Team Go Dog, Go! Modified Partial Streamliners

[fordboy628]

http://www.landracing.com/forum/index.php?action=dlattach;topic=6167.0;attach=55043

Bo,

When I view the photo of the tappet you posted, it does not appear that you require a "larger diameter" tappet.   The "wear pattern" does not "run off the edge" of the tappet diameter being used.

Without having more specifics of the hardness and metallurgy, (which could change my opinion), I'm thinking all your wear issues are related to:

A/   "bed-in" procedures,
2/   pre-lube, oil and oil additives,
d/   "bed-in" valve spring pressure.

Unfortunately, steel cams combined with steel tappets, and high velocities/accelerations combine to push those cams into the "very high contact pressure zone".    THAT is what requires special "bed-in" procedures.   WHAT, EXACTLY, that will end up being for your engine, I don't know.

BUT, I do know this:    If it was me, I would take the "shotgun" approach to cam "bed-in" and use every bit of advice I could glean from ANY source of useful information about steel cams, whether for bikes or cars.    The lengthy, "pain in the a$$" procedure I posted on the MM's build diary works for steel cams with steel tappets fitted to Lotus Twin Cam racing engines.    I did it that way not because I wanted to add complexity to the builds, but because it was the only method that worked.    I had to fabricate some special tools and define some special procedures, but it then worked.    BTW, those cams were ~ .520" lift and 320 degrees duration, in a 2 valve, semi-hemi DOHC 1600cc.   NO OTHER CAM GRINDS MADE THEIR KIND OF BRAKE HORSEPOWER . . . . . . .

 
Persistentboy

[Old Scrambler]

Bo............Mark has good advice ...............Could you machine the existing tappet buckets?...............or machine new replacement units?  Lighten the spring pressure and follow the break-in advice?  Work - Yes, Cost..........minimal.   BTW.......did you play with timing while on the dyno?

Dave and others have advised me to NEVER let a motor idle with a new cam in it...........until its known to be 'worn-in'  And, yes, Dave agrees that the buckets should rotate with cam-contact.

If you won't be running your bike..............will you be at BMST as a spectator?  I always learn so much from other competitors..........especially when it counts

[fordboy628]

Bo............Mark has good advice ...............Could you machine the existing tappet buckets?...............or machine new replacement units?  Lighten the spring pressure and follow the break-in advice?  Work - Yes, Cost..........minimal.   BTW.......did you play with timing while on the dyno?

Dave and others have advised me to NEVER let a motor idle with a new cam in it...........until its known to be 'worn-in'  And, yes, Dave agrees that the buckets should rotate with cam-contact.

If you won't be running your bike..............will you be at BMST as a spectator?  I always learn so much from other competitors..........especially when it counts

Yes.    RPM must be higher than idle, say 2500 to 4000, but well below mid range to maximum.

If the buckets DO NOT rotate when the engine is turned over by hand during final assembly, NO ONE can prevent their destruction.    When the tappets don't turn, you need to be in a conversation with the cam grinder/supplier about WHY they don't rotate, BEFORE starting the engine.

And don't let any of those suppliers BS you that things will be fine when it fires up.   IF THEY DON'T ROTATE, THEY WON'T LIVE.   PERIOD.

    
Verypersnicketyboy, because I have to be . . . . . . . . and you should be too!!!

[wobblywalrus]

Thanks for the advice.  Ducati desmo systems are looking good right now.  Two strokes, too.  Some of these items were done.  The high lift intake cam was too big for the buckets.  The exhaust cam would work with the buckets so that is why I used it as an intake cam.  I do check for rotation when I adjust the valve clearances prior to running the engine.  I did keep the idle above 2.000 rpm as advised by Webcam.  Kibblewhite checked spring pack length and I was plenty good in that respect.

The old cams were made by the same company and I broke them in using the OEM valve springs.  This time, I was using full strength racing springs for break in.  Previously I lubed the edges of the lifter buckets with oil.  This time, the bucket edges were lubed with break in grease.  They rotated, but not as freely as if they were oiled.

The rings are seated and the mineral break in oil has been changed to racing synthetic.  This should give better film strength when breaking in the new cams.  Also, I will use light springs for break in and the bucket sides will be lubed with oil and not assembly grease.  Particular attention will be paid to lifter and cam materials and hardness.

All of my various cam profiles will be measured for valve lift vs degree crank rotation.  Then, the head will come off and the damaged parts, head, carbs, filters, etc will be sent to Kibblewhite.  They are going to flow test the new carb and filter setup.  Then, cam design will begin. The goal this year is to be able to understand all of the terminology and data on the PipeMax printout, to interpret it, and to use it.  Learning Egyptian will be easier, but it is something I need to do.

All of this advice is being filed away and it will be reviewed during the year.  It is suggested that I go to speed week as a spectator.  I might do this.     



 

[salt27]

Bo, we will be looking for you at Speedweek.   

 Don

[Koncretekid]

Bo,
Notwithstanding all of the excellent advice  above, in my opinion, no break-in procedure other than what you followed would have saved those buckets from self destruction.  The severe damage you show from a mere forty mile road break-in would have to have been caused by an incompatibility of the metallurgy or design of the parts, and is NOT YOUR FAULT!  Any reputable manufacturer of those parts should step up to the table and replace them without a question and bear the responsibility for the failure.

