390 carb on 5hp briggs

D

Ducar 212

Member
Anybody ever adapt a gx390 carb to a 5hp briggs? My dad has an old WKA flathead that has a rusted tank and wanted to run a different carb on it with a gravity feed tank, it's on a bike.
I was thinking the 390 would definitely be on the big side, but might work. If not I have a clone carb here that should definitely work, I just thought the 390 could give that motor some power for cheap. Any thoughts?
 
You will need to make a manifold, as I assume nobody makes one off the shelf. These are still available https://www.eccarburetors.com/intake-manifold-briggs-flathead. The PZ22 manifold is to adapt the animal carb or if cheap is a real concern, there are China knock offs. The Tillotson has the same bolt pattern as Tecumseh carbs. There are also some Briggs manifolds, part numbers 281247 and 691922 that have the same bolt pattern as the Tilly. They are out of production. https://www.jackssmallengines.com/jacks-parts-lookup/part/briggs-stratton/691922
 
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Chipg56 said:
You will need to make a manifold, as I assume nobody makes one off the shelf. These are still available https://www.eccarburetors.com/intake-manifold-briggs-flathead. The PZ22 manifold is to adapt the animal carb or if cheap is a real concern, there are China knock offs. The Tillotson has the same bolt pattern as Tecumseh carbs. There are also some Briggs manifolds, part numbers 281247 and 691922. They are out of production. https://www.jackssmallengines.com/jacks-parts-lookup/part/briggs-stratton/691922
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Yeah I fabricate for a living, that's no issue, I just wondered if the 390 carb would be too much or possibly be hard to tune or run right, but I believe it would run good and probably make power. The venturi is small enough, it should get good fuel signal. I figured there was probably a ton of people who have done this on here
 
Probably not many (if any) who have done it on here -- this is mostly a kart racing group and that adaptation really doesn't fit anything that is currently being raced.
The carb should work fine, the adapter will take some handywork.



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Awesome, yeah this is just homemade horsepower basically. I build and fabricate things much more complex than that all the time, the adapter is not a big deal. It's just a fun motor, thanks for the info!
 
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