----- Original Message ----- From: "Dallas Larson" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, May 13, 2000 3:31 PM Subject: Fw: [COUPERS-TECH] stromberg carb. (fwd)
I neglected to identify to Tracy that the blue fuel residue visible on the gaskets were the results of a leaky gasket which I might add also let extra air in consequently resulting in too lean of a mixture and no doubt the reason for running hotter than normal. Dallas(93555) ----- Original Message ----- From: "Dallas Larson" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, May 13, 2000 3:21 PM Subject: Fw: [COUPERS-TECH] stromberg carb. (fwd) For the benefit of Tracy with the carb problems. I had similar problems and I sent a letter to Syd Cohen explaining my dilema. In the meantime we (mechanic and I ) think that we have solved the problem. Read the enclosed letters and if you would like to contact me feel free to do so. I was really frustrated! Appears to run great now. Dallas (93555) ----- Subject: Re: [COUPERS-TECH] stromberg carb. (fwd) ---------------------- Forwarded Message: --------------------- From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: [COUPERS-TECH] stromberg carb. Date: Mon, 08 May 2000 19:28:29 -0700 Tracy: > and a stromberg carb. Engine really hesitates and stumbles on > acceleration when throttle is advanced. Throttle has to be advanced > extremely slowly to avoid this, but it runs great once it catches. What are you calling very slowly? You should be able to go from idle to full throttle in 3 or 4 seconds at most. Try it with carb heat on. If it's better, then the problem is that the mixture is too lean. Often an air leak in the intake can cause this. Places to look are the rubber sleeves that connect the intake runners at each end, the joint between the carb and the spider, and the float bowl gasket. Low float level can also cause stumbling, as could a partially clogged fuel passage. If the plane sat with auto fuel in it for a long time, the carb could be gummed up. > Also, mixture does not work > to kill engine at idle, only at higher power. Is this normal? The mixture control works by using venturi vacuum to reduce the pressure in the float bowl, thus reducing fuel flow. When the throttle is closed, there is no vacuum to speak of in the venturi, hense no effect on the mixture. -------------------------------------------------------------------------- -- -------------------------- Syd, Hey, it's been a while since we met at the fly-in in Wisconsin this past winter. The name of the town just slipped my mind. It might have been Wausau. Have to check my logs. If you remember, you and your friend had your good-looking Ercoupes there. Also, I have not looked at the "mailing list" since last fall for reasons we discussed when you and I were visiting. Are they on track yet? Well, anyway, I enjoyed meeting you. If I may, I would like to "pick your brain". Last fall, I had problems with my carb at idle, and the only way to keep it running was to pull the carb heat out. I had the carb cleaned by an A & P and I & A . Also, put new rubber connectors(sleeves) on the intake tubes. It seemed to run fine except in cold weather when I would pull the carb heat out about one/third, mainly during warm-ups and 'touch and gos'. Well, I had my annual done late in March this year and didn't do anything to the carb. When I flew it around the patch to check out the post-annual performance, it absolutely wouldn't run at mid-range rpms. I decided to fly it over thirty miles to the same mechanic who had worked on it last fall. When I left and all the way over, the plane ran absolutely perfect. Same thing happened last fall on the way over there, ran perfect. Can't figure! We, again, took all the cowling off, including the prop to gain access to the carb. He cleaned the bowl, removed this insert(I guess this is the venturi) from within the carb throat and removed some crud from it . This insert has a tiny space on four sides that apparently lets air in. He, also, set the float higher. But, regardless, when we put it back together, it ran perfect. I flew it a total of three hours and it started acting up again. The problem starts at about 1300 rpms and subsides around 1900 rpms. The only way it will run at those rpms is to have the carb heat pulled all the way out. It will then speed up. Low and high rpms are fine. The only way to check the mags at 1700 rpms is to have the carb heat on and they both drop about 75 rpms. Without the carb heat on, when I check the mags, it will backfire and spit and sputter. If I check the mags at 2100 rpms with no carb heat on, the drop is still around 75 rpms. By checking the exhaust, it looks as if it is running lean. Do you have any suggestions as to a remedial procedure that may cure my problem? Is there anyone that has experience with the Stromberg carb? So many of the mechanics don't want to fool with carbs. If you e-mail your phone number, I could call you. It takes too long to type. I would rather talk than type. I am getting frustrated, plus it is getting to make a dent in the pocketbook. Thanks in advance for any suggestions. Dallas Larson Lakeville, MN 55044 [EMAIL PROTECTED] Syd, Thanks for the response. Monday I pulled all the four-hours-old spark plugs out to check if any were running hot. One was much whiter than the others. The exhaust residue was also white-gray in color, so it presumably was running lean. I also checked the screen on the sediment bowl, was clean. Then I opened the idle-mixture up to 1.5 turns and still no appreciable effect. Yesterday, I flew it back to the mechanic 28 miles away and told him I had done what he suggested. We both scratched our heads in bewilderment. There was an airworthiness inspector there who had previously owned an Ercoupe, but he, also, couldn't come up with any possible solutions. Since I had identified which cylinder had the excessively white spark plug, we decided to check the gasket between the cylinder head and metal piece(I belive it was elbow shaped) that meets with the intake or I believe induction tubes. (I'm describing some parts in laymen's terms as I don't know the correct name of some of the parts.) Yes, it had excessive blue fuel stain residue and was extremely petrified. So, we replaced all four and one other one was excessive also. They were extremely hard to peel off. I had replaced my exhaust stacks last fall at the same time that I had carb work done. Yesterday, I noticed one of the bolts that connect the stack to the cylinder had actually fallen out or had inadvertently not been put in when the stacks were installed. Seems unlikely that it would just fall out. Regardless, we replaced it. When we decided to run-up the engine, same problem occurred. I had put the idle-mixture back to its original position before flying to the mechanic. He, then, turned it out one full revolution and it ran 75% better, then another half-turn which seemed better yet. I suggested one more half-turn, which he did and that is where we left it. The jury is still out but all indications are that the problem is presently resolved. HURRAH! It seemed to perform normally during my flight back home. The oil temp stayed at around 180 degrees. I flew it about a half hour. The last time I flew it that amount of time the temp was at 200. So, I think that it will be running cooler now. It was running hot enough before that the new aluminum exhaust stacks were weeping little shiny miniature droplets of aluminum on the horizontal portion of the stacks. We will see if it runs cooler now and these droplets don't reoccur. Thanks again for your suggestions. Hope to see you again. The nationals will not be an option for me as we have a wedding and ten days in Colorado during that time span. Would have been fun. We need to meet at a fly-in focusing in on the Ercoupe in our area sometime soon. Let's organize something. Happy and Safe Flying, Dallas --------------------------------- to unsubscribe send mailto:[EMAIL PROTECTED] ___________________________________________________________ T O P I C A The Email You Want. http://www.topica.com/t/16 Newsletters, Tips and Discussions on Your Favorite Topics
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