A Few Dreaded Newbe Questions

[Crumpite]

Folks,

I sure am glad I found this site !

I managed to snag a 6/1 Metro Listeroid for $650 US... Yikes !
It's been blueprinted to the best of my ability's and mounted on a 6" Ash timber frame and hooked up to a 5 Kw ST head with a serpentine belt.
I've had it loaded to 2.8kw and it doesn't seem to even notice the load.
I finally got it moved into the garage and and in the process of re-assembling it (I've got a narrow doorway) and hooking up the permanent cooling system/heat recovery setup.
Oil tanks and filtering system is setup and working well.
I'm in the process of running the electrical sub panel and transfer switches.

So now for a few questions...   

I've seen reference to "offset idler and hollow dipper fixes". Is there something I should know ?
What are folks using for exhaust gas heat exchangers? I can't find any reference anywhere except for expensive factory made ones.
I haven't been able to source anything for vibration isolation. Any leads on where to source them ?

Thanks in advance,
Daryl

[quinnf]

Congrats on snagging the engine for almost nothing.

Check out http://www.mcmaster.com/#vibration-mounts/=4h0t2s  The relevant mounts are on page 1359 and beyond.

Last year a mechanical engineer friend ran the calcs and figured out the proper hardness, deflection and weight capacity I needed, but I can't find the reference just now.  It was a surprisingly soft mount, I thought.  If I run across the calcs, I'll post them.

you're right about the load.  These engines don't seem to notice the load until you're over 3 kw.  On mine, I start getting dark gray smoke around 3.8 kW on a resistive load, so probably anything over 3 kW continuous is pushing it.  

Dave, xyzer, is the guru of all things to do with the offset idler and hollow dipper.  

Re: your installation, like all things here, PICTURES OR IT NEVER HAPPENED!    

Enjoy!

Quinn

[mobile_bob]

the offset idler is a creation of a fellow member here "xyzer", it was made to correct the cam idler gear
location relative to the crank gear and the cam gear, apparently most listeroids have issues with where
the indians placed the idler bolt bore in the case, this of course causes issues with gear tooth engagement
with the two other gears, causing in some cases accellerated wear and tooth fracture.

the hollow dippers again something "xyzer" has supplied are used to provide positive oil flow to the big end
brg of the rod, and are a must have it you plan on useing the plain upper brg that another member "JohnF"
has provided to many folks.  The plain brg and hollow dipper has proven to extend the life of the brg and its
service intervals substantially, whether this is something you feel you need will depend on how you run your engine
and what your expectations are.  if you are going to expect high output levels, running 8-16hrs or more per day
you might want to look into this modification.

vibration isolation ranges from a cow mat, all the way to engineered mounts, again it is something you will have to decide
for yourself depending on what your needs and expectations are. you may not need much more than a rubber mat
or some rubber conveyor belting, but then again you may need far better isolation, every situation is different.

exhaust exchangers typically are messy to work with, at least those that are used by most folks here, they clog up
and need frequent cleaning which is not a pleasant task for those that are not used to getting their hands flilthy.

bob g

ps. looks like Quinn beat me to it!

[quinnf]

This probably merits a new thread, but I said I'd post the calculations here, so here goes.  Bob B., Sailawayrb on another forum helped me out with the calculations, an example of which are posted here:

http://www.karman.com/selectvibro.cfm

Problem with commercial mounts is that the low frequency of vibration is unusual, so commercial mounts that are exact matches are not easy to find.  Karman Rubber has them, but they're expensive.  McMaster doesn't, but they have something close.  And since we're not dealing with a tuning fork here, close is probably fine for our purposes.

Caterpillar says that spring mounts provide the best isolation.  But woe to you if you encounter a point of resonance while accelerating to speed, or shutting down!

Quinn

[veggie]

Re: Mounting and vibration

You might also find something useful here...

http://www.microcogen.info/index.php?topic=208.0

Veggie

[quinnf]

Those are fine, too.  But the calculations show that for optimum isolation you want 4 mounts with about a 520 lbs/inch spring constant.  So most mounts are much too hard to absorb the vibration at the low frequencies these engines generate.  Something like the McMaster 6219K88 or K87 spring mounts should work well.  But at $38/each, X 4, you might want to try stall matting or make stacks of rubber from blown out truck tires you can find by the side of the road and end up with something that works.

