Air Filter Element

[billiard13]

What's the best filter to use on a Weber? 1 1/2" or 2 1/2"? What are the pros/cons or advantages/disadvantages if any? Is there a specific application for these or is is simply preference?

Thanks guys,
Claud

[namba209]

My personal opinion is get the largest that will fit. Better to have too much filter, almost impossible, that to have too little, a bad thing. The smaller filter may plug up and restrict flow,whereas the larger filter may plug up but still have ample filter area to allow air flow through it. JMTCW.

Ron

[jimsky]

K&N air filter will provide excellent filtering and the highest volume air flow. And make sure the air you're feeding your engine is "cold air", not the stagnent warm air from under the hood.

Either use the OEM snorkle and pop a K&N air filter element in it (see p/n in Product Reviews) or make a custom cold air intake. I've seen people use an adaptor on top of the Weber, run some 2" to 3" pipe or hose up to the front engine wall, then install a Rice Boy tapered cone K&N filter somewhere above the battery on the other side of the front wall.

You don't want forced or ram air, that will screw things up with the carb.....just lots of cool, fresh, dense air.

[billiard13]

I found a 'K & N Custom Plenum Weber Adapter'...which appears to be what I need to fashion a cold air intake to attach to my carb. One question, how do I know which one to purchase as they make several models?

Looks like maybe the 'Mini-Plenum' along with the DGV adapter?

(found this link.....http://www.knfilters.com/Racing/plenum.htm)

[billiard13]

Wow! Checked pricing on the plenum adapter at Advance Auto and it came up 229.99 for the plenum and another 97.xx for the Weber adapter??? Are these numbers correct or did I pull up the wrong products?

Are they serious? An adapter and plenum over 300 bucks for a carb that sells for less than 300 bucks?

Wow, how disappointing.

[jimsky]

Check out the adaptor listed in the Product Review section:
http://opelgt.com/rp/showproduct.php...7&cat=3&page=1

[billiard13]

Awesome, thanks Jimsky!

[kwilford]

I bought a new 38 DGAS off eBay last month, and it came with the plenum adaptor that Jim provided the link for (a very nice piece, by the way). I was hoping the throat dimension would be close to the stock air filter outlet and rubber bellows connection, but it is MUCH smaller (only 2 1/2 inch diameter versus probably 3 1/2 inch). So I will have to fabricate some kind of concentric reducer or bushing to get them to work together.

Or you can do what George Rust did (opelenvy) and just use a 2 1/2 inch inlet pipe with a K&N filter. It looks a bit "rice burner", but George did a beautiful job.

Another choice is to do what John Warga (here in Calgary) has done. I don't have photos, but he found that the throttle body cap (very similar to the plenum shown, made of black cast aluminum, with fins and everything) from a Chevy Corsica had the right throat size to adapt to the stock Opel air filter. Then he used a rubber closet flange adaptor (yep, from a toilet, which he discovered on a hardware store's shelf) and cut out the base to fit the Weber carb. The Corsica throttle body cap fit it PERFECTLY. If I get the chance, I will ask John to provide some details.

HTH

[Chuck Luther]

Got the one from Jam engineering on the product review page - 62.00 and 8.00 for shipping. I like it, its amazing the height difference between the old and new. I just recently bought the Formed Hose for a STOCK GT air cleaner for the return PCV breathing -- from OTGS - and now it doesn't work with my new setup... planning ahead right? doh.

What are some other options for this hose? I see opelenvy has a killer set up, but from the picts on his site I can't quite see what he had done with this hose.

Also if you look at the bottom right pict "snug" there is a shot of the clearance of the butterflys on the carb... its a tight fit. is that restricting? or should I get a spacer made? to bring that clearance up?

thanks in advance anyone!

[opelenvy]

I tapped and drilled a hole in the pipe and then threaded in a pipe threaded 1/2" fitting. I had a nut to put on the inside to hold it on, but it threaded in tight enought that I didn't even need it.
HTH

[Chuck Luther]

Thanks opelenvy!

I'm assuming the pipe that you built to go to from the adapter to the air filter... not like the side of the actual Weber part... am I right?

what about the clearance..? did you worry about that?

[opelenvy]

Originally posted by Chuck Luther Thanks opelenvy! I'm assuming the pipe that you built to go to from the adapter to the air filter... not like the side of the actual Weber part... am I right?

?? I don't understand the question. Yes I built the pipe. You can see the details on http://www.opelgt.cc

what about the clearance..? did you worry about that?

No, I did not worry about the clearance. I don't recall it even being an issue.
I would go check, but I have my hands full with two kids and a minor surgery haven't been in the garage much in the last couple days.

[Chuck Luther]

opelenvy thanks for the quick answers... you do have your hands full!! yeah, by pipe I meant what you did...off the side of the pipe for the positive crank case vent. I had checked your site out previously but I didn't check out the full details. duh.. you have it explained quite well.

where do i get one of these? " I used a 2.5" mandrel bent "J" pipe for $23 locally"

I found this page... that I could order one.. did you just get it from an exhaust shop?
http://www.magnaflow.com/02product/hardware.htm

[opelenvy]

That's what I used (the "J" pipe). I got it locally at an exhaust supply shop. They have them at JC Whitney as well. http://www.jcwhitney.com I think.