Saturday, May 14, 2011

Shovel Heads Revisited

(note: revised 5/16/11)

My first Harley was a Shovelhead, and way back when I started out in the motorcycle industry, Shovelheads were the "State of the Art" .... well, at least in the Harley world! In other words, I am no stranger to Shovelheads. In fact, I never did find myself calling them "Troubleheads" as some in the industry did after the Evolution motor de-throned the Shovel. Don't get me wrong, I am still a dyed in the wool knuckle guy when push comes to shove (or is that push comes to shovel?), but I do appreciate a strong running Shovelhead.

For that reason, I never did shy away from doing porting work on Shovels, though admittedly, those jobs came in pretty infrequently for a number of years. When I started building the Knuckledragger a while back, it got my friend Niel to thinking that it would be fun to build a hot Shovelhead for nostalgic reasons ...not a competition bike mind you, just something to make people shake their heads and wonder. To do that, of course, would take some fairly impressive head work.

Well, that got me to thinking, and thinking got me to doing a little R&D work on Shovelheads for the first time in quite a number of years. It had seemed that I had sort of "hit a wall" when it came to flow on the Shovelheads that I had been porting over the years. I had some ideas that I wanted to try, but never seemed to find the time, or the right set of heads to work with for that matter.

However, some time back a long time friend, Krazy Karl, brought in an engine that he had purchased as part of a basket case. Included with the engine were a brand new set of S&S Shovelheads. As it happened Karl wanted OEM heads on this build, and since he was short on money for the rebuild and I was short on Shovelheads for R&D work, we wound up doing some mutually beneficial horse(power) trading.

As per my oft repeated modus operandi, the project has dragged out for what seemed like forever, but the end is finally in sight ...well, perhaps only with a high power telescope, but in sight, none the less! The results are, I think, fairly impressive. Now here is something many of you might not realize, but the S&S Shovelheads only flow slightly better than a stock OEM Shovelhead casting. Here are some flow figures comparing a new, fresh out of the box S&S Shovel intake port to a stock unmolested OEM port:

.100"---69.0 (S&S)----66.8 (OEM)






These figures are all at a 28" test pressure. Keep in mind that stock Shovelhead ports are notorious for their core shift, so those figures will not be consistent from one head to the next. But let's cut to the chase. Here are the figures for a set of my "best ported" OEM castings compared with my prototype intake port on the S&S head (both heads use a 2 inch valve):

.100"---65.1 (ported OEM)----66.7 (proto S&S)







Just to put this in perspective, somewhere around 25 years ago (give or take), I built a 114 cubic inch Shovelhead engine for my friend Neil Ryan's drag bike. (If you are paying close attention you may remember him from the beginning of this post.) In any case, this was just before I began porting heads, so he had the heads done by the legendary Dave Mackie. That motor, with those heads went on to run the world's first 5 second eighth mile pass for a Pro Stock Harley. The flow on those heads? Less than the "best ported" OEM heads shown above. Can you imagine the potential with an extra 30 cfm of air?

So, as I await the finished version of the prototype valve I made up for the prototype head, the big decision is this: do I have the ports digitized so that it is easily reproduced through CNC porting? Is there enough demand to justify the cost? Hard to say. Anybody out there up for building a fast Shovelhead?


St. Lee said...

I certainly hope no one misconstrued me as denigrating Dave Mackie's porting work. The heads he provided couldn't have done their job any better; after all world's first is worlds first! Besides, his work has set so many records he likely can't keep track!

St. Lee said...

Oops. Caught a mistake in this post. I just revised the flow figures for a Stock shovel head. I had inadvertently used a test that was on an earlier "stock" S&S Shovel head rather than an OEM head. The correct figures make the S&S head look much better in comparison. I apologize for any confusion I may have caused.

Dave Vickery said...

Hi Lee, thanks for your info, I always enjoy reading the stuff you post. I'm interested in building a big bore shovel and have toyed with some do it yourself porting...there's some interesting views from nightrider website . I don't ahave a flow bench so was contemplating just smoothing out intake harsh edges and general polishing in lieu of redesign? Appreciate your thoughts if you care to comment...thanks Dave

St. Lee said...

Thanks for adding to the comment section Dave. I began considering an answer to you question and then realized that it would better fit the size of a blog post than a comment here. I will attempt to get something published on my blog concerning this in the very near future.

Dave Vickery said...

Thanks Lee - will keep checking