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Old 11-27-2016, 12:53 PM
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Sputtering at 65 MPH

I have an 89 yj with a 4.2, I am slowly but surely getting it running properly.

Right now I am trying to pass emissions; however the vehicle has been Nutter'ed and has the team Rush upgrades. All the emissions have been removed except for the factory air cleaner, the EGR, and the canister.
The other day after doing more work on the motor, I went for a ride, and on the highway doing 65mph, the motor started to sputter like it was starving for gas, it seems to run fine at 55-60mph.
Question: Does this sound like a fuel filter issue? I have a new mechanical fuel pump installed. Does the BBD need rebuilt? If anything, the carb, looks filthy.

I have replaced the timing chain and set the timing to 10 deg BTDC. To do this I timed it while running at 1600 RPM's.
Question: when I initially set the timing to the 10 deg BTDC, the RPM's changed, I then set the RPM back to 1600 RPM and adjusted timing again. Is this the way to do it?

When I did the Team Rush install, I set my spark plug gap to .035, my thought process is, that I did not upgrade my coil or add the Ford E-Coil.
Question: Should I adjust my spark plug gap to .045 even though I did not upgrade the coil, I do not want to go to the e-coil, but should I upgrade the normal coil?

The last time I was at the emissions station the vehicle was running horrible, and gave them enough reason to look under the hood, any other vehicle I take they never look under the hood, so by getting the jeep running well, I hope they do not look. (Fingers crossed)
To improve my chances of passing, I am hoping to get the vehicle tuned as well as possible, this along with a newly installed cat, air-filter, PCV valve, and running high octane fuel.

Thanks for any advice.

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Old 11-27-2016, 05:20 PM   #2
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With the Nutter, you should set the timing at idle with the vacuum hose disconnected and plugged. At least that what I do. I have a HEI. Both the HEI and the bypass the computer. Is your stepper motor disconnected? With the Nutter, it should be. You may have to reset the stepper pins.

DREDnot recommends a 3 way cat. The cheaper ones are two way and can contribute to a failed emission test. Keep track of the money you spend while trying to pass emissions. In Colorado, I believe there is a dollar amount limit, and then if you hit that limit you may be eligible for an exemption. Check the state website for additional information.

Don't go back to the same emission station.

Good Luck, L.M.

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Old 11-27-2016, 05:47 PM
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I did reset my stepper pins and it is disconnected. I have the Magnaflow High Flow Cat.
I plan on going to the Parker station next time.

I pulled my carb, there is a huge chunk missing from around one of the idle screws. I think there is leaking.
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Old 11-27-2016, 06:54 PM   #4
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I got my BBD from National Carburetors in Jacksonville FL. It should have been plug & play but due to my altitude (slightly higher than Parker), I had to rejet it. It was running way rich. The technician from National offered to rejet it for free, but I declined. I didn't want to give up using the Jeep for the time it would take to ship my carb both ways. He mailed me two #84 or #86 jets for free. It took about a half hour to change the jets. Since I live where there is no emission testing, I bought a non-stepper carb.

Talk to the technician at National. I seem to remember another poster with a National carb stating that even the stepper carbs come with the stepper motor disabled.

Other than the jets, the carb worked well and now it's even better.

Good Luck, L.M.
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"Wrangler....It's not just a vehicle, It's a lifestyle".
.................................................. ........................
1987 YJ-4.2L-Standard Shift- Re-manufactured Carter Carb-2" body Lift-31X10.5X15 BFG KOs-190K Miles No back seat.
HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 11-27-2016, 07:24 PM
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Thanks LuckyMac.
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Old 11-27-2016, 07:53 PM
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LuckyMac, being at about the same altitude as you, when i call National what jets should I tell them to use?
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Old 11-27-2016, 09:46 PM   #7
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I asked the salesperson to jet my carb for 7000'. It came with stock #92 jets and ran very rich. Apparently my request didn't make it to the rebuild bench. My invoice even states "jet for 7000 feet".
When I called the 1-800 tech line the technician that I spoke with told me to lean out the metering rods (turn screw clockwise). I did that and it helped a bit but jeep still ran way rich. Plugs were black and sooty, as well as inside the rear of the exhaust pipe. I called back and the technician said he would send a set of #84 or #86 jets. They came right away. I put them in a couple weeks ago and then had to fatten up the metering rods one full turn of the screw to cure a bog on acceleration. I also bumped the timing up to 9*.
I have been busy with prepping the property for winter and installing new stairs to the basement, so I haven't pulled the plugs since re-jetting.

