Neck, I though this was an interesting question, so took some time googling it.
It looks like they started making aluminum engines in 1953 along side cast engines. You said "small engines" so I guess that would be the model 14 series which was 2.6 to 5.75 HP depending on model. This was made from 1948 to 1963.
Heres a pretty cool site: Old Briggs Model Series - Horse Power & Operating Speed Range
It looks like they started making aluminum engines in 1953 along side cast engines. You said "small engines" so I guess that would be the model 14 series which was 2.6 to 5.75 HP depending on model. This was made from 1948 to 1963.
Heres a pretty cool site: Old Briggs Model Series - Horse Power & Operating Speed Range