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Unread 03-06-2014, 07:45 AM   #106
moto450r
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Quote:
Originally Posted by douglasbigland View Post
Do you guys know if seals on the pump have to shaft?
There are no seals on the pump shaft itself. (see post #29). The gasket between the upper body part of the carb (where the pump shaft extends thru) and the middle body part of the carb (where the pump well is) provides the seal.


(Hat tip: 86cj74.2L and LumpyGrits)
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Unread 03-13-2014, 09:45 PM   #107
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Working on tuning the Jeep now after the carb rebuild, which includes the timing. The timing recurve has been taking more effort but since the carb and timing go hand in hand and I'm working on both in parallel, I thought I'd better post the fuel/air mixture info here in this thread rather than the 'timing' thread

I hooked up a totally redneck A/F gauge today. I was able to do this because the Jeep is now Nuttered. I was trying to keep the computer, but after changing the timing curve the Jeep still did not seem to run as well with the computer as it did without the computer.



After running the Jeep a couple times around the neighborhood it appears the carb is running 'Rich'. .80v - .85v was the reading while driving at any steady speed.

I adjusted the gap to .025 on the vacuum piston assy, dropping the metering rods down, but this didn't lean it out.

I'm thinking recheck the float measurement and since I'm at 2200ft the stock jet sizes are probably to big.
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Last edited by moto450r; 03-13-2014 at 09:46 PM.. Reason: spelling
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Unread 03-14-2014, 04:15 AM   #108
86cj74.2L
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.8 to.9 is a good idle mixture setting.

Do you know someone with a DVM to preform the same test again? The innova DVM from Walmart is not a bad deal for a toolbox meter.

Readjust the step up piston again.

You know, back out the idle screw and make sure the throttle plates are fully closed.

Then remove the cover plate and loosen the screw and push down on the needle to bottom out the spring and then retighten the set screw. That will make sure the needle assembly is in sync with the throttle plates.

Even with sloppy shaft bushings I was still able to effect the mixture by adjusting the Allen screw for the needles.
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Unread 03-14-2014, 06:11 AM   #109
Mike Romain
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Quote:
Originally Posted by moto450r View Post
Working on tuning the Jeep now after the carb rebuild, which includes the timing. The timing recurve
When I think on putting a hotter timing curve in, I always think folks do that only to match up with a hotter cam. Stock cam, stock curve. But hey I have been known to be wrong...

Something like putting a big 4bbl on with stock exhaust, lots of in and no out means choked.
Quote:
After running the Jeep a couple times around the neighborhood it appears the carb is running 'Rich'. .80v - .85v was the reading while driving at any steady speed.

I adjusted the gap to .025 on the vacuum piston assy, dropping the metering rods down, but this didn't lean it out.
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Making the gap smaller makes it richer. Pins in deeper to the needles needs a larger gap. 025 is full rich 050 is full lean. I run mine around 040 to 042 range.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 03-14-2014, 06:32 AM   #110
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From my experience, the advance curve on remaned Motorcraft distributers is a crap-shoot. Every one I've had has had a different curve, with a different advance head and spring combo. The one thing they all had in common was at least one ridiculously heavy spring that caused a lazy and flat curve. I had one that only provided 8* of centrifugal advance right out of the box. A normal distributer will provide 20-25* of centrifugal.

That's why it's often necessary to re-curve these beasts in order to wake them up. I think Moto can attest to this, as well.

Matt
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Unread 03-14-2014, 06:51 AM   #111
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Quote:
Originally Posted by Mike Romain
Making the gap smaller makes it richer. Pins in deeper to the needles needs a larger gap. 025 is full rich 050 is full lean. I run mine around 040 to 042 range.
Please explain this. I guess I don't understand how the vacuum piston assy works.

The way I understand it is, The metering pins adjust in or out within/above the main jets. Dropping the taper of the metering pins deeper into in main jet will 'lean' and raising the taper out of the main jets will enrichen.

Does decreasing the gap 'drop' the metering pins deeper into the main jets?
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Unread 03-14-2014, 06:51 AM   #112
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Quote:
Originally Posted by Matt1981CJ7 View Post
From my experience, the advance curve on remaned Motorcraft distributers is a crap-shoot. Every one I've had has had a different curve, with a different advance head and spring combo. The one thing they all had in common was at least one ridiculously heavy spring that caused a lazy and flat curve. I had one that only provided 8* of centrifugal advance right out of the box. A normal distributer will provide 20-25* of centrifugal.

