Thanks Cajun, your pics answer so many questions. First, got to have my eyes checked, the part numbers for the carb bodies are different between the 68-69 3-4hp models! And your pictures show that everyone except myself was right, the carb throat is obviously larger behind the venturi. The little rib right next to the the 3hp carb throat seems to be a good way of identifying the 3hp carb body. The part number for the carb body changes from 1969 to the mid 70s, so who knows what other minute changes were made during the years.
The 4hp nozzle is obviously different, even though it is the same overall length. Those numbers cast into the carb bowls must be engineering casting numbers, they don’t correspond to the part numbers, which are different. It seems counter intuitive that the 4hp carb bowl seems more shallow, which would indicate that the 4hp bowl held less fuel than the 3hp bowl, but who knows. The high speed needle tips seem to be the same, but the 4hp needle is slightly longer than the 3hp needle. Again, the part numbers for the low speed needles are the same, so I don’t think motor pan depth is the issue, the 4hp needle tip must seat deeper into the nozzle than the 3hp.
The lesson here is a good one indeed….Don’t get these pieces mixed up! Knowing myself as I do, I could easily see myself grabbing what “looks to be the same” carb bowl (or other piece) from my junk pile and really creating a problem….
Thanks again “Cajun”, this was a great learning experience….
