OT - 8 hp Tecumseh motor vibration - very long post

[wierdscience]

They used to make a gen set that utilized a 2-71 Detroit running at 900 rpm that powered the generator.
Used for powering train refrigeration cars when they came in to station or something.
I seen a guy on youtube has one. Just running at basically a fast idle, all day long......
That rig ought to last 100 years running at only 900 rpm.
Would make a perfect house/shop backup genny.

-Doozer

Got one, though mine runs at 1200 rpm, 25kw at 220v 3~. Burns about 2-1/2 gph at full load. And yes, very bullet proof with normal maintenance.

Wanna see something cute?

https://www.youtube.com/watch?v=bTjJ_daB0Hk

[Doozer]

Oh, I am in love.
! ! ! ! ! ! ! ! ! ! ! ! !

-D

[lakeside53]

sweet!!!!!

[Willy]

I don't want that....I NEED THAT!
I see there's a place in Idaho that claims to have the largest supply of 2-71 gensets.
May have to check it out closer when all of the Covid dust settles. Not that far from here.

https://www.deucepower.com/

[wierdscience]

I don't want that....I NEED THAT!
I see there's a place in Idaho that claims to have the largest supply of 2-71 gensets.
May have to check it out closer when all of the Covid dust settles. Not that far from here.

Would you believe back about 2006 or so Harbor Freight was selling recon 2-71 gensets for $4800? Ya, me neither, but they certainly were.

[JoeLee]

No internal balancer oh the Tecumseh 8HP Snowking engines, strictly old tech.
These are 3600 rpm engines although they operate and live longer @2800-3400 rpm.

1800 rpm generator engines are designed to function with 4-pole generators in order to maintain frequency @ 60HZ. vs 3600 rpm engines which are designed to function with 2-pole generators in order to maintain 60 HZ.

A nice reliable idle on small engines usually hovers around 1400-1700 rpm, although you would swear the rpm is about half of that when listening to one. Very deceiving.

I was going to mention the same thing. I had a guy that pulled a 12HP Briggs apart and didn't know he had to time the "synchro balance" counter weights that are on the inside of each end cover. The thing jumped all over the place and would barely run past 1/8 throttle. Don't think that running too lean would cause it. Sounds like something may be bent, broken piston skirt or even the wrong piston.
Saw that happen once before too, the piston fit the bore and the wrist pin fit , but the piston weight was way off. The head was much thicker and the skirt was longer. Threw the whole thing out of balance.

JL.............

[Willy]

I was going to mention the same thing. I had a guy that pulled a 12HP Briggs apart and didn't know he had to time the "synchro balance" counter weights that are on the inside of each end cover. The thing jumped all over the place and would barely run past 1/8 throttle. Don't think that running too lean would cause it. Sounds like something may be bent, broken piston skirt or even the wrong piston.
Saw that happen once before too, the piston fit the bore and the wrist pin fit , but the piston weight was way off. The head was much thicker and the skirt was longer. Threw the whole thing out of balance.

JL.............

Yes good point, Without knowing what has been done to the engine lord only knows what's inside it or what has been done to it. Wrong piston weight as an example, could make for one heck of a paint can shaker.
Another issue of course is trying to"diagnose" online what is excessive vibration. What is excessive to one not familiar with a certain type of engine may be completely acceptable to one that is.
If my Honda lawnmower shook like my Tecumseh powered snowblower I'd shut it off until I could fix it.

[I make chips]

Tesuckems vibrate like mad. Run it or put something different on it. Timing is by point gap and regardless, it won't affect vibration.

[A.K. Boomer]

So I am upgrading my log splitter from 5 hp, single stage pump to 8 hp 2 stage pump.

Why not just try it with the 5 hp AND 2 stage pump? you will have both speed and low end grunt like never before and it might be enough,,, You will most likely have a little more speed due to being able to rap it out a little higher ---- you will also keep the stored momentum due to the parts spinning faster - although smaller parts the higher speed will allow for stored power to get through the tuff stuff maybe just as good unless the tuff does not let up then the real HP comes into play,,, but then again that's also what the two stage pump is for...

to bypass all the hoopla about ignition timing and carb, just give it a rev and see if it's also vibrating on the deceleration off of peak RPM's --- if it is then it's most likely mechanical...

