Author Topic: V-Twin - Construction Comments Part I  (Read 1472 times)

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V-Twin - Construction Comments Part I
« on: May 11, 2015, 03:53:34 PM »
I started building the Howell V-Twin four months ago, although I have a long way to go, I would like to share some thoughts and ideas I picked up along the way. Disclosure: I am a self-taught machinist.

There are dozens of small parts on the Twin. None of which are difficult to make, with the exception of one, the gear case. It’s not for the faint at heart. Precision is a must. If you’re going to make the Twin, make the gear case. After you complete the case and cover, go on with the rest of the Twin. It’s downhill from there. Don’t get discouraged. it took me four tries to finally get the case right.  Pay particular attention to the depth of the gear pockets. Their depths are each measured from the top surface of the case, not the bottom of the 2.250 dia. x .270 deep cut out. The dimensions can be confusing so read the construction notes first. Note: The holes are first drilled on the “O” ring side, then turned over to bore the pockets.

Several gears will be needed; fortunately, you won’t have to make them. All, including the tail shaft and oil pump gears, can be purchased very inexpensively on eBay; however, they will require some simple modifications. The Howell drawings specify 14 ½ degree pressure angle. The PA of the gears I purchased was not specified, but they seem to work perfectly so far.

Before drilling the holes in the gear case, test drill the holes in a flat plate. Put the gears in place on the plate to verify the dimensions to assure smooth rotation. You may have to make minor adjustments to achieve minimal backlash.  

To make life easier I used a 1” ID DOM Steel Round Tube for a cylinder liner (available on line). The tube required modification of the cylinder as designed but it resulted in a perfectly round, and non-tapered inside diameter. No lapping is needed as the inside is perfectly polished. In addition, I’m going to try to use Viton "O" rings instead of cast iron rings. More on that latter.

I intend to add more as I proceeded, so stay tuned. And please, feel free to email me [] with any questions.

« Last Edit: June 07, 2015, 10:12:12 AM by ernie »