Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Hi all,

I need to adjust the RPM of my Tecumseh L-Head (9 HP / 318 cc) engine that I bought in 2007.

For that purpose, I plan to purchase "digital photo (laser) tachometer".

From my understanding this tool works by sticking a piece of reflective tape on a rotating part of the engine (such at the shaft near the pulley where the belts are located). The tool then counts the number of time this piece of tape passes in front of the laser beam in one second and multiplies by 60 to display the RPM.

Did anyone ever used such a tachometer? If yes how are you satisfied with this tool?

Also, I need to know the RPM values that this engine should be adjusted to at: full throttle and also when idling. Do anyone know these RPM values.

trouts2 wrote:
Trouts:

Is this what you're looking at? 

http://www.contractorstools.com/redington.html

I have one of these (Readington model 5140-0311) as well as a Tiny Tach.  Both devices are quite ruggedly built.  The Readington unit reads higher rpms than  the Tiny tach does and it also has a slot in the back of the unit where the impulse wire is placed while taking a reading.  That make is easier to move around.  For my purposes, I just put a piece of suitably sized wire on each machine I want to monitor and just move the tach from machine to machine without having to take the wire off of the spark plug lead.  Another nice feature of the  Readington tach that I have is that it reads up to 20000 vs 9999 of the Mini Tach.   I don't like the idea of batteries either.  If you can get one that's powered by electrical impulse, that's the way I'd go. 

Yes, 5140-0311, Inductive Model- Surface Mount, Inductive, Hours with 1:1Tach

I looked at that tach because of your reply in post #2. 

The Tiny-Tach goes to 1,9999 and the 0311 to 7000.

Both have batteries in potted cases so not replaceable. 

The 0311 is 15 year, the Tiny 5 year but prior posting on Abbys say the Tiny's battery lasts much longer.  I'll snoop around for one without a bat.

The 0311 literature on hookup wire they call "Lead wire" only shows one end.  That looks like a plain wire which wrappes around the plugwire a few times and has an allegator clip end to clip onto back onto the lead wire.  The other end is not shown.  Can any wire be used?  What is required on the other end?  Do you have to have something connected to the wire or do you just connect bare wire to something?  Is there a hole you stick the wire into?

The Tiny talks about coax wire for the pickup.  Maybe they have a length of coax and a short wire for a setup like the above soldered to the end of the coax.  What about the other end of the coax?  How is it connected to the device?

Can both use a plain wire on both ends?   I have coax I can strip if there is no elaborat connectors requires on the ends.

The model 51 uses any wire that can be squeezed into the slot on the back. 

The Tiny tach that I have uses two normal pieces of wire that are permanent parts of the instrument.  One wire goes to the spark plug lead and the second wire is a ground.  I prefer the single wire unit.

Can't tell you any more because these are the only two units I own.  I don't know anything about units that use coax.   For me, my preferences would be:  a) no battery, b) single wire), c) removable wire.    

  It might be that what I read was about a newer model.  It mentions the coax. 

Strange language "transmits" versus carries.  There is no transmitting going on. 

I doubt the "winds around" refers to coax but since coax is used and so few wires involved coax is probably in there.  Probably most of the length of the pickup wire is coax and then some flexable wires going to the center wire and a grounding clip on the coax jacket.  ?? No pictures no explination. 

So your's has two wires running directly into the unit and not able to connect and disconnect.  I guess if something breaks it's ok as long as it's not too close to the device body. 

New Standard TT2A - TINY TACH™
RPM reading adjustable from 1 spark per 2 revolutions to 8 sparks per revolution. One TINY-TACH™ now works for most gas engines.
RPM display from 1 to 19,000.
RPM update time 1/2 second.
Hour meter records total actual running time on your engine.
Job timer can be reset to record run time for record keeping.
Coax cable transmits signal without EMF interference.
1 Antenna cable winds around your spark plug wire to give you the RPM reading – clean and simple to attach. Signal strength can be controlled by the antenna wire.
Standard cable length is 6 feet. Additional length can be added at the factory for $10. If not standard, please specify total length needed in the "comments" section at the end of the order page.
TINY-TACH™ unit is potted to prevent damage from moisture and vibration. Lithium battery life 5+ years, not replaceable.

I think you mentioned having one at a camp which I assume is unheated.  So they take cold ok at least -30F?

I found one in China, no bat, cheap - $18 includes shipping, tach and hour.  Probalby clones of.....

Never had a problem with cold temps.  I had the Readi-alert on my snow blower for a while.  It always worked regardless of temp.

$18.00 is  good price.   You can buy 2.5 of those for the price of the one I bought. 

In using the laser tach, there must be an unobstructed view of

the piece of tape. If the tach gets interupted in "seeing" the tape,

the readings will be inaccurate. BTDT

T.J.

Can any reflective tape be used?  There's fake chrome tape.  Will that work?  I'm thinking of using it to meter rakes and impellers.  Not sure if tape on am impeller would reflect back in the right way.  I think you would have to have the tape on a surface square to the meter.  That might be tough to do on an impeller.  For a rake it would be easy.

The laser ones usually come with some tape.  I have heard of people cutting the tape into strips, but not peeling the backing off then using scotch clear tape so they can reuse them instead of buying more tape.

trouts2 wrote:
I have read that people using  the shinny duct tape works perfect. I believe any shiny material will work.

To check the impeller rpm with a laser tach.  I'm guessing you would probably have to take the reading looking down the chute, or take the chute off.  Either that or I think you could get an unobstructed view shooting in right above the auger gear case.

Amazon has a number of them for sale. With reviews