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Discussion Starter · #1 · (Edited)
I've had the idea of a big twin OHV top on a big twin side valve case for some years. People keep telling me they've see them, but i've yet to actually see one that came to fruition (granted there's probably one in some 70's motorcycle magazine). So with the agreement of a friend knowledgeable on cams to assist (without this, I wouldn't have bothered), I decided to go for it. It's been 6mo. so far and I've ruined the value of several expensive parts in the process. With any luck, this may come to life by end of summer, or at least by years end.

I post regular updates on Instagram because its so much easier ((#80Magnum), but figured I'd add it here for the annals.
  • stock 42U cases. will not be modified, except for knocking the front cylinder baffles out.
  • 4.25"' crank from Truett&Osborn. Using the '41+ taper for the crankpin, I provided shovel rods, and pinion shaft grooved for 360 degree oiling.
  • Feed and return oil pumps from Calas HP in sweden. I figure the oiling is necessary given the OHV top end.
  • 74" shovelheads and cylinders. STD bore cast pistons. I like the idea of off the shelf parts when i can, and I see no need for making the motor more complex than it already will be.
  • significant modifications to the cylinders for return oiling.
  • significant modifications to the cylinders, rockerboxes, and heads to accommodate the change in pushrod angle.
  • the tappets accept early panhead adjuster screws (thankfully)
  • Added K-model style oil returns in the Tappet blocks and cases, to account for add'l oil flow from the OHV top end.
  • Stock U motor cam set, with a custom set of lobes (closely matching Andrews AB grind).
  • I'm still in the process of sorting out the pushrod and tube situation, but I'm getting there.
  • I'm on the fence for carburetion. Super E is like the chevy 350, and SOOO boring, but i'll likely start the motor with an equivalent to get it sorted, then I'm thinking dual DC Linkerts and a common two-throat manifold (possibly).

I'm not sure why JJ cant get with the times and make it possible to post images from Google Photos in the thread (you feel me forum owners, before this forum becomes irrelevant?), but here's a link to what the motor will look like. https://photos.app.goo.gl/qcxtDAYrwEbm6z5M7

and the photos thus far are here https://photos.app.goo.gl/99ewMdwuUGtHYbmT7
 

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Oh man. Just going by looks alone, this is a wildly cool/interesting project. Thanks for the show&tell.
 

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Bit of a bummer if you can't post photos here...

I've just imported this one, but really, you need to post photos here, not links, otherwise chaps won't be interested...



Nice project anyway!!!

Patrick I'm not on instagram, I'm not on tweeter, I rarely visit facebook... What can I say, old dude, old way of doin' things where I can actually engage with continuity on sommat/someone, not troll through upteen pages of both boring, unknowledgeable, silly and irrelevant stuff to answer one querry 3 weeks ago...

Forums might be in decline, but all the above are not the answer if you want to build and learn... They're just show of for people with no interests at all except their own vacuous narcicism...
 

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I've had the idea of a big twin OHV top on a big twin side valve case for some years. People keep telling me they've see them, but i've yet to actually see one that came to fruition (granted there's probably one in some 70's motorcycle magazine). So with the agreement of a friend knowledgeable on cams to assist (without this, I wouldn't have bothered), I decided to go for it. It's been 6mo. so far and I've ruined the value of several expensive parts in the process. With any luck, this may come to life by end of summer, or at least by years end.

I post regular updates on Instagram because its so much easier ((#80Magnum), but figured I'd add it here for the annals.
  • stock 42U cases. will not be modified, except for knocking the front cylinder baffles out.
  • 3-9/32' crank from Truett&Osborn. Using the '41+ taper for the crankpin, I provided shovel rods, and pinion shaft grooved for 360 degree oiling.
  • Feed and return oil pumps from Calas HP in sweden. I figure the oiling is necessary given the OHV top end.
  • 80" shovelheads and cylinders. STD 80" bore 8.3:1 cast pistons. I like the idea of off the shelf parts when i can, and I see no need for making the motor more complex than it already will be.
  • significant modifications to the cylinders for return oiling.
  • significant modifications to the cylinders, rockerboxes, and heads to accommodate the change in pushrod angle.
  • the tappets accept early panhead adjuster screws (thankfully)
  • Added K-model style oil returns in the Tappet blocks and cases, to account for add'l oil flow from the OHV top end.
  • Stock U motor cam set, with a custom set of lobes (closely matching Andrews AB grind).
  • I'm still in the process of sorting out the pushrod and tube situation, but I'm getting there.
  • I'm on the fence for carburetion. Super E is like the chevy 350, and SOOO boring, but i'll likely start the motor with an equivalent to get it sorted, then I'm thinking dual DC Linkerts and a common two-throat manifold (possibly).

