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Unleaded Gas And An Unrebuilt 60's Tecumseh.

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#1 boostedbuick OFFLINE  

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Posted July 04, 2012 - 09:24 PM

Engine is a 7hp tecumseh from late 60's, probably 68 or later but don't know for sure. Never been apart, and never been run since the 80's. I realize it's run most of it's life on unleaded gas, but is it SUPPOSED to be run that way? I've seen car engines eat exhaust seats out with unleaded gas (several hours from home on the power tour). Didn't know if it was a concern on small engines or what year it would apply to. It's in a struck mini dozer (read my lengthy thread in the other brands section).

#2 bowtiebutler956 OFFLINE  

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Posted July 04, 2012 - 10:09 PM

I have several old small engines that I run regularly without any problems on unleaded. It might be a concern if you are using it as a full time worker, but otherwise you should be fine. If you are putting lots of hours on it you could have a machine shop install hardened valve seats in it. :thumbs:

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#3 superbsuburban OFFLINE  

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Posted July 04, 2012 - 11:14 PM

i have a buddy who rides 50s harleys alot,he recommends either two stroke oil,or top end lube added to the gas,at maybe 100 to 1 ratio,to halp fight the effects of unleaded

i add some premix for my weedwacker ( it doesnt store well anyway) to the gas on the two 60s sears i use,it cant hurt



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Posted July 05, 2012 - 07:20 AM

Quicksilver 2 cycle gas mix seems to do a good job keeping things status quo.

#5 Bruce Dorsi OFFLINE  

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Posted July 05, 2012 - 07:45 AM

If your Tecumseh engine has an aluminum block, it will have hardened valve seat inserts for both the intake and exhaust.

Some cast-iron engines had an insert for the exhaust, but the seat for the intake was the cast-iron block.

Other cast-iron engines had no seat inserts, and both seats were cut into the cast-iron.

I don't think you will have a problem using today's gasoline. .....Most of the small-engine valve problems I have seen are from over-heating due to clogged cooling fins or being run low on oil. ....Dirty oil usually wore the guides prematurely, especially in aluminum-block engines without replaceable valve guides.
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#6 boostedbuick OFFLINE  

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Posted July 07, 2012 - 05:38 PM

She's aluminum block so I guess I'll stop thinking about it. Thanks everyone.