Briggs NG/LPG conversion

[hugenbdd]

Hello
This is my first post.  Decided to post as I can't find much information on these conversion and this part of the forum doesn't see much action. 
I have a Briggs & Stratton (screamer, 3600rpm) generator 5500w bought about a year ago.  Before I came to learn about the slow speed diesels.  (Lister/Changfa clones etc).  Since I'm working with what I have, I decided that I didn't want store all that much gas.  So I got a propane conversion kit from US carb.  (I'm Not connected to them in any way.)

I was surprised how easy the install was since I'm not the most "handy" person in the world.
   Remove the choke
   Remove air filter and housing.
   Add the venturi (Circle piece where the NG/LPG is added to the airstream).
   Splice and extend the line that goes between the air filter housing and the OHV housing... (I'm not sure what this line does but I'm sure most on here do).
   Screw the regulator to the frame.
   Connect the regulator to the venturi.
   Put the airfilter and housing back on.
   Done...

I then set out to test this modification with the 55 foot 3/4 inch hose I also bought.

Connected everything up, and started the generator on Gasoline.  Everything started fine.  However when I try to move the choke to the "Run" position it seems to hunt for the speed.  I have settled on moving the choke to a middle position.

I proceeded to shut off the gasoline and and turn on my NG line.  I primed the regulator a few times and figured that the remaining gasoline would pull the NG through the long 55ft hose.  It did, and the system sputtered for a second.  The regulator has a small screw on the top that appears to control the amount of NG that makes it into the system.  I opened this a bit further and the system came right back to normal.  With the gasoline gone and running on NG I moved the choke to the "Run" position and it did not hunt anymore.

Now all I need is a power outage to test it out with!!! 

Does anyone know why the system seems to hunt when the choke is put into the run position?  Could there be an air gab between the carb, mod, and/or filter housing?

Thanks
Dave

[mobile_bob]

did it hunt running on gasoline before the conversion?

usually my gas engines do that when the gas gets bad, requiring me to remove the carb and thoroughly clean out
all the jets, passages and bowl.

as for the rubber hose going to the crankcase, or valve cover, it is a crankcase vent, epa requires that the crankcase be
vented to that the fumes are consumed and burnt in the engine, however

(there is always a "however") 

if this line goes back into the carb between the air filter and the carb, when the filter starts to clog it will pull oil out of the
crankcase at an alarming rate,  the engine will die a horrible death if you don't keep up on checking the oil level
and keep a clean filter, or

you can cap off the carb side connection and fit the hose on the intake side of the air cleaner, then as the filter clogs
it cannot increase vacuum on the crankcase, the downside is the filter element if paper will get a bit oily over time, but
i would rather have an oily element as have the thing suck itself dry of lube oil.

don't ask me how i know this!

(ok, gonna tell you anyway)

i had a coleman powermate 1800 watt generator
it lasted 5 hours total before it decided to suck the crankcase dry between
about 4.5 and 5 hours

and yes i checked the oil each time it was used, its only use was intermittent 15 to 30 minute runs
and was full before the last 30minute run when it sucked the crankcase dry.

what started out to be a useful tool ended up being only so much low grade scrap

btw, i like seeing  your propane conversion

thanks for posting it!

bob g

[WGB]

I don't know!
But welcome!

[veggie]

hugenbdd,

Put the engine under a bit of load and see if the governor takes care of the hunting.
Say 2kw's or so. Give the governor something to do 

veggie

[hugenbdd]

Thanks Mobile_Bob and Veggie.

I will put it under load and see.   It did not do this before.  I ran it about a month ago and it did not hunt, even while not under load.  It may be the gas, the gas is about 10 months old but it was treated.

I think the hose is going from the Air Filter to the OHV area and not the carb.  The carb would be where I adjust the choke right?  So  I think it's the crank case vent like Mobile_Bob mentioned.  If not and the engine dies a horrible death, then I just have an excuse to get a slow speed diesel.   

Thanks
Dave

[hugenbdd]

Well I ran the generator under load today for a bit longer test.  Seems I didn't have the replacement "studs" screwed in good enough.  After about 45 minutes and while I was testing our stove they managed to rattle out and the generator shut down.  I put some lock tight on the studs and screwed them back in.  Hopefully better this time.  I will run the test again in the next few weeks and see how it does.

I have a few general questions about these generators.

• Volts: Utility tends to run around 120-122, but the gen runs at about 127-128, is this normal and okay for my electronics?
• HZ: utility runs dead on at 60, generator can bounce between 58 - 62, again is this acceptable?
• Seems when it was run under load with about 12 amps on each segment (convection stove running) the HZ was able to hold 60hz pretty steady, and the volts dropped to about 118.
  

Also, does anyone know where to get 3/4 inch quick connect sets for less than $80 or so?  I can't seem to find any cheap ones.

Thanks
Dave

[mobile_bob]

your bullet point questions all look to be normal to me
128vac no load is right at the top end of asme spec's iirc
droop to 118 is normal as well
58 to 62 is adequate for most all loads today in my opinion, save for AC motorized clocks and old LP turntables
where the music will drift from sharp to flat, and the clock will gain and lose a bit of time each day

bob g