Replacing OEM carb, Scag 48in SWZ with Vanguard engine

ngant17

LawnSite Member
Mechanics just diagnosed my Scag WB 48in mower, it has original Briggs Vanguard V-twin 16hp engine (code is 9702141). Which means it's over 20 years old. Running fine, strong compression but burns a little oil over time. Finally it seems the carburetor(Aisan?) is DOA according to local mower shop.

Unfortunately the original carb, the Briggs Flo-Jet side-draft one-piece, it was discontinued in 2014 and no longer available as an OEM replacement. Looked for Aisan and Mikuni carbs but nothing matches original design to remove/replace.

I'm considering fabricating an intake manifold and adapt a Kohler #30 carb as used on Kohler K-341 engine, which is a 16hp engine used on the John Deere Tractor 316 and Cub Cadet 1600. Widely available and low-cost carb, likely sourced from China. Good reviews of this item on various sites.

I have access to welder to weld the intake manifold but I'm wondering if anyone has been in the situation before. Advice always appreciated. Not ready to get rid of Scag 48in. mower just yet.
 

BigFish

LawnSite Fanatic
Location
chesapeake, va
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ngant17

ngant17

LawnSite Member
Engine on Scag mower is:
Briggs 16hp Vanguard V-Twin
Model #303776
Type 1046A2-5429
Code 97021411
no P/N or ID stamped on carb, but Briggs Vanguard engine reference manual states"...Model Series after 303700 are equipped with an Aisan carburetor...one-piece Flo-jet side-draft".

Diagnosis of bad carburetor was made by an established local mower shop which services Scag mowers. I trust their call on this, they've done good work on it in past. The OEM carburetor is NOT made at this time, B & S discontinued its production about 5 years ago.

Not interested in a questionable (used) replacement carb. Will consider complete R&R engine at some point after possible carb replacement / intake manifold fabrication.

The Kohler #30 carburetor looks like a potential candidate for 16hp engine size of mower. Although has a 30mm diameter throttle bore which is slighter larger than the OEM (Aisan) throttle bore of 22mm.

Cylinder compression of the older Vanguard engine was tested at 150 psi previously. I don't see a problem with using the slightly bigger Kohler carb here.
 

zlandman

LawnSite Bronze Member
Location
Ohio
I'd just go to smallenginewarehouse.com and pick a new engine and be done with it. Time you buy other parts and fool around with it you'll wish you had repowered.
 
OP
ngant17

ngant17

LawnSite Member
Appreciate the info, re: Carb part number 808728. OEM carb is out of production, confirmed by my Scag mechanic at shop.


I have to assume some modifications will be required for any current substitute carburetor.


Engine R&R is long term solution but have to wait until business account can cover that cost.


my prototype manifold should run on the Kohler #30 carb .


I have a section of 32mm OD x 1mm thick carbon fiber tubing. About 6in long.Looks like it will make a good transition from original carb throttle bore and the 30mm bore of new Kohler #30 carb. Epoxy glue to connect the 2 different throttle base mounts. Governor controls will require more work.
 

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