It is not that simple. MA 4SPA represents a 150 to 160 HP displacement with an accelerator pump. The different part numbers can represent may things.
- If the venturi has been updated from 2 piece to a single piece
- What float the carb has (brass, Plastic, or epoxy)
- The size & type main jet (atomizing or not)
- Style lean arm installed
- Style throttle arm installed
- Type accelerator plunger installed (leather, or synthetic)
- Accelerator arm linkage position
- Idle circuit jets installed.
- Venturi air temp sensor installed.
There are many factors that go into part numbers. However, the majority of the MA 4SPA carbs will interchange without issue. You just want to make sure you have the safety updates installed (epoxy float & single piece venturi). The only thing that may be a concern is if you install a 150 HP on a 160 HP engine. You may need to increase the main jet size to provide enough fuel at WOT on a cold day at lower altitudes.
