Tecumseh To The Rescue!

cannonball2

cannonball2

Well-Known Member
After doing some of Quentons mods to my 2007 NE5 I was unable to get the stock 22mm carb to run clean. Not being a stranger to carb work having been in the lawn equipment business for years, I finally concluded I either have a bad carb, or the needle profile is all wrong. I could either get it to run well at top throttle, with a miserable low and mid range or vice versa. After 2 days I finally gave up and went for one of my favorite carbs a Tecumseh carb for a 5hp horizontial engine. Just happened to have one in stock. It took a couple of quick file strokes on the flange holes and she slid right on, installed the fuel line, fired it up and adjusted. The beauty of this carb is an adjustable main jet. After warming up it was out for a quick run. WOW! Smooth clean running all the way to the top. Not having the throttle linkage worked out yet I was having to operate the butterfly with my right hand. I let it go at 48mph, as I realized I really didnt need to hit the road. I am satisfied to say the least. Now it just a matter to make a small bracket for the throttle cable and a spacer to flow the Tecumseh into the Whizzer cylinder smoothly. The Tecumseh bore sits slightly higher than the stock carb. The stock air filter is pretty period correct looking also. This is a faily easy straight foward conversion. I believe I am finally going to be happy with the way the Whizzer runs now.
 

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You might be on to something. I'm interested to say the least!! Keep us posted on how it runs. I might buy one from you.
 
I love it. I was wondering when someone was going to try something diferent. Also you can use a chain saw, weedeater type carb. What you do is take off the diafram and make a new plate ( about 1/4" aluminum ) so you can drill and tap it for a 1/4" fuiel line fiting. It will work as gravity feed this way. You have high and low jets if its a older one. Some of the new ones are fixed so you can't ajust.
There was a enginer in Farm Show mag. that did this this to a farmall cub with a chain saw carb. Works realy good......Curt farmshow.com and get a free isue
 
If you want to run a pumper carb you can easily pick up the needed pulse from the intake runner or the tappet cover. The valve cover is a good place on OHV engines. Hope to finish the conversion today so I can get some time on it to see if it has any issues.
 
How about a Briggs carb? or did you just use the Techumseh because you had it on hand? Have you seen ( my latest B&S build Under DIY home built ) Can't waqite to see how yours works out. I had them carbs on a couple of mini bikes that were my kids and seem to work well. Can't say that much for the engines....Curt
 
The Briggs Walbro type carb will fit also. If you get the one off an engine with an idle circut like a horizontal, it should do fine. The same carb is on lawn mowers but most dont have a true idle circut. The Briggs doesnt have an adjustable main jet though(the later Tecumsehs dont either) which is the reason for the early style Tecumseh being used.
 
Carburetor looks similar to older versions of the Carter "N" carburetor. I have seen a few of vintage Whizzers running similar setups, and the conversion is much easier because the vintage motors have the studs located in the center of the pattern.

Keep us posted on the progress, and any information on size, model number, etc, would be helpful.

Have fun,
 
Here is a pic of the "flow" adapter to match the Tecumseh carb to the Whizzer cylinder. The red outlines the flow relief. Was able to use the stock throttle cable. This is almost too easy! If it runs well enough I will post part numbers and any hints necessary.
 

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Well Im stoked! I have about a half mile straight run in front of my house, just comlpeted 2 runs into and out of a 10mph wind. First run got 43mph into the wind 46 out, second 45 into 49 out. I feel the engine was better warmed up on the second run. I bet if I had lay down I might have got 50. Any way I am happy with the conversion. The best run I got from the stock carb was just 40mph. It never ran clean enough to let the engine wind out. There are only two issues I have found. One is for what ever reason this carb was spec. with a 3/4 choke plate, needs a full plate. Second, if you snap the throttle from idle it will momentarily stumble before it grabs and just plain halls butt. This carb has 2 transition holes. I am sure I have seen carbs with 3 maybe more. I can richen the idle mixture and the stumble disappears but the idle quality(which normally is excellent) degrades. So the conclusion is there is probably a better carb from Tecumseh. I have a feeling what would work perfectly would be a go kart carb from either the H35 or H50. This carb is just fine for me, once I change out the choke plate. If a person was going to go this way, I believe I would let my local small engine shop order a carb specified for an older(flathead) kart engine. I will be happy to post the part# I have if desired. Pics(not real good) are the final conversion minus the air filter which is off for paint. Dont ask me how the bike guy got in there?!
 

