Milwaukee Midget

[38flattie]

Midget,

Any response from St. Dema?
 
Fordboy

Seems Buddy might have been bending his ear about the Flatcad last Tuesday on his visit to Dema's shop, which I think was the day my cam arrived!  

Buddy, hope you enjoyed your visit.  I hope to meet him myself someday soon.

News from Harland Sharp is, as of this morning, they do not have the information on their BMC rockers regarding the moment of inertia.  Randy said he's still working on it, and we CAN proceed without that info, but I guess I'd like to know before we move any further on this valve train.

So - turning to the great brain trust that is the land speed racing community - can somebody give me a method of calculating the moment of inertia on a billet rocker?  It's a shaft type, and I'm thinking maybe using a method similar to checking end weights on a connecting rod might be a good starting point.

Guilty! I was at Dema's, and just like everytime I talk to Dema, it's an educational experience!

Chris, this build is getting very high tech! I didn't realize until today that there was a car involved!

I thought this thread was about beer, broads, and religion!

[Milwaukee Midget]

I thought this thread was about beer, broads, and religion!

Hmmm - Now that you mention it, Tony hasn't posted up in a while. 

He needs to lose that avatar - it's old enough to vote.

Cam is back from Dema, and he recontoured my lifters.  Should be able to start screwing a few things back together this weekend.

Sorry to pull the plug on all the fun, but I've got an engine to assemble.

[fordboy628]

Cam is back from Dema, and he recontoured my lifters.  Should be able to start screwing a few things back together this weekend.

Sorry to pull the plug on all the fun, but I've got an engine to assemble.

Midget,

Along those lines, redirecting to 'back on track'.

Current home project should conclude sometime next week.  Will be able to trek to Apex to machine depth plug to install replacement guide, and complete head repairs.   Also, am off to Bloomington & Peoria this weekend to visit my daughter.

Ask St. Dema if he has an electronic copy of the cam profile & if he is willing to e-mail it to you/me.  I'll load it out to Cam-Pro & post-up the info/graphs.  I'll also create a spreadsheet for the valve spring analysis from the cam info.

I'll be bock..........
 
Fordinator

[Milwaukee Midget]

Request has been sent - I also asked what radius he put on the lifters.

Ah, Bloomington - nothing Normal about that place.

Peoria - sounds like a urinary tract condition only treatable with large doses of antibiotics.

Why stop there - head to Iowa and make it a road trip -

Oskaloosa, Grimes, What Cheer . . .

Ahh, yes, What Cheer, Iowa - the vacation capitol of Keokuk County.

I can just hear Mrs. Fordboy - "Honey, be sure to wipe your feet before you get back in the car."

Okay - be safe - see you when you get back.

 

[Moxnix]

I was in the service with a rambling schmuck from Keokuk, but never visited myself.  Did the oversized & overweight box make it to beertown?

[Milwaukee Midget]

I was in the service with a rambling schmuck from Keokuk, but never visited myself.  Did the oversized & overweight box make it to beertown?

Baby is in the cradle.  Haven't opened it yet - taking it home this weekend.

[manta22]

MM;

"Baby is in the cradle."

Hmmm....where have I heard that before?

Regards, Neil  Tucson, AZ

[Milwaukee Midget]

Ask St. Dema if he has an electronic copy of the cam profile & if he is willing to e-mail it to you/me.  I'll load it out to Cam-Pro & post-up the info/graphs.  I'll also create a spreadsheet for the valve spring analysis from the cam info.

I'll be bock..........
 
Fordinator

Bock is typically a beer of springtime - made from the last of last year's barley. 

I trust you'll be back before pitchers and catchers report?

No word on the grind - and it's likely a proprietary thing from a different application.

He did forward me this info -   

The diaptre on the reground lifters is .5 which is a radius of 41 inches.  I hadn’t thought of it in those terms, but when one is precision grinding large curvatures on a surface, models from optic manufacturing would be an excellent place to start.

The negative acceleration is -.00020.

Thinly, thinly, cheezy, slicey . . .

[Milwaukee Midget]

Well, okay then – the cam is back in.

After a thorough cleaning with hot soapy water, brake cleaner, compressed air and WD40, the cam and the lifters are clean and installed.  I haven’t tightened everything down – waiting for the head to show so I can apply some spring pressure to check the timing, but when I took the timing chain and sprockets off, I was able to take them all off as a unit.   I just hung them from a nail on the wall through the cam sprocket.  They are indexed as they came off, so timing should be close.  I’ll be able to tweak it with the vernier, if necessary.




I’m furious with my niece, Tracey.  She went and got engaged before her dad and I had the opportunity to hire a reputable black-ops security firm, bust some heads, or even do a complete and thorough background check. 

Of course, I’m kidding – it’s just that I continue to think that I’m too damned young to have nieces getting married.

Congratulations, Tracey.

    

[SPARKY]

applies to first grand children also   

[Dean Los Angeles]

In the non-helpful replies category, which I'm VERY good at . . .

Bock beer . . .

The diaptre on the reground lifters is .5 which is a radius of 41 inches.

it's dioptre.
The reciprocal of the focal length measured in metres (that is, 1/metres)
1/2=.5
2 metres = 78.7402 in. = 41 in.?

do a complete and thorough background check

What you need is the "APPLICATION   FOR  PERMISSION TO  DATE  MY  DAUGHTER"
http://www.freemaninstitute.com/dateapp.htm

[Jack Gifford]

... The negative acceleration is -.00020...

