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  #1 (permalink)  
Old 05-01-2021, 06:03 AM
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Default Please help with air filter breather combo

Ive got what im pretty sure is a 428 fe. Dont know all the specs, but I do know it has performer rpm heads, performer rpm intake and a holley 48 with the standard oval 1 inch air filter set up. From what ive read the performer rpm heads and intake should be good till around 6k or a little higher.
This car pulls HARD and runs great, until 4800 rpm where it just runs out of power. My rev limiter is set at 5500 so it isnt that. Linkages are all correct and secondaries are working. Can anyone recommend a circular filter set up that will fit the holley and flow enough air? My gut feeling is this car is running out of air. Could anyone chime in with suggestions? I love the look of the air cleaner I have...but would prefer the power of something with a different design.
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Last edited by Soundkillr; 05-01-2021 at 06:18 AM..
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Old 05-01-2021, 06:15 AM
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Run it down the road once without a filter just to verify the problem.?
ERA 626, rads42, Grubby and 1 others like this.
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Old 05-01-2021, 06:20 AM
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Quote:
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Run it down the road once without a filter just to verify the problem.?
Thought about doing that...pollen is still high in my area...but maybe im paranoid. That would definitely tell me if it's running out of air! I may end up doing that!
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Old 05-01-2021, 06:30 AM
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Ive seen the k&n full top filters. For anyone running those would you recommend? Im open to ideas obviously....but need a direction to start...
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Old 05-01-2021, 07:44 AM
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You may find this thread informative.
Air Filter Calculator
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Old 05-01-2021, 08:25 AM
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I ran a K&N top filter on my 428 CJ and it worked fine.
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Old 05-01-2021, 08:46 AM
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I did this for my 482" side-oiler. I have twin carbs so my new filter panel placement was between the. You could put a panel on either end. That should cure your inadequate air flow.

Oval air cleaner for 427 FE?
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Old 05-01-2021, 09:15 AM
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I did the panel cutout before on my factory five, it worked. I think I used two square honda civic filters and a spare China lid I bought on ebay.

Now, I'm running a 9" k&n extreme on my roush 427r. Doesn't seem lacking for air.

Acton cobra sells a nice dropped base version for more. Me, being a cheap bastard, dropped my own base by using a mallet and hammering it. Shockingly, it worked, and clears my hood.

Acton's base drops maybe another 1/4" more than MC Hammer.
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Old 05-01-2021, 01:02 PM
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I would not think you are running out of air. Sure you are not running out of fuel? I had the same air cleaner on my 514 but with the K&N filter and it was fine. Recently switched to get some more air and let the heat rise out better. I also tried running my without the PCV valve, and that did not work well.
New one.

Old one
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Old 05-01-2021, 03:12 PM
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Maybe it's me but the throttle cable distance to threaded adapter looks short. Are you sure you're getting full carb travel with the pedal?
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Old 05-01-2021, 03:52 PM
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I bet it isn't the filter. Yeah it is likely sucking off some horsepower, but not your primary problem.

John
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Old 05-01-2021, 06:34 PM
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Scooter...what model filter are you currently using? To the others...im not sure on it running out of fuel. Im not sure what the fuel pressure is set too. While im at it...what other area should I be checking? It seems to me this thing was set up well...and set up to run higher than 4800-4900 rpm. Im really hoping it's an air restriction but...maybe it isnt.
I have tried to hold the rpms steady at 4300 or so and stab it...My thought was the bowls would still be full.....but it still falls out of power exactly as before. Edit: full travel in linkage. I can verify carb throttle blades are fully open at floor.

Last edited by Soundkillr; 05-01-2021 at 06:41 PM..
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Old 05-02-2021, 05:32 AM
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Quote:
Originally Posted by scootter View Post
I would not think you are running out of air. Sure you are not running out of fuel? I had the same air cleaner on my 514 but with the K&N filter and it was fine. Recently switched to get some more air and let the heat rise out better. I also tried running my without the PCV valve, and that did not work well.
New one.

Old one
Also...I like your throttle spring return set up. Can you tell me where to get that style arm and springs? Much better solution than what I have....
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Old 05-02-2021, 08:14 AM
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Default Throttle return spring

Quote:
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Also...I like your throttle spring return set up. Can you tell me where to get that style arm and springs? Much better solution than what I have....
Had a very knowledgeable carb tuner point out that the return spring should work against the pull of the throttle from the opposite side, otherwise you are loading up the throttle blade axle all in one direction.

OP think you are running out of fuel. I agree, pop the air cleaner off for two minutes in a clean area and see...
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Old 05-02-2021, 08:40 AM
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Default Trs

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Old 05-02-2021, 08:41 AM
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I've heard the same thing about the throttle springs also that they should be in front hooked to the top. I've just never changed mine.
I also have the Wagner adjustable PCV valve.
The air filter I found on Amazon. I figured it has about 20% plus more filter area then the large oval one.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.summitracing.com/search/...rder=Ascending
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Old 05-02-2021, 08:51 AM
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I like the idea of starting with and ruling out the simple stuff first. I frequent the 460 forums and the below link is one with many thoughts on a similar sounding issue (obviously on a 385 series engine), if helpful. The Mad Porter contributor there is a premier big block engine builder, his advice and troubleshooting is generally of high value. Again, there may be simpler things to rule out before some of these considerations. However, if certain build and tune specs are unknown (cam, springs, timing, etc.), itís feasible that one of more such issues apply.

https://www.460ford.com/threads/engi...00-rpm.231217/

Best of luck. Brent
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Old 05-02-2021, 09:02 AM
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Quote:
Originally Posted by tortuga View Post
Had a very knowledgeable carb tuner point out that the return spring should work against the pull of the throttle from the opposite side, otherwise you are loading up the throttle blade axle all in one direction.
.
Dual springs, please -- it's the #1 rule of carb safety. And the springs should offset themselves in pull so it's smooth, easy, and joy to live with. And the #2 rule is a rev limiter, because when you're unexpectedly stuck at WOT most of us instinctively throw in the clutch to get to the side of the road and clean off the seat. Without a rev limiter, a bad day can quickly turn in to a new engine.

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Old 05-02-2021, 05:01 PM
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Guys, thank you for the tips, pics and links! This has been very helpful. As soon as weather permits ill chime back in with what I find. I know fuel pressure is adjustable but it has no inline fuel pressure gauge. I also have no clue if it has a fuel return...so unsure if pushing pressure up would create more issues...
When im ready to check fuel pressure, I can post what setup I have so maybe I can get better suggestions. Off to look at all those links now and aircleaners...

Last edited by Soundkillr; 05-02-2021 at 05:16 PM..
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Old 05-03-2021, 08:28 AM
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Default Better Pic of Spring Force Offsetting

Here's a better pic on the simple, but important, point of having two springs on opposite sides of the throttle shaft pivot point. Each spring pulls in the opposite direction of the other spring. And these are not hardware store springs that you put on your screen door. They are PAC Racing springs and neither spring has a point of failure in common with the other. This really does make the throttle feel right, and it's safer too. If one spring breaks, you'll notice your throttle pedal feels different, but it will still be safe to drive home. If you're going to do it, you might as well do it right. Especially when it only costs you about ten dollars more. For some reason, a single spring on a carb always breaks when you're at WOT, never when you're idling in the driveway or staring at it in the garage.


Last edited by patrickt; 05-12-2021 at 03:08 PM.. Reason: typos
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