Hi Guys,
Has anybody installed a Edelbrock Performer RPM Air-Gap Intake Manifolds 7501 on a C3 1974 Corvette with a SBC ?
I'm worried about hood clearance, right now I have a Weiand X-CELerator and a Holly Sniper EFI 550-511K installed and I'm looking for a few more HP's.
On the Summit website I clicked on Check fit and it says yes, but I would like to make sure before I tear into it.

Thanks in advance,
Ron

 

Edelbrock's web site says no Air Gap on all Corvette hoods. That is a claims protection, so some customer doesn't poke the wingnut through the hood.
But there are ways around this.
Just did this Eddy 7501 swap last fall on my '77 stock hood but with Holley 4150.

You have to purchase a Drop-Base air cleaner. I think mine is around 1.5" lower, chrome, 14" dia. open element, 3" tall.
I put Silly Putty on the cleaner lid. Was shocked I still had 3/8" clearance. But here is the deal breaker. I found a 2 & 3/4" tall filter at NAPA. That will be swapped out with the 3" filter.
And because there is all this room now, I will be installing a carb heat shield and a 1/4" tall wood spacer under the carb. Waiting for decent weather.

So it can be done. Eventually I will post photos in my albums. Click on avatar, look for Eddy Air Gap.

Just a note here about Drop-Base air cleaner lids. Holley wants 3/4" space above the fuel bowl vents. Lars says if the vents are partially blocked, performance will falter. Most chrome lids are domed near the bowl vents. The lid tapers from the outside edge, rising some to the wingnut center. They may be all you need. Again a piece of Silly Putty will show how much gap you have at the vents with lid installed.
Also, if you go this route with chrome lid & Holley, make sure to order air cleaner base specifically for Holley. There will be indentations in the base part for the needle valve adj screw.

I wasn't satisfied with the gap between vent & base unit, so I found some custom Holley bowl vents that vent out the side, instead of the top. They are brass, were pricey but fit the Holley with a press-fit. Problem was, they were too tall. Off to the machine shop. Put on a lathe and turned down to proper height.

 

I agree with the above.....and the Edelbrock claim about hood clearance is obviously missing some important facts. The most important is that the hoods on C3 Corvettes vary widely on what model year....so by default, Edelbrocks statement that it will not fit on a C3 is blatantly wrong. Up to 72, stock 350 hoods have ZERO rise above the intake manifold, and therefore can tolerate NOT any increase in carb height. Early C3 factory big block hoods have more rise, and of course the L88 hood has huge rise. Starting in 73 up to 79, the raised center portion of ALL stock hoods in those model years WILL allow increased carb height......but on my 77, with the same intake manifold you have, requires a drop base air cleaner, I think mine is a 1 inch drop, and I have more than adequate clearance. The tight spot is the forward edge of the air cleaner lid....I have about 1/4 inch, measured with rolled up aluminum foil with hood closed. I cannot speak for 80-82......but it appears the hood rise is less than 73-79.....so may not work with your intake manifold.

 

Thanks guys.

I already have a Drop Base air filter so that's good, I checked the clearance with some putty and I have 1 1/2".
TheWeiand X-CELerator Intake Manifold Height: 3.575 in. and the Edlebrock Performer RPM Air-Gap Intake Manifold Height: 4.720 in.
The difference would be .855, that's a bit too close for me, I will try and find a 2 1/2" air filter at Napa, just to be on the safe side.

 

I run a RPM Air gap on my 70 with a stock hood. I use the factory LT1 drop base air cleaner with a 3 inch filter and it fits. I cannot use a wing nut on the air cleaner but a bolt works just fine. You should have no problem on a 74.

 

I wouldn't go that short on the element. You will lose some CFM flow.
I will get you the part number for the 2 & 3/4 element.
With the 0.855 that is over 3/4 inches. Plenty.

 

Cool, thanks Head U.P.

 

rcauchon,

Found my filter receipt from NAPA. I was wrong, its not 2 & 3/4" tall.
This is from NAPA web site:
Outside dia, 13.875
Inside dia, 11.62
Height, 2.64
Part number FIL 6037

If I did the math right, comes out to 2 & 5/8 tall not 3/4.
EBay listed this element at $32.
My local NAPA had one day shpg, and was $19.99 + tax.

That might work for you better than the 2.5" H. More vent clearance.
I believe it is a Wix Gold.

 

Thank you for the part number, I will keep it in mind.
I spoke to me engine builder and he said depending on how much the Drop-Base assembly is I would need to be careful of the clearance between the carb and the Air filter cover.
I also have a 16" drop base filter that I notched the back so it doesn't touch the distributor.
I'll have to see what will fit and work.

Thank you for your input.
Ron

 

I was able to get everything to fit, with about a 1/4 free under the hood, here's what worked for me.
Edlebrock PRO-FLO high-flow 14" round air cleaner #43662,
Holley 120-511 Air Cleaner Base 1 in. Drop Base Plate.
K&N E-3735 High Performance Custom 2.5" Air Filter.

 

I have one on my '79. Although I no longer have the stock hood, I did have the 7501 on there when I did and it will fit if you're careful. I wanted a 3" air cleaner and a decent insulator under the carb, so I went with the L88 hood, which allowed me to have it all.

 

On an '82 a trim job on the crossfire air intake area and a k&n L-88 style air filter with an element top works great!

 

BTDT, bought the Tshirt over 20 years ago, even did a back to back comparison between the RPM Air Gap and a Vic Jr. intake on the same 550HP 406ci engine. The RPM Air Gap is a fantastic intake sticking with Vic Jr. in HP and TQ (and no the Vic Jr. did not give up any TQ. ) throughout the RPM range of 2000-6000 only losing a couple of ponies to the Vic. Jr above 6000RPM. You will be happy with that intake!

 

anything's better than crossfire.....

 

With a drop base you have to be very careful not to get the carb to close to the top lid of the air cleaner otherwise you chock the car for air because there is not enough space to let it breath