Clearance for RPM Air Gap...

Discussion in 'Fuel and Air Systems' started by 7milesout, Aug 24, 2018.

  1. 7milesout

    7milesout Well-Known Member

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    So, before buying the dual plane Air Gap, I wanted to check how much clearance I have between the hood and top of the air filter. To make sure I would have enough room for the taller intake.

    I found the below, having never noticed this before. Shouldn't be an issue, right? :D

    upload_2018-8-24_8-16-37.png

    upload_2018-8-24_8-17-1.png
     
  2. Frnknsteen

    Frnknsteen FABO Gold Member FABO Gold Member

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    Yeah,... Looks like you have plenty of room to spare. You have options though. See how much taller the Air Gap intake will be and get a drop base air cleaner that gives you at least that much extra drop. If you want to keep your current air cleaner, I think you are out of luck though! :) Unless you can find a shorter filter that will work.
     
  3. ragtopfury

    ragtopfury Well-Known Member

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    Looks like your current set up is already into the hood insulation more than you thought it was. A drop base aircleaner base will definitely be needed to hope you get enough clearance.
     
  4. AJ/FormS

    AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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    Your air-filter house on a 750DP, on the Ag, fit under my hood; 68 Barracuda 367, with the engine shimmed to fit the TTIs on factory biscuit-mounts. The center stud had to be shortened tho, and I raised up the rear edge of the hood slightly, on the hinges.
    It didn't stay that way for long tho, until I cut a hole in the hood, and gave the engine the fresh cold air it wanted. So then I put the filter on top of the hood, in a nice oval package, and sealed the DP to the underside of the hood
    If you do something like that, you will discover that the carb is not under the center of your hood,lol.
     
    • Agree Agree x 1
    • 7milesout

      7milesout Well-Known Member

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      I hate to pull that hood insulator off. I prefer to keep it original. Besides a drop base filter, would you guys pull that insulator off?
       
    • Ottmundr

      Ottmundr 68 Fastback

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      I got rid of that insulation years ago and threw it out. I am building my car for me, not some judges at a concourse car show.
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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      I wonder if they catch fire and burn?
      Mine's gone. I want that hood to be a giant heat sink in direct contact with the wind passing over it, to help get rid of all that underhood heat.
       
    • Frnknsteen

      Frnknsteen FABO Gold Member FABO Gold Member

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      I'm on the opposite side of the others I guess. I just bought the insulation for my Barracuda, and am getting ready to install it right now. My air cleaner will be a close fit too. I am running a 3" filter, so I am going look for a little thinner filter element, or look into different drop base air cleaners.

      I prefer not to have the paint on my hood be part of a giant heat sink with the wind passing over it! :) (Messing with AJ!!) :)
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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      Lol I get it, and like it.
      As you know an engine is just a heat pump; the hotter it runs, the less power will go into the rad and/or exhaust. Leaving more power for propelling the vehicle. That is why I run at a minimum of 205*F at the stathouse.
      But the fuel system and the engine hate hot air,especially if it is forced to inhale it at WOT. And so I did everything I could to make it easier on her. And getting rid of the hot underhood air was a big priority for me. So I'm not kidding, that hood runs too hot to sit on with bare legs, don't set your grandkids on it,lol. But when I come in from a hiway run, it ain't that bad.I even ventilated it so it could breath after shut-down.
      I know you're just funnin', and I enjoy it, and not everybody is looking for the Nth degree. I mightabin a lil anal back then
       
      Last edited: Aug 24, 2018
    • 7milesout

      7milesout Well-Known Member

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      You guys should have a policy, everybody agrees which way to do something. Insulator on, or insulator off. :D Actually that insulator would be for sound aborption. Not that I have an issue with sound. The exhaust note on my car is rather bad-ass. Except at certain rpm, it is rather quiet. 40 mph sounds awesome. 42 - 52 rather quiet, then 55 mph kind of loud again.

      The engine makes a lot of clatter that is not exactly flattering. My son and I were riding back home one day, and he had met me and left his car (2005 G35 6 speed) in a parking lot earlier. On our way home after I dropped him back off at his car, near the house I got to thinking I wanted to be first in the driveway cause the Scamp goes in the garage, and his stays (in my way) on the driveway. We came to a light that was red but turned green before we slowed down too much. I whomped on the Scamp and went screaming by. I asked him if it sounded good, and he said, "it was just loud noise." Ok, I get it. Late model Mustangs with loud exhaust sound phenominal. But that's a function of 4 valves per cylinder, engine rpm, exhaust configuration, and years of learning how to quieten the mechanical noise of the engine. The ole 360 does make a lot of mechanical noise, as well as sucking air through the filter, carb and intake.

      All that being said, not that the insulator is a hugh noise absorber, but the less that noise I hear, the more I get to hear the exhaust. So, I'll leave it on if I can.

      Now … about that policy. Everyone should agree with me now... :D
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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      Ok Seven I'll bite, lol
      I once had an engine like your son describes. It was a 318 with a 340 top end and cam.....And 2.76s..... It was all noise and posturing until 50/55 mph at the top of first. Then into second it was back to a whole lotta noise and very little go, until about 80.
      Unlike yours, mine sounded like a really really low-compression built-from-left-over-parts,pos, teener....... which it was.
      I agree, some combos just shouldn't be screwed together.lol
       
    • 7milesout

      7milesout Well-Known Member

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      AJ - Don't misunderstand me though, mine doesn't sound bad, or cheap, or inappropriate. It sounds relevant to the time period. That's not a complaint. That's just the nature of the beast. I like it original-ish, so I am OK with the sound. It just doesn't sound as pleasant to the ears at full throttle like late model mustangs do.
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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      Hang on Seven, that's just me trying to be funny.
      I agree, some guys just aren't funny,lol., and
      I agree those Mustangs do sound pretty good
       
    • KnuckleDuster

      KnuckleDuster Well-Known Member

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      Late model Mustangs sound like crap!
      Cannot stand all that crackling and popping! It literally makes me cringe!

