Weber filters

mtpockets · #1 (**permalink**) 03-03-2008, 01:25 PM

Ok, the motor is running real strong (open stack). If I put on the 2 3/4" standard mouth stack screens, it stumbles and pops.

Does anyone have any experience running filters on their Webers? If so, what brand? How did you get past the restriction from open stacks to filtered? I hate to touch anything now, it's running so well open stack.

Cobrabill · #2 (**permalink**) 03-03-2008, 02:00 PM

You re-tune them for the stack screens.Then if you switch to socks,you get to re-tune them again.and if you go back to open stacks,...you guessed it.Ain't Webbers fun?!!!

BigGuy · #3 (**permalink**) 03-03-2008, 02:01 PM

mtpockets - usually I run open or with just the screens.

I'll try to find the part # for my screens tonight. These screens are pretty wide and just keep birds and larger stuff out. Anything else that "filters" is too much and causes stumbing and worse.

.

Terry Brown · #4 (**permalink**) 03-03-2008, 02:40 PM

I ran without filters/screens for awhile but as much as I have invested in the engine I really want it to last.

After trying the screens, the nylon socks, RamFlo filters, and a couple home-made ideas I have settled on the individual filters made by K&N for Roush for their fuel injection stacks. They fit the 48s pretty well and do a much better filtering job when compared to the other options. Very limited impact on airflow. I do not need to make any modifications when running with or without them.

These slip on and off with no hardware. Rubber grommet fits over the stack. Not only do they work well, I think they look pretty good too!

Good luck.

Bxx1 · #5 (**permalink**) 03-03-2008, 03:04 PM

Beautiful Webbers!

Brownsville , CA?? Bet you have nice smooth country roads up there.

mtpockets · #6 (**permalink**) 03-03-2008, 03:38 PM

Terry:
They do look good. What's the part #. Did you tune them with open stacks first? If so, what adjustments did you make to the K&N filters? What jets are you running now. Our motors are similar. I'm running 408w, dyno 511 at the crank, 550 torque. Only has 500 miles on it and I also have lots invested, I'd like it to last. My last Cobra I put 12,000 miles on it in two years.

68gt500 · #7 (**permalink**) 03-04-2008, 04:38 AM

I am still running without filters, because the stack screens really disrupt the original tune.

Cause is probably that the pressure difference between the filtered Air on the stacks and the jets under the screen.

K&N also makes a filter that encloses both the stacks and the jets - that should not change the tune - at least in theory.

The bad part is that these filters will interfere with the export brace on my Shelby - so I have not installed them - yet.

Maurice Johnson · #8 (**permalink**) 03-04-2008, 07:58 AM

Has anyone come up with a simple manometer to measure the relative air flow efficiency difference between stack,sock, and filter element. Attach item to end of vacumn cleaner extension tube, fit a small venturi jet attached to a vertical u-shaped hose with colored water into extension tube, switch vacumn cleaner on, and compare change in water levels. A good "Sunday morning after church" physics challenge.

Terry Brown · #9 (**permalink**) 03-05-2008, 08:17 AM

Thanks for the kind words!!

Yep, the roads are great when the snow thaws. Had a bunch this year :-(

Yes, tuning was done without the filters. Tweaked the idle a bit after installing but it was minimal. Not sure the filters even changed the idle.

Sorry for the delay but I looked all over for the invoice and part number and haven't been able to find it. I purchased the filters from Frank at Hillbankmotorsports.com who is a spf dealership. I'm sure anyone who handles Roush engines can get them.

I think it is a Roush specific part made by K&N (K&N stamped on the chrome top ;-)

Ok, I found it!! --> Roush's part number is 401390. Their web site is:

ROUSH Performance : Online Store Ford Vehicles

You can download their catalog. The filters are shown in the last section of the catalog.

37 choke
F-7 et
60 idle
100 idle air
45 pump
60 bleed
160 main
170 air

Good luck!

Derald Rice · #10 (**permalink**) 03-14-2008, 03:58 PM

I tried the screens, could not get the motor to clean out. These are redline filters, clones of K & N's. Absolutely no problems.

mtpockets · #11 (**permalink**) 03-24-2008, 09:15 PM

Terry:
I just received the Roush K&N individual filters. Question, they slip over the stacks, what then? They slide up and down the stack, the fit isn't tight enough to keep them in the up position. Down all the way, it blocks off the stack. Another problem I have that you don't, my motor sits further back in the engine compartment. The stacks at the rear sit almost under the lip in the body the hood sits into. Scratching my head, trying to figure it out. How did you get your filters to stay up on the stacks?

