Jeep Enthusiast Forums banner
Cancel
Create thread New Garage Forums

Air intake for Weber

Jump to Latest
1 - 20 of 36 Posts

Renegade82

· Registered
Joined
·
5,341 Posts
Discussion starter · #1 ·
I know a lot of folks out there have put Weber carbs on your 258's. I have a new one (32) but I got it with the small rectangular K&N filter instead of with the stock air cleaner mount. I'm wondering how one performs over the other, because due to the hot air under the hood I'm contemplating either ordering the adapter to use the stock air cleaner snorkel or fabbing a rectangular one out of sheetmetal and ducting it to the stock grill intake port. I'd prefer to be able to leave the big stock snorkel off if possible.

My concern is two fold, one is the hot air from the engine when moving at a snails pace. And the other is having the filter element exposed to catch any water (from the road/trail), or anti-freeze splash should a leak occur.

Maybe some schooling on airflow to the carb is in order from one of you technical experts. I know that engines prefer cold air over hot air, but how much effect does it really have? And what about the exhaust manifold heat riser that should activate on cold morning start ups, is that a concern?
:tea:
 
#2 ·
Dont know if it helps or not buy i too have the weber.... originally had rectangular filter on it. Ean fine in Texas heat. Now I have the adapter as I like the look better of oem air cleaner. I dont detect a difference in the way jeep runs but now i can use the air hose originally designed. Have pics if interested.
 
#3 ·
Renegade82,

The last heated exchange I had on this forum was over this subject, so I'm a little hesitant to comment.

Here's how I look at it. AMC engineers put a lot of time and effort into designing the factory breather. They made it draw heated air from the exhaust manifold when cold, and fresh cool air from the outside when warm. I don't presume to be smarter than the engineers, so I assume they had valid reason for designing it this way, or why would they do it?

I can tell you this, those dinky little open filters last about 2 weeks where I live. If you never have your CJ off the pavement, they may last longer.

Matt
 
#5 ·
Get adapter to use stock air cleaner......
 
Save
Reply Quote Like Like
#6 ·
I would use the stock air cleaner assembly as well because as Matt1981CJ has said, AMC Engineers design it for the purpose of keeping hot dirty air from entering the engine and to help start and run the engine during cold start ups. It also serves as a snorkel to help prevent your engine from ingesting water. I know that one all to well from a Toyota 4x4 pickup that I use to own where I put on a open element filter that soon became clogged with dirt and water. The engine ingested that crap and the piston rings were shot to a point it used to burn more oil than gas.

I'm currently looking into getting a Weber 38 to replace my 32/36 carb to gain a few more ponies but they don't make an adapter to use the stock air cleaner with it. I say "doodly-squat" to that, and will modify the one I have now or make another from scratch.
 
#8 ·
I called and asked them and they said the 38 is different around the intake castings. I looked at a lot of closeup pictures, including ones that you had taken, and can't really see a big difference except in the front were the metering jets are. I don't think it would be a problem either.
 
#10 ·
Here what I know on this subject. AMC made the manifold to be heated by the coolant to help keep the fuel in suspension. I know it sounds contradictory since a cool air charge will deliver more oxygen to the cylinders than a hot air charge.
The 6 cylinder inline manifold is probably the worst way to deliver air to the engine since its a log with three different length of intake runners. Cylinder 1 and 6 have the longest runners, 2 and 5 have medium length and 3 and 4 have the shortest length runners.
The air charge goes through the carb or TBI and slams down into the floor of the manifold then it has to make between three to four 90 degree turns before it enters the combustion chamber. The intake manifold heater has spikes on it to create turbulence to help keep the fuel in-suspension along with giving my surface area to heat the air. At any of the changes in direction fuel can condense in the manifold thus creating a lean condition so by heating the air charge the fuel is more or less a vapor instead of a mist.

I will touch on a related matter here while I am answering this. The stock manifold performs better than the aftermarket manifold such as Clifford or Offenhouser hands down. And the reason is the size of the aftermarket intake runners are large and that slows the velocity of the air and that allows the fuel to come out of suspension at low RPMs thus causing hesitation at lower RPMs. The dirty secret is that these manifold were designed to run at high RPMs such as desert racing and they work well at that. Jack Cliffords philosophy was give the engine what ever it wants at high RPM. But few of us here race our Jeeps so adding a aftermarket manifold is just an annoyance when driving the Jeep under normal conditions.

Adding a cold air type kit in this scenario really will not help with any performance since any cool air is heated by the engine anyway. Now having said that if your worried about water entering your engine do a snorkel or something like that.
 
#11 ·
gmakra said:
Here what I know on this subject. AMC made the manifold to be heated by the coolant to help keep the fuel in suspension. I know it sounds contradictory since a cool air charge will deliver more oxygen to the cylinders than a hot air charge.
The 6 cylinder inline manifold is probably the worst way to deliver air to the engine since its a log with three different length of intake runners. Cylinder 1 and 6 have the longest runners, 2 and 5 have medium length and 3 and 4 have the shortest length runners.
The air charge goes through the carb or TBI and slams down into the floor of the manifold then it has to make between three to four 90 degree turns before it enters the combustion chamber. The intake manifold heater has spikes on it to create turbulence to help keep the fuel in-suspension along with giving my surface area to heat the air. At any of the changes in direction fuel can condense in the manifold thus creating a lean condition so by heating the air charge the fuel is more or less a vapor instead of a mist.

