Swapping vents on IDFs

[oprn]

[racecougar]

[ORANGECRUSHer]

Just updating this latest carb journey again.

I think sometime last week I swapped my mains. I had 140's in there and went to 135's. This was the first time actually pulling my main stacks without pulling the motor. First I had to loosen the band clamp on the air cleaner boots and then unbolt the air cleaners from their support frame. Then I could reach in the air box and loosen up the access hole cover nut. With the cover off I was able to reach into the airbox with some long reach pliers to grab and pull out the passenger side stacks. The driver side was too far under the body so I had use a shorter screwdriver to loosen them as well as a bent piece of wire to hook the stack and carefully pull it out. I wish I had something that fit the airhorns snugly so that I could pop it on them before reaching in there to loosen stuff up. It's only a matter of time before my retarded fingers drop something down there.

Anyway, after changing to the smaller 135 main I have hardly affected the WOT richness. I think I'm going to go to 130's today if I get time on my break at work. Just seems kinda crazy that I'm down to 140 mains on dual 44's and a 2110 and still getting 11AFR. It feels ok driving there. I could probably get away with leaving it, but that's not the point is it?

I have a feeling when I go to 130's, which are the smallest I have and the end of the line for now, my transition problem will comeback. That or I'll start getting popping or probably both. If that's the case, I will have to run the 135's and see what kind of difference I can make by changing the ignition tuning with the megajolt. I know the AFR can be affected using timing I just haven't read about it in awhile.

Don't think I should be this low in the main. Perhaps I should have gone back to the 40 IDFs? I kinda feel like this 2110 is on the fence when it comes to running 40's or 44's. I also wonder how much of all these problems I'm encountering come from that mystery cam I'm running. It has a high lift but duration was never measured. I was thinking it was very close to a 120 so I went with it. It was in a motor built for the dunes so it wouldn't surprise me if it was a clone. Never mind the fact that I can't be sure if I'm running the right rockers or not. Maybe they would like a slightly hotter rocker? Dunno. I'm not that savvy with engine building.

It's running good so I'm not complaining. Just reaching for as much efficiency I can get with my limited attention span and expertise. As always, feel free to comment if you got a thought. I can take it.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

Still scratching my head.
Runs almost the same on 130's except im seeing 12.5 more often. I like 12.5 to 13.0. With the 130's acceleration does not seem better. It might feel a little weaker despite the AFR still telling me I'm at lower 11's. WOT I'm around 12.5, but as soon as I let off and cruise I'm back to lower 11's. Leads me to believe I need to come down in my air jet to lean the middle more. I'm not getting any hesitation yet, but when I got back from a hot run down the highway, the oil alarm was going off and the idle was low. When I adjusted the idle mixes I could hear a little subdued backfire. Not popping out loud, just something you can hear when your head is down there and your paying attention. I turned the idle adjusters ever do little to keep it off the oil buzzer and then was on the idle mixes and curiously, I got the idle to come back but I don't feel like the mix changed any. Hot oil from running lean perhaps??

Maybe this latest O2 sensor is reading rich when it's actually lean? Might have to attempt the ole spark plug reading baloney. It's possible I go smaller on the air jet (170 or whatever is under the 190) and maybe give her a little more squirt if she begins to hesitate. Maybe take a little timing out to help with the temps?
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[BFB]

So re reading through your posts about your air boxes, it seemed after you built them you made a comment about the AFR being 11:1 vs the year before it was 13:1, is that right?

Are your velocity stack “extensions “ the same ID as the carb throat? If not you may have built in a version of a modulator ring. I 3D printed a various sized set and put them on a boosted buggy i was tuning. First time id ever used them and they definitely do work, too well in fact. His has 44 IDF’s and under boost , and only under boost, he’d go lean, like 15- 16:1. I dont remember what size(s) but one set of rings dropped AFR to 9:1, could’ve been even lower than that though because thats what the gauge bottomed out at. But that was all across the board, even on the idle jet side. No other changes were made aside from the rings.
I played with things a little and eventually made a set of rings that worked , not quite as well. Haha! I want to say that i think they were 42mm, so not much smaller than the carb throat. So if yours were even a few mm’s small it could make a difference. I’d pull the boxes off and run it without them , just with a set of velocity stacks, and see what your AFR is. That eliminate the possibility.
_________________
"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[ORANGECRUSHer]

Obviously, I had some thoughts already about the vents which is why I changed them. As for the riser, it is the same ID as the air horns(velocity stacks-same thing). So aside from the added 1.5-1.75" of riser between the where the airhorn ends and the vent begins, it should be the same dimensions.