Using lower spring pressures or rpm or special oils during break-in may have shown up the problem, but would not have changed the final outcome that the parts were defective, period.

Tom

[wobblywalrus]

Hi Tom, as usual with fiascos where I am involved, my fingers are in the pie, as they say.  The guy that sold me the cams did not tell me about needing different buckets.  I did not have time or the desire to deal with him so I found buckets on my own.  This is a three ring circus, the cam vendor, the cam manufacturer, and me who made the big decision.  I need to get my facts straight before I start demanding stuff.  The valve train expert will look at things.

The head, cams, etc will be going back to Kibblewhite.  I need to collect data before they go.  Measuring valve displacements vs crank angles for the cams is the current task.  Last night I made this special tool to record valve event degrees.  The best degree wheel is this one from the local speed shop.  I really need one that reads from 0 to 720 degrees to give me direct readings of crank angle.
   

[wobblywalrus]

The degree wheel is ready to go.  The crank is rotated through this little hole in the case.  Normally the wheel is attached to the crank.  This requires the oil to be drained.  The system I am designing does not require this.  More on this subject in the next post.

[wobblywalrus]

TDC can be determined by a mark on the flywheel that is seen through this little hole.

Note that the cam gear is welded to the cam.  It is a simple matter to grind these off and to alter the cam timing.  This offers the possibility to do some cam timing adjustments at the dyno facility.  They have a grinder and welder.  It will be more convenient to do this without removing that alternator cover or dropping and refilling the oil.

[fordboy628]

TDC can be determined by a mark on the flywheel that is seen through this little hole.

Note that the cam gear is welded to the cam.  It is a simple matter to grind these off and to alter the cam timing.  This offers the possibility to do some cam timing adjustments at the dyno facility.  They have a grinder and welder.  It will be more convenient to do this without removing that alternator cover or dropping and refilling the oil.

Bo,

Rather than the grinding/welding cam timing PITA*, is there room on the cam/cam drive gear for some slots fitted with "button" head socket cap screws?   What I am thinking of is a threaded hole in the drive gear, say 6mm x 1 pitch; a slot in the cam drive flange; and secured with 3 to 6 "flanged" bhcs.

This is what I'm thinking:

https://www.google.com/search?q=images+for+kent+vernier+cam+drive&biw=1920&bih=911&noj=1&site=webhp&tbm=isch&imgil=Rfz4_qD-46H_XM%253A%253BMJx0QdwvD-OWEM%253Bhttp%25253A%25252F%25252Fwww.briskoda.net%25252Fforums%25252Ftopic%25252F292003-kermit-perhaps-highest-bhp-8v-1289cc-favorit-in-uk%25252F&source=iu&pf=m&fir=Rfz4_qD-46H_XM%253A%252CMJx0QdwvD-OWEM%252C_&usg=__TPEeXwlZs38FQf1OhApTpzsHL9c%3D&ved=0ahUKEwihtd7_yZjOAhUi74MKHXvVCfcQyjcIRA&ei=ID-bV6GlBqLejwT7qqe4Dw#imgrc=_

ALSO, on pages 35/36:

http://www.kentcams.com/documents/downloads/Kent%20Cams%20catalogue%202016(7).pdf

Kent also makes steel tappets and shims in various sizes, one of which might be suitable for your application:

Obviously, if the room does not exist to fit some securing fasteners, that's a deal killer.   BUT, I would be EXTREMELY creative on the possible fitment though . . . . . .

You have got to think "out of the box" on this, to solve this critical tuning issue.

 
Forgetabouttheboxboy

edit:   After looking more carefully at your photos, it seems to me that there is room somewhere in the cam drive train to incorporate a vernier adjustment, even if it is only an "offset dowel" setup.   Get creative.

[wobblywalrus]

Thanks for posting that info, Mark.  Sending a cam to kent Cams and asking them if they have ideas will be the best route.  They have the degree wheel I need.

       

[wobblywalrus]

Another tool was made so the bucket travel can be measured by a dial indicator.  This shaft is mosquitoed into the workings so it touches the top of the bucket.

The entire lift profile will be measured.  This thick shim is installed to make valve lash zero.  This way, lift is measured all around the cam including the base circle.

   

[wobblywalrus]

The valve travel is being measured by recording the bucket movement.

A few years ago I went on a navy ship with my son and posted pictures on the forum for off-season entertainment.  Rose got accepted to go on the same cruise with my youngest boy on the USS Harpers Ferry.  The vacation leave I saved to go racing will be used to spend a week in Hawaii with her before she boards the ship.  It has been a rough year and I need a break.

[wobblywalrus]

Is there an on-line calculator or way for PipeMax to display or list piston demand at 28 inches vs crank angle for pistons with offset pins?

[wobblywalrus]

There is some good information about piston pin motion with and without offset on the i-net.  The small 1 mm offset on my pistons does not make enough difference to justify the extra work to use it in the calcs.  I will use PipeMax to figure out piston demand.