Home › Forum › Ask A Member › Differences between ’50’s era 30, 35 and 40 hp big twins? › Re: Differences between ’50’s era 30, 35 and 40 hp big twins?
I happen to own two 25’s, a 30 and two 35’s. Each 35 is different builds. R.C. pretty much got it.
The bolt patterns were the same from 1951 to 1954 on the lowers, which was a 6 bolt pattern. The 7 bolt started on the 1955 models". The 25 and 30, if I’m not mistaken, had the smaller pinion gear and I understand that the other two are smaller too. The single wall motors went into 1958 and the Super Quiet model started in 1958, so, both style motors were only built in that year. 1959 on was Super Quiet only, until the introduction of the 28hp, in 1962. This was just a later style 25/30 with a fiberglass hood and two ring pistons. In 1965, the 33 replaced the 28 and that was basically a later style ’57 35 with a fiberglass hood and two ring pistons. The single wall mid section looked a lot like the ’50’s versions, but the cosmetic appearance is slightly different too. Everything inside is pretty much the same though.
Here’s the kicker though. The Super Quiet and the single wall style motors have entirely different mounting surfaces on the lower units and powerheads plus entirely different cooling systems too, so be careful, if you buy a lower unit, or powerhead for your motor.
I hope this helps