I'm not sure why JJ cant get with the times and make it possible to post images from Google Photos in the thread (you feel me forum owners, before this forum becomes irrelevant?), but here's a link to what the motor will look like. https://photos.app.goo.gl/qcxtDAYrwEbm6z5M7

and the photos thus far are here https://photos.app.goo.gl/99ewMdwuUGtHYbmT7
Scott; this is worth a look:

This chap has done what you're considering, interesting viewing!

Also:

4cam shovel!

Rhys
 

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I'm not sure why JJ cant get with the times and make it possible to post images from Google Photos in the thread (you feel me forum owners, before this forum becomes irrelevant?).
Good to see you back Scott and looking forward to the project.

As far as pics, I find this easy enough:

1). Right click on your pic Google photos and "Copy Image Address".

2). in your post here, click on the "Insert Image" icon above.

3). Paste your copied image address and hit OK.

4). You will see the image address in your post, but if you hit preview, the image will appear. Once ready, hit submit and the photo will be in your post.

Here is one of your pics:

 

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My question isn't exactly helpful to your thread; sorry. But if you have convenient access to any pictures of the cylinder (?) / crankcase (?) baffles that you removed, I'd like to see 'em.
 

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Here's a picture of the bike featured in Supercycle magazine years ago. UL with shovel top. I believe it is the same motor in the thread posted by Rys. Glad to see you back!
 

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Somewhere I have a picture of a shovel top, UL cased bike built by a Cleveland HA in the mid 80s. It was made from a bunch of parts he scrounged and was called the 80-80-80. 80" cases, 80" Shovel top all in a 1980 swingarm frame. I believe the motor was built by Motorcycle Specialties.
 

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Just a couple of comments, Just measured this morning, The deck height of a BTSV is about 7/16" higher than that of a shovel, pan, etc. So shovel rods aren't going to work, too short. I didn't see any pics of the crank ass'y so I'm just guessing you haven't done any of the ass'y work on that aspect as yet. Also BTSV flywheels have a smaller diameter so you'll need to have T&O turn them down, or do it yourself if you have a lathe. This may all be old news to you, I just didn't see any pics that depicted that part of the build.

Should be a fun build, BTSV's are a classy looking bottom end, and strong too. Talked to Paul Freibus who races BTSV's at the salt flats, holds some records, and he's never had problems with the cases, as opposed to early Knuckles which are fragile.

Good luck.
DD
 

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Discussion Starter · #12 ·
Scott; this is worth a look:

This chap has done what you're considering, interesting viewing!

Also:

4cam shovel!

Rhys
Great thanks rhys. Now that I see it's been done (and running examples), I'm just pushing this lump into the storm drain...... thanks for blowing up my spot. Kidding. That was interesting though. The knucklehead one was spot on about having to weld the pushrod holes (they are WAY off). For the shovelhead, I noticed he welded the cases for cylinder oil drains rather than modify cylinders. That's the kind of detail I find interesting.

As far as pics, I find this easy enough:

1). Right click on your pic Google photos and "Copy Image Address".

2). in your post here, click on the "Insert Image" icon above.

3). Paste your copied image address and hit OK.
Hd48fl, you're right, that works. I think I was using the "preview" which never shows up, so I assumed it wasn't working.

I still have to remove the baffles, which is the only modification I'm doing to the cases. I also don't feel bad doing that because I'm not convinced they did any good.

Just a couple of comments, Just measured this morning, The deck height of a BTSV is about 7/16" higher than that of a shovel, pan, etc
correct, my measurements actually indicate a deck height of .39" higher. So U rods were too long for shovel pistons, and it's not like I could use flatty pistons. So I'm using 74" shovel pistons and taking about .201" off the cylinders.
 

