The Stovebolt Site Forums The Shop Area Engine Shop Carb problem

55.2 3100 235 Rochester B carb. With the air filter off, I can adjust the A/F screw out about 1 1/2 turns runs fine(idle). Put the air filter on it dies. With the air filter on I have to adjust the A/F screw all the way in to make it idle, and as soon as I take the air cleaner off it dies. Air filter is new, I even tried one of those cheapo chrome air cleaner filters, same deal. Truck drives down the road fine, starts fine, last trip I got 15 mpg, which I think is good. Any idea?

TIA.

Brian

What air filter are you running?

Air filter pushing on choke or something on carb. Interfering with a cable or linkage or a butterfly or something is hitting the filter. Mechanical issue not air flow.

what bartamos says............when did this problem first start up. see if you are missing any beer caps...........just joking

I started to ask about air flow restriction in my first post but realized that the mechanics might be at play so limited my question to the basic info needed.
We still don't know what this "New" air filter is...

Has the carb recently been worked on?

It does it with two different filters. Old and New. But you are right, would like to see pics of both of them installed and pics of them on the bench. On another note: If he puts air cleaner on , adjust carb and it starts fine, runs down the road fine, what's the problem? You don't take the air cleaner off while driving do you? If it ain't broke, fix it? It could just be that this carb/filter set up runs only when they are tuned together, that's OK! Semi-normal.

Check the float level. A high or low float level can cause problems like this.

My air filter interferes a little with how the two cables work. When I have reinstalled the carb, I have had to fiddle with the cables to get around the problem.

http://s1184.photobucket.com/user/b...011-09-08140115.jpg.html?sort=6&o=28
This is the style air cleaner I have with a new Fram CA77 paper filter installed.---- With the choke open, and with the air cleaner base and filter installed, and the A/F mixture screw turned about 1 1/2 turns out it idles fine. As soon as I put the lid on top of the filter it dies.
Wrenchbender ret, this would be the carb I got off of you last Oct. Not complaining, just letting you know what I'm working with.
I'm in my sixtys and I never had a carb idle change that much on any engine I've had just by putting the air cleaner on after adjusting it.

Just a shot in the dark. If there is a vacuum leak, manifold, throttle shaft, or other, increasing the resistance on air entering the carb by adding the air cleaner may cause it to suck more air through the leak.

You are correct Shaker, it should not change idle too much, just some. The big question now is when did you put on the Carb and when did you notice all this? Did you just put it on after a year or did you just rebuild carb? What is the recent history here???

Shaker: Very different cable clamp than I have. But I don't think that is the problem. Metal mesh filter is very much like the filter I have with out the "basket" or "can" that I have. With just the diameter difference for air flow. With that said I have never had to adjust my air/fuel mix after putting the filter back on. I can't imagine that changes the air flow that much. Try pushing the cables aside with out the air filter in place and see what happens. I think you will see the choke butterfly move. And then you can figure out why. Just a guess of course but that is what I would try. Look for any leaks of course but I think this is mechanical. If I can figure how to post some pics I will tomorrow.

Bart it's been on since spring. It's probably been messing up for a couple of months now, and I just getting around to talking about it. With the air cleaner off it idles good. 20" vacuum and a steady needle. Carb has not been rebuilt since I had it, but looked like it could have been before I got it.

Steve, like I said with the base of the air cleaner on with the filter it idles fine, and you can see that the choke is open. Just setting the lid on will kill the engine, and the choke cable isn't being touched when I do this. I don't have the throttle cable installed yet.

So at 'normal' atmospheric conditions (no cleaner) it runs normally at normal (1 1/2 turns out) setting. Carb works as intended.

Put a nylon brillo pad over your mouth and breath. Next try a paper towel or three. If you can tell a difference I'd guess it's about the amount of fuel you need to reduce ("all the way in") to get to the ratio needed to combust when the new paper air filter is added.

From your description of putting the lid on, the filter must be affecting the air flow.

Brian, the Fram filter that your using instead of the wire mesh
spark arrestor is made for a much, much smaller engine. There
isn't enough surface area with a small paper filter so it
chokes it down. Replace the paper filter with the old wire mesh
and you shouldn't have any problems. If you're really concerned
with getting clean air to the engine then look for an oil bath
air cleaner that will fit that carb.
http://www.pbase.com/dennygraham/image/115069462/large

Denny Graham
Sandwich, IL

If you are correct, Denny, you win the "successful sleuth" prize of the day - good suggestion.

It is nice to see you posting more often. That oil-bath suggestion might get some interesting responses. Maybe someone will post a warning/belief that oil bath air cleaners are worthless (as has been posted recently). "if they are so good, why are they not used on modern vehicles?"

Denny, I had thoughts along the line of what you mentioned. But I can't grasp that there is that much restriction, for the small amount of air going through it at idle. But what you say makes sense, cause it runs fine till you put the lid on, and the all the air has to go through the filter. Big problem with a simple fix.

55 SHAKER: Try K&N website might have a filter about the same diameter that will flow enough and fit in your housing. Or try to find what Denny Graham posted. That is a good looking bath filter. The wire mesh you have must be clogged badly.

