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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › Help needed, OS 91 C-Spec
02-08-2006 01:11 PM  12 years agoPost 1
Blademan7065

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Greenfield, Ma.

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I am running a C-Spec with the third needle mod to the stock carb. I was wondering what people are running for low, high and fuel return/3rd needle valve settings. Also where is your pump pressure set screw set at. I know that these are going to be a little different for everyone but I am looking to get an idea for a good starting point. I am fighting with an engine right now and think that I may have a bad pump.

Also may not be related but here goes.

With the engine off should the fuel be draining out of the line that conect the header tank to the pump and the pump to the carb. In my past experience this should not be happening. I mean the thing empties in about 2 seconds. Completly empty from the header tank to the carb. I was under the impression that the fuel will not syphon through a pump. At least this is what I have found on the VP-30 on a plank engine. I assume that it should be the same on a heli, it is the same pump.

Thanks for all the help.

Dan

Fromeco Rep
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02-08-2006 04:34 PM  12 years agoPost 2
Gary

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Crosby, Texas

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I'm sure I won't be in the majority here but oh well. I rebuilt a C-Spec for a friend of mine last week. The only parts that weren't new were the carb and the case. I put the pump back on it that was on the motor originally and could not get it to run right to save my life. I tried 3 other pumps changing pressures and needle settings. Still would not run right. I finally decided to block off the pump and run it without the pump and on the first re-tuning it non pumped the motor ran smooth as glass. The idle was good, the transitions from idle to mid-range to top end was smooth and the fuel economy was tons better. Not saying this is what needs to be done on all of them but it sure worked on this one.

"Who said obsession was a bad thing"

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HomeAircraftHelicopterEngines Plugs Mufflers Fuel › Help needed, OS 91 C-Spec
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