Right now I'm getting right at 12MPG, and I think I can squeeze another 2-3MPG by fiddling with the metering rods and timing.

Hope this helps.

Good Luck, L.M.
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"Wrangler....It's not just a vehicle, It's a lifestyle".
.................................................. ........................
1987 YJ-4.2L-Standard Shift- Re-manufactured Carter Carb-2" body Lift-31X10.5X15 BFG KOs-190K Miles No back seat.
HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 11-28-2016, 07:37 PM
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I ordered my carb today from National. 7 - 10 days to build and ship.
I hope it is sooner rather than later. I specifically made sure to mention the altitude adjustments and they said they would put in the #86 jets.

When I took my old carb off the manifold, there was a plastic spacer. Do you know what that is, and is it needed?

Thanks
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Old 11-28-2016, 08:10 PM   #9
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Quote:
Originally Posted by Luckymac View Post
I asked the salesperson to jet my carb for 7000'. It came with stock #92 jets and ran very rich. Apparently my request didn't make it to the rebuild bench. My invoice even states "jet for 7000 feet".
When I called the 1-800 tech line the technician that I spoke with told me to lean out the metering rods (turn screw clockwise). I did that and it helped a bit but jeep still ran way rich. Plugs were black and sooty, as well as inside the rear of the exhaust pipe. I called back and the technician said he would send a set of #84 or #86 jets. They came right away. I put them in a couple weeks ago and then had to fatten up the metering rods one full turn of the screw to cure a bog on acceleration. I also bumped the timing up to 9*.
I have been busy with prepping the property for winter and installing new stairs to the basement, so I haven't pulled the plugs since re-jetting.

Right now I'm getting right at 12MPG, and I think I can squeeze another 2-3MPG by fiddling with the metering rods and timing.

Hope this helps.

Good Luck, L.M.
LM, I have close to your set up only at sea level and I find my Heep runs great at 10 to 12degs BTDC, there is not a lot of Mec advance built in to these Dizzy's we are not running high RPMs with a 4.2, and I believe they get max advance at 2,600, "I maybe wrong, that might my Shovel Head, CRS!" any way I run 12 degs BTDC and burns clean. Dot Not run High Octane Fuel to get Low Emission, High Octane Burns SLOWER!
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Old 11-28-2016, 08:14 PM
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Thanks Nubby55, I was under the impression, it would burn hotter.

What about my spark plug gap being at .035, should I open it at all?
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Old 11-28-2016, 08:57 PM   #11
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The instructions that come with the HEI state to gap plugs at .045". Until you have a HEI installed, I would leave them at .035"

Good Luck, L.M.
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"Wrangler....It's not just a vehicle, It's a lifestyle".
.................................................. ........................
1987 YJ-4.2L-Standard Shift- Re-manufactured Carter Carb-2" body Lift-31X10.5X15 BFG KOs-190K Miles No back seat.
HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 11-28-2016, 09:23 PM   #12
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Quote:
Originally Posted by Nubby55 View Post

LM, I have close to your set up only at sea level and I find my Heep runs great at 10 to 12degs BTDC, there is not a lot of Mec advance built in to these Dizzy's we are not running high RPMs with a 4.2, and I believe they get max advance at 2,600, "I maybe wrong, that might my Shovel Head, CRS!" any way I run 12 degs BTDC and burns clean. Dot Not run High Octane Fuel to get Low Emission, High Octane Burns SLOWER!
High octane doesn't burn slower, it has a higher resistance to ignite. It's burn rate the same as any other octane. It takes a spark to make it pop, not just heat from compression. Hence it's resistance to "ping"
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Old 11-28-2016, 09:46 PM   #13
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clogged fuel filter?
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Old 11-29-2016, 04:08 PM   #14
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I kept my plastic spacer. It must be there for a reason. Perhaps a heat insulator to prevent vapor lock from the EGR being right underneath.

