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I'm disappointed with the reality that my AG can't really breathe as is!
I measured from the choke horn to the top of the filter w/straight edge.
Somehow 1 5/8 is not enough room to my inexperienced self.
I'm considering cutting a hole in the hood and running a 4" filter w/o drop base AC.
Your thoughts please?
R
An air gap is 2.75" tall vs an LT-1 at 2.5" tall The LT-1 intake, air cleaner and 3.0" tall filter do fit an LT-1 hood but just barely. There just is not another 1/4" for an air gap intake. You'll kill more HP with a tiny air filter to get that to work, than you will ever gain with a "better" intake. Just put the right intake on it. Save those things for Chevelle's, or put a scoop on it. Stock 73 up hoods are about the same as the BB hood. Stock 68-72 hoods are even 1.0" lower.
I have been collecting air cleaner heights as well as owners comments about what fits.
Corvettes are hood height limited vs other chevies vs hi-perf intakes.
An air gap is 1/4" to 1/2" too tall, on a C3, even with an OEM drop base air cleaner.
Drop base air cleaners:
OEM Open element = 2.0" drop and 3.0" tall filter
Most aftermarket are 0.5 to 1.0" drop = not enough
I've got info for Weiand Team G single plane manifold if your interested. I'm running it with my Sniper 2.
Just want to point out the air gap and non air gap version of the rpm intakes perform virtually identically if you cut the notch in the center divider like the air gap has... the rest of the advantages of the air gap are fairly ineffective once at temp on the street. the notch is the single best improvement for many engine combos running the dual plane that can take advantage of it at higher rpms.
I literally just yanked my 355 out of my car 30 minutes ago... going with a knockoff airgap style intake I ported to match my heads and 1206 gaskets. but I have a high rise greenwood hood so ill be using a open spacer and aces killshot 2 TBI with my drop base cowl induction setup. Ive been watching a LOT of shows like engine masters to brush up for the 406 swap and overdrive trans.
I believe my performance products air gap style intake is only like 4.65 but could be wrong.
This might be of use to other 73/74 owners
For the 73 and 74 stock air cleaner with the stock air filter there is just over 1 inch from the lid to the top of the Qjet . Based on Lars' math, this is about as bad as it can get.
Not wanting to cut the hood, or even swap to an aftermarket air cleaner, I found an air filter from a 79 is the same but 1 inch taller and it fits under the hood of my 73.
Far from ideal, but it was an improvement. 73 element (Wix - 42101) (Fram CA327), the taller 79 filter (Wix - 42098) (Fram - CA326).
Also needed a longer stud for the wing nut.
This is a great thread to read. Not too old, a bit crusty, but no mould yet. But so much information that I've long lost track of who was referring to which hoods, which drop bases, which intakes, etc. I've traded my ignorance for overwhelming confusion.
The conclusion I reached for the engine I'm building is... with a stock '79 L82 hood, 350 (383) block, planning to use AFR heads, Edelbrock EPS 2701 intake, 4150 style carb with VS, a 1.5" drop-base, a 3" high filter, and a flat-ish lid. That should fit under my hood, right? Or am I still confused? Not looking to change the hood. I'd go measure it all up but the car is in storage.
I bought a used RPM Air Gap intake on marketplace for this project based on something someone said on a forum, but it sounds like the context must have been for an L88 hood set up or something. I'll be selling it I suppose. It's too polished and shiny for me anyway.
This is a great thread to read. Not too old, a bit crusty, but no mould yet. But so much information that I've long lost track of who was referring to which hoods, which drop bases, which intakes, etc. I've traded my ignorance for overwhelming confusion.
The conclusion I reached for the engine I'm building is... with a stock '79 L82 hood, 350 (383) block, planning to use AFR heads, Edelbrock EPS 2701 intake, 4150 style carb with VS, a 1.5" drop-base, a 3" high filter, and a flat-ish lid. That should fit under my hood, right? Or am I still confused? Not looking to change the hood. I'd go measure it all up but the car is in storage.
I bought a used RPM Air Gap intake on marketplace for this project based on something someone said on a forum, but it sounds like the context must have been for an L88 hood set up or something. I'll be selling it I suppose. It's too polished and shiny for me anyway.
..Todd
When you get it all sorted, please post the results in this related thread!
That sounds like it should fit. Maybe. The 79 hood is just a little taller than 68-72 std hoods. If it does not clear, you can always move to a 2.0" drop base air cleaner, from a Corvette vendor. But I'm guessing you'll make it. Let us know! Put some clay or wadded aluminum foil on top and give us a measurement.
For whatever its worth I was able to fit a 3" tall round filter on top of my Edelbrock Pro Flo 4 system using this drop base. I have an (what I believe to be) aftermarket L88 hood - its not a super a tall cowl and required some clearancing underneath to allow the opening on the underside of the hood to close over the air cleaner.
I'm also using a filter style lid simply for the looks. Its a street car so any slight power loss from the filter lid is acceptable to me.
That sounds like it should fit. Maybe. The 79 hood is just a little taller than 68-72 std hoods. If it does not clear, you can always move to a 2.0" drop base air cleaner, from a Corvette vendor. But I'm guessing you'll make it. Let us know! Put some clay or wadded aluminum foil on top and give us a measurement.
