Carb Drop Base vs Air Cleaner Hgt

[63qcar]

I remember a while back a thread about flow characteristics of the various carb bases and air cleaner heights . That started me thinking , which is always dangerous , about what I have . Car is a Cobra replica with very little underhood clearance . Intake is an E`brock RPM with a Holley 4150 on a 482 FE engine . Max rpm is 6600 and hp was 670 . Currently running an L88 repo drop base and a 14" x 3" filter . Looking at the setup , it looks like the lower part ( about 1/3 ) of the air cleaner doesn`t see unobstructed air flow , however some of the other "high performance" carb filter bases really block off a lot more of the lower filter area . So , would I be better off reducing the base plate drop some and going to a shorter filter element so the air has a more unshrouded path on the bottom area of the filter or stay with what I have ?
Anyone done any dyno/flow tests on this ? I did read the thread about filters and air flow , but didn`t see where this was addressed .

[turbo2256b]

Might start by cutting off the carbs choke horn

[427dart]

That L88 air filter assembly was probably the best single 4 bbl. setup built plus it worked well in competition and I've used them over the years.
I'm surprised you can fit all that under the Cobra hood.
Have a friend with a similar Cobra but he is running a Ford Racing crate 460/550 HP engine and he doesn't have much filter room but he is running the single plane intake it came with. That thing tears your head off in 3rd gear!!
Just put a KN element on it and call it a day!

Little story on the above mentioned Cobra...the guy's brother wanted to buy it and he wanted me to tame it down for him by swapping the BG 850 carb for a smaller Holley 750 double pumper. Well I set it up for him and got it tuned in and if anything it made it stronger in the mid range and didn't seem to hurt it much at 6000 RPM!

[F-BIRD'88]

The very bottom of the filter may seem restricted but it is not blocked.
On some of the other drop bases it is essentually blocked there.
The GM L88 base has a good shape. x2 on the holley choke horn.

Nothing stopping you from adding a spacer between the base and the filter element and road test it.... But don't expect much there. You'll probabily find more in lid contour experimentation.

I trust you have intergrated your L88 style air cleaner base into some form of sealed Cold air induction or Ducted ram air setup. Fresh cooler dense high pressure air is best. Under hood air not so much.
The filter helps defuse air turbulence.

[PackardV8]

Back in the L-88 days, GM had the engineers and the cash to get it as right as could be done with the constraints of production requirements. I've never found a better drop base for an open element air filter.

I trust you have intergrated your L88 style air cleaner base into some form of sealed Cold air induction or Ducted ram air setup. Fresh cooler dense high pressure air is best.

The Studebaker Avanti has the same hood/carb interference as the Corvettes/Cobras. Thinking as you suggest and remembering Trans Am Camaros, I tried cutting through the firewall and into the HVAC air intake at the base of the windshield. Turns out, that's racing-only. Maybe if the driver is wearing a helmet and ear plugs, but the intake noise level coming right up through the defroster vents was absolutely impossible to tolerate on street/highway.

The best compromise turned out to be a early-'70s Eldorado air cleaner made with a snorkel and flex hose to pick up fresh air in front of the radiator core support. It's a huge diameter ugly thing, but has the requisite drop base, contains the intake roar and provides fresh air intake.

[63qcar]

Guys , thanks for the replies .
Turbo2256 , the choke horn was removed long ago . What I was also thinking about is adding a 1" super sucker spacer and reducing the element height , but without a dyno it`s seat of the pants only . However , to do that , I have to dump the L88 base and go with a 1" shorter element.
No room to run hoses for cold air , so looking at building a box that seals to the hood ..... but in all honesty , for what I think I may pick up ., it ain`t worth it. I can burn the tires in the first three gears already .... this is just a toy to play with and try things out on .
As far as clearance to hood .... I have about 5/8" between the lid and the hood , and yes , it touches on WOT .
May try an R2C element next just to see what happens .
Again, thanks

[MadBill]

. Thinking as you suggest and remembering Trans Am Camaros, I tried cutting through the firewall and into the HVAC air intake at the base of the windshield. Turns out, that's racing-only. Maybe if the driver is wearing a helmet and ear plugs, but the intake noise level coming right up through the defroster vents was absolutely impossible to tolerate on street/highway....

I hear you Packard! In 1971 I adapted a '69 Camaro cross-ram system to my '70-1/2 Z28 and connected the fabricated aircleaner box to the HVAC plenum. At full throttle, especially at lower RPM, it sounded like a drowning rhinoceros!

Re the L88 drop base, an often-overlooked fact is that as designed, there was an ~ 1" tall foam gasket between the base and the hood-mounted element, so that the flow path was not as torturous as with a full height filter of the same dimensions. That said, any filter area is better than none, so going with the maximum usable height, say 3.5" should help.

David Vizard in a couple of his books describes using a homemade U tube manometer to check pressure drop through the aircleaner system and suggests no more than 1.5" H2O for a zero power loss system.

Also, K&N has a filter sizing formula that I believe would show a 3" tall element (But NOT a 2" one!) would suffice for this app: https://www.knfilters.com/filter_facts.htm

[DCal]

Guys , thanks for the replies .
Turbo2256 , the choke horn was removed long ago . What I was also thinking about is adding a 1" super sucker spacer and reducing the element height , but without a dyno it`s seat of the pants only . However , to do that , I have to dump the L88 base and go with a 1" shorter element.
No room to run hoses for cold air , so looking at building a box that seals to the hood ..... but in all honesty , for what I think I may pick up ., it ain`t worth it. I can burn the tires in the first three gears already .... this is just a toy to play with and try things out on .
As far as clearance to hood .... I have about 5/8" between the lid and the hood , and yes , it touches on WOT .
May try an R2C element next just to see what happens .
Again, thanks

That's about what I have too. The solution for my needs was a solid driver side motor mount

[F-BIRD'88]

I had that big ugly dual duct hose GM air cleaner that had the same base contour/drop as my L88 base too. It came on my 1970 Canadian Built Pontiac Safari Wagon. The Canadian built Ponchos came with a all Chevrolet drivetrain instead of the American Pontiac V8.
Mine had a Chevy 454-390HP LS-5 BB th400 Chev 12 bolt.

[ptuomov]

I personally liked the engine masters episode on this issue, with the salad bowl and all.

[lefty o]

I personally liked the engine masters episode on this issue, with the salad bowl and all.

the salad bowl is awesome!

[Krooser]

I found the salad bowl works best with the Spring Mix and Italian dressing... But I had a backfire and the dressing blew all over my windshield...

[lefty o]

I found the salad bowl works best with the Spring Mix and Italian dressing... But I had a backfire and the dressing blew all over my windshield...

you need to use a light oil, that italian will just mess stuff up!

[barnym17]

Use Thousand Island its so thick a back fire wont move it.

[63qcar]

Hey DCal ... my problem , other than the carb filter base , is that I have to change the passenger side motor mount out every year .I have so much torque it compresses the mount about 1/8" by the end of the year. The driver side mount I ran a 7/16" bolt through it , put a locknut on it and tightened it down but left about 1/32" clearance . Does the same thing as a brace , but looks neater . Where the air cleaner lid hits the hood is on the rebound ..... i.e. when I lift off suddenly ( going into a turn from WOT ) .

So you`re in the Mooresville area ? I go through there about every 3 to 4 weeks to my place up in Wilkes County . A good friend of mine , who passed away some years ago used to have a shop in Mooresville . Harold Elliott , he did all the coatings on my bearings and ring gear and pinion on my Galaxie and also the Cobra. Used to be en engine man for Junior Johnson .