Weber Air Filters

[crazycasey]

Hey gang,

I’m setting up some 48 IDA’s for a 289 in a Mustang, that will eventually make it’s way into a 289 FIA car. The Mustang has little more room for an air cleaner than I would assume the Cobra would have, so the discussion may be relevant.

What are you all running for air cleaners? Most of the photos I see have either the screen that pops into the velocity stack (sold by Redline), or the mesh screen that pops over the velocity stack (black band around the bottom). Based on my rudimentary measurements, I don’t think I have room for something like a K&N (even the shortest one). I’ve seen a few people running the foam disc type filters, though I’ve heard they’re terribly restrictive. I’ve seen no one running UNI filters, which surprises me because they actually work pretty good on motorbikes. Is there anything that I’m missing?

What would also be great, is if folks would post what effect whatever type of filter they ended up going with had on their jetting.

Thanks for reading!

Casey

[1985 CCX]

I run mine open, screens could help but its about the air intake and velocity.
There are folks that run the filters and I am unsure of how that works. I find restricting the air flow causes flooding. When I use a nylon sock with a fine mesh it is fine around town, problem comes when you hit the units wide open.
=FLOODING

So I am in year 6 with wide open stacks, screens would keep out large rocks but the fine dust dirt is no doubt the biggest issue.

My $0.02

[t walgamuth]

I have K and N on mine but have not actually been able to run it that way. I can testify that they do stick up pretty high.

[1985 CCX]

It's a situation if your car sits the motor like an original.
Weber's sit high in a FIA/SS buggy spring frame, cleaners might not clear the hood.
Mine are the slightly taller alloy horns however it only leaves a 1" gap for cleaners to mount.

[1795]

Like Jeff (1985 CCX), I run with them open, albeit mine is just a race car. I was running the mesh screens initially but was told that even they are restrictive and will cost you about 50 HP. I can attest to that, as after I removed the screens there was a huge gain in performance.

If you will be driving in sandy areas or on gravel roads you might want some filtering. With a race car I am rebuilding the engine every couple of years so getting a little dust in there is not as concerning.

[crazycasey]

Originally Posted by 1985 CCX

When I use a nylon sock with a fine mesh it is fine around town...
So I am in year 6 with wide open stacks...

Are you talking like, women’s hosiery? Could be a good idea to keep some in the glovebox for when you encounter a dusty road I suppose...

In 6 years have you experienced any real detriment to running open stacks? More frequent oil changes maybe? Any compression loss?

Originally Posted by 1795

With a race car I am rebuilding the engine every couple of years...

So, I am VERY curious about this. Back in the day folks ran chrome (chromoly) rings in dusty conditions. They’d last longer than cast rings, but would also wear the cylinders faster. My 289 has plasma moly rings that are supposedly pretty unforgiving in dirty conditions...

When you rebuild so often, are you able to “ring and bearing”, or are you finding the added abrasive in the system is wearing bores and journals too? What about valve guides? I would be very curious to take apart a motor with a couple years of use in dusty conditions just to see how much of the cautionary aspect of filtration holds true.

[1795]

Have not run in any real dusty conditions. Typical rebuild/refreshing is rings, bearings, valve springs and seals. Running an aggressive cam at high rpms on a continuous basis is tough on the springs, bearings and rings.

Jeff i right in that if you have an original style transverse leaf spring suspension, there is not a lot of clearance to the hood from the horns.

[Morris]

Filters should always be used on motors....even if it’s a air box around the Weber’s with a filtered input opening.....

All of our race motors used filtration on air intake and we rebuilt based on the leak down test after every race.....usually every 10 hours we’d rebuild the motor because the valve would leak the most....which is dirt coming in thru the air intake .....once our leak down got to 15% to 20%...we’d rebuild motor....ingesting dirt/dust & reversion is the common component for loosing HP.....

[razerwire]

ITG filters are used by some. I have them on my engine. I wish I could find older thread with pictures of the engine showing filters, on and off, taken on Kroyer chassis dyno. Pictures had closeup in high definition.

[crazycasey]

Originally Posted by razerwire

ITG filters are used by some...

Are they run in a manner similar to this?

(I’m trying to glean some more info from this gentleman over on the VMF forum.

[1985 CCX]

FYI SAI did not use filters either

[crazycasey]

Originally Posted by 1985 CCX

FYI SAI did not use filters either

Neither did they wear rubbers, I’d wager.

I mean, I’m not trying to be a jerk...just pointing out that the thinking has changed on some things...

[razerwire]

Yes, I lightly oil them and have washed them. Four dealers in States now. Part number JC70/JC71

[BigGuy]

Is that part number for the screens or filters?

Thanks,

[crazycasey]

Originally Posted by razerwire

Yes, I lightly oil them and have washed them. Four dealers in States now. Part number JC70/JC71

Do you run the bases with a grommet like the picture I posted, or do you bolt them to the velocity stack hold-down/jet well location? I ask because I only have 1” of clearance over the stacks at my tightest spot, and I know ITG’s want a 3/4” gap between the stack and the inside of the filter. If I set them where they want to be, the bases are going to be sitting right on top of the jet well screens. If I bolt the bases to the carb bodies, I’m going to be a little tight on the clearance to the inside of the filter (about 5/8” according to the dimensions published online).

Thanks for your help!

[razerwire]

https://imgur.com/a/f7J6D
If you click on pictures they get bigger. one side of filter/screen hooks on and three quick screws hold it on. Hope I answered both questions. Foam and screen are bonded

[Gaz64]

Originally Posted by crazycasey

Do you run the bases with a grommet like the picture I posted, or do you bolt them to the velocity stack hold-down/jet well location? I ask because I only have 1” of clearance over the stacks at my tightest spot, and I know ITG’s want a 3/4” gap between the stack and the inside of the filter. If I set them where they want to be, the bases are going to be sitting right on top of the jet well screens. If I bolt the bases to the carb bodies, I’m going to be a little tight on the clearance to the inside of the filter (about 5/8” according to the dimensions published online).

Thanks for your help!

You would do better with something like this:
https://www.merlinmotorsport.co.uk/f..._tray_dims.pdf
Allows the base to be fitted flat without the screens, don't need them since they will be supplied with filtered air.

Also allows much easier jet removal than some other setups.

[crazycasey]

Originally Posted by Gaz64

You would do better with something like this:

After looking at some of these pics I’m amazed at how much room some of the Cobras have. I have 1” at the lowest point from the top of my stack to the underside of the hood. Going by the measurements online, if I flat mount the bases (I’m going to have to dimple them or something to clear the needle valve plug) I will have 5/8” above the stack and the filter itself will just touch the bottom of the hood. Certainly not ideal, but I don’t see any other way to do it other than to try and lower the engine.

[razerwire]

Would there be enough material to mill top of manifold to lower carbs?