The filter you tried is for a 58 Cu In Simca engine!!!!(as Denny says). Your engine is 4X larger. So I'm not up on AD filters but: Is this a dry filter with just mesh? Did you remove the mesh and put in the paper? Did you leave the mesh in and install the paper? Will your old canister only take this 7" x 3" paper filter? Did you clean the mesh out real, real good? The air filters I have seen that have spark arrestors in them also take a filter. Is yours a spark arrestor/filter mesh all in one or what? Is the mesh not a spark arrestor as some have said? It seems like everyone already knows all this but I would like to know also. Having trouble seeing what you have and what you have tried, so I can give an educated guess as to what is wrong or understand the good suggestions. Denny says just use the mesh, isn't that what you started with and does not work when lid is put on? If it was me I would start with an EMPTY old canister with the lid on to be sure of the mechanical then add the biggest quality paper that fits and see. I realize you said you fitted it all up without cover and it ran good until cover installed. Take out everything inside canister first for a baseline. This will prove that it's the air flow not the canister shape, size or a mechanical interference. You don't need a spark arrestor. They are for boats, forestry equipment and various state requirements for OHV's.

These trucks came stock with the "spark arrestor" Bart. The only
other option was the oil bath filter, which by the way was a
pretty good filter, not as good as the "properly sized" dry
filters in use today, but pretty good.
And you are correct Bart, the paper filters that replace the
wire mesh and fit in the "spark arrestor" housing are for lawn
equipment engines.

Denny Graham
Sandwich, IL

Bartomos if you read his reply post on the first page he said it's a new paper filter which made me look again at the symptoms he described.

You say mesh filter I say Brillo pads and paper towels... It couldn't breath through the paper filter.
No AIR means less fuel and his need to adjust "All the way in".
Why people choose a certain filter over another and the issues that raises is the reason this place stays busy...
Do it this way... Try this?... Here's what I did...

It's Bartamos. Yes he put a new paper filter in but did he take all the mesh out and try, because as Denny says it's too small of a surface area to begin with and having the dirty mesh in there with it is too much restriction. Somebody please tell me what is inside this stock air cleaner. Some mesh you call spark arrestor? an additional mesh filter? Combo mesh filter/arrestor? Do they typically get all gummed up? I wouldn't have that mesh on there if you paid me.

guess he did not have spell check..lol

I remember when folks would run without air filter because some thought the sound was cool..

It does sound cool. Like a pretend gasser. Joker, I know you are behind this. I've had two different guys spell it that way tonight.

probably like me, can't spell worth beans... now,you just met Jack and
you dont know him or me..lol

back on topic, here is the cure to the air cleaner problem

here is the cheap one I had on my 52, worked well for me, drove that booger many yrs ever where..no problems

now, dont make fun of it..........worked really good

My spell checker didn't catch it for some conspiratorial reason, sorry bout that BartAmos...

I wasn't really caring so much What made it act that way as Why it needed to be starved for fuel to run...
I run the original filter with the mesh. Mine is like a nylon brillo pad/mesh.
Also,I just had a lawn mower refuse to run on the dirty filter a week ago so I get where the need for air flow and one of those filters comes from

Caso, you are so right.. I have seen lawn mowers not start because of a dirty filter and a truck run like crap because of one being dirty.

The mole is active, be careful. They are after me just like I predicted.

My air cleaner never had a spark arrestor or filter when I bought the truck. So when I got the truck together and running I just went to a flaps and found a paper filter that would fit. So with the help of my fellow stove bolters, and you too Denny. I've come to the conclusion that I have to come up with a better filtration system.---Thank you all for your help!!!!!!

Brian

Now.........after all this page after page of discussion, I
gotta come out of the closet and admit, that I've been running
a Car Quest 87373 paper filter in place of the stock mesh. The
87373 is made for the Kohler and Tecumseh 8 thru 16hp lawn
equipment, Had this filter in place since 2006, which amounts
to about 10,000 miles of driving on my stock 216.
Taint had any trouble with it and I've run the 'B' and a Carter
W-1 both over the years.

So.........where does that leave Brian? Back to square one???

And Bart, seems to be some cornfusion on your part as to what we
mean by "spark arrestor". That was the term that Chevrolet used
to describe the stock "air filter" that the 216-235 would have
come from the factory with. It refers to the whole unit, the
two piece housing with a wire mesh filter in between. This
whole thing is the "spark arrestor": http://www.pbase.com/dennygraham/image/121329450

Denny Graham
Sandwich, IL

I went out and looked at my other filter that did the same thing. And it's a CARQUEST #87373.

Thanks Denny. Shaker: If you tried the same thing as Denny is using and it won't run, then you are back to Square one. Square one is the carburetor, vacuum leak somewhere, choke getting sucked closed, float valve, etc. Boy if you had another carb to try, you would sure solve it quick. One day it seems like restricted air flow, the next day it seems like carb. Exhaust flapper OK? Return spring OK? check float level and drop.

easy fix, drive it without one for a few days,
if you have no problem then you know using
your filter is effecting it some way for sure..

It don't mess up now when I put the air filter on. I got me a 14" X 3" air filter mounted on there now with no change in vacuum reading when the filter is installed.

Thanks for the follow up Brian, to many find the problem and
never report back in.
Can't figure though why my 216 runs well and as you know I get
it out on the highway and run it a lot, like a trip to Princeton, via Dover.

Denny Graham
Sandwich, IL