Ed.
Excellent analysis. Running lean can be a cause for that kin of trouble. Under lean condition, the effects get worse when only one spark plug is firing in a cylinder. The quick test is to pull carburetor heat and see if the symptoms smooth out or disappear. A lean condition can be caused by the carburetor itself but also any intake leak along the way to the cylinders. Hartmut To: [email protected]; [email protected] From: [email protected] Date: Mon, 9 Nov 2009 06:17:13 -0600 Subject: RE: [ercoupe-tech] intermittently bad run-ups Linda, I am NOT any kind of mechanic and must not play one on the Internet. However, I'm a tech support geek whose business is to solve technical problems. So, I'll stick my ignorant oar into the puddle. You say the mag drop happens on BOTH mags whenever it happens. But, the event is intermittent. This pattern has been repeatedly demonstrated. To me, this means: 1. If it is the ignition switch or mag related, then the problem is in the ground wire or the ignition switch's ground which are the only common elements. 2. You said the big mag drop is coincident with dieseling. Doesn't dieseling come from something in the cylinder(s) being too hot causing ignition in the absence of a spark? What causes hot spots in the engine? Running way too lean? Thus, I would look for something that could cause excessive leanness and is common to both mags. I'd be looking at the carburetor and, in particular, a. the float, b. the mixture control section (looking for clogs and to clean it completely (I once had a fiber air filter shed fibers which clogged the air passage on the Stromberg carb causing excessive leanness)) c. fuel flow issues (which I'd check by finding PERFECTLY clean pavement and doing a high power runup to see if it's the same) -- possible causes include fuel hose collapsing internally, sloshing compound, clogged screen in the gascolator, d. if it's running lean, then the carb heat should richen the mixture causing a mag rise e. ?other?. Next, I'd look at other common elements such as the air filter. I can't see the individual mags or P-leads or spark plugs causing this drop on BOTH mags at the same time, intermittently. The only common element is the grounding wire from the ignition switch and the switch itself. BUT, I'd expect this kind of electrical failure to do something radically different from a 200 rpm mag drop. Just my non-mechanic, technical analysis thoughts, for what it's worth. Ed Ed Burkhead http://edburkhead.com/Ercoupe/index.htm ed -at- edbur???khead.XXX change -at- to @, remove ??? and change XXX to com _________________________________________________________________ Windows Live: Keep your friends up to date with what you do online. http://www.microsoft.com/middleeast/windows/windowslive/see-it-in-action/social-network-basics.aspx?ocid=PID23461::T:WLMTAGL:ON:WL:en-xm:SI_SB_1:092010
