| JayChicago | -- 09-18-2016 @ 7:02 PM |
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40 Ford, all stock I get a splat of soot blasted out the tail pipe upon cold start up. Leaves a big black stain on the garage floor. Engine starts easily. I use minimal choke and open the choke totally a few seconds after engine running. This engine does not have obvious smoke out the exhaust any other time. Sound familiar? What does this indicate?
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| ken ct. | -- 09-18-2016 @ 7:22 PM |
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Could be excess carbon build up in cyl. from previous running , it should clear up with a good run on the interstate,worth a try ?? ken ct.
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| 40 Coupe | -- 09-19-2016 @ 4:11 AM |
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Remove the plugs to check if they have carbon build up (black soot) it could be the engine is running rich. Usually due to the incorrect size jets in the Carb. If you have done Carb work do run the engine hard to see if you can clean out deposits from a previous problem.
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| len47merc | -- 09-19-2016 @ 4:41 AM |
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As you very likely know, moisture condenses in your exhaust system while running - under the right ambient conditions sometimes a considerable amount. This is particularly prevalent during cooler and more humid periods when you see the water vapor behind the car and the drips of condensed moisture dripping from the pipe. During the previous operation should you not have driven the car or operated the engine for an adequate period of time to fully dry-out the exhaust system the moisture will sit and pool in low areas of your system and dissolve any surrounding exhaust deposits into a pool of black soot that will, as you say, 'splat' out on the next crank of the engine. It does make a mess and is virtually impossible to remove from a concrete garage floor (not to mention walls, shelves, other equipment, etc.). The best way to avoid this is to ensure you are not running too rich a fuel mix in your motor and always operate/drive your engine/car at rpm for at least 30 minutes minimum to allow the engine to fully warm to temp and as well fully dry out the exhaust system. Once making a car safe and operational I never crank it for any reason without planning on a drive adequate to dry out the exhaust system, not only for this reason but to avoid the rusting effect of the moisture in general (45 mins min for me). If the car cannot be driven or the motor has to be run for some maintenance I try to operate it long enough to dry out the pipes or drive it first for 30 minutes if possible, respectively. Once you've confirmed your engine is not running excessively rich, if this drive-time doesn't work for you, cover the floor or temporarily zip-tie an old sock over the tailpipe to catch the initial blow (latter sounds crazy but I've seen it done). Btw, from my experience, it is not unusual for a properly set-up and adjusted flathead to leave a minimal amount soot in the pipes. I'd be careful how far you 'lean-out' the fuel mix - IMHO an absolutely not black but dark-to-mid gray exhaust pipe is far better than a light-to-whitish-gray, from both performance and engine health perspectives. Typically a flathead's exhaust pipe will show a very minor amount of darker-to-mid-gray deposits with plugs showing as burning properly. Steve This message was edited by len47merc on 9-19-16 @ 5:31 AM
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| joe b | -- 09-19-2016 @ 6:09 AM |
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I think they all do that when they have been sitting for awhile. It is just a Flathead acting like a dog to mark it's spot. Len47 has a good explanation.
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| TomO | -- 09-19-2016 @ 8:44 AM |
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The muffler(s) need to have a 1/8" drain hole at the bottom front and back. Your 40 is probably running rich or your power valve is leaking. You should not see a black "splotch" when you start your engine. Oil Eater degreaser does s good job of removing the black carbon stain. Tom
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| ken ct. | -- 09-19-2016 @ 9:45 AM |
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His carb has .049 MJ in it so its not on the rich side !!! ken ct.
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| JayChicago | -- 09-19-2016 @ 12:33 PM |
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No, Ken, the splat-out-the-exhaust symptom is with the original carb still on the car, not with the rebuilt carb you sent me. I will post a follow-up when I get your carb installed. Thanks for the info everyone. The plugs are black with short running time on them, so I guess its obvious the engine is running too rich. This could also explain why the miss I was experiencing was more prominent under steady cruise and not so obvious under acceleration....the engine might like a rich mixture under acceleration but can't handle it under light-load cruise.
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| ken ct. | -- 09-19-2016 @ 2:06 PM |
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Let us know what # jets are in the old carb when you change them. I would install new plugs 1 step hotter and gap to .025. ken ct.
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| JayChicago | -- 09-21-2016 @ 5:04 AM |
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Follow-up: Installed the new carburetor, engine is running great. No more blowing carbon out the tail pipe on startup. Drove to our regional group's meeting last night, ran great, no more missing. I'm happy. I really appreciate all the help I received here. Ken: I removed the two jets visible in the barrels above the venturies. I assume those are the main jets. No number on them. I examined with a magnifying glass, no number. Previous owner had this carb rebuilt ten years ago, maybe using some cheap kit?
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| len47merc | -- 09-21-2016 @ 5:27 AM |
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Don't be discouraged if down the road on a cooler, more humid day, when you are more heavily condensing water and emitting vapor from the exhaust, that you see some additional 'marking' out of the pipe. Likely still have some deposits in there that may take a more than a few runs to completely clear out. Glad to hear you've found your problem. Still stand, as a good general practice and good advice, on driving the car no less than 30 minutes each outing to completely dry-out your exhaust system. On those days when you are emitting heavier vapor out the pipe you may still have at minimum drips on the garage floor if you do not move the car out immediately ('sprays' if you rev the engine). TomO's suggestion of drilling an 1/8" hole at the bottom front center and bottom rear center of your muffler - if they are not already there - is very sound advice as well. Steve This message was edited by len47merc on 9-21-16 @ 6:02 AM
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| ken ct. | -- 09-21-2016 @ 1:38 PM |
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Jay sending a parts sheet on carb breakdown w/ parts ID. snail mail. ken ct.
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| TomO | -- 09-23-2016 @ 7:01 AM |
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Steve, I did not mean to suggest that driving the car for at least 30 minutes, each time you take it out, is not necessary, I just felt that the carbon splats are more related to a rich mixture. I agree that you should drive the car for at least 30 minutes each time, mainly to reduce the condensation in the engine that causes sludge. Tom
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| len47merc | -- 09-23-2016 @ 8:51 AM |
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Did not take it that way at all Tom and appreciate your coming back. I agreed with you as well and note I also stated in my write-up that he should ensure the car was not running rich first, so I'm glad he found his root cause. Just wanted to make sure the point was reinforced and not overlooked because the root cause was determined. Your points were on the mark. Thanks - Steve
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