Tecumseh HM80 Performance Carb Suggestions

[pulsar2121]

I have a Tecumseh HM80 off of an old snowblower that I plan on using in a future kart build. I've done a mild rebuild and some old-school hot-rodding tricks: removed the governor, removed the flywheel fan, open header exhaust, etc.

Anyway, I'm looking for some carburetor suggestions. I'd like to switch it over to a slide carburetor. I'm looking at the PZ series carbs. I've had good luck with these carbs in past builds. They come with throttle bodies ranging from 13mm to 32mm. I'm leaning towards the PZ30 which is a common size and is very affordable. Would this be a good match for a 19.41 cu in engine?

 

[karl]

Did you cut the fins off the cast iron flywheel? That could be really unbalanced and dangerous.

I would use the stock carb or hm100+ carb, and make a direct, straight, short intake manifold, instead of the factory restrictive elbow

 

[KartFab]

One way of thinking about it is:

1) measure the valve size for the intake, and go 2-5 mm smaller on carb venturi size.

Another way of thinking about it is:

2) measure intake port diameter, and match the carb output side diameter to the intake.

Option one will get you where you need to be without accidentally going too big.

 

[pulsar2121]

Karl, It actually had a snap-fit plastic fan on the cast iron flywheel. So, it was easy to remove without changing the balanced weight of the flywheel, much like a predator engine.

KartFab, Thanks for the input. I'll take off the head again and take a digital calipers to the intake valve to see how big I can go. That will be easy enough since it's a flathead engine.

I definitely want to upgrade the factory carb. I prefer slide carbs because it eliminates the need for throttle linkage, looks cleaner, and is easier to mount a pod air filter up to it. I will probably end up making a custom intake manifold as well as karl had suggested since the factory intake has two elbows and it places the carb below the intake port instead of level or above.