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  #11  
Old 01-09-2009, 07:48 AM
David-aviator David-aviator is offline
 
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Location: Chesterfield, Missouri
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Quote:
Originally Posted by airguy View Post
I beg to differ. I do understand the purge valve, both it's function and it's operational purpose. My point is that it's not needed for a cold start. Using it is no detriment, but neither it is a great advantage, and it's certainly not required. The purge valves specific purpose is to recirculate fuel from the flow divider back to the fuel supply, (hence the name PURGE valve) which has the side effect of dumping all the pressure on the injector lines which allows it to be used as an excellent idle cutoff tool. The whole operational point for the existence of the purge valve is to solve hot start problems by removing heated fuel from the FWF area.
But it is convenient.

I am still on a learning curve with it but I am having success using it as a primer valve on a cold start , about 5 seconds on, then off, hit the starter and when the engine fires back to on. If one did not use that procedure, you'd have to do the same thing with the manual mixture lever or the engine would be flooded or you'd have to turn the pump on and off.

I was messing with the idle mixture setting yesterday, it is very sensitive. A one flat adjustment is noticeable. I will not crawl down to make that adjustment while the engine is running as it is about 10" from the prop but it can be accomplished starting the stopping the engine. Don says go fly and then fine tune it after the break in...so that's the plan as soon as I get the oil temp gauge to work which should be as soon as a package arrives from GRT.
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  #12  
Old 01-09-2009, 09:14 AM
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flyingbeaver26 flyingbeaver26 is offline
 
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Default Silverhawk with no purge

Guys, I have the silver hawk fuel injector. So I don't have a purge valve. Is this a big mistake? I bought my IO360 M1B factory direct from Lycoming through vans. Is there a way for me to install one? The distribution hub on the top of the engine has a AN4 NPT-to-flare fitting on it that is supposed to hooked up to something. Is this where I hook one up? or is that where I get my fuel pressure sensor to connect to? Thanks for the advice. -Brad
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  #13  
Old 01-09-2009, 09:36 AM
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JonJay JonJay is offline
 
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Default Search the threads for Hot Start info...

Quote:
Originally Posted by flyingbeaver26 View Post
Guys, I have the silver hawk fuel injector. So I don't have a purge valve. Is this a big mistake? I bought my IO360 M1B factory direct from Lycoming through vans. Is there a way for me to install one? The distribution hub on the top of the engine has a AN4 NPT-to-flare fitting on it that is supposed to hooked up to something. Is this where I hook one up? or is that where I get my fuel pressure sensor to connect to? Thanks for the advice. -Brad
I do not have a purge valve. It took a bit of experimenting but I found a Hot Start procedure that works well for my set up. They are all different. I usually start on a Hot Start within 6 blades if not sooner. Once in a while, I need to re-engage, but rarely.
The biggest challenge is to know, when is it a Hot Start? You learn this too so after you have been sitting on a hot ramp for a few hours, do your Hot Start procedure, it does not catch, well, do a normal cold start and off you go. You will learn all of this. I learned it and never drained a battery or got stuck somewhere.
I suspect a purge valve makes procedures a little more consistent and less thought in regard to if it is a Hot Start condition or not.
Consider these things before going through the expense and work to install. However it is not that difficult to do and can be added in.
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  #14  
Old 01-09-2009, 12:12 PM
David-aviator David-aviator is offline
 
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Quote:
Originally Posted by flyingbeaver26 View Post
Guys, I have the silver hawk fuel injector. So I don't have a purge valve. Is this a big mistake? I bought my IO360 M1B factory direct from Lycoming through vans. Is there a way for me to install one? The distribution hub on the top of the engine has a AN4 NPT-to-flare fitting on it that is supposed to hooked up to something. Is this where I hook one up? or is that where I get my fuel pressure sensor to connect to? Thanks for the advice. -Brad
Check with Don at AFP. He knows more about all these systems than anyone here.
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  #15  
Old 01-09-2009, 12:32 PM
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w1curtis w1curtis is offline
 
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Quote:
Originally Posted by flyingbeaver26 View Post
Guys, I have the silver hawk fuel injector. So I don't have a purge valve. Is this a big mistake? I bought my IO360 M1B factory direct from Lycoming through vans. Is there a way for me to install one? The distribution hub on the top of the engine has a AN4 NPT-to-flare fitting on it that is supposed to hooked up to something. Is this where I hook one up? or is that where I get my fuel pressure sensor to connect to? Thanks for the advice. -Brad
NO. Hot starts are not a problem with the Bendix (Silver Hawk) type injection system. As noted above, this is much ado about nothing with the easily acquired technique.
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  #16  
Old 01-09-2009, 02:32 PM
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Caveman Caveman is offline
 
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Location: Oklahoma
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Quote:
Originally Posted by flyingbeaver26 View Post
Guys, I have the silver hawk fuel injector. So I don't have a purge valve. Is this a big mistake? I bought my IO360 M1B factory direct from Lycoming through vans. Is there a way for me to install one? The distribution hub on the top of the engine has a AN4 NPT-to-flare fitting on it that is supposed to hooked up to something. Is this where I hook one up? or is that where I get my fuel pressure sensor to connect to? Thanks for the advice. -Brad
I have the Silverhawk on a TMX-IO360 M1B with no purge valve. Hot starts are as simple as:

Try a normal start. If that doesn't work, pull the mixture to idle cut-off and crank till she starts, then slowly feed the mixture control in.

No other steps necessary. No fiddling with the throttle or other stuff, period. I do have an LSI Plasma II and one mag with impulse coupling. I have both switches on to start. Maybe, thats why mine starts so easily?
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  #17  
Old 01-09-2009, 04:38 PM
David Clifford David Clifford is offline
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I was discussing this subject of a purge valve with the current owner of the Cozy MKIV we built. It is powered by a Superior XP IO-360 and after a short period of trail and error during taxi testing, hot starts have never been a problem without a purge valve. I don't plan on installing one in my RV-10. It adds time, costs, and complexity for a problem that does not exist provided proper starting proceedures are followed. I don't see how an IO-540 would be any different from an IO-360. I may be proven wrong later, but if thats the case I will install one then.
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  #18  
Old 01-15-2009, 11:22 AM
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flyingbeaver26 flyingbeaver26 is offline
 
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Default Silverhawk question

My silverhawk distribution manifold has a NPT-flare port on it. Its the fitting with the red cap on it in the picture below. Since the silverhawk has no purge valve, what does this fitting do? Is it used to sense fuel pressure? My factory direct Lycoming engine came with this FI system but they do not include any instructions for it.






2nd question, a little off topic. The throttle body has four 5/16th nuts that secure it to the sump. Do these nuts require the star-type lock washer to be used on them? Torque should be 110 - 150 "/#'s? I have no instructions on this so your advise is very helpfull.





Thanks,
Brad Vier
RV-8 FWF
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  #19  
Old 01-15-2009, 11:49 AM
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Kahuna Kahuna is offline
 
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Location: Gold Hill, NC25
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Picture 1, red cap is at head pressure for the spider. Fuel Pressure could be had from here. Its not for the purge valve. If not used, remove that fitting and put in a plug.

Picture 2, yes a lock washer, star or split, should be used there.
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