Scott-Atwater/Firestone 3.6 HP

[patti]

What has the last year they had a rope start sheave? When did they switch from the 4 bolt head to 6 bolts. ❓

rboatguy@comcast.net

[frankr]

Not sure about the first question. I suspect it appeared off and on over the years

Second question, the change was made for 1947 models. Horsepower went from 3.5 to 3.6 at the same time.

[patti]

Thanks Frank. I’m trying to acquire a 6 bolt head rope start Firestone. Do you think they made any?

[frankr]

I know they made them in Scott-Atwater version. Models 470 and 480 (1947,1948)

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GravelyShoals

[thumper]

They likely made them as Firestone as well because Firestone sold motors that were older left over scotts. The 1951 Firestone is similar to a late 40s scott

[melugin]

The 3.6 is rated as a 4hp in the full gear-shift model Firestone single. Any difference in the powerheads, or did the gearing make a difference?

[frankr]

Firestone continued to offer a rope start in 1949, model 133-486. Model # suggests they were leftover 1948 motors.
It looks like all the singles were 2-1/8" bore X 1-3/4" stroke and rated at 4000 RPM. I don’t know what they did to get more ponies.

AHA! The 3.6 non-shift used cylinder head # 470-1883, The 4hp shift used cylinder head # 491-1883. Both 6 bolt, but probably higher compression.

[melugin]

Frank really knows what he is talking about. Thank you.

[patti]

Are these heads interchangeable?

[frankr]

quote Patti:

Are these heads interchangeable?

My guess is that they are. Note: "Guess"

[Author]

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