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Registered
Join Date: Aug 2003
Posts: 4
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backfire
My 1976 911 Targa backfired out the exhaust and stopped running. It turns over but won't start. I assume the timing chain jumped.
Is it possible nothing bent if it only jumped one tooth? Or do I just start ripping the thing apart? |
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drag racing the short bus
Join Date: May 2002
Location: Location, Location...
Posts: 21,983
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Are you sure it's not the pop off valve? Do you have a pop off valve?
Check under your airbox - the pop off looks like a toilet plunger. It might just need re-seating, which you can do by hand. Cheaper than "ripping the thing apart." ![]() Hopefully you have one of these valves. Otherwise, you might've blown your airbox. ![]()
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The Terror of Tiny Town |
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Registered
Join Date: May 2000
Location: Los Alamos, NM, USA
Posts: 6,044
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I agree, likely either an unseated "pop off" valve or a blown air box ($$). I would check the point dwell too as a good "thump" sometimes loosens the points if not they were not properly tightened. Good luck. Jim
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Author of "101 Projects"
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Do a bunch of research on this site and here (http://www.101projects.com) before you start tearing stuff apart. Sounds like you might have blown your CIS airbox, or at best, blew a hose and you now have a vacuum leak...
-Wayne
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Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of: 101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 Check out our new site: Dempsey Motorsports |
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Author of "101 Projects"
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Oh, and you can't knock out your timing with a backfire - the timing is controlled by a beefy metal chain.
-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of: 101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 Check out our new site: Dempsey Motorsports |
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Registered
Join Date: Aug 2003
Posts: 4
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It has a pop off valve. It also backfired out the exhaust so it wouldn't be likely to blowup the air box that way. BTW I didn't mean the timing got knocked out with the backfire I ment the backfire may have been the result of a jumped timing chain. EG the plug fires while the ehxhaust vale is open.
Also, I just did a compression test and the right bank is low. So... when I get to pull the covers next week (I'll be out of town till Wed.) can I expect to find the timming out? If I do, is it possible it didn't break/bend anything? |
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Author of "101 Projects"
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I think you're barking up the wrong tree with the backfire and timing. I'm going to move this back to the regular forum, unless this is a recently rebuilt engine?
-Wayne
__________________
Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of: 101 Projects for Your BMW 3-Series • 101 Projects for Your Porsche 911 • How to Rebuild & Modify Porsche 911 Engines • 101 Projects for Your Porsche Boxster & Cayman • 101 Projects for Your Porsche 996 / 997 • SPEED READ: Porsche 911 Check out our new site: Dempsey Motorsports |
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Registered
Join Date: Dec 2002
Location: Central Indiana
Posts: 601
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I had a set of points do this to me ( 77s ) about a month ago . I replaced them and the car has run fine since and by the way the points were only about a month old.
Jim
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77S 04 Titan 03 Xterra |
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