Weber Set-Up and Tune Discussion - Page 30 - JeepForum.com

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post #436 of 1100 Old 07-03-2012, 12:44 PM
svenster
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roughly. a little lower than the inlet though

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post #437 of 1100 Old 07-03-2012, 01:07 PM
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post #438 of 1100 Old 07-03-2012, 01:16 PM
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Quote:
Originally Posted by swatson454 View Post
The 45 idle jets are definitely a no-go. I'm willing to bet 50s with roughly 1.5, possibly 2 turns out on the mixture screws, depending on which cam you have, will probably get you where you need to be.

A pair of F7 emulsion tubes (possibly even F5s) will wake that carb up like no other! I'm guessing the 155 main jets are quite a bit too large, as well. 150s will probably be good and you could even try the original 145s.

If you can get (assuming you don't already) a PCV inlet and a port for manifold vacuum to the distributor, install 50 idle jets and drop in those F7 emulsion tubes with 165 air corrector jets and 150 main jets, it'll be like a whole nuther beast.


Shawn

Edit: If you're set on running the fuel pressure at 4 psi, you might consider their 2.5mm viton needle and seat assembly.
I agree with Shawn, The Clifford manifold has very large ports and plenum which slows the velocity of air/fuel to each cylinder. Add a little longer duration camshaft, with no heat to speak of in the manifold and this becomes very sluggish at idle and low RPM. (I like the stock Jeep two barrel manifold the best)

The idle jets will probably be .55mm to .60mm depending on your altitude.
The 1.55mm or larger main jets are also just blowing fuel out the exhaust.

Shawns guide lines are very very close, and will definatley get you within the tuning specs that work so very well.

UPTILLNOW

Also, the larger Viton needle and seat is # 79519.250
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post #439 of 1100 Old 07-03-2012, 01:55 PM
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i have the 38 DGAS. that part number looks to be for the DGV, DGAV/EV carbs. am i wrong?
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post #440 of 1100 Old 07-03-2012, 02:00 PM
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Quote:
Originally Posted by svenster View Post
i have the 38 DGAS. that part number looks to be for the DGV, DGAV/EV carbs. am i wrong?
Nope you are not wrong.
This Viton needle and seat is for all DG & DF series carbs, plus the DFT's, ICT's, and more.

Also.. Edit Edit Edit...
You may be able to eliminate your pressure regulator, when using the Viton needle and seat. This will eliminate "potential" fuel delivery problems.
IMHO
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post #441 of 1100 Old 07-03-2012, 02:23 PM
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My Clifford manifold has antifreeze running through it, so it is heated. I bought mine a long time ago. I don't know if it is better it is just what I did. I will try to post a picture in a couple of days when I am in New Mexico.

CJ7 79 258 Clifford Stage II, intake, headers, cam, and head. Weber 38x38 w Cagle, Rancho 2 1/2 body Mallory dist and MSD, dual batteries Ramsey winch T18 Dana 20 with Teraflex gears AMC 20 ARB disc Dana 30 Lockright Aero 26 gal tank Tomken Machine bumpers and swing out spare tire. 33" procomp Xterrain tires.
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post #442 of 1100 Old 07-03-2012, 02:23 PM
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ok thanks. ordered. and yes coxhaus, mine is plumbed with coolant as well
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post #443 of 1100 Old 07-03-2012, 02:33 PM
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I hate to nitpick on a seemingly trivial point, but I think it's more important than most guys think. If this is your fuel filter, then I repeat, it needs to be re-configured.

Assuming it is, the filter is too low, and it's sitting too close to the exhaust manifold. Being to low will cause fuel to drain from the carb when you shut down, as it flows to the low point in the system. Having it sitting on the manifold, as it appear to be, will cause potential vapor lock issues.

Also, the fuel line from the filter appears to loop way down below the carb before it loops back up to the carb inlet. That's not correct...again, assuming I'm seeing your picture correctly.

Matt
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post #444 of 1100 Old 07-03-2012, 03:36 PM
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good eye matt. you are correct. i can re-route my hard line over the VC to help with that. but, i had to mount my fpr on the top of the fender well, which sits lower than the carb inlet. any suggestions? thanks for the nit pick btw. i'm sure it all helps in the long run.
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post #445 of 1100 Old 07-03-2012, 03:47 PM
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meow
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post #446 of 1100 Old 07-03-2012, 03:58 PM
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Svenster,

Here is how I have mine setup. Not that it's the only way, but it works well for me.

As you can see, I fab'd a simple bracket to mount my FPR in a appropriate spot.

Hope this helps,

Matt
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post #447 of 1100 Old 07-03-2012, 04:01 PM
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You could use this bracket 444.551-04. (about $8.00)
Mount your accelerator cable into it and eliminate ALL of the bell cranks, rod ends, and multiple adjustments. etc.
Just an idea, for reliable and clean installation...
post #445-B
UPTILLNOW
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post #448 of 1100 Old 07-04-2012, 01:15 PM
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But wouldn't the fact that sven is running the 4.0 head and a hotter cam, both of which flow much better than the 4.2 head... be enough to justify using at least 155 mains, or maybe 152's? And a 55 idles at the least?

