Sundays are mine.......

Lately, I've left Sundays for myself, to get things done on my personal projects. I just turn on the football games, and try and get at least one or two things accomplished from the build list. Today, I decided that one job that I have procrastinated on needed to be polished off, and that was notching my downtube so my Shovel and the front exhaust pipe could once and for all fit the frame right, and have both easily removable.

Here was my problem solving for today. My WCC CFL frame with the curved single downtube was originally built to house a Evo engine. I've had an Evo in this frame to check clearances before, and the front exhaust pipe had no problem clearing the single downtube. I wanted to use a cone Shovel instead, so I figured out it would fit no problem. Well.....

The Evo is a little taller, and the exhaust port is set on an angle away from the downtube. But, on a Shovel, you can see in the above photo how far out to the front the exhaust spigot, pipe mounting flange/bolt, and the pipe stick out. No problem on a stock-type frame layout, but on this frame, when we slid the Shovel in it for the first time, the front exhaust spigot ran smack into the middle of the curved downtube before it was even close to mounting up. Fuck.

If this engine was to fit this frame, a little judicious frame notching was in order. It had to be done, it had to look good after it was finished, and it had to not compromise the structural integrity of the downtube itself - especially a single downtube. Fortunately, the downtube is 1 1/2" OD, 1/4" wall DOM, so it made things a little easier structurally for the notching.

I started off by grinding down the old spigot until I got enough initial clearance on the downtube (and digging out an old helicoil exhaust bolt repair coil), and a good shape to the port area itself.........

......then I took the head over to Rick Labriola (Labriola Machine - home of the 5 Speed Suicide), and he built me a new exhaust spigot positioned 90 degrees to the left. Rick used my head to try out his new zoot pre-heating oven, and his new water-cooled TIG torch setup. Came out perfect, I've never seen Rick to do any less.

Here's another view of the repositioned spigot. Rick's work is flawless. You can see how much tubing would have had to be removed for the original head flange and exhaust pipe to fit. I would have had to notch the tube right to the outside wall for clearance.

I didn't shoot any photos of the actual work involved, because notching frame tubes like this is slow, tedious work - hence me putting it off for the last few months. You have to cut and grind little amounts of material off at a time, and it's easy to get impatient - otherwise, you wind up with a frame tube that looks like a bag of smashed assholes.

I will tell you that I started off by making a posterboard pattern of the initial shape of the notch, then I marked it on the tube with a Sharpie. Then, instead of going over the Sharpie line with a soapstone line, I used an old trick of tracing just inside my line with a series of centerpunch ticks, which are way easy to follow as you cut. I did the initial cut with a torch (I don't have a plasma cutter, way easier) with the flame set for a fine kerf line, cutting just on the centerpunch tick line. After that, it was grind, fit, grind, fit, until I was satisfied I had my final shape and clearance.

Here's the final notch shape from the L/H side. The notch at the deepest point didn't even get a 1/4 of the way into the diameter of the tubing. Once boxed, it'll be plenty strong, and there's enough room now for the engine to slide out without any hassles.
Top of the notch mirrors the shape of the exhaust spigot, as seen from the R/H side. Little details.......
The pipe looks closer than it is to the frame (at the small black arrow), but there's about a 1/16" between it and the frame notch area. When I get the tube boxed in again, I'll be able to take a slight recess of an additional 1/16" in that area under the exhaust, giving me about an 1/8" total, without sacrificing any strength, and you won't see it.

When I build my 2 into 1 collector system, the front pipe will angle down in approximately the same way as the big black arrow is pointing. It won't be anywhere near the magneto. Also note the nice, thick Fab Kevin exhaust flange. We made it, everything fits, and another thing off the "to do" list.