A/F Rich when cruising

GARRICK.CLARK · Posted: Fri Jul 24, 2015 11:01 am Post subject:

Hi Guys. Sorry to butt in. I'm also doing emulsion changes and air jet changes trying to get the low speed cruise AFR in the right place. I have just done the wire trick to the air jets / emulsion tubes. I got some 0.8 stainless mig wire and slotted it into the 160 air jets and down into the emulsion tube. The wire stop at the bottom of the E tube. The wire trick saves buying more air jets. Now what size is a 160 air with 0.8 mm wire filling the hole. I will check the outcome of this tomorrow. Also could someone please put a picture up on site of an emulsion tube and point out which part of the tube would be idle/mid range and WOT.
This would help me and others understand more about how the tubes work. The holes in the tube are to create a leaner mix at a certain rev range is it not. So If i could find the low speed cruise area of the E tube I could add another hole or 2. Or maybe enlarge the existing ones.
Cheers.

Doug Berg · Posted: Fri Jul 24, 2015 11:51 am Post subject:

Using the radius squared x pie (3.1416) gives you the area of the hole,,, (160 = 2.01 mm of area) (the .8 mm wire = .502 mm of area) so (2.01-.502 = 1.508 mm of area) which is equal to approx. a 139!!! The idle jet feed's the progression circuit,,, which control's low speed A/F up to part to 1/2 throttle where the main (e-tube) begins to come on!!! Doug...

Baja_Tommy · Posted: Fri Jul 24, 2015 1:44 pm Post subject:

Wouldn't the wire affect the flow of air through the hole as well? There would be more surface area for the air to flow over than if you just had a smaller hole.

It seems like I need to go further with the emulsion tubes, since those made the big difference. I could block some of the lower holes on the F2s with tooth pick tips and see what happens.

Or I could drill out my 50 idles, since they don't work for me anyways.

About the progression holes and the idle speed adjustment needing to be around 1/2 turn in at idle. I'm just about 1 full turn in at Idle with the air screws turned way out. It seems I still have part of the progression holes uncovered. I haven't taken the carb off to make sure though.

Image may have been reduced in size. Click image to view fullscreen.

http://www.clubcobra.com/photopost/data/500/emulsionTubes.jpg
Ive tried the F7, F11, 2, and F15 with best results from the F2 and F15. That makes sense, since it says lean low end for those two. From the picture above, I would guess the lower holes richen up the lower rpms.
_________________
A Baja Bug with some power is like a dirt bike. Quick not fast. Fun at low speed but scary at high speed.

If you're too old for dirt bikes, get a Baja Bug!

modok · Posted: Fri Jul 24, 2015 5:14 pm Post subject:

Emulsion tubes only change the fuel curve about 10%.

You need to figure out if the rich spot is main, idle, or both, or what rpm and throttle position before further tinkering. i can't get more specific than to say.... If fitting a 10% smaller main jet does not "fix" the problem spot, then the emulsion tube will not fix it either.

If you could narrow down where this rich spot is then maybe I can tell you what to change to fix it, but as it is I don't know what to tell you.

j-dub · Posted: Sat Jul 25, 2015 12:54 pm Post subject:

Can someone post a picture of the welding wire trick on the air jet or emulsion tubes. I am looking for examples just to make sure I understand the implementation. I understand the reason, to make the hole smaller to lean it out less at that particular point.

Thanks,
Jeremy
_________________
1957 Oval rag
"POLICE STATION TOILET STOLEN ... Cops have nothing to go on."

GARRICK.CLARK · Posted: Sat Jul 25, 2015 2:08 pm Post subject:

Hi Jeremy. I don't no how to post pics but what I did was to get a length of 0.8 stainless wire thread it down the air tube till it stops. Hook it round so the wire fits in the screwdriver slot and the rap it round the air tube a few times and snip off the excess wire.
I've got 36mm vents in my 40 Dell's. I would have thought going to a 36 would help delay my mains but its not. I see 13.1 AFR at 60 mph. How guys can get there motors to cruise in the 16's is beyond me.
I'm gunna try a 2mm lower float height next.

käfertom · Posted: Mon Jul 27, 2015 7:20 am Post subject:

GARRICK.CLARK · Posted: Mon Jul 27, 2015 7:38 am Post subject:

Hi. Could you tell me. How did you plug the holes. I may need to plug the 1st progression hole on mine to go leaner on cruise.
Cheers.

GARRICK.CLARK · Posted: Mon Jul 27, 2015 7:38 am Post subject:

Double

käfertom · Posted: Mon Jul 27, 2015 8:45 am Post subject:

Hi.
I don't know the exact english term. But this is from product url:
"liquidmetal epoxy resin adhesive"
Hope that helps.

It was exposed to gasoline more than a year without any affect.

käfertom · Posted: Mon Jul 27, 2015 9:07 am Post subject:

rs58rag · Posted: Mon Jul 27, 2015 6:37 pm Post subject:

kafertom......difficult to see top drilled holes in progression circuilt, but they look like someone opened them up. Measure them, could be the culprit.

käfertom · Posted: Tue Jul 28, 2015 3:14 am Post subject:

j-dub · Posted: Tue Jul 28, 2015 6:41 pm Post subject:

modok · Posted: Wed Jul 29, 2015 4:52 pm Post subject:

nope sorry. I use solder.

j-dub · Posted: Wed Jul 29, 2015 6:37 pm Post subject:

modok · Posted: Wed Jul 29, 2015 7:00 pm Post subject:

lead/tin/silver
62/36/2

You could use any kind of solder, but life is short, use the expensive kind! It flows nice

Oh, and rosin flux and a tip cleaning set for acetylene/oxy torches.
Coat a tip cleaner in flux and just clean/flux the hole. that way the solder goes in the hole instead of everywhere except in the hole.

Baja_Tommy · Posted: Sun Aug 09, 2015 2:28 pm Post subject:

I drilled a 1.6mm(1/16") hole in both of the throttle plates. Once I richened up the Idle adjustment, the idle speed was higher(1200 rpm). With the idle speed then adjusted back down, other than this change to the idle, there were no other noticeable changes with the holes and the air bypass screws open. No noticeable change to the rich spot.

I just remembered that I forgot to check the positioning of the throttle plate relative to the progression holes. That would have been helpful.
_________________
A Baja Bug with some power is like a dirt bike. Quick not fast. Fun at low speed but scary at high speed.

If you're too old for dirt bikes, get a Baja Bug!

käfertom · Posted: Tue Aug 11, 2015 6:24 am Post subject: closed fourth transition hole

I made a first test with closed fourth hole. This must be right way. After the 55s were crazy rich I changed the idles to 50s. Still rich (11:1) but at every speed below 65 miles with no rich spot. Then Car went to 13.5:1 on emulsion tubes and 12.5:1 on main jets. Now I change to 45 idles and F2 (from F11) emulsions. But testing that has to wait. I have to finish changing wheel bearings, brakes and axle boots.

But I am very confident with the carb mods.

käfertom · Posted: Wed Aug 12, 2015 12:26 pm Post subject:

Hi. The last test shows that the acceleration/half throttle situation is a little lean with the E/T F2. But the other readings are really well. And after changing to F7 the readings are extremely well. The car runs always between 12 and 13:1. It is only dependant on road nature. The only negative thing I noticed is a short lean spot at opening the throttles a little more after start up.
This is the result from a short test drive and I will test'n tune a little more.

These are the recent specs:
2007cc CR 9.8 Scat C25 D/P Head 32x35.5
Single Weber 44 IDF 61
Venturi 36
Idle 45
Main 165
Air 160
E/T F7
closed fourth progression hole


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