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Join Date: Aug 2013
Posts: 2,123
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Big boom
Yep...that’s what happened on start up this morning after 3-4 cranks in my 1982 SC. It was immediately followed by smoke coming from the engine bay and two four year olds peppering me with questions to which I had no answers.
I tried to restart the car to no avail. A visual inspection of the air box, its peripherals, the pop off valve and screws show no conspicuous damage. Yesterday I had the car out for a run to warm it up to get the thermostat open and check the oil level. She ran fine and shut down with no drama. I’ve been reading backfire threads for a few hours. Where’s the best place to start? Smoke test the intake and look for leaks? Thanks in advance. |
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11-25-2017, 02:48 PM
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Join Date: Jul 2013
Location: South East England
Posts: 1,700
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Did you actually put a screwdriver on the screws, particularly the ones inside the airbox? If they are loose and won't tighten, the box is split.
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www.classicretrofit.com |
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11-25-2017, 02:55 PM
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Join Date: May 2006
Location: Rocklin, CA
Posts: 803
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I would also check the rubber boot that bridges the air meter plate to the throttle body. It could be torn under the hose clamp areas allowing unmetered air to enter.
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11-25-2017, 03:45 PM
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Join Date: Aug 2013
Posts: 2,123
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I checked the screws inside th air box. All are tight and don’t spin. The pop off valve feels secure. I’ll try to get that big rubber boot off for inspection. Thanks for the initial feedback.
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11-26-2017, 05:04 AM
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Reiver
Join Date: Nov 2011
Posts: 57,476
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Oldspool....check every connection to the box..and any that have been blanked off for non use. Take some silicone rubber seal lubricant (pool store) and put some on the pop off seal. Then try a start,
I've found the problem is usually a lean mixture that can be caused by being out of adjustment at the fuel head or cold start system not working properly.
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De Oppresso Liber Strength and Honor 5th Legion |
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11-26-2017, 07:47 AM
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Join Date: Aug 2013
Posts: 2,123
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Reiver- followed your advice sans lubricant. I found this guy loose and tightened it up:
 It took about 8-10 cranks but the car started and settled into a normal idle. Thanks all! Sent from my iPhone using Tapatalk Pro
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1987 Marine Blue 930 1982 911SC White Plains, NY |
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11-26-2017, 11:23 AM
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Reiver
Join Date: Nov 2011
Posts: 57,476
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I'd check your CO/AFR....and your cold start system.....the best thing I ever did to my 83 Euro was put an AFR gauge in place of the clock...I can adjust/fine tune my AFR...and, I have found, that over time it can wander a bit for whatever reason.
Glad it worked out for you but get some lube for the pop off gasket...makes a great seal and keeps the rubber in soft/good shape.
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De Oppresso Liber Strength and Honor 5th Legion |
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11-26-2017, 03:37 PM
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