81 Scarab project from hell
#401
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Location: Sandown, NH - Sebago Lake Region, ME
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Could still be fuel. You could have a piece of dirt in one of the needle vlaves in the carb. Backfiring in the exhaust could be a sign of a too rich condition. Did you completely drain the fuel system over the winter or at least put a ton of fuel stabilizer in it? The fuel of today is junk!
Is it a consistant condition where it backfires every firing cycle?
Is it a consistant condition where it backfires every firing cycle?
#403
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Checked timing- it is set @ 10 degrees advanced. Starts right up, runs good- just the backfire at idle. It is not consistant- or it doesn't seem to be. Cleaned the carb last night( thought it might be a vacuum leak, or plugged jet, no go.) Switched carb from other engine, ruled that out. I am going to buy a cap and rotor today, I will let you guys know what happens.
Thanks for all the input-
Scott
Thanks for all the input-
Scott
#404
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Checked timing- it is set @ 10 degrees advanced. Starts right up, runs good- just the backfire at idle. It is not consistant- or it doesn't seem to be. Cleaned the carb last night( thought it might be a vacuum leak, or plugged jet, no go.) Switched carb from other engine, ruled that out. I am going to buy a cap and rotor today, I will let you guys know what happens.
Thanks for all the input-
Scott
Thanks for all the input-
Scott
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#405
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So I was working on it tonight- trying to get it ready to watertest, and now the right engine keeps backfiring out of the exhaust at idle. It sounds like the right bank, I think it might be my distributor cap and/or rotor, any other ideas? I don't think its fuel because the left engine runs fine. Any advice would be appreciated-
Jason
Last edited by Rookie; 05-01-2009 at 07:21 PM.
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Well- putting on the cap and rotor helped quite a bit- but it still does it very occasionally at a low idle.(800rpm) I guess it could be a valve but I have hydraulic rollers- and it runs really good at everything above 800 rpm. If I set the idle at 1000 it never pops- kind of weird. I'm kind of leaning towards 502's thinking, because the gas is old- so I am going to mix in some race gas when I fill it up. One more question- should you use throttle return springs, and if you do, is there a trick setup out there I should look at? Thanks guys for all your input-
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