Thank you. That's what I was hoping to hear, especially from one of the hood clearance officianados, such as yourself. I appreciate it. I'll leave the purchase of the drop base to when I've got the car available to measure up.
@benjiboy, thanks for the link to the 1.75" drop base. And yeah, I agree. Mine is a street use car too, and I've built enough additional power into the engine so that I don't have to worry about a few minor inefficiencies here and there. Good thing you left that jack stand showing in your photo, cause that tire clearance is in the monster truck territory.
I'm running Snipe 2 EFI on a Team G 7530WND single plane intake. I'm using my stock SB Corvette dual snorkel air cleaner and I only have 1/4 clearance on the drinkers side under the hood. I've got pictures at home that I'll post later. As far as HP loss with my setup if I'm losing 1 to 5 HP I won't feel in in the seat of my pants dyno. I'm not pushing 500+HP but probably close to 400 I would guess. Never had it officially dynoed.
Originally Posted by stingr69
Augie,
You might not need the tall dual plane with EFI. I would not worry much about low RPM torque impact. This is a real small plenum single plane. Big inch SBC has plenty of low speed torque. You probably wont notice any real difference there. EFI will fix that. Healthy top end improvement. I really like your cold air intake and would do whatever you need to keep it. A Weiand IMCA single plane would be worth considering. You can get the hood closed and make great power. Check out the paragraph 2d in the EFI Sticky in the Tech section.
Popular IMCA racing single plane. Easy to find and very low profile.
This Weiand Team G Street Ram intake below would also be good but they are very hard to find. It's a baby single plane that works great for a hot street car. Weiand Team G 7525 EGR style intake. Long out of production. 2000 - 6000 RPM range. Very low height to fit under the hood of any C3. If I did not have it, I would just buy the IMCA intake above.
Last edited by theandies; Aug 18, 2025 at 06:24 PM.
Havent read this whole thread so this question may have been answered previously. I’ve owned my stock 76 since November and noticed that the front of the stock air cleaner leaves an impression in the insulation. I say stock but the carb is not, it’s a Holley 4165. Yesterday I put a wad of aluminum foil on the front edge of the air cleaner, closed the hood, and the foil was smashed down to 1/2” thickness. I originally thought that my dry rotted front body mounts had allowed the front clip to sag (maybe that’s possible, don’t know), but on closer examination of the air cleaner, the snorkel is pointing up and not directly at the cold air intake on the radiator. Using a mirror I could see the front of the air cleaner is not sitting down on the carb due to the bottom hitting the front bowl of the carb. Want to keep the cold air intake, is it possible to modify the intake, or possibly a taller gasket for the top of the carb? I do have the original qjet that came with the car and will eventually have Lars put it back together and reinstall. TIA.
Havent read this whole thread so this question may have been answered previously. I’ve owned my stock 76 since November and noticed that the front of the stock air cleaner leaves an impression in the insulation. I say stock but the carb is not, it’s a Holley 4165. Yesterday I put a wad of aluminum foil on the front edge of the air cleaner, closed the hood, and the foil was smashed down to 1/2” thickness. I originally thought that my dry rotted front body mounts had allowed the front clip to sag (maybe that’s possible, don’t know), but on closer examination of the air cleaner, the snorkel is pointing up and not directly at the cold air intake on the radiator. Using a mirror I could see the front of the air cleaner is not sitting down on the carb due to the bottom hitting the front bowl of the carb. Want to keep the cold air intake, is it possible to modify the intake, or possibly a taller gasket for the top of the carb? I do have the original qjet that came with the car and will eventually have Lars put it back together and reinstall. TIA.
I ran one of these for a while too and never noticed any issues because I dont race the car. In the engine masters showdown though they show that the air coming in from the top interferes with the air coing in from the sides and causes a lot of turbulence which in the end makes this filter perform worse than the cheapest no name chrome/paper 14 inch filters out there I now you dont want to hear this as I didnt either and used it for similiar reasons as you chose it but the testing was pretty conclusive. I have the misfortune of not checking my aces killshot throttle body for clearence till aftr I purchased and found I cant run any type of drop base which puts me in a quandry with my drop base cold air intake.
Just wanted to follow up that I instead went with the newer aces killshot 2 efi setup which allows for my original drop base air cleaner to fit and allows me to even use a spacer with my air gap intake (The assault brand air gap intake is only 4.65" tall btw). I have everything mocked up on the 406 in the car now.. just need to finish installing the straps for the new fuel tank and run the lines, set up the tv cable on the new 2004r trans and bolt on the accessories. the killshot 2 throttlebody is identical looking to this fusion model which I think is a steal for $500 = shipping right now. https://acesefi.com/products/killsho...AA3fUVXxVS1Zu8. I wanted the newer touchscreen and remote mount ECU so I went with the slightly more costly killshot 2 but that was before they launched the bluetooth module that lets you use your phone as the interface instead. This stuff changes so quickly its hard to keep up.. Anyway now I have to sell the killshot 1 I bought last year and never installed. I also can remove most of those gauges under my hood as the info is mostly all on the touchscreen now.
I appreciate it. I'll leave the purchase of the drop base to when I've got the car available to measure up.