Good Luck, L.M.
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"Wrangler....It's not just a vehicle, It's a lifestyle".
.................................................. ........................
1987 YJ-4.2L-Standard Shift- Re-manufactured Carter Carb-2" body Lift-31X10.5X15 BFG KOs-190K Miles No back seat.
HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 11-29-2016, 09:02 PM   #15
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Quote:
Originally Posted by Ov yj View Post
High octane doesn't burn slower, it has a higher resistance to ignite. It's burn rate the same as any other octane. It takes a spark to make it pop, not just heat from compression. Hence it's resistance to "ping"
https://arstechnica.com/civis/viewto...?f=23&t=644647
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Old 11-29-2016, 09:36 PM   #16
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Quote:
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If it's gasoline , anything front 86-93 has exact same burn rate, octane doesn't change the rate of burn, resistance to burn is the difference. The post you quoted is not incorrect, but worded incorrectly. Burn rate and combust abilities are 2 diferant things.
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Old 12-26-2016, 04:29 PM
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I have my new National carb installed and adjusted, I have never had the jeep idle so smooth.
The only problem I have, is there is too much raw fuel getting through and the numbers for my emissions is not more than double allowed on the CO.
I was told to reduce the jets on the carb, thereby reducing the fuel and potentially getting me into safe levels for emissions.
I contacted National, unfortunately they will not be open until after the New Year.
I had them jet my carb for 7000' elevation, does anyone know what jets I will need to reduce the amount of fuel getting to my carb.
Next question: anyone know of a write up on how to change the jets in a carter bbd?

Thanks
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Old 12-26-2016, 06:11 PM   #18
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Read my #7 post.
Pull a couple plugs and take a look at them. Make a mental note of how black and sooty they are (or replace them). Reinstall the plugs.
Take off you air cleaner and on the top of the carb you will see a little tin plate that's held on to the top of the carb with 3 screws.
Remove the tin plate and you will see a small allen head screw. Turn that screw 1 full turn clockwise.
Drive the Jeep for 5-10 miles and then pull the same plugs. Compare the tips now to how they were.
You may need to remove the tin plate and turn the allen head screw one more full turn clockwise. I don't know that I would do this more than 3 times.

As far as changing the jets, if you are planning on digging that deep into your carb, you should have a Factory Service Manual. It will have a detailed description of a complete carburetor rebuild. It's a pain to reseat the metering rods in the jets during reassembly and requires quite a bit of patience and a lot of fiddling around to get them just right. If they aren't just right the top of the carb won't go on properly. At that's how my jet changing went.

It's possible that your instructions to use #86 jets never got to the technician on the rebuilding bench. That's what happened to me.

I advanced the curve in my HEI and that seemed to cure the bog, even though I had no bog until I changed my jets from #92 to #86.

Tridaddy, please be advised that I am by no stretch a mechanic. I have some knowledge of carbs because when I was younger I wanted a fast car and couldn't afford to pay anyone to do the work for me. So, I had to learn what would work on my specific car (Olds 442 with a Quadrajet). It's been 40+ years since I did engine work. I am still learning on my Jeep.

Good Luck, L.M.
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"Wrangler....It's not just a vehicle, It's a lifestyle".
.................................................. ........................
1987 YJ-4.2L-Standard Shift- Re-manufactured Carter Carb-2" body Lift-31X10.5X15 BFG KOs-190K Miles No back seat.
HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 12-27-2016, 09:40 PM
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I have not done anything to the carb yet but pulled the #2 and #5 spark plugs. Here are two sets of pictures of the plugs. In each pic the #2 plug is on the bottom

What do you think?
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Old 12-27-2016, 10:44 PM   #20
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Plugs look fine.

If you have too much fuel entering the combustion chamber I think the plugs would be black and sooty.

What makes you state that there is too much raw fuel getting through?

Good Luck, L.M.
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.................................................. ........................
1987 YJ-4.2L-Standard Shift- Re-manufactured Carter Carb-2" body Lift-31X10.5X15 BFG KOs-190K Miles No back seat.
HEI distributor with computer and all related relays and wiring removed.
12K Badlands winch with dual batteries.
Warn front bumper. Matching imitation Warn bumper on the rear.
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Old 12-28-2016, 12:43 PM
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After my last visit to the emissions station, my failure was the result of high CO. My last hurdle in passing.
I took it to a shop with the results and was told the cause of high CO is due to raw fuel. Before replacing the carb with the rebuilt carb from National, my CO was good. Now it is close to double the minimum allowed.

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