[aribert]

Thank you all for the responses. I think I over reacted (and over rev'ed the engine) when it was vibrating so severely. Several of you have mentioned these engines are not the smoothest running to begin and based on that what I have found on-line is that they tend to become shakers when over rev'ed.

I reassembled the engine (never opened up the internals), cleaned the carb and did a real quick test run (inside the garage, with the door closed, in a rush because I was already late in leaving for the day). I will not be back for a couple of days - plenty of time for the fumes to dissipate. I did not have time to get out the optical tachometer. With the engine at full throttle, NOT touching the governor, the engine was not as smooth running as my former Honda push mower, it did not vibrate excessively. On Saturday, I will roll the splitter outside, run it while checking the rpm with the optical tach. My experience with 4 to 6 hp Briggs on my push mowers and pressure washer and a 5.5 Tecumseh on my tiller and chipper/shredder and an 18 hp Briggs single on my riding mower leads me to believe this engine is running a bit slow. I am guessing that the engine at full throttle might be in the 3000 rpm range, and I am willing to leave the full throttle set there. I split a couple pieces of already split to firewood size logs (super well aged so not a great test but that is all I have at the moment) and the motor never sounded like it was being loaded and the pump never even switched to the high pressure/low flow mode.

Unfortunately the carb is still too lean but I now have an identical (tho very dirty, junk) carb to be able to "adjust" the fixed idle jet and main jets from the junk carb while still keeping an unmodified set of jets as a base line (I have number drills to 80 and some fractional mm metric drills from making & modifying Weber jets on my Triumph. More challenging and probably quicker to solve than waiting for a Chinese carb to arrive.

Again thanks for your postings as I "went off on a wild goose chase".

[Willy]

Amazon has them for $12.99 if you need it, won't take but a few days.

[lakeside53]

Make sure the carb throttle shaft/body isn't worn out before you muck with jets, and the inlet gasket -air sucking in there can mess you up. And don't over think it... these carbs are so damn simple they were likely in use by Fred Flintstone.

I have a 1980 11hp Briggs I'm going though. POS potentially as it has the aluminum bore, but home generators don't get a lot of hours, so if it runs well it's my candidate for a log splitter. I'm going to have to remember how to adjust points again or convert it to electronic.

It was part of my recent (2 months) haul from neighbors.
- 11hp briggs 5000 watt generator - "won't hold speed" - tank and carb were fill of rust).
- 5hp Honda (GCV unfortunately) powered 2000 watt generator - wont start, sitting for years...
- 6.75hp Kohler powered big wheel Toro Lawn mower - "wont go into gear". lol
- 10hp Tecumseh 5000 watt POS total garbage generator - generator lost internal neutral and fried $2k of house systems. Motor will go to my Chipper
- 6 hp Honda powered (Yay, GX160) Pressure washer with Cat pump (meaning I can rebuilt it). Been sitting for 10 years, but still turns over fine.


Of course, my neighbors know if I don't keep them I'll just fix and give it to someone else. lol

[wierdscience]

It was part of my recent (2 months) haul from neighbors.
- 11hp briggs 5000 watt generator - "won't hold speed" - tank and carb were fill of rust).
- 5hp Honda (GCV unfortunately) powered 2000 watt generator - wont start, sitting for years...
- 6.75hp Kholer powered big wheel Toro Lawn mower - "wont go into gear". lol
- 10hp Tecumseh 5000 watt POS total garbage generator - generator lost internal neutral and fried $2k of house systems. Motor will go to my Chipper
- 6 hp Honda powered (Yay, GX160) Pressure washer with Cat pump (meaning I can rebuilt it). Been sitting for 10 years, but still turns over fine.


Of course, my neighbors know if I don't keep them I'll just fix and give it to someone else. lol

I tell people to take the carburetor and fuel lines off when they store their generators. That way when they go to use them again they are that much ahead of the game.🙄

[lakeside53]

I can't even get my neighbors to turn off the gas, never mind run them dry. I have 3 gallon of really disgusting stinky gas to get rid off.

Just reading the L-head service manual. My 1980 11hp Brigs has the "new-fangled" dual balance cams. "Synchro-balance". That at least makes it interesting. lol