I will touch on a related matter here while I am answering this. The stock manifold performs better than the aftermarket manifold such as Clifford or Offenhouser hands down. And the reason is the size of the aftermarket intake runners are large and that slows the velocity of the air and that allows the fuel to come out of suspension at low RPMs thus causing hesitation at lower RPMs. The dirty secret is that these manifold were designed to run at high RPMs such as desert racing and they work well at that. Jack Cliffords philosophy was give the engine what ever it wants at high RPM. But few of us here race our Jeeps so adding a aftermarket manifold is just an annoyance when driving the Jeep under normal conditions.

Adding a cold air type kit in this scenario really will not help with any performance since any cool air is heated by the engine anyway. Now having said that if your worried about water entering your engine do a snorkel or something like that.
Click to expand...
That's why we should get something like this:

Image


or more specifically:
Image


Hook your snorkle up to this:
Image


Or something like this:
Image


Just kidding.
It would be cheaper to put a MPFI kit and a 4.0 head.
And never have to worry about heated manifolds again.

Image
 
#12 ·
i installed a weber carb on my jeep many years ago.

the previous owner did not leave me a std breather, so i used the breather system that matched up with my new carb.

it works fine, i first bought the k&n filter insert, but on the farm in very dusty conditions, all that (special oil) did was cake up the filter.

i am a ky redneck, what i learned in my low tech, school of hard knocks, more air flow means more dirt flow.

so i bought a regular air filter insert from one of the part stores and threw that k&n filter away. when i took the K&N air filter off the Jeep, it had a hole in the fiber material on the back side, guess you know how that made me feel, not for me.

not for my jeep, also took the k&N filter out of my dodge truck and when back the std 4" thick air filter.

if it good enough for Cummins, its good enough for me.
 
Discussion starter · #14 ·
Hmmm, never had issues with K&N filters and I've been running them for decades in my Jeep, from sandy socal trails to dusty Pa. mtn. roads. Have also used them in atv's and cycles. Cheaper than buying Fram's once or twice a year. But I can see issues when they're outside of a housing or not wrapped with a pre-filter.

That was one of my concerns. And thanks for the insight gmakra, makes sense to me. I guess I'll just use the stock snorkle housing, but I'll have to call to find out which adapter fits. They have a couple on their site but don't mention it fits a Jeep. Anyone happen to have a part numbers from theirs?

Thanks for all the replies.
 
#15 ·
Interesting thread.

If you run a K&N, it would be interesting to run an oil analysis and look at the silicon content. I have not done this, but those that have report a significantly increased Si content in the oil... grit getting through the filter.

Jeep used to supply an oil-wetted outer filter that wrapped around the paper element. This was intended to increase the life of the paper element, not to serve in place of a paper element. The wrap could be removed and washed, extending filter life. Unfortunately, this additional barrier certainly does not improve performance.

I expect the K&Ns do improve performance, but at the cost of less filtering. Likely does not matter on a street car, but for a Jeep that travels dusty trails, I would pass.
 
Save
Reply Quote Like Like
#17 ·
John Strenk said:
That's why we should get something like this:

Image


or more specifically:
Image


Hook your snorkle up to this:
Image


Or something like this:
Image


Just kidding.
It would be cheaper to put a MPFI kit and a 4.0 head.
And never have to worry about heated manifolds again.

Image
Click to expand...
Very interesting.

The side draft carbs are definitely the way to go on inline engines - IF you run a carburetor.

However, that's all mid-20th-century stuff. Cool and nostalgic, but not practical. Like John says, today, I'd just do the MPI thing.
 
Save
Reply Quote Like Like
Discussion starter · #18 ·
timgr - A K&N filter or a K&N type filter? There are many knock-offs out there today.

I just got off the phone with Carbs Unlimited (where I got the carb) and the adapter part # is 99010.600 for $33.95. But then I noticed John's link to Weber Carbs Direct so I went there and they have it for $19.95. Guess who's getting my money?!
 
#19 ·
timgr,
that is what i do for my old farm jeep as it is mostly a work jeep, pulling trailers to the garden around the farm fields, runing through plowed ground, grass, gravel roads, etc:

i use the std filter on my weber carb then i bought a foam pre air filter that wraps about the main paper filter.

the one i found that fits about the jeep filter was made to fit around a large lawnmower engine air filter

when it gets dirty, i take the prefilter off: wash it in kerosene, let it drip dry then a light coat of oil, then slip it around the regular paper air filter on the jeep. This pre filter keeps the heavy dirt off my regular filter.

this system has worked fine for many years, i do have to replace the foam outer prefilter from time to time as on the farm it gets very dirty.

but it keeps the regular filter much cleaner,

on a sunny day i take the main air filter off, if i cannot see through the filter material, i replace the air filter, these jeep engines do not need to suck dirty air or there will be problems.
just good maintenance, keep all filters and fluids changed

1984 jeep and it still works hard, runs and pulls good, is always ready to take the grandkids to the local filling station for a treat!!!!!
 
#20 ·
Renegade82 said:
I just got off the phone with Carbs Unlimited (where I got the carb) and the adapter part # is 99010.600 for $33.95. But then I noticed John's link to Weber Carbs Direct so I went there and they have it for $19.95. Guess who's getting my money?!
Click to expand...
Do you have a standard or power brake air cleaner assembly? Power brake units must be raised 1 inch off the valve cover in order to sit atop the Weber carb which is 1 inch higher than the factory Carter carb.
 
1 - 20 of 36 Posts
About this Discussion
35 Replies
13 Participants
Last post:
John Strenk
Jeep Enthusiast Forums
posts
19M
members
765K
Since
2000
A forum community dedicated to all jeep owners and enthusiasts. Come join the discussion about performance, engine swaps, modifications, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
TJ Wrangler Technical Forum General Discussion YJ Wrangler Technical Forum Jeep CJ Forum XJ Cherokee Technical Forum