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Unread 08-25-2012, 02:02 PM   #1
lumpyd
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1981 CJ7 
 
Join Date: Dec 2011
Location: Waterford, CT
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Exhaust question

I have an 81 CJ7 with the 6 cyl. engine. I can't seem to find an exhaust (everything behind the manifold) without a catalytic converter. Any ideas?

And while I'm here... while I'm on the highway the jeep runs about 2500 RPM in 4th gear at 65. My gas mileage is HORRIBLE. Not sure what my gears are, but short of changing the gears or tranny to a 5-speed, is there anything I can do? Could there be an issue with my carb? The engine does chug a little when idling.

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Unread 08-25-2012, 02:36 PM   #2
titomars
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All domestic 81's had a cat conv. If you are trying to go without you will have to have a muffler shop bent up a custom head pipe.
What's horrible? I get 12.6 on the freeway and 9.8 in town/off road.
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I don't worry about my MPG's. I see it as the price of admission...............Damn what a ride!!!
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**Originally Posted by wm69 **
This is the kinda whiny crap I would expect to see in the JK forum. We drive rough riding, leaking, gas guzzling CJ's. Rattle can it and throw it in your Jeep.
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1981 Jeep CJ7 258 4.0 HO head, T-5, D300, D30, D44, SOA
1994 Jeep XJ 4.0 HO, AX-15 (My Beater)
1946 Bantam T3-C (original Calif trailer, no rust)
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Unread 08-25-2012, 02:54 PM   #3
james04si
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Or you could probably get an exhaust for a 77 since they didn't have a cat on the I6. Not sure if it bolts up exactly right but would have the bends in the right locations and no cat. Be sure its an offroad vehicle because it won't pass a visual inspection if they look.
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Unread 08-31-2012, 08:37 AM   #4
lumpyd
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Apparently 76-78 are available as are 83-86. I went to Morris 4x4 NAPA, Auto Zone, and no one has 79-82. I don't get it. I thought everything was pretty much identical on them all. But why they would just not make that pipe for 79-82 is beyond me. Sigh
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Unread 08-31-2012, 09:40 AM   #5
WindKnot
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Take this as you will...

Removing the cat is a violation of Federal Law and will make the Jeep not street legal, regardless of what your state says.

Do what you will, but be informed.
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Unread 08-31-2012, 09:43 AM   #6
titomars
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76 to 79 Has a different exhaust manifold attached to the intake for a heat riser, so the head pipe may be different. 82 to 86 has an ECM so the head pipe has a provision for the pulse AIR injection. also the manifold changed slightly again in those years. though I don't think the manifold change affected the head pipe. Just take the rig to a local muffler shop they can make a new head pipe to fit. They can make the whole exhaust system also.

Windknot is correct. With this country going on this "going green" thing smog laws will only get tougher. Local, state and the feds are just looking for ways to get the old iron off the streets.
__________________
I don't worry about my MPG's. I see it as the price of admission...............Damn what a ride!!!
---------------------------------------------------------------------------
**Originally Posted by wm69 **
This is the kinda whiny crap I would expect to see in the JK forum. We drive rough riding, leaking, gas guzzling CJ's. Rattle can it and throw it in your Jeep.
---------------------------------------------------------------------------
1981 Jeep CJ7 258 4.0 HO head, T-5, D300, D30, D44, SOA
1994 Jeep XJ 4.0 HO, AX-15 (My Beater)
1946 Bantam T3-C (original Calif trailer, no rust)
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Unread 08-31-2012, 10:00 AM   #7
WelderX
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You need to buy the header pipe for a 79 no cat back (I think I bought mine from quadratec)then go to summit racing buy the muffler and tail pipe for half what the catalogs want.
Just did my exhaust on an 85.
Summit doesnt list the tailpipe but if you search this number it comes up. WLK-44784. Everywhere I looked wanted to sell the tailpipe with the kit. This pipe is the one that kicks out over the spring for the big 20 gallon tank.
This is the muffler I used. 18389
I barely had $100 in my total system with shipping.
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Unread 09-01-2012, 04:01 AM   #8
RWise
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Quote:
Originally Posted by titomars View Post
Just take the rig to a local muffler shop they can make a new head pipe to fit. They can make the whole exhaust system also.

Windknot is correct. With this country going on this "going green" thing smog laws will only get tougher. Local, state and the feds are just looking for ways to get the old iron off the streets.
I take mine to a local muffler shop, fast cheap and easy. (all welded with warranty, and they have all the tools and parts) Mine is without the cat (by PO) no inspections here for now, but I will have one out back in (may get rid of the cherry bomb (by PO, and I hate the sound) and just use the cat and no muffler (I can have straight pipes as long as they go 18" past the rear axle by state law)


The tree huggers are winning, if this keeps going we will not be allowed to drive anything that is over 10 years old! My Dad ran an auto salvage since 1954 (now closed as he has passed), He (and everyone else) got money from the government to crush out anything that was more than 10 years old,,,
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