Terry Brown · #12 (**permalink**) 03-25-2008, 09:02 AM

I went to the wider stack (3 1/4" I think) from Inglese (Comp Cams) for a tighter fit. I also had the old rubber grommets left over from the original screen set up. Using that grommet (I guess that's the right word - rubber part used to hold the screen on) the air filter fits much better. Still a little play but pretty snug.

Because I have one of the older SPFs my hood did not clear the filters in the back until I dropped to a 1 1/2" stack height instead of the 2 1/2". Does not seem to affect performance and with the filter on you can not see the height difference. That may help in your situation too. Stacks sell pretty quick on Ebay!!

If you'd like, I'd be happy to email pictures with the filters off. Let me know. You will be happy once you get them where 'ya want 'um.

Good luck - Terry

mtpockets · #13 (**permalink**) 03-25-2008, 01:15 PM

That helps lots, thanks for the intel. We're having our Texas Cobra Club Spring Meet this weekend and I won't have time to get them set up, but it'll be on my list when I get home. For now, I have "Outerwear" (hair nets my fiance calls them) on the stacks to keep trash, sand and small children from being sucked in. Thanks again for your help with this.
Bill

Flat-Tyler · #14 (**permalink**) 05-20-2008, 06:43 PM

I went with these filters. They don't sap anything like filter screens do. I paid $117.00 Shipped for 4. Anyone need filter screens?

Frank

ENTDOC · #15 (**permalink**) 05-20-2008, 07:09 PM

if you are running 37mm venturies you will never get a good flow on that motor with filters. Try 40mm

Snakebit · #16 (**permalink**) 08-02-2008, 07:02 AM

Pierce Manifolds has Weber filters that look like tea strainers but have a filter sandwiched between the 2 screens that filter down to .9 microns. They are tapered to match the curve of the stack and claim no restriction to the air flow.

Caprimaniac · #17 (**permalink**) 09-01-2009, 01:40 PM

Two weeks ago i ran my webers with K&N air filters much like Derald Rice & Flat-Tyler show on page 1 in this thread.

this weekend I tried a set of tea strainers as offered by Pierce (as Snakebit shows above).

My feeling was that there were more power with the K&N filters, although I have no proof whatsoever. And it's not a strong feeling either....

What I wanted to ask is: did anyone test these setups on the dyno?
(I know, I know: open stacks is the best....)

I think Mike from Germany (68GT500) is into something when he say the pressure difference between the stacks & inlet for main system may mess things up. ( I had a theory of this while running "pressurized" (from scoop) air into the air horns only and getting a bad running engine).

So therefore; Is large area K&N's surrounding the top of the carb is the best filtering solution available?

bobcowan · #18 (**permalink**) 09-02-2009, 07:27 AM

The tea strainer filters cost me 100hp. Yup, dyno proven 100hp.

Notice what happens to the fuel curve. I think you could get some of the power back by leaning it out a little. But you'de never get it all back.

Caprimaniac · #19 (**permalink**) 09-02-2009, 01:30 PM

Bobcowan!

Thanks alot.
Informative graphs, no doubt. And maybe toutching what I brought up: when covering stacks only, the other carb openings get a different air pressure or whatever which make them behave a little off track, resulting in the bad A/F ratio....

Can you inform us on what tea strainers were used in this comparison? The ones above?

Still miss a comparison of Tea Strainers VS K&N'S.

RS

bobcowan · #20 (**permalink**) 09-02-2009, 05:19 PM

The tea strainers look like this:

Of course, on the dyno the car is stationary and the hood is open. So all stackes get pretty much the same air flow.

On the track is a differant story. At triple digit speeds the air rushes into the hood scoop and heads for the back of the engine bay. The first few cylinders get staved by the venturi effect, and the last couple get force fed. So, I made this diffuser for the front of the hood opening. It's worth 6-8mph at the top end.

On the street, I use these filters. It's a custom made billit housing from Momar EFI, and K&N filters. It loses a few hp, and I do have to take out some fuel in the upper throttle ranges when these are on. But it's not nearly as noticable as the tea strainers.