gets around 10 miles to the gallon. Glad im not alone

young olds

i looked at this thread twice before i had an idea i had to try. i had an open element air cleaner top laying around all i needed was a longer wing nut stud, so i got one. i dont care for the look of an open element air cleaner but i think this looks pretty cool.

71 Cutlass

I thought the more air and fuel the motor got, the more horsepower it could make...we've all known this to be true since day one. I'm not following the "Less" air is better logic. Many in the hotrodding industry refer to engines as "Giant air pumps", meaning that more air and fuel means better performance. The "Howl" that is heard from the upside down lid is more air getting into the motor...somehow this is bad????????? Someone explain what has suddenly changed regarding the way a motor functions best. Cannot believe posts saying less air and fuel is better for more power. I have a full 360 degree open element on my car, plus the X-treme air filter lid. This is hurting my horsepower ...couldn't be.

Lady72nRob71

With the size of this snorkel opening, i figure any additional openings would help...

71 Cutlass

exactly !!!

tonycpe

how big is the intake port in the head for each cylinder?
your motor only fires one cylinder at a time.

71 Cutlass

Give the gentleman a cigar.

66ninetyeightls

Yes but that is purely ignition. On an 8 cylinder engine there is more than one cylinder at different stages of the intake stroke at any given time.

Bluevista

The engine can only pull in so much air, air is still air no matter how it gets there, air temperature is more of a factor.
The GM engineers wore out a lot of slide rules figuring out how big that snorkel opening had to be.
That four barrel air cleaner opening is huge compared to my two barrel.

66ninetyeightls

Very valid points Blue. lol

Lady72nRob71

You're kidding, right?

71 Cutlass

That was just to get it down the road and to be reliable, not to give the motor the most outstanding performance gains possible.

69oldsguy

The deciding factor is your carb. If you have a factory Q-jet, 650cfm is probably the max air it can move. Unless your snorkel will not move the same you will never get more air than that. The upside down air cleaner lid has been debated/argued since the first person did it who knows when. Bottom line is, as Joe said, you will only see the hp gains on the coveted butt dyno. The increase in sound that you hear is not more air but simply less obstruction to the sound. Put your ear next to the snorkel and have someone snap open your 4bbl.
With that said, I'm all for the sonically tuned butt dyno. Throaty carbs = morning wood any time of the day.

BlackGold

You can't talk volume of flow without also talking about pressure drop. The carb does not restrict the flow to any particular number. If I remember corectly, the industry standard is to rate 4-bbl carbs at 1.5" Hg of pressure drop and 2-bbl carbs at 3" Hg pressure drop.

The Quadrajet, as installed on big-block Olds, is typically rated at 750 cfm. If that is indeed at 1.5" of pressure drop, then if the throat of your air cleaner nozzle has the same area as the Q-jet's throttle bores (sounds like a good approximation to me), you now have 3" of pressure drop. Add in another inch or two for the air filter element, and we're now looking at an intake manifold vacuum of 4 - 5" at wide-open throttle (but only when really flowing 750 cfm, which would only happen at really high RPM).

Anyway, the point I'm trying to make is that the throat of the nozzle is probably about the same amount of restriction as the carb, and the air filter, which is not insignificant. Will you gain lots of HP by flipping the lid? Doubtful. But it probably nets you a couple HP (provided the rest of your combination isn't really restricted somewhere, like in the exhaust).

71 Cutlass

Utterly and completely incorrect. The sound is more air coming in. My 360 degree filter was at one time old and dirty (and paper). I changed it with a K&N filter. The first time I floored it, the sound of the improved AIR FLOW was enormous. Same exact set up, but the new filter allowed more air to ROAR into the carb.

JimMorrisonFan67

Hi,
My hubby and I have searched the web looking for a replacement air filter cover for our 72 cutlass 350. I've searched this forum and we haven't found what we are looking for. I figured this was a good place to post this.
Can anyone give us suggestions on where to look. We have already looked at YearOne, The Parts Place, Original Parts group. The closest on Original Parts group still doesn't look OEM to us. Our current cover is too pitted and rusted to keep. Your advice is appreciated.

Lady72nRob71

Put out a post in the "parts wanted" section that you seek an air cleaner lid for a 72 350. Also specify if 2 or 4bbl.
You should be able to find a good used one and just clean and repaint it. After then it will look as stock as can be!

starfire

OK, so my 1987 442 with the monsterous 307 4bbl has an air cleaner with two snorkles, one that is just open to the engine compartment and one that extends with a hose to the battery area.

What is the engineering idea with that? Why not have just the "cold" air intake, why the hot air on the other side? My '68 has half the air intake my '87 has.

Highwayman

For all these years I thought GM engineered the snorkel to keep the car quite so respectable folks could listen to the radio and hear themselves think. Then they put open element filters on the performance cars for the rest of us.