Original Posted By: Gary Gower
Has anyone installed a spring on the Stromberg carb to bring it to full open in case of a linkage failure in flight? I went out flying today, using a runway with no good emergency landing spots on the departure end. Sitting around the hangar chatting later, that subject came up and it sounded like a good idea. Dick N.________________________________________________________________________________Date: Sun, 4 Jun 2006 10:33:32 -0700 (PDT)
Pietenpol-List: carb
Re: Pietenpol-List: carb
Original Posted By: Dick Navratil
I know quiet a few pilots that have the "spring" on their carbs. I thought about it and came up with a few observations. I think the cable would probably break when you PULL the throttle to closed and put tension on the cable. I don't think it would make sense for a cable to break by PUSHING it through the jacket. If it broke inside the jacket, it seems that it would still push through, but might be harder than normal due to frayed ends. This would leave the throttle on Open. If the cable came off the carb lever by breakage or the bolt wearing thru or falling out, then adding a very soft spring would be the best idea in the world and you would be patting yourself on the back for a long time after landing successfully. If the spring is heavy, you will experience throttle creep and will be constantly adjusting the throttle, it also puts a constant strain on the cable. Look at the hardware stores or on the internet and look for a spring with at least 1/2" diameter and very soft and pulls very easily. If the ends are not long enough, an extender can be made from med to heavy safety tie wire and anchored somewhere on the engine, not to the motor mount to isolate constant vibration. My 172 has one, but the 150 that I own with a partner does not. Go figure. Our Piets are not flying yet. We just replaced the cable on the 150 and it had several thousand hours on it. It was not having a problem, but replacement seemed like cheap insurance, especially if our kids take it out for a spin. If you ever feel a binding in the throttle, even just once, it is time to take a look at that cable. By being a stranded cable, usually one or two strands will break first and cause some friction. Consider this your fair warning. You need to have in mind a plan to cope with this type of emergency. Either turn the engine switch on and off and blow the ends out of the mufflers or get into a safe position at the airport, shut the engine down and do a dead stick landing. Barry ----- Original Message -----
I know quiet a few pilots that have the "spring" on their carbs. I thought about it and came up with a few observations. I think the cable would probably break when you PULL the throttle to closed and put tension on the cable. I don't think it would make sense for a cable to break by PUSHING it through the jacket. If it broke inside the jacket, it seems that it would still push through, but might be harder than normal due to frayed ends. This would leave the throttle on Open. If the cable came off the carb lever by breakage or the bolt wearing thru or falling out, then adding a very soft spring would be the best idea in the world and you would be patting yourself on the back for a long time after landing successfully. If the spring is heavy, you will experience throttle creep and will be constantly adjusting the throttle, it also puts a constant strain on the cable. Look at the hardware stores or on the internet and look for a spring with at least 1/2" diameter and very soft and pulls very easily. If the ends are not long enough, an extender can be made from med to heavy safety tie wire and anchored somewhere on the engine, not to the motor mount to isolate constant vibration. My 172 has one, but the 150 that I own with a partner does not. Go figure. Our Piets are not flying yet. We just replaced the cable on the 150 and it had several thousand hours on it. It was not having a problem, but replacement seemed like cheap insurance, especially if our kids take it out for a spin. If you ever feel a binding in the throttle, even just once, it is time to take a look at that cable. By being a stranded cable, usually one or two strands will break first and cause some friction. Consider this your fair warning. You need to have in mind a plan to cope with this type of emergency. Either turn the engine switch on and off and blow the ends out of the mufflers or get into a safe position at the airport, shut the engine down and do a dead stick landing. Barry ----- Original Message -----
RE: Pietenpol-List: carb
Original Posted By: "Phillips, Jack"
Re: Pietenpol-List: carb
Original Posted By: Phillips, Jack
JackI was hoping you would respond. I was thinking of your problem at Brodhead when I posted. If you would have lost that bolt in flight maybe even a lighter spring could have given you power to find a landing site??? If the bolt had departed as in your case on start up and the spring opened the carb before start, the idler jets should be cut off and the engine hopefully would not start.Just a few thoughtsDick ----- Original Message -----
JackI was hoping you would respond. I was thinking of your problem at Brodhead when I posted. If you would have lost that bolt in flight maybe even a lighter spring could have given you power to find a landing site??? If the bolt had departed as in your case on start up and the spring opened the carb before start, the idler jets should be cut off and the engine hopefully would not start.Just a few thoughtsDick ----- Original Message -----
RE: Pietenpol-List: carb
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Or, if the bolt came loose before engine start and I had such a spring inplace, old John could have found himself in front of a prop going fullthrottle, with nothing but my marginal brakes between him and beingshredded!I think such a spring is a good idea, but I have so much friction in mycable, I'm not sure it would help in my situation. Of course, if the boltcame loose in flight at cruise or climb power, it wouldn't be much of aproblem. Only if I had throttled back to idle, then decided I needed morepower (often the case, considering the wondrous glide capabilities of aPietenpol) would it be a problem. -----Original Message-----
Or, if the bolt came loose before engine start and I had such a spring inplace, old John could have found himself in front of a prop going fullthrottle, with nothing but my marginal brakes between him and beingshredded!I think such a spring is a good idea, but I have so much friction in mycable, I'm not sure it would help in my situation. Of course, if the boltcame loose in flight at cruise or climb power, it wouldn't be much of aproblem. Only if I had throttled back to idle, then decided I needed morepower (often the case, considering the wondrous glide capabilities of aPietenpol) would it be a problem. -----Original Message-----