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Discussion Starter · #1 · (Edited)
hello there,

i have some problems for probably jetting my weber.

first, this is the engine:

opel 2,4l (c24ne) CIH Block
P2E head (20E)
camshaft from 22E (very moderate, 67° overlap)

first i tried this setup:

...........................primary..........................secondary
main:...................142,5............................140
air correction:.....165..............................165
idle:.........................55................................50
emulsion:.............. f50................................f6
Venturi:...................3,5...............................3,5

at this point i had too lean acceleration . half throttle 14 AFR and more. @WOT high 13's
in cruising condition it was to rich: 13,5 AFR sometimes peaking to 11's

then i tried a jetting which i found for the 2500 commodore engine:

...........................primary.........................secondary
main:......................155.............................160
air correction:.....185.............................160
idle:...........................55...............................50
emulsion:................. f6................................f66 (should be an f6 but i only had one f6)
Venturi:....................3,5..............................3,5

this resulted in fairly good acceleration values but cruising went waay to rich.
now in constant speeds the mixture goes to 11-12 AFR

i tried 45 idle jets. but i couldn't see a difference.

i believe my particular engine setup (the whole thing is basically the opposite of an race engine) generates a very strong vacuum in idle. could that be the reason for very rich cruising AFR?


a friend suggested to try bigger venturis. i have some 4.5 laying around, but i'm a bit tired of trying around, not really knowing what im doing. maybe you folks can enlighten me.

thanks
Dän
 

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You might be better off with that engine running a 38/38 DGAS. I think a 32/36 is a bit small for a 2.4.
 

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Discussion Starter · #3 · (Edited)
i think i've read somewhere, that 2.4l is the upper end of the range for the 32/36.
see, i didn't want to build a sporty engine. it's more like a "gasoline tractor"
i'm not aiming for high horsepower or revs. i just wanted the displacement.
for you as an US american citizen, i don't have to tell u about the benefits of unnecessary displacement ;-)

just joking.

if it works on an 2500 6cyl, it should work on mine too
 

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Opel Rallier since 1977
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I'll make some suggestions to try:
  • Your cruise mode with that size of engine is going to be using the primary main circuits (much more than cruising on DCOE's for example). So that is probably why, when you enriched the primary main circuit, the cruise AFR got even richer.
  • Go back to the emulsion tubes that you started with, and the original main primary jets, and try some smaller main primary jet to get the AFR leaner for cruise only. Just worry about the cruise mode first for level ground and slightly uphill at steady speeds.
  • Once the primary seems better for cruise, then put in larger secondary jets (fuel and air) to try to get the acceleration mode richer.
  • Make sure that the power valve in the secondary is working and adjusted properly; that is part of the enrichment at WOT.
 

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They do use them on the 6-cylinder Jeep’s and other larger engines. Most people go FI or side drafts on those due to the downdraft 1.9 intake not being a direct bolt on without mods. We’ll assume that you have your timing dialed in without any vacuum leaks and you’ve worked out the mismatch issues bolting up your intake manifold to the 2.4 cylinder head. I’ll add on to What Manta Rallier just said.

The out of the box jetting (it sounds like you’re running a DGV) 60 140/165m F50 emulsion primary 55 140/160 F6 emulsion secondary what happened when you ran that, or have you tried that yet?

Can you get a good idle with a 60 idle jet and the throttle plates completely closed?
(idle speed screw about 1.5 turns in)
What’s the AFR just at idle?

Be sure that you see all three progression holes above the primary throttle plate.
If you’re opened too much there that would cause you to want to step down your idle jet because you’d be pulling extra fuel from your progression hole(s) causing it to idle too rich. Careful not to fall into that trap like I did.
This will have a big effect on eliminating the lean spot off idle if set up properly. 1.5 turns out from bottom on the mixture screw is about what you’re looking for when set up right judge the selection of the idle jet with that in mind.