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For anyone interested I looked up the carb for the Tecumseh H35 on my old home built motorbike I built nearly 30 yrs ago. This engine was originally on a kart I bought for my kids, so it is the ideal spec for the conversion. The original part# is 631070A it rolls to the current # 631921 it might be found NOS under the old#. Should be ideal as it was designed for a application that required quick throttle response. My current conversion is running very well. It acquired nearly 25mi of trouble free pleasnt riding yesterday.
 

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Not cheap. These carbs used to sell in the $50+ range which wasnt too bad. I think now they are closer to $80. Just type the part# number into Google or ebay you should find some.
 
Nice write up.
I am wondering what the flow adapter you have is made from? I have an aluminum spacer on mine. That looks like Teflon or something like that. With that material a flow adapter would be very easy to make as long as it can handle the heat.

Jim
 
The adpter is HDPE. I have used it for spacers and carb adapters for years. It cuts and machines very nicely and quickly. It took well under 10min to make the adpter(less the shaping for the port matching). Have had no issues with it heat or otherwise. A commoin source are cutting boards at the local Wal-mart. You have to watch out for some of the thicker boards as some are made by folding a thinner dimension over on itself, leaving a small gap and vacuum leak in the middle. A $3 cutting board will make a bunch of spacers.
 
cannonball2 said:
The Briggs Walbro type carb will fit also. If you get the one off an engine with an idle circut like a horizontal, it should do fine. The same carb is on lawn mowers but most dont have a true idle circut. The Briggs doesnt have an adjustable main jet though(the later Tecumsehs dont either) which is the reason for the early style Tecumseh being used.
Click to expand...

How about the ones off a snow blower would it have the idle circut?
 
cannonball2 said:
The adpter is HDPE. I have used it for spacers and carb adapters for years. It cuts and machines very nicely and quickly. It took well under 10min to make the adpter(less the shaping for the port matching). Have had no issues with it heat or otherwise. A commoin source are cutting boards at the local Wal-mart. You have to watch out for some of the thicker boards as some are made by folding a thinner dimension over on itself, leaving a small gap and vacuum leak in the middle. A $3 cutting board will make a bunch of spacers.
Click to expand...

Its not very thick about 1/2" ?
 
Being a Southerner I am not familar with snow blowers. The Intek horizontal carbs have the idle circut. Its easy to tell, the non idle carbs have no idle mixture adjustment screw, they are usually on walk mower engines. The Briggs carbs are also excellent carbs and have the advantage of having the fuel inlet on the same side as the Whizzer carb. They are fixed jet carbs however, but the jetting is probably close enough. Changing jetting will be up to you and your number drills however. The spacer is not quite 1/2". I am sure thicker boards are out there, Wal-mart is my only local source, and they carry only the thinner boards in HDPE. They can be stacked, I simlpy glue them together with thick CA glue.
 
Some of the woodworkers supplys stores have them thicker? be more money though. How thick is the one you made? Snow blower have a seperate gas tank like a mini bike. THANKS FOR THE INFO. I will keep on the lookout for the ones with idle mixture screw.
AWESOME were there is a will there is a way....Curt

WOW just looked on partstree.com And that carb is listed for $113. Start snooping
 
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The spacer is about 11mm. I found the Tecumseh carb by searching the part# on Google at one vendor for around $80. Ebay has MANY similar looking carbs for the H30-35 engines in the $40+ range. Not knowing what the spec is might be a gamble though.
 
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