V-TWIN---MAYBE V-4

[Brian Rupnow]

So--we are almost ready to rock and roll!!! Head gaskets are in, rings are in, everything that bolts together is bolted together (except the gear guard) which will be installed after the engine has been ran. I have to set the valve and ignition timing before I attempt to start the engine, and do a bit of electronic rigging for the ignition. Wish me luck peoples.-----Brian

 

[stevehuckss396]

Best of luck brian!

 

[Basil]

Looking forward to seeing it run Brian

 

[Steamchick]

Ok, if you need luck - GOOD LUCK!
But I think your expertise is sufficient!
K2

 

[Brian Rupnow]

So, what did I do today on the engine?---Not much that shows, really. I cobbled together a wooden base that would hold one of my cylinders truly vertical. Setting up the valve timing is a lot easier if I start with a cylinder that is truly vertical, rather than laid over twenty five degrees. Of course, before you can set the valve timing, you have to set the correct valve lash. This took me down the road of having to finalize my valve lash adjusting screws and soldering the knurled tops onto the #5 bolts---and putting c-washers on the rocker shafts and on the shafts for the hardened donut that fits on the end of the rocker arms.---In the middle of all that a man with an idea for a new invention showed up at my place and we discussed that for two hours.---Then I had to mow the lawn, whipper snip the weeds, and blow all the cut grass off my Unistone driveway so it wouldn't start sprouting grass all over the driveway. Then I got an email from someone I had sold a set of drawings to for my 7/8" bore horizontal engine, saying that a bunch of drawings were missing from the package I sent him. I went thru all the files on that engine and he was right, I had to chase down about 20 drawings, save them as pdf files and send them to him. It was an interesting day!!!

 

[Steamchick]

Hi Brian. I like the simple solutions to make the calculations "more direct". I would have just fiddled on adding and subtracting the 25degrees here and there - maybe including errors!
And now you also have the front slope for a car wheel-ramp to add to your collection.

K2

 

[Brian Rupnow]

So---we're all ready to set valve timing. Piston is at top dead center, timing pointer is pointed straight up at "0" degrees (you can just see the tip of it sticking up past the degree dial.) Enough of the starter hub is exposed to let me turn the crankshaft to move the timing pointer. Both intake and exhaust cams are exposed thru the side of the camshaft support block to let me rotate the cams into the correct position. Now I have to go and help my good wife get set up for a family birthday party!!

 

[Gordon]

Maybe I am missing something here but why tilt the engine instead of just rotating the degree wheel by 25°?

 

[Brian Rupnow]

Because I'm old.--EDIT--EDIT--Sorry Gordon, that was a bad answer. it's just that I always find this timing procedure somewhat complicated, and the fewer numbers I have to juggle, the better I like it.----Brian

 

[Brian Rupnow]

Okay, it's time to rock!! Valve timing is set. Ignition timing is set. Gas line is hooked up. Gas tank has been leaktested. Electrical connection to the the points are ready. My "coil box" that I use to run all my single cylinder engines will do for one set of points. I have a spare ignition coil and switch, so tomorrow I will have to cobble up a second "coil box" to run the other set of ignition points.

 

[stevehuckss396]

 

[rick9345]

)long time lurker, and an old guy self taught machinist,(79) BIG THUMB UP!!

 

[Brian Rupnow]

Progress is slow. In order to give a second ignition system for the second set of points on this engine, I have to have a second coil, switch, and on/off light. I've had a 12 volt coil hanging on the wall since 2013 with a note on it "Coil may be bad". I'm going to assume that the coil is good, and having dug around in my cupboards I've found a switch and an on/off indicator. This second ignition source will be nowhere near as sophisticated as my original "coil box" but it should get the job done.

 

[Badhippie]

Brian
She looks like it’s ready run very nice build
Good luck
Tom

 

[Gordon]

I am not sure about this design and I may be completely wrong. I was wondering if you could use your dual snowmobile coil but then I realized that the two cylinders are not at 90° to each other so they are not firing in a true four cycle sequence. Aren't the cylinders fighting each other for part of the cycle since they are both on the same crank throw? On most multi cylinder engines the crank throw is offset so the cylinders are not fighting each other. I am trying to wrap my head around this and as I said I may be completely wrong.

 

[Steamchick]

Hi Gordon, while I do not really understand these things, I have heard of twins at 360 degrees, 180 degrees, 75 degrees, 45 degrees, 60 degrees, 90 degrees, and someat weird numbers, all to do with variations on balance factors. Brian uses 50 degrees. He can explain that one. But racing bike multi-cyinder engines sometimes have 2 cylinders firing together, for a big- bang effect which gives the rider more feel for the rear wheel grip when cornering!
The v-twin makers either do it for packaging, or for balance, when the axial imbalance of one cylinder can be off-set against the transverse imbalance of con-rod etc. waggling sideways back and fro....
I have a book on steam loco design where balance of engines, rods, wheels all combine and the same equations can be used on infernal combustion engines.... or a bit of fiddling with a stick-on weight or 2 on the flywheel!
So all things are possible?
Does that help?
K2

 

[Steamchick]

Hi Gordon, pardon me, I was thinking of engine dynamic balance.
We're you querying the firing?
On a simple 50 degree Vee, the firing would be 1 fire + (360 + 50) = 410 degrees to fire 2, then (360-50) =310 degrees to the no 1 next firing. So not a problem? Even more off-beat on Vee-twins with up to 90 degree Vee.
Is that a help?
Or have I still missed your point?
K2

 

[Gordon]

Hi Gordon, pardon me, I was thinking of engine dynamic balance.
We're you querying the firing?
On a simple 50 degree Vee, the firing would be 1 fire + (360 + 50) = 410 degrees to fire 2, then (360-50) =310 degrees to the no 1 next firing. So not a problem? Even more off-beat on Vee-twins with up to 90 degree Vee.
Is that a help?
Or have I still missed your point?
K2

I am wondering about firing. It would seem like one cylinder would be in part of the stroke ,starting compression for instance while the other cylinder would be in another part of the cycle, finishing power for instance and the two cylinder are fighting each other. 90° means that they are on opposite ends of the cycles. In a multi cylinder engine this can be avoided by offsetting the crank throw. I am not at all sure about this but most "V" engines seem to have 90° offset or a crank with the proper offset for the two cylinders so that the pistons are on opposite ends of the cycle. I probably am not expressing this well.

 

[Brian Rupnow]

As best I can explain this.--Engine rotation is clockwise when viewed from flywheel side. First piston comes up on compression stroke and fires. At the same time, second piston is coming up on exhaust stroke. First piston fires, and 50 degrees later the second piston reaches TDC and starts down on it's intake stroke. This gives the engine a noticeable "lope" when it is idling, but smooths out as engine speeds up.

 

[Gordon]

I built the Jerry Howell "V Twin" and this is what he said:

This is a V-Twin engine that is machined entirely from bar stock. It has no prototype as it is entirely my own design. Being a single crank pin 90 degree engine, it is extremely smooth and vibration free. V type engines other than 90 degree can not be balanced except with special balancer shafts, etc. that you wouldn't want! Witness the vibrating 45 degree motorcycle engines​

Perhaps the problem is balance more than ignition