Since you’re rich you might want to stay down in your main. Just remember air correctors usually have more of an effect on the top end, your mains have the biggest influence once you crack open the throttle plates. Don’t be afraid to come down on the air correctors if you’re too lean, try keeping your primary main to the 140 for now HTH
 

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Your idle jets are way too small, even for a 1.9. Here lately I’ve been stepping up to a 65 idle jet primary for the 2.0 conversion. The secondary is 55
 

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Detritus Maximus
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They do use them on the 6-cylinder Jeep’s and other larger engines. Most people go FI or side drafts on those due to the downdraft 1.9 intake not being a direct bolt on without mods. We’ll assume that you have your timing dialed in without any vacuum leaks and you’ve worked out the mismatch issues bolting up your intake manifold to the 2.4 cylinder head. I’ll add on to What Manta Rallier just said.
Ah, but he is running a 2.0 head!
 
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Detritus Maximus
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i think i've read somewhere, that 2.4l is the upper end of the range for the 32/36.
see, i didn't want to build a sporty engine. it's more like a "gasoline tractor"
i'm not aiming for high horsepower or revs. i just wanted the displacement.
for you as an US american citizen, i don't have to tell u about the benefits of unnecessary displacement ;-)

just joking.

if it works on an 2500 6cyl, it should work on mine too
My experience with my 2.0 was a huge boost in low end torque with the change from the 32/36 to a 38DGAS. It did come at a price, though, I had to suffer with much more power everywhere..
 

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Discussion Starter · #9 ·
@ opelbits: 38DGAS sounds good. but i'll have to stick to my carb for now.

thanks for the reply's. i'll try some of your suggestions out and keep you posted.
at first i'll count the turns on both screws. maybe with differerent idle jets

Make sure that the power valve in the secondary is working and adjusted properly; that is part of the enrichment at WOT.
i'm not sure to understand u right. how can i adjust the power valve?
 

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'Adjust' is the wrong word..... it is a spring loaded system that responds to the vacuum level in the manifold. Make sure the rod works freely, the spring is there and free, the passages are clear, and the diaphragm is not leaking. I just suggest looking at this since you're having lean issues at the more open throttle positions.

And it has not been mentioned but make sure the float level is exactly right.

I am a bit perplexed as to why enlarging the idle jets will improve this.... it will make light cruise mixture even richer. OP, are you have off-idle stumbles or hesitation? If not, then the idle jets are probably not the issue.... at least if I am reading the symptoms correctly.

It will help to connect a vacuum gauge to the manifold, and observe the vacuum level and RPM's at which each symptom is occurring. This will help you (and us) know what part of the carburator is in operation.
 

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@ opelbits: 38DGAS sounds good. but i'll have to stick to my carb for now.

thanks for the reply's. i'll try some of your suggestions out and keep you posted.
at first i'll count the turns on both screws. maybe with differerent idle jets


i'm not sure to understand u right. how can i adjust the power valve?
You may have heard of people that trim the springs on the full power valve. The factory set up is for it to lift up at about 14” of vacuum . If you have a high lift cam with a lot of overlap (which you say you don’t have) those are the people who trim the springs to put less resistance on it so it stays up and doesn’t flood prematurely. As Manta Rallier said, get a vacuum reading at idle from the intake manifold and let us know what it is.
RallyBob posted a very good way to test the opening pressures on your full power valve spring it’s the same full power valve as the 32/36 see post #13
38 weber tuning
Your engine should probably be pulling between 18-21” of vacuum at the manifold so I don’t think you’re a candidate to be modifying anything.

Also count the turns on (in) the idle speed and (out) on the mixture screw and let us know where those are at. When I was opening the idle speed too far on my 32/36 I went to a 55 idle jet, once I had that corrected by getting the speed screw closer to 1 1/2 turns in I put a 60 Idle jet in because the progression holes were not dumping the extra fuel and the idle was leaner. I have completely eliminated all lean/flat spots. All this was seen by using the air fuel ratio gauge like you are using, it’s a very helpful tool 🙂
 

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And the AFR is a great tool.... but it ought to be complimented with a manifold vacuum gauge too when you are tuning. The vacuum gauge is the best tool to figure out which circuit is (or should be) in operation for a given set of engine operating conditions once you are at cruise throttle settings or more... and that's how you figure out where to focus many of the tuning changes. Long before we had these nice wideband AFR meters, the vacuum gauge was being used, and the AFR does not give you the info that the vacuum gauge does.
 

