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Again, the carb body part numbers (no throttle plates/shafts included) are the same for the 3 and 4hp engines in 69, so the venturi sizes must be the same. I’m sure there is not part number stamped on the bowl, so that won’t help in identification. I would love to what the differences in the high speed needle and bowls are, seems like mixing this stuff up could create quite the running issue. I think I have some of these carbs laying around, will pull them apart and have a look. Seems like the only way to know is to be able to identify these pieces by eye….
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Would the 4 have required maybe a longer or shorter high speed needle valve shaft to get it to the bezel and maybe a different way of attaching the knob? I’ve got a bunch of 3’s here, but I can’t compare because I gave my only 4 to a young guy who wanted something to duck hunt with in exchange for 3 more project (or maybe parts) motors his folks wanted gone..
DaveWould the 4 have required maybe a longer or shorter high speed needle valve shaft to get it to the bezel and maybe a different way of attaching the knob? I’ve got a bunch of 3’s here, but I can’t compare because I gave my only 4 to a young guy who wanted something to duck hunt with in exchange for 3 more project (or maybe parts) motors his folks wanted gone..
DaveI don’t “think so”, but perhaps the needle valves are different lengths…The motor pans are the same dimensions, but the 4hp intake manifold is different, so maybe that required different length needle valves…But, why are the carb bowls different?? Just looked again on marineengine, the low speed needles are the same part numbers, so that seems to dismiss the different needle valve length theory….Hmmm
Again, we are comparing the 1968 3hp to the 1969 4hp. Both of these models had the completely enclosed powerhead, side mount starter, remote tank, etc. These carbs have nothing in common with the older 3hp models….
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Here are the photos of the 1968 Evinrude 3hp carburetor on the left and the 1970’s Johnson 4hp carburetor on the right.
1968 Evinrude 3hp carburetor
– Front of carburetor Venturi. 0.910 inches
– Back of carburetor Venturi. 0.618 inches1970’s Johnson 4hp carburetor
– Front of carburetor Venturi. 0.906 inches
– Back of carburetor Venturi. 0.744 inches
Here are the photos of the 1968 Evinrude 3hp high speed needle on the left and the 1970’s Johnson 4hp high speed needle on the right.
High Speed Needle
1968 Evinrude 3hp high speed needle
– Tip length of high speed needle 0.426 inches
– Length of whole needle. 2.277 inches1970’s Johnson 4hp high speed needle
– Tip length of high speed needle. 0.431 inches
– Length of whole needle. 2.372 inchesLow Speed Needle
1968 Evinrude 3hp low speed needle
– Tip length of low speed needle 0.241 inches
– Length of whole needle. 2.585 inches1970’s Johnson 4hp low speed needle
– Tip length of low speed needle. 0.246 inches
– Length of whole needle. 2.581 inches
Here are the photos of the 1968 Evinrude 3hp high speed nozzle on the left and the 1970’s Johnson 4hp high speed nozzle on the right.
High Speed Nozzle
1968 Evinrude 3hp high speed nozzle
– length of high speed nozzle – 1.4435 inches
– ID of high speed nozzle – 0.073 inches
– OD of high speed nozzle – 0.133 inches1970’s Johnson 4hp high speed nozzles
– length of high speed nozzle – 1.445 inches
– ID of high speed nozzle – 0.083 inches
– OD of high speed nozzle – 0.134 inches
Here are the photos of the 1968 Evinrude 3hp carburetor bowl on the left and the 1970’s Johnson 4hp carburetor bowl on the right.
1968 Evinrude 3hp carburetor bowl dimensions
– height of carburetor bowl 1.3545 inches
– circumference of carburetor bowl. 1.806 inches1970’s Johnson 4hp carburetor bowl dimensions
– height of carburetor bowl 1.3575 inches
– circumference of carburetor bowl. 1.800 inches
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….1 user thanked author for this post.
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