happy cap???

"J'-remy

"J'-remy

Member
long ago when racing a flathead we could only fill the tank up to the seam because the engine would cut out around the corner. TS racing advertises a happy cap that allows you to fill up the tank. some said that's not what it does/doesn't work. Chavis said it has to be installed correctly????
question 1 why does it cut out with too much fuel?
If the happy cap lets you fill it up how does it work? and how do you install it correctly? not tight?

the tank is essentially a float bowl for the carburetor, and it has a diaphram.
curious a i ran out of fuel in the middle of a race due to not starting/ cautions
 
Exactly what flattop said. It was just a baffled cap that allowed it to vent without pouring fuel out and still allow air in. With the standard caps one guy I wrenched for would still fill all the way but have to blow into the cap to get it started sometimes.
 
We've ran happy caps the last 13 years. I had one left that decided on its own to leave us last month. Luckily it was at night and we were so far ahead that the flaggers never seen the fuel pouring out the tank in the corners.
 
J'-remy said:
long ago when racing a flathead we could only fill the tank up to the seam because the engine would cut out around the corner. TS racing advertises a happy cap that allows you to fill up the tank. some said that's not what it does/doesn't work. Chavis said it has to be installed correctly????
question 1 why does it cut out with too much fuel?
If the happy cap lets you fill it up how does it work? and how do you install it correctly? not tight?

the tank is essentially a float bowl for the carburetor, and it has a diaphram.
curious a i ran out of fuel in the middle of a race due to not starting/ cautions
Click to expand...
Too much fuel, no air space to vent properly, and the cap had to be turned a certain way to work
 
B35BA5A6-771F-4D58-AEB8-697F816F6B51.jpeg
 
Thanks. Now the real question that everybody is waiting on me to ask. Ok I'll bite! Brian it's been a couple days now, lol. Can you let us in on your why it matters as well as where to position it while tight? 🤔😉🤣
 
Here’s a question, what is the tank insert for? I was told you didn’t need a happy cap with it? But it needs to be installed a certain way? (Seen one fail tech)
 
Quote : Mr. Carlson.
The tank insert is particularly helpful for road course racers on high G right hand corners. It keeps the fuel from draining back into the tank as quickly. It can help some for oval racers, but generally is not needed
 
KKania17 said:
Here’s a question, what is the tank insert for? I was told you didn’t need a happy cap with it? But it needs to be installed a certain way? (Seen one fail tech)
Click to expand...
If they are installed incorrectly, they can be used to pressure feed a carb - particularly helpful on small plate engines. The fuel has nowhere to overflow, so it is pulled past the diaphragm rather than solely through the short stem. If done on purpose, it is usually couple with the ear on the diaphragm folded back and or a small hole in the diaphragm. Also look for ways to circumvent the restrictor plate to match the more air needed (ie 1 gasket, gasket cut, bolts loose, bolt drilled, port drilled, etc etc.)
The WKA manual used to have a good diagram for correct/legal installation of the tank repair kit.


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
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34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
If you drill a hole through the left screw holding the carb to the tank you will not need a happy cap. Its illegal if you get caught though. :)
 
I heard tell some would fill the tank with water and freeze it to stretch the tank bigger. im willing to try lol. Last race was in I almost ran out of Fuel AGAIN. I barely made weight and 2nd place made me rescale the kart. that's how close I was. next race im stopping for every caution. flagman doesn't seem to know what fuel we have is a gamble. I could barely get two laps under green and CAUTION!! we would drive around 4 laps to line back up. when they tested my fuel we nearly had the kart upside down to get a shot glass full. and I have a happy cap
 
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