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Unread 10-09-2006, 12:42 PM   #1
AMC Power
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AMC 258 header question

Is it ok to run the engine without an exhaust system and just the header? The engine is freshly rebuilt and I need to drive it to get a custom exhaust system installed. Would it be ok to do this or would it hurt the engine?

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Unread 10-09-2006, 01:02 PM   #2
Baloo
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I don't know if it's harmful or not, but I drove my old 304 CJ5 around town one night with open headers and didn't have any toubles with it afterwards. It was an old engine though, not a freshly rebuilt one. You just have no backpressure running them open. I would trailor it if it's far. You might get pulled over too.
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Unread 10-09-2006, 03:33 PM   #3
CJ7 Vette
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make sure you have ear plugs. it will be VERY loud lol.
out of curiuosity, why not just get the rest of the exhaust from one of the catalogs? it just bolts into place....probably cheaper than a custom shop. i put mine in from the header back when swapping motors and it took maybe 20 minutes with the help of a friend.
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Unread 10-09-2006, 04:06 PM   #4
BLS33
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Quote:
Originally Posted by CJ7 Vette
make sure you have ear plugs. it will be VERY loud lol.
out of curiuosity, why not just get the rest of the exhaust from one of the catalogs? it just bolts into place....probably cheaper than a custom shop. i put mine in from the header back when swapping motors and it took maybe 20 minutes with the help of a friend.
the catalog exhaust systems I've come across are pretty expensive, having it done by a shop is usually pretty cheap

As far as driving it to the shop it should be fine
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Unread 10-09-2006, 04:56 PM   #5
Galt
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Hope like hell you doin't ignite gas fumes from the carb that sits right over top of it and burn your jeep to the ground. I would tow it.
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Unread 10-09-2006, 05:26 PM   #6
BLS33
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Originally Posted by IOIIIIOI
Hope like hell you doin't ignite gas fumes from the carb that sits right over top of it and burn your jeep to the ground. I would tow it.
I dont understand that theory are you saying running headers runs the risk of igniting gas fumes?
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Unread 10-09-2006, 06:24 PM   #7
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My old 304 would sometimes shoot a small fireball out of the sidepipes. I guess it is possible.
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Unread 10-09-2006, 08:39 PM   #8
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I have the dual outlet header for the 258 and I haven't seen any exhaust systems that keep the dual pipes seperate from each other. I know they sell y-pipes, but I want true dual exhaust. I want my exhaust to exit in front of the rear wheels.
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Unread 10-09-2006, 08:41 PM   #9
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Quote:
Originally Posted by BLS33
I dont understand that theory are you saying running headers runs the risk of igniting gas fumes?

You don't understand that the flames that can most definitely shoot out of a header can ignite gas fumes? I blow flames out the *** of my RX7 all the time. Thats all the way through a down pipe, a mid pipe with a borla welded in and then through a catback. I am certain I could get some out flame of a header all of 15" long. If you want to drive with an open exhaust then have at it. I would advise against it.
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Unread 10-09-2006, 08:57 PM   #10
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The end of the header is really not too close to the the carb or where any gas fumes are.

I've driven trucks around with open headers a ton of times just to move them from place to place and have yet to be ungulfed in a fireball. It just doesnt seem like a very big risk at all, and I'm speaking from experience. I dont get how flames coming from the end of a header could possibly ignite any fumes.
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Unread 10-09-2006, 10:09 PM   #11
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Quote:
Originally Posted by AMC Power
I have the dual outlet header for the 258 and I haven't seen any exhaust systems that keep the dual pipes seperate from each other. I know they sell y-pipes, but I want true dual exhaust. I want my exhaust to exit in front of the rear wheels.
cool!
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update: no rust, new floors, stripped, primed, filled, blocked, and repainted with PPG Concept Garnet Metallic. Hardtop freshly painted, all trim painted in black metallic with a bit of flatener mixed in. New seats, carpet, console, roll bar pad, seat belts,dash, flares, windshield, seals, tire carrier and more!
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Unread 10-10-2006, 11:04 AM   #12
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I test drove my fresh 360 about 10 miles with open headers in 97 degree weather with no engine issues. However it was LOUD! So loud that I could not hear that my starter solenoid was stuck and it fried my starter. (The starter gear was mashed over like a mushroom. Luckily it did not damage the flywheel ring gear.) I also drove it to the custom muffler shop a few days later. I was more concerned about getting a ticket than anything else, especially since I live a few houses away from a County Cop.
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Unread 08-29-2010, 04:36 PM   #13
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Quote:
Originally Posted by CJ7 Vette View Post
make sure you have ear plugs. it will be VERY loud lol.
out of curiuosity, why not just get the rest of the exhaust from one of the catalogs? it just bolts into place....probably cheaper than a custom shop. i put mine in from the header back when swapping motors and it took maybe 20 minutes with the help of a friend.
X2 on loudness! Back when my Bronco had headers 2 of the collector bolts fell off and the exhaust pipe was held on by one bolt and it exposed the collector opening and that was unbearably loud! I couldn't imagine it with no exhaust at all! But I got sick of the headers and put manifolds on it so I would have some ground clearance, did away with the old rusty exhaust pipes and straight piped it, now it sounds perfect to my ears anyway, the tree hugger neighbors hate me though!
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Unread 08-29-2010, 05:04 PM   #14
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When you get the pipes done, please post some pics. I' haven't decided on single or dual outlets and like to see how yours come out. Any clearance problems with the duals? Thanks
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Unread 08-29-2010, 05:36 PM   #15
CT84CJ7
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backpressure

I have heard that exhaust provides backpressure that helps the engine rings seat with a new engine. I think you would be fine, I would not drive a long distance. Also something that I would do is slow easy acceleration then let off with and keep in gear for a slow down that will help the seating of the rings. Just once or twice and nothing extreme.
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