1974 CJ5 258 with Weber 38 - backfiring issues - Page 3 - JeepForum.com
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post #31 of 60 Old 02-14-2013, 01:46 PM
Matt1981CJ7
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Nice work, Evan.

Where did your lean best idle settings end up with the larger idle jets?

Matt

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post #32 of 60 Old 02-14-2013, 02:08 PM Thread Starter
cj5huntingrig
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My idle speed screw is 1/8 turn in and my idle mixture screws are 1 1/2 turns out! E

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post #33 of 60 Old 02-14-2013, 02:25 PM
Matt1981CJ7
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Good deal. How different are those settings from the lean best settings with the smaller jets?

Matt
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post #34 of 60 Old 02-14-2013, 02:36 PM Thread Starter
cj5huntingrig
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I never really could find lean best idle with the factory 45s. I was maxed out on the idle speed screw @1/2 turn and my next yr screws ended up past 2 and a half turns out. the mixture screws are only good for about 2 turns out. E

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post #35 of 60 Old 02-14-2013, 02:37 PM Thread Starter
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sorry for any misspellings I'm using voice recognition on my phone

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post #36 of 60 Old 02-14-2013, 02:51 PM
swatson454
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Nice job on the idle jets.

I would, however, completely forgo the idea of larger air correctors and larger main jets. That's a tail you can chase to kingdom come. I would leave the current jets in place and swap your emulsion tubes from the current F-50s to F-7s. It makes a world of difference! You can even entertain dropping the air correctors down from 170 to 165 but I'm not at sea level so I'll leave that up to you.

Here's a shot of three options. Your current F-50 on the left, F-6 in the middle and the F-7 on the right. Those four, large holes above the fuel level in the emulsion well bleed off a lot of signal and make a pretty unresponsive, lean hole around 2,000 rpm. The F-7 makes for a much more responsive and powerful acceleration.



Either way, the emulsion tubes are where you'll find your performance gain.


Shawn

Live in a way that those who know you but don't know God will come to know God because they know you.
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post #37 of 60 Old 02-14-2013, 03:16 PM Thread Starter
cj5huntingrig
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Thanks Shawn for the great explanation. Vinnyabs made the same recommendation and it makes perfect sense. Especially now that I see your picture.
It sounds like I need to call Redline again. I'll let you know what happens.
All the best! Evan

Does anyone have a source for the F7 tubes? Ebay lists some from Canada...?

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post #38 of 60 Old 02-14-2013, 03:16 PM
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Shawn,

I was scratching my head over Evan using larger ACs, too. If anything, he could try a size smaller ACs, but it's not likely to change much.

Evan, just for comparisons purposes, here's the jetting that ran best at my 6000' elevation.

45 idles
135 mains
F7 emulsion tubes
170 air correctors.

Heck, if we get enough guys to play along, we could build a nice database of jetting specs based on locations.

Matt
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post #39 of 60 Old 02-14-2013, 04:20 PM
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You're quite welcome and here you go http://www.carburetion.com/Weber/WeberDGESParts.asp. Scroll down a bit and click the drop down bar to select F-7 tubes in the emulsion tube box: second box down in the center. You'll need two of them.

That's a sweet idea, Matt.


Shawn

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post #40 of 60 Old 02-14-2013, 09:14 PM Thread Starter
cj5huntingrig
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Thanks Shawn!

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post #41 of 60 Old 02-14-2013, 11:47 PM
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Deja vu! I remember those days! What PIA!! Once solved though it sure is nice! Even with my new 35's that combo puts out a nice response! Good luck E!

Earning an engineering degree one CJ7 hiccup at a time
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post #42 of 60 Old 02-15-2013, 02:05 PM Thread Starter
cj5huntingrig
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Ordered the F7s and viton needle and seat

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post #43 of 60 Old 02-20-2013, 12:51 PM Thread Starter
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Okay Gents, I'm still waiting for my F7s but in the mean time, I did a compression check again and checked my spark plugs. Compression is awesome and even on all cylinders.
These are my plugs. Please help me read/diagnose the plugs.
Also, I re-checked my intake manifold for leaks with carb cleaner and after soaking the intake down hard, it appears I do have a couple small intake leaks that I didn't catch the first time I tried the cleaner trick. This explains some of my problems but I still would like your input on the plugs. I'm assuming the differences between the cylinders is caused by my leak issues.
Thanks, E
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post #44 of 60 Old 02-20-2013, 02:58 PM
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Spark plug reading is hit and miss, but I'll take a stab at it....

#5 looks lean

#2, 4, and 6 look OK

#1 and 3 look rich

Matt
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post #45 of 60 Old 02-20-2013, 06:43 PM Thread Starter
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Could anything other than the intake leak cause the different fuel volumes in the different cylinders? Can sticky valves or lifters do this?
Thanks. Evan

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