      Nothing sounds as sweet as an old Mopar!
      If people get too close on the freeway, I step on it a little, and my 410 growls at them!

      You are gonna have to watch the Engine Masters episode on air cleaners!
      I agree with AJ, get a scoop and break out the sawzall, or buy another hood.
      You're not going to get much surface area with an Air Gap under a stock hood.
       
      Last edited: Aug 24, 2018
    • 71DodgeDemon340

      71DodgeDemon340 FABO Gold Member FABO Gold Member

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      What intake are you running now?
       
    • SGBARRACUDA

      SGBARRACUDA ROY FABO Gold Member

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      I run the Edelbrock air gap with a 750 HP and a 1" carb spacer. Had to run a drop base air cleaner with a 3" element, but the hood closes.

      My 68 Barracuda-3.jpg
       
    • 7milesout

      7milesout Well-Known Member

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      As far as I know, it is the original intake for an LA360.
       
    • 71DodgeDemon340

      71DodgeDemon340 FABO Gold Member FABO Gold Member

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      Oh ok, i thought the rpm air gap was the same height as a rpm performer
       
    • 7milesout

      7milesout Well-Known Member

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      SGBARRACUDA - That engine sure is purdy! Is that wood below the radiator? :D Which drop base filter housing did you use? I'm guessing I'm going to have to find the biggest drop available … since my filter housing is already up in the insulation.

      AJ - The whole "hole in the hood" idea has really got me thinking. I like that idea a lot. The problems (for me) might outweigh the advantages.

      Problems:
      1. I would have to BUY another hood. I don't like buying things because it causes me to pay for things.
      2. I would have to PAINT whatever hood I just bought. And then I'd have to pay for painting the hood. #1 and #2 sound like a lot of paying, my seat cushion is getting pinched between my buttocks just thinking about it. :D
      3. The paint from #2 would not match the paint of the car well enough. The car is 46 years old with original paint (fade). I would always see the difference (I don't care about a judge) and it would bug me.
      4. I would think a hole / scoop in the hood could be left open, and use one of those air filters / filter housings that have the filter media (not just around the perimeter but) in the top as well. Of course then I guess the issue is that the carb could scavenge under hood air...
      But I like the availability of cooler denser fresh air entering the carburetor. However, I'm running pizza cutter tires due to the fenders and leaf springs location. So, I'm going to pretend that I choose to run header-warmed air as a form of traction control. Not because I'm cheap. :D
       
    • 7milesout

      7milesout Well-Known Member

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      Did a bit of research here. What I have learned is that the Performer intake is very similar in height as that of a stock intake. That is what I have read, but don't know the fact of the matter. Does anyone know if that is true?

      I also read that the Air Gap is around 3/4" taller than the Performer.

      If the above is true, it appears that the Air Gap intake should be ~3/4" taller than my stock intake.

      The quickest solution therefore would be a 1" (or greater) drop base filter housing, paired with the Air Gap intake.

      Do these numbers sound realistic?


      7milesout
       
    • SGBARRACUDA

      SGBARRACUDA ROY FABO Gold Member

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      No that is the concrete floor. I don't remember which base I bought. Sorry
       
    • 7milesout

      7milesout Well-Known Member

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      Guys - I'm going to go for a 1" drop base filter, and remove the fuzzy hood liner. I should not have an issue with clearance. With a 0.79" increase in intake height.

      What I am questioning is: Right now the current filter base has a fitting in it, and it is plumbed to the passenger side valve cover. The driver's side valve cover is plumbed to the center fitting at the front bottom of the carburetor. The replacement drop base will not have a fitting on it. So I'm going to lose that vacuum attachment.

      What am I to do? I'm guessing I can place a T-barb fitting at the front of the carburetor and plumb from the front-bottom of the carburetor to both the driver's side and passenger's side valve covers. Am I right?


      7milesout
       
    • Frnknsteen

      Frnknsteen FABO Gold Member FABO Gold Member

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      Is the fitting not removable? Usually, at least on the air cleaners I have, that fitting is held on by two bolts. You would be able to unbolt it from the old air cleaner and move it to the new air cleaner base. Might have to pop the holes open though. I just bought a new drop base for mine and it already has the mountings for that fitting stamped. I would just have to drill them open.
       
    • 7milesout

      7milesout Well-Known Member

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      Well, that could be the case. I haven't laid eyes on the new drop base as yet.

      But let's pretend it's not set up for it. Would the T fitting idea I mentioned work reasonably?
       
    • Frnknsteen

      Frnknsteen FABO Gold Member FABO Gold Member

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      What is on the other end of the hoses that go to the valve covers? I assume one is a breather and the other is a PCV valve? I don't recall it being common to have hoses hooked to both valve covers.

      Most instances I can think of, at least on these old Mopars, have a hose coming from the PCV valve to either the air cleaner or the vacuum port on the carb and the other valve cover has a breather. This allows fresh air to be pulled into the motor on one side, and pressure in the crankcase to be drawn out through the PCV valve.

      I don't know that you would want both lines T'd into the vacuum port on the base of the carb. I believe the engine crankcase needs to be able to breath.