That's why it's often necessary to re-curve these beasts in order to wake them up. I think Moto can attest to this, as well.

Matt
I can easily buy that. Last year mine died and I bought a non computer engine one for my 4.0 hoping to see a nice boost. Got nothing at all extra that I could feel.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 03-14-2014, 06:53 AM   #113
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Quote:
Originally Posted by moto450r View Post

Please explain this. I guess I don't understand how the vacuum piston assy works.

The way I understand it is, The metering pins adjust in or out within/above the main jets. Dropping the taper of the metering pins deeper into in main jet will 'lean' and raising the taper out of the main jets will enrichen.

Does decreasing the gap 'drop' the metering pins deeper into the main jets?
No. The gap works backward. Increasing the gap pushes the pins down.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 03-14-2014, 07:01 AM   #114
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Quote:
Originally Posted by Mike Romain
No. The gap works backward. Increasing the gap pushes the pins down.
I'm measuring the gap between the piston and the plates per the FSM, not between the tang and slot per the rebuild instructions . Is that the difference?
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Unread 03-14-2014, 08:46 AM   #115
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Quote:
Originally Posted by moto450r View Post

I'm measuring the gap between the piston and the plates per the FSM, not between the tang and slot per the rebuild instructions . Is that the difference?
My FSM shows the same for adjusting as the rebuild kit. The FSM is where I got the specs from.

Figure it this way maybe. The piston is fixed in place, the gap is below the piston so more gap means the pins go lower.

I posted a drawing of this part from my haynes manual and the gap a couple years back, but the censors on the group pulled it for copyright if I remember right.

Yours has the worn pins and odd sized jets right? I sure wouldn't change those jets to the same size or I would be expecting cylinders 4-6 to run too lean. There is a reason amc made the outer one different The pins could be changed which would Also lean you up a tiny amount.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 03-14-2014, 09:46 AM   #116
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Quote:
Originally Posted by moto450r
I'm measuring the gap between the piston and the plates per the FSM, not between the tang and slot per the rebuild instructions . Is that the difference?
Go the other way with the Allen screw and watch your meter. You know soon enough.

I've been known to pull into a parking lot and tweak the needles.
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Unread 03-14-2014, 09:54 AM   #117
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My FSM has the vacuum piston settings on page B-233 and the drawing of the parts on page B-245 and I sure see what you mean about a crappy view of the gap!

The carb rebuild kits have a proper view. There is a notch there.

They do at least say that turning the adjuster screw clockwise makes it richer. Clockwise pulls the pin plate up.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 03-14-2014, 10:19 AM   #118
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Quote:
Originally Posted by Mike Romain View Post
My FSM shows the same for adjusting as the rebuild kit. The FSM is where I got the specs from.
Thats interesting because there is a difference between the FSM and rebuild instructions that both 86CJ74.2L and I have. See posts #20 and #26 on page #2. Depending on which measurement point is used, will determine if a bigger gap or smaller gap will make it leaner or richer. LumpyGrits thought there was a SB that clarified which measurement to use but I haven't been able to find it.

Quote:
Yours has the worn pins and odd sized jets right? I sure wouldn't change those jets to the same size or I would be expecting cylinders 4-6 to run too lean. There is a reason amc made the outer one different The pins could be changed which would Also lean you up a tiny amount.
Yes, one of the pins was worn and they were the wrong # also. I have 2376 rather than 2384.
That is good to know why the jets were two different sizes, thanks!
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Unread 03-14-2014, 10:21 AM   #119
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Quote:
Originally Posted by Mike Romain View Post
My FSM has the vacuum piston settings on page B-233 and the drawing of the parts on page B-245 and I sure see what you mean about a crappy view of the gap!

The carb rebuild kits have a proper view. There is a notch there.

They do at least say that turning the adjuster screw clockwise makes it richer. Clockwise pulls the pin plate up.
Rodger that.
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Unread 03-14-2014, 10:22 AM   #120
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I have always used the rebuild kits directions to get my results.
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89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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