Friday, December 22, 2017

When a Plan Comes Together




To quote a classic line from a semi-classic television show, The A Team: "I love it when a plan comes together." Now to be sure, I needed to look up the source of that line, because even though it has become a common catch phrase, I had no clue as to the origin.  It seems that I just didn’t watch much TV in the decade of the 1980’s, doubtless due to the transition I was undergoing from scumbag biker into dedicated drag racer.  In any case, it does reflect my thoughts on the project I am finally getting around to writing about.
 
Well over a year ago I received a call from Zach Waters in regards to porting a set of Knuckle heads.  His plan involved the following:

  1.  Put his 1947 Knucklehead on the salt flats
  2.  Set a record in the appropriate vintage class
  3.   Return the bike to normal street use.

Okay, now that may not sound so terribly challenging on the face of it, but there were a couple caveats that certainly made things a bit more interesting.  One was that the particular class in which Zach had slated to compete demanded that externally everything on the bike must appear stock.  The second was equally interesting from a performance standpoint; the motor would be left in the same configuration when returned to street use as it had for Bonneville competition. 

This paint would look more at home in a bike show than on a bike competing at Bonneville
 
Everyone would probably agree that one of the keys to speed is horsepower, and likewise one of the keys to horsepower is airflow.  Thus, Zach’s decision to send the heads to me.  But the second caveat, that of leaving the engine in the same configuration for street use, was a big factor in every aspect of the build. 


You have to appreciate the classic profile!
 

The engine work (outside of the heads) was taken care of by Bob Moreland of Bob’s Garage in San Marcos.  Foregoing lightened flywheels, Bob instead balanced them to provide Zach with a short block that runs as smooth as silk. The compression ratio was left low enough to compliment the mild Andrews “S” grind cam.  You may note that the S grind is the mildest “performance” cam which Andrews offers for Knuckle engines; the only one less aggressive being deemed a “stock” replacement. Obviously all of those things enhance the street-ability of the whole package.



For my part, since the heads would soon see full time street duty, I avoided adding any porting epoxy. Experience has shown me that it tends to have a limited duty cycle in cast iron air cooled heads.  Instead I gave the heads a good porting job using only 1.950” x 5/16” stem intake valves, along with attempting to manipulate the boundary layer flow in lieu of adding material.  My thinking on the relatively small intake valve size was that the heads would still readily outflow the M-35 Linkert (mandated by the rules), and would also insure no material would need to be removed from the pistons for clearance, sacrificing compression ratio in the process.

Zach credits Phares Cycle for their additions to the quest for power, along with Jeff Montgomery for guidance in tuning.  Of course, the real heroes of the story are Zach and his dad, who put in the time and effort, not only in research, but also untold hours of trial and error tuning.  

Ready for action


The results?  Only shattering the previous record speed by over 15 MPH.  I love it when a plan comes together!

Verification of Engine Displacement

 Now Zach is quick to point out that even this resounding success left plenty of room for improvement.  Further tweaking with the addition of dyno time would likely prove beneficial, as would some experimentation with the gearing since he felt it may have been a bit higher than optimum.  Even the inconsistency of the salt conditions played a big role in limiting the MPH.  Zach’s best run of 107.8 MPH was considerably faster than the preceding 97 MPH pass which was the result of poor track conditions.  This left the two-way average, record breaking number, at an official 102.4 MPH.   

Do you think there might be a story behind this kicker pedal?

 So, belated congratulations to Zach and his team, along with a big thank you for allowing me a small part in a plan that definitely came together.

2 comments:

Juhana H. said...

Wow!
Amazing performance for 74" streetmotor with Linkert.
How much RwHp in Dyno?

St. Lee said...

I don't believe Zach had the opportunity to dyno it.