Shawn set me up pretty darn good. I have headers, an HEI, and what's sounds like a stock to possibly a very mild cam in it.
Im currently running, 60 idle jets, 150 mains (they were 145's originally, then 155's), 160 air correctors, and F7 emulsion tubes (were F5's)

Absolutely purrs at idle... everyone thinks I have a 304 under the hood, pulls like a train all the way up to 3000rpm. The 4.2 just doesn't really flow after that... but I imagine the 4.0 head would keep keep flowing well beyond that, and require more fuel than the 4.2 would.
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post #449 of 1100 Old 07-05-2012, 01:13 PM
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Quote:
Originally Posted by I6CJ7 View Post
But wouldn't the fact that sven is running the 4.0 head and a hotter cam, both of which flow much better than the 4.2 head... be enough to justify using at least 155 mains, or maybe 152's? And a 55 idles at the least?

Shawn set me up pretty darn good. I have headers, an HEI, and what's sounds like a stock to possibly a very mild cam in it.
Im currently running, 60 idle jets, 150 mains (they were 145's originally, then 155's), 160 air correctors, and F7 emulsion tubes (were F5's)

Absolutely purrs at idle... everyone thinks I have a 304 under the hood, pulls like a train all the way up to 3000rpm. The 4.2 just doesn't really flow after that... but I imagine the 4.0 head would keep keep flowing well beyond that, and require more fuel than the 4.2 would.
The Clifford manifold with LARGE plenum and ports, the 4.0 head flowing much better than the 4.2, larger camshaft with more duration, all of this adds up to slow velocity at idle and low low speed. (slugish)

He is running .45mm idle jets and can't get it to idle on the idle circuit of the carburetor. (less than 1/2 turn in AND ZERO vacuum at the "S" ported vacuum source). By increasing the volume of fuel at idle (.55mm or .60mm) you are suppling enough fuel for the engine to run on. With the throttle plates above the enrichening hole, it is using that fuel to idle on and then he has a flat spot as when the throttle plates open, it does not have any enrichening holes to gain that extra fuel that is needed on accelaration.
BOOM... flat spot. (Speed screw 1/2 turn in MAXIMUM... Change the jets to find the Len Best Idle around 1 1/2 turns out.)

As far as the "extra" fuel from the main jets 1.55mm is a large jet. If you want to, try a 1.50mm main jet and see how much performance you may loose. We all tune with different goals in mind, like most power without black smoke out the rear, good power and without studder or hesitation, or just the leanest you can get without the lean problems, burnt valves etc.

This is when a better way to measure (wide band Lamda) performance can help guide you to better, burnable mixtures without going to "pig rich" as they say. I have been pretty lucky useing the seat of the pants method for main air and fuel adjustments. I have been on a few dynos that can control, record, and mearsure power verses air fuel ratios. Again, 1.55mm mains along with the .60mm idles is allot of fuel. Your F7's and 1.60 - 1.70mm air jets are great.

Hope this helps define my ajenda when it comes to lean vs rich main circuit jetting.

UPTILLNOW
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post #450 of 1100 Old 07-05-2012, 01:59 PM
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Quote:
Originally Posted by uptillnow

The Clifford manifold with LARGE plenum and ports, the 4.0 head flowing much better than the 4.2, larger camshaft with more duration, all of this adds up to slow velocity at idle and low low speed. (slugish)

He is running .45mm idle jets and can't get it to idle on the idle circuit of the carburetor. (less than 1/2 turn in AND ZERO vacuum at the "S" ported vacuum source). By increasing the volume of fuel at idle (.55mm or .60mm) you are suppling enough fuel for the engine to run on. With the throttle plates above the enrichening hole, it is using that fuel to idle on and then he has a flat spot as when the throttle plates open, it does not have any enrichening holes to gain that extra fuel that is needed on accelaration.
BOOM... flat spot. (Speed screw 1/2 turn in MAXIMUM... Change the jets to find the Len Best Idle around 1 1/2 turns out.)

As far as the "extra" fuel from the main jets 1.55mm is a large jet. If you want to, try a 1.50mm main jet and see how much performance you may loose. We all tune with different goals in mind, like most power without black smoke out the rear, good power and without studder or hesitation, or just the leanest you can get without the lean problems, burnt valves etc.

This is when a better way to measure (wide band Lamda) performance can help guide you to better, burnable mixtures without going to "pig rich" as they say. I have been pretty lucky useing the seat of the pants method for main air and fuel adjustments. I have been on a few dynos that can control, record, and mearsure power verses air fuel ratios. Again, 1.55mm mains along with the .60mm idles is allot of fuel. Your F7's and 1.60 - 1.70mm air jets are great.

Hope this helps define my ajenda when it comes to lean vs rich main circuit jetting.

UPTILLNOW
I'm using the whole Clifford setup also (intake,cam,headers,bigger valves, 4.0 head) along with a DUI. After about 6 months of screwing around with the 38, I found that .60mm idle jets are what works best too. My engine is slightly sluggish in the beginning, but around 2500 rpms it really has some power especially for a 258. Probably should have went v8 for all the money spent, but I ALWAYS look forward to driving my CJ5 to work everyday.
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