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marknmel Samba Member
Joined: January 29, 2003 Posts: 24 Location: Tucson
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Posted: Wed Jan 29, 2003 8:12 pm Post subject: backfire |
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hey all! my 73 camper is backfiring and i don't know why!! it only happens when i let off the gas or am down-shifting. someone suggested it might be a hole in the exhaust. is there some way i can check for a leak? any suggestions would be appreciated. thanks! |
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chabanais Samba Member
Joined: July 27, 2002 Posts: 4866
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Posted: Wed Jan 29, 2003 9:05 pm Post subject: backfire |
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When my Bus did that the timing was off and the Carb was set to too rich. |
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Mark Samba Member
Joined: January 20, 2003 Posts: 1523 Location: Victoria, BC Canada
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Posted: Wed Jan 29, 2003 10:13 pm Post subject: backfire |
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Did you notice this recently? It sounds exactly like the problem I had, which was a HUGE exhaust leak. To check, cover the tailpipe with a rag in your hand while the engine is running and have a look & listen around the manifolds & exhaust connections. If the engine idle doesn't change and/or you hear hissing from the exhaust then it's leaking. In a tight exhaust, the idle should drop noticeably, even stumble with the tailpipe blocked. Hope that helps. |
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marknmel Samba Member
Joined: January 29, 2003 Posts: 24 Location: Tucson
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Posted: Sun Feb 02, 2003 12:39 pm Post subject: backfire |
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thanks for the tips! checked for the exhaust leak, and that wasn't it, so it must be the timing. i have been having some trouble getting it right, mostly because i keep getting different advice on where to set it. factory specs say 10atdc, but the distributor was replaced at some point with a 009 mech advance, so i'm not sure if the factory settings still apply... any suggestions? |
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Bags Buses Samba Member
Joined: January 24, 2003 Posts: 99 Location: Beach Lake Pa
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Posted: Sun Feb 02, 2003 2:42 pm Post subject: backfire |
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Mark with the 009 it might be 180 out I know mine is in my 1700 I took one out of another one and it was the same way so your timeing so be the the other way. Switch to electronic ignition, the best I found is pertronix.
Karl |
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marknmel Samba Member
Joined: January 29, 2003 Posts: 24 Location: Tucson
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Posted: Sun Feb 02, 2003 3:06 pm Post subject: backfire |
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thanks Karl for the MUCH needed info. just wondering, is electronic ignition expensive or exceedingly difficult to install? |
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Amskeptic Samba Member
Joined: October 18, 2002 Posts: 8568 Location: All Across The Country
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Posted: Sun Feb 02, 2003 5:29 pm Post subject: backfire |
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10*ATDC is stock with vacuum retard.
Your 009 will be happier at 5-7.5*BTDC.
Your carbs will hate you for that if they are original. Strangely enough, the stock dual carb buses backfire like hell when they are lean, it is a case of slowed flame fronts blasting out the just opening exhaust valves, exacerbated by retarded timing, I might add.
Colin |
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Bags Buses Samba Member
Joined: January 24, 2003 Posts: 99 Location: Beach Lake Pa
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Posted: Mon Feb 03, 2003 3:47 am Post subject: backfire |
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Hi Mark You will spend about $65.00 for a electronic set up , easy to put in ,and you don't have to screw around with points any more. I run them in both of my busses. |
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