Holley 390 with Clifford intake on a 1979 258

Tiny
MWALSHCJ5
  • MEMBER
  • 1979 JEEP CJ5
  • 4.2L
  • 6 CYL
  • 4WD
  • MANUAL
  • 100,000 MILES
Any help is greatly appreciated! I have finally got the CJ back together. I decided to go with a Holley 390 on a Clifford intake with a Hedman header. I had the carburetor dialed in and running great. My only issue is it smells super rich. To the point where the smell comes into the house from the garage. I eliminated the return when putting everything back together and the new fuel lines are 3/8” running to the carburetor. I feel like this is where I went wrong. Feeding too much fuel and no return may be causing all the vapors I’m smelling at stop lights and in the garage. Do I need to go back to 5/16” line? Add the return? Or just get a regulator? Thank you for the help! Be nice :)
Thursday, March 14th, 2019 AT 10:23 AM

12 Replies

Tiny
KENW1
  • MECHANIC
  • 213 POSTS
Thanks for visiting 2CarPros.

The line diameter shouldn't be causing issues. If you're getting heavy fuel odors at idle try readjusting the idle air/fuel mixture with a vacuum gauge attached to intake vacuum. You want to adjust until highest vacuum is obtained. If this does not resolve it you may want to step down to jet sizes. As far as a regulator and return goes if you're at a max of 7psi you're good.
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Thursday, March 14th, 2019 AT 4:07 PM
Tiny
MWALSHCJ5
  • MEMBER
  • 7 POSTS
Okay, thank you. I will check my fuel pressure tomorrow at idle and under load. I installed a fuel pressure gauge. Also, the Jeep used to have a charcoal canister that was hooked to vacuum and vented the tank.I do not have this hooked up anymore either. I read that it wasn’t needed. Could this be part of the issue? Or maybe just rich, I had a performance shop tune the carburetor, and I know they put a wide band in to tune it because I welded in a bung for them. It shouldn’t be so rich unless something else is going on.
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Thursday, March 14th, 2019 AT 5:49 PM
Tiny
KENW1
  • MECHANIC
  • 213 POSTS
Thanks for the additional information. If the charcoal system is open it can cause fumes. You could cap it or run it to the carburetor if it has bowl vents.
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Thursday, March 14th, 2019 AT 6:36 PM
Tiny
MWALSHCJ5
  • MEMBER
  • 7 POSTS
Okay, I’ll cap the old return and vent line that went to the canister. Should I get a vented gas cap or just leave it non-vented?
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Thursday, March 14th, 2019 AT 6:43 PM
Tiny
KENW1
  • MECHANIC
  • 213 POSTS
I would go with a vented cap.
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Thursday, March 14th, 2019 AT 6:44 PM
Tiny
MWALSHCJ5
  • MEMBER
  • 7 POSTS
Thank you sir. I’m driving it to work in the am so I went ahead and took the rubber ring/grommet out from under the cap I have now. The cap still closes on just let’s air in and out easily. Essentially vented :) we will see how it goes with these changes and I’ll report back on fuel pressure as well.
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Thursday, March 14th, 2019 AT 6:51 PM
Tiny
KENW1
  • MECHANIC
  • 213 POSTS
Sounds good, I think you'll have it taken care of. I like your vented cap mod.
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Thursday, March 14th, 2019 AT 6:52 PM
Tiny
MWALSHCJ5
  • MEMBER
  • 7 POSTS
I hope so. Something so simple could be the fix hopefully. It’s a strong smell though. So we shall see. When I changed to a header I also did the exhaust because the entire system was toast. I went straight out the back drivers side and have read that down and out at a 45 degrees behind the back wheel would of been a better option. That could be a partial contributor to the fumes. One step at a time.
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Thursday, March 14th, 2019 AT 6:55 PM
Tiny
KENW1
  • MECHANIC
  • 213 POSTS
The exhaust like that can make it more noticeable for sure. If it persists after capping off the canister let me know and we can work on leaning it out some. I've seen wide band tuning be a little too rich at idle a few times.
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Thursday, March 14th, 2019 AT 6:58 PM
Tiny
MWALSHCJ5
  • MEMBER
  • 7 POSTS
I will try to get in contact with the shop to see what jets they put in it.
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Thursday, March 14th, 2019 AT 7:28 PM
Tiny
MWALSHCJ5
  • MEMBER
  • 7 POSTS
Okay so the raw fuel smell is almost completely gone. Now I just have exhaust fumes running into the jeep. I think I’ll reangle that exhaust tailpipe to come out the side behind the drivers side tire instead of straight out the back. My last issue (for now) the shop that tuned the carb set the idle at 500. Sometimes when I come to a stop sign I notice it may even at 400 and the jeep feels like it’s as low as it could idle without stalling. What should my idle be set at. My curb idle (terminology?) And if they set it too low does that mean all jetting/tuning/timing will have to be adjusted to match? I’m starting to wonder if im getting all the performance I should be with the intake and carb I put on the motor because if the idle is set wrong who knows what could be overlooked. Secondaries, vacuum advance etc.
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Friday, March 15th, 2019 AT 10:23 AM
Tiny
KENW1
  • MECHANIC
  • 213 POSTS
Glad to hear that helped so much. 400 is pretty low for sure once warmed up. I would shoot for 5-600RPM when hot and at idle. This can effect timing and base fuel mixture some.
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Friday, March 15th, 2019 AT 1:03 PM

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