As I was curious initially regarding how this lengthened riser combined with the vent size(36mm) was possibly changing how the fuel was being delivered. Going down to a 32mm vent cured my extreme hesitation off idle. So I think there was something to it. I know I say a lot of maybes, but maybe, what I really need is 34's. Step back a bit. Since I was too lean off idle with 36's and too rich with 32's. I don't think that's how vents work though. It's very similar to jets I suppose. Restrict air flow in and you get less atomization. Open it up too far and it leans out but then it also slows down and is less turbulent resulting in less mixing between the air and the fuel. That can cause incomplete combustion which ends up looking like a lean condition with black fuel squeezing out of every joint in your exhaust. See, I understand this stuff only enough to screw stuff up and not enough to solve the puzzles it creates with any certainty.

On top of the ID of the intake components, your intake tract length creates a frequency and can influence pulses in and out of the engine. I've effectively lengthened every part of the intake. What kind of difference is that making? My dumb ass doesn't know, that's for sure!

I imagine if I were to pull the motor and pull all this off and just have bare carbs running on there again, my jetting would be similar to what it was before I started this endeavor and I'm not sure what that'd tell me.

BFD, were your extensions different ID's or different lengths???? If was lengths then, yes, that could be a part of my issue.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

Possibly, a good test would be to remove my intake system and install carbs with risers equal to the effective rise in my airboxes and not install all the air cleaner mess and see what happens.

Maybe this is what you meant? Maybe. Just Maybe.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

One thing I do have to comment on is, and I'll probably jinx myself by saying it, I have enjoyed not having a single plugged idle jet this whole time. My carb throats look sparkly clean which never happened with the gauze filters.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

So I went to 175 air jets today. While it sounds clearly more lean, popping while warming up being the worst of it it still drives the same. Still 11's with WOT.

I figured the small airs would definitely lean out the top end but I was wrong. I am getting more 13's while cruising. I still haven't played with the timing mainly because last time I was in my tuning software it didn't display the map I have in the megajolt and I'm afraid if I start in with it I will end up losing the map in there and having to pull a new one out of my ass. I honestly have no idea which map I'm running right now. I had saved a few and I guess I will just have to take my chances if I want to tune further.

So at these settings:
130 main
52 idle
175 air
55 pump
32mm vent
10mm float
2.5-3psi fuel

I am experiencing increased leaness during warm up. Takes a little more to get it started, but then it warms up normally. Idling now around 11.5-12.5. Cruise is a solid 11.0 and WOT varies depending on rpms and can be anywhere from 11.0 to 12.5. Idle speed seems a little less stable.

I played with the idle quite a bit trying to get it centered on 12.5. It tended to want to be around 11 after the air change. This started getting me thinking about my IDLE AIR VENTS. The little holes drilled through the carb tops above the idle jet orifices that do the same thing with the idle jets as the air jets do with the mains. Last year, BRIAN E from the performance forum had suggested I try drilling them at one point. He said he's had to in order to improve problems with getting a good transition. When you increase it's ID you increase the rpms at which the idle circuit is still influencing the mixture just like how a bigger air jet will bring the mains in at a lower rpm.

I'm thinking maybe I have idle fueling all the way into my WOT circuit. It would possibly explain why I keep changing the Main circuit yet I can't get my WOT number to change. I'm curious if going to a smaller idle jet might choke the flow enough to lean out the top of the idle circuit. I'd just have to screw them out further to get the 12.5 mix I like at idle. I think I'll try this next. Do I have 50's??

I also think it's possible I have an issue with my accellerator pumps. After going to the leaner air jets I was turning in the pump nuts because I could see my AFR spike lean momentarily when I came off idle. Not enough to make the car hesitate, but it was there. Then I suddenly decided to turn the nuts all the way out effectively turning off the pumps. There was no affect. Nothing changed. Initially, I thought maybe things had leaned out without the pumps. i was seeing 13.5 more often for about 5 minutes and I was getting excited thinking I had stumbled onto something. Leaking pumps. But I think it was transitory maybe just maybe from sitting idling for a few while I turned those nuts or possibly fuel having gotten hot in the bowls. So I'm driving with 130 mains, 175 airs and absolutely no pump dialed in and it's behaving no differently albeit a little leaner at start-up.

Starting to scratch my head and think maybe I have something assembled wrong again....maybe my pump diaphragms are leaking?....maybe I need to give 34mm vents a try?....maybe I should go smaller on the main yet again???

It's just unheard of to be running a 120-something main in a 2110...But then again, most people aren't running an ignition with as much energy as mine. You'd think I had fuel leaking into that circuit somewhere, but the fact that the amount of richness is so consistent and anchored to one point... that doesn't happen with a leak. It would be more erratic wouldn't it??


I see you people sitting on the fence over there going at my "issues" and rambling lol
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[BFB]

Ok, here’s a link to CB’s modulator rings
https://www.cbperformance.com/product-p/7369.htm

And here’s a pic of the ones i 3D printed and that are in the boosted buggy i was telling you about.