Quinn

[XYZER]

After trying 6 rubber type mounts from MacMaster.....they were smaller than the ones I have mounted in the picture I could see after 2 years they were loosing the battle! I went to the auto parts store and talked the counter guy into letting me wander the engine mount isles. I found a nice sturdy one like in the picture and they are a transmission mount off a 70ish Volvo. The first set cost $20.00 ea and my second set I found on eBay for $10.00ea. I don't have the part numbers handy but if anyone wants to try them I'll look them up. I must say you still need a tamed engine if you use these mounts!

Sorry for the big picture! How do you guys do the thumbnail pictures?

[Ronmar]

The offset idler bolt allows you a little control over the tooth emgagement between the crank, idler and cam gears. This can allow tou to tighten the overall gear train backlash.  Since the camshaft alternately loads the shaft in both directions as the top/peak of the cam lobe passes under the tappet, excessive backlash in the gears can cause them to hammer themselves to pieces. 

You can hear the effect of this backlash in your engine by slowly rotating your flywheel and watching the intake lifter and pushrod.  As you rotate the flywheel just past where the rising pushrod has pushed the intake valve fully open, you will hear a clunk from the gear train as the intake valve spring pressure pushing down on the backside of the cam causes the camshaft to rotate forward faster than you are rotating it by the flywheel.  This noise accounts for a large portion of the valve noise when running.

[Crofter]

Ronmar, I agree totally with the cyclic loading of the gear train because of rise and fall of the cam lobes. The more the clearance between the gears the greater the velocity difference when they "collide". I think an even greater pulsating contact load is created by crank gear accelleration upon combustion and reversal on compression stroke. The inertia of the rotating camshaft and governor assembly causes a considerable energy exchange every power pulse.

Torsional resonance can throw some weird curves into the mechanics of the issue also: I wonder if the different length, weight and spring of the camshafts of the twins, plus their off beat power pulses, might have as much to do with shaft breakage as the extra load of the additional cylinder.

I didnt measure it but the gear lash on my 10-1 was obviously way loose; anxious to get it running I chose to build up and machine 35 thou. eccentric on my idler bolt to achieve crude effect of what xyzer builds into his. Gear lash is now around 10 thou and when I pull it down later to install the plain upper bearing from John and the hollow dipper, I will see what the wear patterns and clearances look like; I may well be able to offset the idler a fair bit more for closer mesh without getting into oil clearance issues or wonky contact patterns.

[Ronmar]

I put in one of Xyzer's .040" offset idlers and the geartrain noise was noticeably reduced.  I measured the backlash before and after, but I don't recall the numbers.  I think I posted them on the old forum:(  Sadly I think that information is lost.  I will look in my log to see, but it reduced it substantially.  If I recall the discussion, backlash numbers below .010" were acceptable.  Above that, and things start to get tougher on the gears... 

[Crumpite]

Thanks for the great info !

I didn't check the geartrain lash when I had it apart, I'll check it when I put it back together.

I like the idea of using old rubber as vibration isolation - I'll check and see what I can find.
Some old-timers told me to use a wood frame for one-lungers as the wood can flex a little and keep the vibration down.
We'll see just how well it works in a while...

I realize that exhaust heat exchangers would need frequent cleaning, but I thing that doubling the heat output might be worth the trouble.
I've got a design for one in mind that might be easy to clean. Again, we'll see when and if I ever get it together. (I'm disabled, and can't do much work at a time. The brain still works though, sort of 

My camera finally died a lingering death, and I'm waiting for the after-holiday sales to get a new one.
I do have a couple of pictures of the setup when I was running it outdoors, but I can't figure out how to post a picture in the reply.
Can someone point me out how to do it ?

Thanks again for all the help, it's nice to find an active group !
Daryl

[dubbleUJay]

Crumpite, at the bottom of the window your posting on it says: "Additional Options..." click on the + sign, there is a place there to attach files.