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Discussion Starter · #13 ·
didn't had much time today. only little testing:
1st: no progression holes. its a slot. about 2 or 3mm long

2nd: ildle is almost perfect:

with the two 45idle jets its 1 + 3/4 turns mixture screw
with the 55primary and 50 secondary its 1 + 1/8 turns to achive 13,8-14,2 AFR (i tend to keep it this way)

1 + 1/2 turns speed screw with distibutor on ported vacc at carb
1 + 1/4 (or bit less) with distributor on manifold vacc (as i usally prefer)

speaking of: manifold vacc @ idle is 23"
 

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And the AFR is a great tool.... but it ought to be complimented with a manifold vacuum gauge too when you are tuning. The vacuum gauge is the best tool to figure out which circuit is (or should be) in operation for a given set of engine operating conditions once you are at cruise throttle settings or more... and that's how you figure out where to focus many of the tuning changes. Long before we had these nice wideband AFR meters, the vacuum gauge was being used, and the AFR does not give you the info that the vacuum gauge does.
You should get zero vacuum at the ported connection on the carburetor if the idle speed screw is properly adjusted. If you’re between 18-22” (Steady) at the manifold both are where you want to be.
Yes, if you haven’t done so already be sure that the float level is good
Weber recommends setting the height of a plastic float at 35mm from the bottom of the float to the bottom of the carb top plate (no gasket), with the plate held vertically and the floathanging downwards, making light contact with the needle valve.
41mm for the brass float, 10mm stroke.
There’s two stop tabs to adjust one for open one for closed.
I mark a popsicle stick up and use it to measure.

Best of luck! Let us know how things are shaping up 🙂
 

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didn't had much time today. only little testing:
1st: no progression holes. its a slot. about 2 or 3mm long

2nd: ildle is almost perfect:

with the two 45idle jets its 1 + 3/4 turns mixture screw
with the 55primary and 50 secondary its 1 + 1/8 turns to achive 13,8-14,2 AFR (i tend to keep it this way)

1 + 1/2 turns speed screw with distibutor on ported vacc at carb
1 + 1/4 (or bit less) with distributor on manifold vacc (as i usally prefer)

speaking of: manifold vacc @ idle is 23"
Interesting, is it possible someone modified your carburetor? I looked on the internet for some pictures of normal looking progression holes and came up empty. That would explain why you run rich at part throttle or cruise 😳

Your manifold vacuum sounds very good. Double check the ported vacuum (on the carb) at idle, should be zero, the speed screw sounds right on, it’s just something you can do to verify it is set up properly.

I’ll take some pictures tonight of one of my spare 32/36 progression holes to let you know what you should be seeing.
 

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Discussion Starter · #16 ·
@ cub: its a brass float an setting is correct at 41mm
i'll check ported vacc tomorrow, but i bet its zero
i'll double check the progression holes too. maybe i didn't look right

btw: the power valve should be fine, since everything with rubber on it is new in this carb

is it possible someone modified your carburetor
don't know. it came from a 2.0 ford boat engine with typical ford jetting
 

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Detritus Maximus
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Is there a chance this is a DFAV, not a DGAV? DF's were commonly on Fords. If so, does the DFAV have different progression holes? If it has a diamond shape around the choke horn, it's a DFAV.
 
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Here’s a picture (top) looking down at an old 32/36 DGAV the red arrow pointing to the lower single hole and the blue arrow pointing to the other two holes. The next picture is taken from the bottom just to get a better look at them. Taking a couple of pictures of your carburetor could help try to get a shot of the holes (easier said than done) you’ll have to crack open the throttle plate to see all three completely and a second one of the linkage to verify that it’s the DGV, DGEV or DGAV or as Opelbits mentioned the DFAV
20341DCE-7238-45EA-B4A5-A4BC089018B3.jpeg

6D880C69-ED7C-445A-99CE-1A3A0B8BF858.jpeg
 

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Is there a chance this is a DFAV, not a DGAV? DF's were commonly on Fords. If so, does the DFAV have different progression holes? If it has a diamond shape around the choke horn, it's a DFAV.
Article I copied and shared a few years back referencing the Holley 5200/Weber DFAV suggested "F" as the "football" shaped breather base as an easy identifier.

Harold
 
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