Help with air cleaner fit under hood

[TNTaylor]

I have a Kirkham 427 street cobra with a Shelby 427/468 engine with a Holley 850 CFM Ultra XP carb. Currently I have a 9" K & N round air filter which I would like to replace with a 14" x 3" round filter. Given I have a street cobra, my car has no hood scoop.

What I need help on is how I can figure out how much space I have, or lack thereof, to fit the bigger filter. Perhaps a straightedge from one side of engine bay to the other, or make up a 1/2" thick 14" round piece of rigid styrofoam temporarily adhered to the top of existing air filter. Then slowly close the hood.

Any suggestions?

[cycleguy55]

Normally I'd suggest cardboard and tape to mock one up, but you're most likely going to need a drop base air cleaner - and that could be difficult to fabricate out of cardboard.

I went into one of the locally-owned, small speed shops which I frequent, and they let me park out front and try different models to see what would work. As it turned out, they didn't have anything. I ended up doing a whole bunch of measurements which indicated I could fit a 14" x 3" air cleaner using a 1 1/4" drop base (http://www.summitracing.com/int/part...3549/overview/).

That was all well and good, but the 460 in my car sits too high and the top of the air cleaner still made contact with the hood. The 460 is most likely higher in my car than your FE, so a combo like this may work for you.

There are a few other Kirkham owners on CC with FE engines, so many have faced and solved this issue. I'd suggest searching the Kirkham forum (Kirkham Motorsports - Club Cobra) for "air cleaner" (quotes included), as there are multiple threads / posts where the issue of which air cleaner will work has already been discussed. If none of those are exactly what you're looking for you can always start a new thread there.

It may also be worth a cruise over to a friendly speed shop with your Cobra to try out a few combinations to figure out what will work for YOUR car.

[rodneym]

TNTaylor,
You should be fine with either K&N drop base. Some have suggested the old Corvette one as well. It wil fit, but drop you must go.

[DanEC]

To check clearance, find some silly putty or something similar. I actually have used a ball of 3M strip caulk. Put a couple of balls of it on your air cleaner - probably at the front edge and at the center stud and shut your hood. When you open it back up you can measure the thickness of the flattened ball of putty or caulk and that's your clearance for those points. I also did this to check clearance on my expansion tank because I thought it had to be real close to the hood. I found out after checking that I had a lot more clearance than I thought.

[Cashburn]

Summit Racing has a very liberal return policy... just sayin'

[Detroit Bill]

I second using clay. What manifold do you have?

[Three Peaks]

Try pulling the vents out of the side and see if you can see the top of the carb and the hood from there with a flashlight. Then just measure what the distance is if you can reach in with a small tape measure. Unless you have big arms/hands like me, you should be able to reach that far and get a measurement, or talk someone with skinny arms to hold the tape measure in place from the other side and read the measurement.

Bob

[TNTaylor]

Originally Posted by Detroit Bill

I second using clay. What manifold do you have?

Shelby dual plane medium rise intake manifold

[TNTaylor]

sd

Originally Posted by cycleguy55

Normally I'd suggest cardboard and tape to mock one up, but you're most likely going to need a drop base air cleaner - and that could be difficult to fabricate out of cardboard.

I went into one of the locally-owned, small speed shops which I frequent, and they let me park out front and try different models to see what would work. As it turned out, they didn't have anything. I ended up doing a whole bunch of measurements which indicated I could fit a 14" x 3" air cleaner using a 1 1/4" drop base (http://www.summitracing.com/int/part...3549/overview/).

That was all well and good, but the 460 in my car sits too high and the top of the air cleaner still made contact with the hood. The 460 is most likely higher in my car than your FE, so a combo like this may work for you.

There are a few other Kirkham owners on CC with FE engines, so many have faced and solved this issue. I'd suggest searching the Kirkham forum (Kirkham Motorsports - Club Cobra) for "air cleaner" (quotes included), as there are multiple threads / posts where the issue of which air cleaner will work has already been discussed. If none of those are exactly what you're looking for you can always start a new thread there.

It may also be worth a cruise over to a friendly speed shop with your Cobra to try out a few combinations to figure out what will work for YOUR car.

I have this base to try out: http://www.summitracing.com/int/part...10615/reviews/

And I have this filter:http://www.summitracing.com/oh/parts...9318/overview/

And the top from a Scott Drake Hi–Po air cleaner assembly

[TNTaylor]

Originally Posted by DanEC

To check clearance, find some silly putty or something similar. I actually have used a ball of 3M strip caulk. Put a couple of balls of it on your air cleaner - probably at the front edge and at the center stud and shut your hood. When you open it back up you can measure the thickness of the flattened ball of putty or caulk and that's your clearance for those points. I also did this to check clearance on my expansion tank because I thought it had to be real close to the hood. I found out after checking that I had a lot more clearance than I thought.

Silly putty! Great suggestion; I will try it! Thanks

[TNTaylor]

Originally Posted by TNTaylor

sd


I have this base to try out: http://www.summitracing.com/int/part...10615/reviews/

And I have this filter:http://www.summitracing.com/oh/parts...9318/overview/

And the top from a Scott Drake Hi–Po air cleaner assembly

Well, I tried the R2C base plate,

http://www.summitracing.com/parts/rcp-ac10615/reviews/

with the 3" filter and it fit PERFECTLY, with at least 1/2" room to spare between the top of air cleaner and hood (remember 427 Street with NO SCOOP.) This is on a Holley 850 HP. I know this is expensive, but unlike the K&N drop bases, it works.