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Discussion Starter · #14 ·
I'm trying this post for the first time using the phone. So we'll see.

Flywheels are here. First time actually seeing whether my calculations were correct. I'd planned for 74" pistons knowing they'd bee too low (because of higher deck height on the cases). They are .201" too low. Since I'd already planned on shortening the cylinders (but my math was for .108") that's no biggie.

But, I was gambling that the smaller diameter flywheels would account for the longer skirts on 74" pistons. Now that's it's mocked up, they are too close. So I ALWAYS think about the next time I have to take something apart or rebuild it. So I'm weighing whether it's better to have to deal with trimming pistons or setting things up for 80" now. I'm going to chew on that, as there's pros and cons to both.

The baffles in the cases still need to be fully removed, in either case.
 

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You might look into stroker pistons on the flattie rods. Wouldn't need to cut cylinders, wouldn't be piston bottom trimming either.
 

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Here's a picture of the bike featured in Supercycle magazine years ago. UL with shovel top. I believe it is the same motor in the thread posted by Rys. Glad to see you back!
This was the first bike I thought of when I saw this. Scott, I have this mag on the shelf somewhere. I recall it being vague on details, but if you want me to dig it out for pics or text, I will happily do so.

On a slightly separate note, this is fuckin' rad. Watching.
 

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Discussion Starter · #17 ·
You might look into stroker pistons on the flattie rods. Wouldn't need to cut cylinders, wouldn't be piston bottom trimming either.
1)U Rods+stock pistons: U rods are almost 1/2" (.468") longer than my later Shovel. So stock 74" pistons would stick out about .267", and 80" pistons would be ~.187". Piston height would be harder to deal with, compared to shortening cylinders, if even possible at those distances.
2) U Rods+shovel stroker pistons:
a)I prefer cast pistons on anything I'd build. They work. They're cheap. They've only gotten better better since 1936. Readily available and will continue to be. Light. I understand why, but having to setup setting up a new piston because it's forged at .0035 TIGHT seems insane to me still on these motors. I don't trust those hyper pistons for these old motors yet either.
b)I prefer off the shelf stuff (at least when planning for the next owners maintenance and rebuilds).
c)For 74" bore, I know only of S&S pistons. If you know others, please let me know. S&S is a great company but until I can get someone on the phone that can give me the exact specs and explain to me how they have one piston part number for '36-84 motors with 4.5 to 4.75" stroke, I'm not considering that.
i) they are really expensive, which in my opinion means they should be specific. Paying top dollar every rebore for generic one-size-fits-all pistons is crazy. There's no way you can make a piston for 3 different heads and 3 different strokes without making some sacrifices.
ii)Using math, I assume that the S&S stroker piston is ~.391 shorter between the Pin and the piston top in order to accommodate for a 4.75" stroke for which they market it. That means I'd still be shortening the cylinders anyways if I used U rods.
3) shortening cylinders is probably half the cost of 1 set of stroker pistons, and then there's 3-7 overbores remaining (depending on 74 or 80").

80" piston is perfect at the skirt (as you might expect), but it means fewer overbores. It also requires more cylinder shortening.

74" piston would need to be trimmed now and in the future, but it would have more overbores and less cylinder shortening, and more generic piston options.

decisions decisions. more to come.
 

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Discussion Starter · #18 ·
Update. Cylinders/pistons are done. Stock 80" pistons (I like to keep things simple for future rebuilds). The cylinders will be semi custom though: oil drains, base flange shave, shortened .30" (.10" at the base, leaving spiggot intact. And .20" at the head, while shortening fire ring the same amount).

I had a couple visible pinholes in the brazing for the oil drains, so I'm epoxying over those rather than more brazing. This is a no pressure situation anyways.
 

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Discussion Starter · #19 ·
Update. Cams have been done. This is the equivalent of andrews AB grind. Pic shows stock lobe next to OHV lobe. Bottom line is the stock cams would be a shit ton of lift if u tried to use them.

Also these are the cannonball.de cams. If u were wondering they are ok, but they could be nicer. They do not grind the lobes after heat treating. Probably fine but just an fyi if u are in the market for U cams.

Final timing will come once the cases are setup.
 

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