I'm guessing that's the maximum value of negative acceleration? And also assuming that's inches per degree-squared of cam rotation? If 'yes', then 2 x 10^(-4) will be quite "gentle".

[fordboy628]

Well, okay then – the cam is back in.

After a thorough cleaning with hot soapy water, brake cleaner, compressed air and WD40, the cam and the lifters are clean and installed.  I haven’t tightened everything down – waiting for the head to show so I can apply some spring pressure to check the timing, but when I took the timing chain and sprockets off, I was able to take them all off as a unit.   I just hung them from a nail on the wall through the cam sprocket.  They are indexed as they came off, so timing should be close.  I’ll be able to tweak it with the vernier, if necessary.
     

Midget,

You don't need the head and/or spring pressure to check the cam timing.  Just use your analog dial indicator (more tension than the digital indicator.....) and the setup we used when we checked it together back on 9/15.  (reference reply #1510 photos & 1509 photos, for anybody following along.)

The negative acceleration is -.00020.

Thinly, thinly, cheezy, slicey . . .

A "peak" value of  -.00020  in/degree squared is at the low end of the range I was expecting.  (-.00020 to -.00025 ish) It is also consistent with other BMC 'race' cams (ground by Elgin & others) in my computerized (386) records.

Engines of this type, tappet diameter, cam lobe "packaging" dimensions (this is critical because the small dimensions available dictate nose radius for a given lift value and therefore: contact pressure....), valve train mass, valve spring packaging dimensions (this is also critical), engine operating rpm band, etc, etc; are consistently in this "range", because this range of results is what can be achieved while keeping the valve train intact........

Uhhhhmmm.......     have I mentioned "It's complicated"?    (I think I have, but my memory isn't what it used to be.........I blame the suds........)

... The negative acceleration is -.00020...

I'm guessing that's the maximum value of negative acceleration? And also assuming that's inches per degree-squared of cam rotation? If 'yes', then 2 x 10^(-4) will be quite "gentle".

Yes, that is a gentle value compared to a GM/Ford/etc V-8 or an OHC bike engine or even a Flathead with a large tappet diameter, but it is also a subjective comparison of apples to oranges.   On the larger engines, with more "packaging" space available, the nose radius can be larger for a given/desired cam/valve lift.   Small nose radius dimensions, dictated by a lack of adequate "packaging" space, result in very high contact pressures between the cam nose & the tappet.   Once the contact pressure exceeds the strength of the materials or the lubricant film strength, etc; the materials are going to spall, the end result being a cam lobe failure.  I suspect that when the contact pressure for Midget's jewel is calculated, that it will be higher than the above examples.  Because of the previous spalling that was encountered, this is a cause for concern.

This is why it is difficult to make equal comparisons between varous engine styles, types, and makes.   The compromises engine designers make at the manufacturing level, determine the strengths and weaknesses of an engine design.   And it ends up impacting what race engine builders can accomplish..........

With Midget's permission, I'll spend some more time explaining my thoughts on some of these cam train/valve train issues in the future.  I don't expect everybody to agree on anything except the depth of my ignorance.............
 
Fordboy


(edit) for anybody out there who is interested, add this to the reading list:
http://www.amazon.com/Cam-Design-Manufacturing-Handbook-2nd/dp/0831133678
http://www.amazon.com/Design-Manufacture-Edition-Mechanical-Engineering/dp/0824775120/ref=pd_sim_b_5

Oh, the price of knowledge is not cheap........

 
Fordboy

[Milwaukee Midget]

Yeah, that's about the same radius as my lifters.

And I can't argue with your math.  I need to contact Dema and clear that up.  In the past, I have taken people's word for things without checking it, only to wind up with stuck valves and recontoured rockers . . .

What you need is the "APPLICATION   FOR  PERMISSION TO  DATE  MY  DAUGHTER"
http://www.freemaninstitute.com/dateapp.htm

Well, that's like shutting the barn door after the horse escapes, but my brother-in-law has another filly in the stable, so I forwarded him a copy for future reference.

You don't need the head and/or spring pressure to check the cam timing.  Just use your analog dial indicator (more tension than the digital indicator.....) and the setup we used when we checked it together back on 9/15.  (reference reply #1510 photos & 1509 photos, for anybody following along.)

Yeah, I know - it's just that it's cold out there and the assembly lube has stiffened up a smidgen in the lifter bores.  I want to try to keep it accurate, and I was thinking a light valve spring would be helpful to that end.  But I can't be a wussy about it, and it ain't getting any warmer this time of year.  I've got the day off, and I bought some kerosene for the salamander.

[Milwaukee Midget]

Okay – as I had hoped, the timing dialed in at 105.5 with no adjustments necessary. 

Time to clamp it down and give it a final check.

One stupid note – When I started today, I turned the crank two full turns, and noticed what appeared to be a .005 bump on the base circle at 180 degrees from tdc.  The cam had just come back from Elgin, and I thought, “Oh come on, WTH?”.  As it turned out, the #2 piston was pushing up the magnetic base of the dial indicator.      

Fordboy!  Looks like the Bears went to Home Depot and bought a 55 gallon drum of shellac to apply to the Titans.