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Wisconsin twin question

John Newman Jr.

Subscriber
Age
64
Last Subscription Date
01/10/2019
I have a Wisconsin twin - don't know exactly what model it is since it is missing its tag, but probably a THD or possibly a TJD. It has a High Temp shut down switch on the head and a low oil pres. shut down switch both attached to the kill button on the mag. Even though I've had this thing for several years, I just recently got it running (all it needed was the points cleaned...)
Anyway... It has a fitting on the bottom of the carb (see picture) that I do not see in any of my books. It is a brass elbow with a shut off valve / screw on the bottom leg. The vertical leg goes up through the bottom and into the throat of the carb. What is this and what is it supposed to do?
Thanks,
 

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Andrew Mackey

Moderator
Last Subscription Date
05/14/2017
It looks like this engine was set up for dual fuel. They used the wisconson twins on hydraulic man lifts, that had both gasoline and propane for fuel. Gas was used outdoors, and propane inside (less CO, and less smell) The fitting would have had a hose that went to an electronic shutoff valve, and then to the regulater. Switching from propane to gas was simple - just turn on the gas switch! Going from gas to propane was another matter. Most guys just threw the switch to propane, which would then load up the engine so bad, it usually fouled the plug :crazy: . You had to switch both valves off, let the engine burn off all the gasoline, and then turn on the propane.
Andrew :D
 

K D Redd

In Memory Of
John,

This is a connection for a LP demand regulator. You can use a Garrettson Model KN. The Model KN needs 11 inch water column pressure input. This pressure is what a regular LP regulator output. I have a THD on a 180 amp Lincoln portable welder I have been aiming to set-up on LP.
You can tell a THD from A TJD by watching the pistons. If the piston come to TOP DEAD CANTER at the same time the engine is a TF, TH, or THD. If they alternate the engine is a TJD.

Kent
 

Mac Leod

Registered
or, as I have been told by a few, you can tell by sound...a tjd sounds like a john deere 2 cylinder engine...

any one interested in THD parts...I have one parted out-need somthing, ask

Mac Leod
 

John Newman Jr.

Subscriber
Age
64
Last Subscription Date
01/10/2019
Thanks for the info! Judging by the way it entered the carb, I kinda thought it might be part of a dual fuel set-up. I know absolutely no history on this engine, so there is no telling what it came out of. Since I will be running it strictly on gasoline, I imagine I should probably keep this valve fully closed - or would I be better off removing it completely and plugging the hole in the bottom of the carb?
BTW - From your remarks, it probably is a THD, since both pistons are at TDC at the same time. I was moving it out of the way to get to another engine in the back of the shop and thought I'd take a look at it to see why I didn't have any spark. Removed the mag and clamped it to the banch and with the cover off snapped it through to see if I got any kind of spark at all while holding a screwdriver against the case and the tip just a hair off of the HT term. There was just the tiniest hint of a spark, so I cleaned the points, checked the gap and tried again. ZAP! Re-installed it and gassed it up, gave it a couple of pulls and it started, but quickly produced a cloud of black smoke and flooded itself to a stop. I then pulled the carb and cleaned it out and checked the float needle. Once I was satisfied with that I put it back on and it fired right up and ran quite well. Not sure what I will end up doing with it, but it has a Rockford clutch on it, so it has great potential.
Thanks again for the help in identifying the mystery fitting.
 

K D Redd

In Memory Of
John,

If you remove the LP fitting from the carb on your THD I would be interested in the part for my welder. I want to convert to LP because of the way this new gas goes bad so fast. Where i have my welder mounted is on a trailer I call my service trailer. I have a 5000 watt Winco LP fuel generator on this trailer along with a 250 Gal. LP tank I use to fuel my LP fueled combind. I also have a demand regulator. I have been aiming to build the fitting for the carb. If you would like to sell the fitting drop me an E-mail. My address is at the end of the GEM artical about the B&S coil convertion.

Kent Redd
 
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