---------------------------------------------------------- Continental-List Digest Archive --- Total Messages Posted Sun 07/28/13: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:04 PM - Re: Carb ice, or vapor lock? (FLYaDIVE) 2. 05:08 PM - Re: Carb ice, or vapor lock? (Jimmy Young) ________________________________ Message 1 _____________________________________ Time: 03:04:04 PM PST US Subject: Re: Continental-List: Carb ice, or vapor lock? From: FLYaDIVE Hi Jim: There are quite a few questions and comments I have to go through: 1 - Did you check your Spark Plugs? 2 - Did you check your Timing? <--- Major issue after an Annual. 3 - WHY DID YOU NOT LEAN? <--- You should be leaning ALL the time. Lean avery aggressively while taxing - So much so - THAT - If you forget to go full rich on take-off the engine will die. You CANNOT hurt the engine and it will prevent lead fouling of the plugs and save you a little taxi gas. 4 - Keeping with the leaning subject - As you altitude increases you will be running way too rich. This could cause a reduction in HP as well as carbon & lead fouling. Extra rich also lowers the temp in the carb which will increase your possibilities of Carb Ice. 5 - I am not a fan of Gascolators - Just way too many issues with them - I do believe very strongly in - IN LINE fuel filters. BUT! I doubt it the Gascolator was the culprit. 6 - ALL your fuel lines should be heat shielded... Well, as much as physically possible. 7 - Vapor Lock - Is easy to prevent. It starts with fuel system design What size fuel line are you using? What is the fuel line made from? How do you have the fuel line routed? How is the overall cooling under the cowl? 8 - From you statement of: "They normally stay between 335 & 360 when running 2350 rpm. My EGT's were climbing as well. This indicates to me that I was running lean, if I am correct." Well you are correct. A CHT of 410 F is above normal IF you compare it to past operations. What were the EGT readings at the time? I'd bet below 1400 F probably more like 1320 F. SOoooo what would cause leaning? NOT VAPOR LOCK! With vapor lock you loose gas flow and the EGT & CHT goes DOWN. NOT CARB ICE! With carb ice you loose fuel flow and EGT & CHT goes DOWN. If CHT goes Down and EGT goes Up --- LQQK at fouled plugs or poor spark. If RPM cannot be maintained and CHT goes Up ---LQQK at AIR LEAKS... Carb, Intake Tubes. 9 - You did not mention OIL TEMPS? OK - Enough for now. Let's hear back from you on these basic checks. *Barry* ________________________________ Message 2 _____________________________________ Time: 05:08:39 PM PST US Subject: Continental-List: Re: Carb ice, or vapor lock? From: "Jimmy Young" Barry wrote: > 1 - Did you check your Spark Plugs? Yes. they looked good, tannish to greyish in color, not fouled. > 2 - Did you check your Timing? Did that at annual. 26 & 28 degrees, same as first flight 1 year previous. > 3 - WHY DID YOU NOT LEAN? No good reason, other than I've been advised that unless I'm flying above 5000' regularly, I don't need to. I usually fly at less than 3000' msl most of the time. > 5 - I am not a fan of Gascolators - Just way too many issues with them - I dobelievevery strongly in - IN LINE fuel filters. BUT! I doubt it the Gascolator was theculprit. Ok, but what then separates water from your fuel? > 6 - ALL your fuel lines should be heat shielded... Well, as much as physically possible. > 7 - Vapor Lock - Is easy to prevent. It starts with fuel systemdesign What size fuel line are you using? What is the fuel line made from? How do you have the fuel line routed? How is the overall cooling under the cowl? Lines are 3/8" Aeroquip rubber hose with AN socketless fittings, except FWF it's 3/8" Aeroquip SS braided hose with firesleeve. They are routed straight from the wing tanks to a tee, to a shut off valve, to the FW bulkhead pass-thru, to the gascolator, and on to the carb. Pretty standard and straight-forward. You ask "how is the overall cooling under the cowl? I've got temp strips on the mags and the firewall. They have topped out between 160 & 180 degrees. Don't really know how one could keep that area cool, as it's purpose is to exhaust engine heat. I have considered running blast tubes to my mags. > 8 - From you statement of: "They normally stay between 335 & 360 when running 2350 rpm. My EGT's were climbing as well. This indicates to me that I was running lean, if I am correct." Well you are correct. A CHT of 410 F is above normal IF youcompareit to past operations. What were the EGT readings at the time? I'd bet below 1400 Fprobablymore like 1320 F. SOoooo what would cause leaning? NOT VAPOR LOCK! With vapor lock you loose gas flow and the EGT & CHT goes DOWN. NOT CARB ICE! With carb ice you loose fuel flow and EGT & CHT goes DOWN. If CHT goes Down and EGT goes Up --- LQQK at fouled plugs or poor spark. If RPM cannot be maintained and CHT goes Up ---LQQK at AIR LEAKS... Carb, Intake Tubes. My egt's each register a little different temps in cruise, but they always stay consistent. I had my hands full flying the plane so I wasn't taking notes, but I do recall when the cht alarm light went off I noticed the highest egt was 1440 or so which is about 75-100 degrees higher than it would normally be. So, I had both higher cht's and egt's occuring at the same time my engine was stumbling & performing poorly. These higher CHT & EGT's may have been partly caused by my having a pitch-up attitude & slow airspeed, trying to hold altitude at low power output for an extended period of time while I was nursing my way to the other airport. This would have obviously reduced the volume of cooling air to the engine. I've noticed when doing slow flight at 1800 & 1900 rpm, my cht's will get up in the mid 300's similar to full cruise due to the same lack of cooling air volume. I've got a question for you on this section. You said "With vapor lock, you loose gas flow and the cht & egt go down." Seems to me the opposite would occur, since you'd have the same air volume and less gas, thus a leaned out condition. What am I missing there? > 9 - You did not mention OIL TEMPS? They never exceeded 210. On a hot summer day they will settle in between 200 & 210 at cruise. In the Texas winter, O/T runs 180 -195. I do not have an oil cooler. I appreciate the input, & please let me know what any or all of you think on these comments. I'm still leaning towards vapor lock. Yesterday, I made a foil-faced insulation blanket and wrapped my gascolator with it. Tied it off with cable ties. Jimmy Y Houston Read this topic online here: http://forums.matronics.com/viewtopic.php?p=405528#405528 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message continental-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Continental-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/continental-list Browse Digests http://www.matronics.com/digest/continental-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.