Pix to follow

[DanEC]

I have 1/2 inch clearance to my ERA street hood using a 1/4 inch insulator gastket, S&H air clearners and K&N filters and haven't had any problems with contact from engine movement. You're probably OK with that.

[YerDugliness]

Originally Posted by rodneym

TNTaylor,
You should be fine with either K&N drop base. Some have suggested the old Corvette one as well. It wil fit, but drop you must go.

There may be another way...K&N has a feature on their website that allows you to search by dimension...14"D by "X" height....that sort of thing. I went from a 3" tall 9" diameter filter to a 2 1/4" 9" diameter filter in order to get to use the nicely radiused K&N air-cleaner base (which positions the filter in a raised fashion at exactly the correct height to fit right up into my hood scoop)...and used the X-Stream 9" filter top.

I second the idea of putty to check clearance...went to the children's toy section in WalMart and just bought a package of different colored clay "sticks". The "lumps on top of the air cleaner and close the hood" system worked perfectly (I covered the lumps of clay with waxed paper so that the clay lumps would not stick to the underside of my hood)!

The combination of the dropped 14" base with either a stock or a a taller than stock 14" K&N filter and the X-Stream filter top might be the ultimate combo, since you don't have a scoop. My local O'Reilley's sells the K&N 14" X-Stream filter assembly...not inexpensive, but if it works, it's worth it, right?

Cheers!

Dugly

[lippy]

I have the same air cleaner set up (K&N 9" with Xtreme top). The car is an ERA with a scoop and the engine is a Pond 427 with a Victor single plane. Because of the height of the intake, my only option is to fit the air cleaner up into the hood scoop. Nothing else will work, no drop base, nothing. One thing I did to give me more height was to use a flat 9" base from Bernica, which allowed me to add about 0.25" to the height of the air cleaner.

[mrmustang]

Originally Posted by TNTaylor

I have a Kirkham 427 street cobra with a Shelby 427/468 engine with a Holley 850 CFM Ultra XP carb. Currently I have a 9" K & N round air filter which I would like to replace with a 14" x 3" round filter. Given I have a street cobra, my car has no hood scoop.

What I need help on is how I can figure out how much space I have, or lack thereof, to fit the bigger filter. Perhaps a straightedge from one side of engine bay to the other, or make up a 1/2" thick 14" round piece of rigid styrofoam temporarily adhered to the top of existing air filter. Then slowly close the hood.

Any suggestions?

You need a K&N 66-3040 unit. I've used this on several of my FE powered Cobra replicas (2-ERA's, 1 Contemporary, 1 Unique). If the air filter clearance is still a bit too close for your comfort, you can replace the 14X3" air filter with a 14X2.5" to 14X2.75" filter (there are four or five height incremental K&N filters available).

Now, with that said, before you spend any money, you need to see exactly what CFM worth of filter assembly you need to properly feed your engine.

Using the simple formula

A= effective filter area
CID=engine displacement
RPM=maximum RPM expected


Using the CFM formula of height X diameter x 6 x 3.14

Also keep in mind that the 14" extreme top flows 500cfm by itself.


Hope you find this helpful.

Sincerely,

Bill S.

[TNTaylor]

Originally Posted by mrmustang

You need a K&N 66-3040 unit. I've used this on several of my FE powered Cobra replicas (2-ERA's, 1 Contemporary, 1 Unique). If the air filter clearance is still a bit too close for your comfort, you can replace the 14X3" air filter with a 14X2.5" to 14X2.75" filter (there are four or five height incremental K&N filters available).

Now, with that said, before you spend any money, you need to see exactly what CFM worth of filter assembly you need to properly feed your engine.

Using the simple formula

A= effective filter area
CID=engine displacement
RPM=maximum RPM expected


Using the CFM formula of height X diameter x 6 x 3.14

Also keep in mind that the 14" extreme top flows 500cfm by itself.


Hope you find this helpful.

Sincerely,

Bill S.

Bill -

Thanks for the info. As noted earlier, I got the R2C bottom plate with 14" x 3" filter.

As for your formulas, here is what I get:

468 x 5500/20839 = 123.5

3" x 14" x 6 x 3,14 = 791

I don't understand what the numbers are telling me, can you help?
Tim

[mrmustang]

Originally Posted by TNTaylor

Bill -

Thanks for the info. As noted earlier, I got the R2C bottom plate with 14" x 3" filter.

As for your formulas, here is what I get:

468 x 5500/20839 = 123.5

3" x 14" x 6 x 3,14 = 791

I don't understand what the numbers are telling me, can you help?
Tim

With your engine specs it means the filter you have now is already flowing more than enough air to properly feed your motor



Bill S.

[gunkk]

in other words, by the formula you could go down to 1" high filter and have A>= 200, still more than you need....

[Gaz64]

Originally Posted by TNTaylor

Bill -

Thanks for the info. As noted earlier, I got the R2C bottom plate with 14" x 3" filter.

As for your formulas, here is what I get:

468 x 5500/20839 = 123.5

3" x 14" x 6 x 3,14 = 791

I don't understand what the numbers are telling me, can you help?
Tim

The consumption of the engine is 468 x 5500 / 3456= 745 cfm.

So you do need 3 inch of height.

[mrmustang]

Originally Posted by Gaz64

The consumption of the engine is 468 x 5500 / 3456= 745 cfm.

So you do need 3 inch of height.

Only if he does not use the extreme filter top, which has a 500cfrm flow rate of it's own.


Bill S.