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bcjm


Location: Washing DC Area
Joined: Dec 2, 2011
Points: 25

Various projects
Original Message   Dec 5, 2011 7:29 pm
 I got interested in small engine repair lately so I bought couple of projects that I am working on. 

1. Arines snowblowe, 924029.  10 HP Tecumseh engine and a 32" auger.  I bought it with no engine.  I got a 13HP Honda GX390 as a substitute.  It just requires too much work.  The mounting holes are different.  The plate that the engine sits on is too small to drill new holes.  The crankshaft height is different so I have to get new belts.  I gave up trying to use the Honda.  I took the Tecumseh 10HP engine from my chipper and made it to work.  Still need to do some adjustment but seems to work fine.  The engine RPM can not be adjusted.  It runs on one RPM once engine starts.   I think I need some extra parts to connect to the governor.  If someone has an extra 10HP engine I will be interested to buy for my chipper.

2. Homelite back pack  leaf blower.  It would not start when I bought it,  I rebuilt the carb. but still not working right.  Idles fine now but can't accelerate.  Adjust high/low speed but still the same.  Leaks gas when idle.  I did not set fuel valve lever since I don't have a gauge.  Not sure if that is the problem.  Let me know if you have any suggestions.

3. I have a 5HP Tecumseh snow blower engine.  It only has 35 psi when I checked with a starter.  I dropped some engine oil in the cylinder and that made no difference.  I assume the leak is from the valves.  Is this a simple thing to do?  Do I need a special tool to do this project?  Do I need to take this to a machine shop to have the valve seats redone? 

Feel free to comment.

Thanks

Replies: 1 - 8 of 8View as Outline
RedOctobyr


Location: Lowell area, MA
Joined: Nov 5, 2011
Points: 282

Re: Various projects
Reply #1   Dec 5, 2011 10:13 pm
#3, Tecumseh 5hp: I had to adjust my valve clearances on my Tecumseh 8hp Snow King a few years ago. I had too little clearance under one of the valves. I think the valve was being opened too far by the compression release when pull starting it, resulting in low compression when pulling it (I didn't have a compression tester at the time, so can't give you a number).

You can check the valve clearances (as well as confirming that the valves are moving) by removing a little cover on the side of the engine, and observing the valves as you turn the flywheel. You can also remove the cylinder head, to observe the valve, and the valve seat.

To grind a few thousandths of an inch off my valve, I brought it to work, we put it on a precision surface grinder (not a typical bench wheel grinder) to take 0.003" off the valve. That's something that a machine shop could do, if you needed to adjust your valve clearance. Might be doable at home somehow, I don't know. It would be tricky, anyways.

You need a set of feeler gauges (cheap) to check the valve clearances. Reinstalling the valve was a challenge, since I didn't have the proper Tecumseh tool for doing it. I managed to rig up something with some screwdrivers, a C-clamp, etc, to compress the valve spring, and keep it that way while I slipped it back inside the engine. But it wasn't pretty :) There must be a better way, hopefully using things that normal homeowners have, rather than needing the special Tecumseh tool.

There is at least one thing you can do to check if the compression release is causing your low pressure. Try turning the engine forwards by hand, in the direction the starter turns it. Feel the resistance, listen for hissing from the compression release, etc. Now turn the engine backwards by hand. The compression release doesn't work when turning backwards. If it is harder to turn backwards than forwards, then maybe your compression release is opening the valve too far (while turning forwards), and bleeding off a lot of pressure. That at least could be due to a valve clearance issue like I had. If it is the same forwards and backwards, then perhaps it's something like a bad valve seat, a valve sticking open slightly, etc?

For a point of comparison, my 8hp Tecumseh shows something like 140 psi when I crank it with the starter. But only something like 40 psi (maybe a bit higher?) when I pull it by hand. I don't know if the electric starter spins fast enough that the compression release shuts off, or if the release just can't vent the pressure quickly enough when it's spinning that fast. But it measures much higher when I use the starter.
bcjm


Location: Washing DC Area
Joined: Dec 2, 2011
Points: 25

Re: Various projects
Reply #2   Dec 5, 2011 10:55 pm
Thank you for the advise. 
Bill_H


Location: Maine
Joined: Jan 12, 2008
Points: 354

Re: Various projects
Reply #3   Dec 5, 2011 11:04 pm
"The plate that the engine sits on is too small to drill new holes." Someone else (I think it was on youtube) ran into that problem and posted about it. He just made up plate that bolts to the engine and was either welded or bolted to the existing plate. Sorry I don't have a link, but think about it - it's probably a lot less work than going out and getting another engine.

Who the hell let all the morning people run things?
carlb


Joined: Nov 16, 2010
Points: 279

Re: Various projects
Reply #4   Dec 6, 2011 10:30 am
I would have modified the base of the snow blower to make the honda fit. The crankshaft height would just require different belts and maybe some modification to the belt cover.
bcjm


Location: Washing DC Area
Joined: Dec 2, 2011
Points: 25

Re: Various projects
Reply #5   Dec 6, 2011 10:57 am
carlb wrote:
I would have modified the base of the snow blower to make the honda fit. The crankshaft height would just require different belts and maybe some modification to the belt cover.

I like to use the Honda also if I can. The problem is that the mounting holes of Honda is right on the edge of the base plate.  The base is like a box. It has vertical plates on each side.  I can't really drill it on the edges.  I have to raise the Honda engine a little bit and mount that to the blower base.  I could not figure out an easy way.
manjestic


Location: North Shore, MA
Joined: Oct 31, 2011
Points: 87

Re: Various projects
Reply #6   Dec 6, 2011 1:37 pm
Perhaps you can get some ideas from what this guy has done?

http://www.youtube.com/watch?v=QNACsm-OQlo
bcjm


Location: Washing DC Area
Joined: Dec 2, 2011
Points: 25

Re: Various projects
Reply #7   Dec 6, 2011 2:04 pm
Thank you for the interesting link.  Why does he want to weld a new plate if the thrower deck has enough area to drill holds for the new engine?  Am I missing something?
manjestic


Location: North Shore, MA
Joined: Oct 31, 2011
Points: 87

Re: Various projects
Reply #8   Dec 6, 2011 2:52 pm
bcjm wrote:
Why does he want to weld a new plate if the thrower deck has enough area to drill holds for the new engine?

My bad.  He was more addressing fractures in the mounting plate.  Sounds like you need something that mounts to the original holes and extends the deck beyond the tractor "box".  Like a cantilever setup.

http://www.ebay.com/itm/JOHN-DEERE-826-SNOWBLOWER-ENGINE-MOUNT-PLATE-M45775-/160540781398
Replies: 1 - 8 of 8View as Outline
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