# Max RPM Spec for Tecumseh OHSK 80 221201A



## tpenfield (Feb 24, 2015)

I have the above listed engine on my new-to-me Toro Powershift. I got the chance to use it yesterday with the 6" snowfall we had in the area. The machine did pretty well with both dry and wet snow (I did the impeller mod in addition to a bucket rebuild), but it seems like the engine has more to give.

Anyway, the RPM of the engine seems a bit low, even for a Tecumseh. I am going to get an optical tach today to see exactly what it is. But, I was hoping to find the spec for the Max RPM in the manuals, but I don't seem to be able to find it. The only mention is to look it up on 'microfiche' (remember that stuff?). So, it must be a trade secret or something that only dealers have access to.:smiley-confused013:

Anyway, I know 3600 is a common spec for the Tecumseh and many other engines, but I have also seen 3300 as a Max RPM spec on some engines. I'd just like to know for sure, in case it is supposed to be 3300 and not 3600.

TIA for any info on what the spec is for that engine ( 1999-ish 318cc OHV Snow King, Tecumseh OHSK 80 221201A)


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## nwcove (Mar 2, 2015)

Didnt Ralph Nader write a book about tech rpms? Or was it about a car?😀


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## tpenfield (Feb 24, 2015)

nwcove said:


> Didnt Ralph Nader write a book about tech rpms? Or was it about a car?&#55357;&#56832;


"Unsafe at any Speed" . . . not sure which that would apply to :grin:

There is a safe speed for Tec's . . . I just want to be sure what speed that is . . .


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## Grunt (Nov 11, 2013)

Someone recently posted this link with Tecumseh specs. Page-28 shows the OHSK90 to have a 3600 rpm limit. No mention of the OHSK80.

http://www.lausonpower.com/CustomerService/ServiceEnginesandAccessories.pdf


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## tpenfield (Feb 24, 2015)

It looks like the 9.0 HP OHV Tec is the same block (318cc), so maybe they make it an 8.0 HP by a lower governor setting.

I got 3200 RPM with the optical tachometer, so there is a bit more that I can adjust.


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## ELaw (Feb 4, 2015)

I think as far as Tecumseh is concerned, the max for all of the small- and medium-frame snow engines is 3600 RPM so presumably that's the maximum safe speed for the engine itself. I think some snowblower manufacturers spec it lower for reasons I don't understand - noise maybe?


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## tpenfield (Feb 24, 2015)

Update:

I set the Max RPM to 3450, adjusted the valve lash, and gave it a test run in the sloppy melting snow that we have left from Saturday's storm.

All seems to be good.

I have a hunch that Tecumseh rates their lower HP engines, when they share the same engine block as a higher HP model, by setting the Max RPM's lower. The 8 and 9 HP both are the 318cc engine.

The 9 HP is spec'd at 3600 RPM, the 8 HP spec's don't seem to be published. . . . 

8 HP ÷ 9 HP X 3600 RPM = 3200 RPM (which was the original setting before I made any adjustments)


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## Mike C. (Jan 28, 2016)

I know your done with this but I found the specification you wanted in my Toro Powershift service manual.

For the 8hp Tecumseh,it says 3300+200,-150 RPMs.

So your setting of 3450 is good.


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