As you can see they are short and these are only like 2 or maybe 4 mm smaller than the carb throat. So these being 44 IDF my rings are either 42 or 40mm ID ( i don’t remember which off the top of my head ).
CB is correct in their description, i have no way of testing whether or not these create a low pressure as they say but it does make sense and they definitely richen things up. It’s easy to see how theyd create a higher pressure above the carb in a boosted application but the ones i tested also worked N/A. My guess would be that itd be similar to extending the auxiliary Venturi which would bring the mains in sooner.
So my point yesterday was that if your air box tubes were even just 2 - 4mm smaller ( 40 -42mm on a 44 IDF ) you could be creating the same scenario as these modulator rings.

Me personally, i think you have something going on thats richening things up.
Are you sure all your jets are seated? I had a set of knock of IDF ( the ones pictured actually) that the main jet threads werent cut right and it felt like they tighten up but the jets werent actually seated in the carb so it ran pig rich.

The chokes, going from 36 to 32 , raise the air velocity and create lower pressure which brings your mains in sooner and helps eliminate that bog. It will restrict higher rpm but most of the guys i know arent pushing much past 5-5500 on street stuff anyhow, even if they could they dont seem to.
_________________
"how am i supposed to torque the rear wheel nut to 250 ft lbs??? " - clonebug
An interesting thing happens in forums where everyone starts parroting the same thing and "common knowledge" takes over.
Most experts aren't.

[ORANGECRUSHer]

Thanks for the info.
Those rings are interesting.
I have definitely brought the mains in earlier then with the 32's.

The thing that keeps messing me up is, even if they come on earlier, why can't I adjust the strength with the main? Why am I at 11 all the time with the pedal to the floor? My gauge goes to 10 so it's not like it's pegging out. Maybe the accuracy is off at the extreme ends? Doubt it. But if it were actually richer than what it was showing and that's why I wasn't seeing the mix change, then why don't I have a bog and why is there not soot coming out my exhaust. Those are two things I've had in the past so I know what rich looks like. I think I may pull my plugs and have a look. Maybe even do a WOT run on the highway and kill it and pull em on the shoulder and see what I see?

I have a feeling I have introduced some kind of weird effect I won't be able to counter. It's just strange though because this is not the first time anyone has used airboxes like mine. They all have risers inside. Maybe it's an imperfection in my carbs, but again, why did I not have the problem before I installed the airboxes? No I think it's a combination of things that changed and amplified when I tried the smaller venturi.

I'm at the smallest main I own. I have a 170 air I could change but that's probably not going to change my WOT afr. I also do not have smaller idles. So for now, I think I'll tweak my timing a little and see what I can come up with. Possibly try balancing again and just try getting everything spot on as I can and order up some 34mm vents in the meantime.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

In a week I'll have some 34's from CB and new rebuild kit. My gaskets were getting pretty ragged from all the messin around and they aren't all that great being chinese to begin with
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[ORANGECRUSHer]

Just found some of the tubing i used to fab the air boxes and it is indeed 44mm ID exactly.
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes

[BFB]

[ORANGECRUSHer]

Installed 34mm vents today. Then upped my airs from 175 to 190's. AFR is much more to my liking.
12.5-13 most of the time. Still jumps up to lean and then dives down to 11's when first accelerating but then it quickly assumes 12.5-13 through most of the WOT range starting to lean out slightly at the very top.

I can tell it's closer to where it needs to be when I'm rolling down the highway around 70 and it wants to keep accelerating. With the 32 vents it was the opposite constantly requiring more pedal to keep it moving.

My intention was to only change the vents and see what changed. Technically, I also replaced the pump diaphragm because I also ordered gasket/rebuild kits. A quick test drive showed me it was going lean on transition although I'm not sure it was hesitating. I immediately went back and changed out the 175's for 190's. Still a lean dive off idle (on the gauge), but I'm going to try adjusting the pumps to help with that right now. I only just got it together before work and drove it in so some more fine tuning is probably in order.

The way it wants to take off even from idle tells me I'm about where I want to be with it. It's interesting that I didn't need to change the idle or main jetting which are pretty small. So I'm gonna do another balance and see what I can do with the ignition tuning to smooth things out.

I think the 34's were the ticket. Interesting how they work.

130 mains
190 airs
52 idle
34mm vents
_________________
Brian H.

OrangeCrushERBerrien Warrior-2.4L Quad4-2x3 arms-1.5Fox coilovers-094-930CVs
LAZY MARY1970 Baja 2110cc-82mm CB forged crank-AA pistons/cylinders-Grant rings-1.1 vw rockers-CB serpkit-CB chromoly PRs-CB maxiflow filter pump-wix51515 filter-Dual 44IDF-cut/turned front beam-AEM wideband-Auber CHT-Donaldson Dual PowerCore filters-custom AL air boxes