Milwaukee Midget

[Milwaukee Midget]

Looks like they’ve been converted to solid by others – but my concern is the diaptre one would need to grind on the face of the tappet to work with an appropriate cam, if that would leave enough material on the face to be safe, and how hard one would need to treat them.

Well, maybe the buckets are more substantial than I thought.

The face is .088, the sides, .033.

[RichFox]

Yes, on the Lotus I had to make shims any time anything got changed. As long as I kept them in order it wasn't too bad after the first time. Assemble the head. Measure the clearance and write it down. Disassemble the head. Measure the shims and do the math. surface shims that are to thick. Make new if you need thicker. Reassemble and repeat.   

[Interested Observer]

Chris,
I assume you are aware of the following.  Seems to have a lot of useful information on the K-series.  Apparently some people have been down this road before...

http://kengine.dvapower.com/

[Milwaukee Midget]

Thanks, IO - it's a site I've been to over the years, but neglected to bookmark - an oversight corrected by your prompting. 

[Milwaukee Midget]

I just had an idea.  If I were to take the stock cams - which will be replaced - and have the lobes turned down to the diameter of the base circle on the new cams - whatever those wind up being - I could use them as set-up gauges during the shimming process.

 

[fordboy628]

Looks like they’ve been converted to solid by others – but my concern is the diaptre one would need to grind on the face of the tappet to work with an appropriate cam, if that would leave enough material on the face to be safe, and how hard one would need to treat them.

Well, maybe the buckets are more substantial than I thought.

The face is .088, the sides, .033.

midget,

R-E-L-A-X.  and not just about your dam* Packers.   (BTW, they deserved to win.  Bears are undisciplined AND poorly coached . . . . so much so, I'm done for the year.)

Mark's rule #3 or #5, whatever, is:  DO NOT RE-INVENT THE WHEEL!!!

We should use solid, Cosworth style, inverted bucket tappets for the following reasons:

1)   It is simple.
2)   It is lighter than modifying the stock hydraulic followers, permitting use of lighter valve springs @ higher rpm.
      (The target peak bhp rpm will NOT be 10,000 rpm, but I want to engineer valve-train reliability up to 10K/10.5K, since I watched the video of your 126 mph run.)
3)   You can "get away" with "flat tappets" because with 4 valves per cylinder, (and 8 ports . . . ) the cam grind does not have to be as "intense" as it was for the "Grenade".
      (WHICH I WOULD LIKE TO POINT OUT, WAS NOT . . . .)
4)   Reducing the base circle diameter of the cam lobes is probably the ONLY way to increase valve lift, since the valve seat to cam centerline dimension is "fixed".
      I doubt that this will be an issue, because with 4 valves per cylinder, "massive" lift will NOT be required.

There are a couple of different permutations of this style.  One uses a short inner "stem" or "post" in the tappet to replace the hydraulic adjuster mechanism.  The other uses a short tappet stem combined with "long stem" valves.   I'm not sure which one might be in use for K's, but we should check on what is available from REC and Piper in the UK.   Both styles utilize a "top hat" style shim in between the valve stem and the tappet as the method to adjust the valve clearance.

AND, yes, adjusting the valve clearance is a "PITA", just as on Cosworths, Lotus TwinCams, or any other twin OHC race prepped engine.   Just the way it is, embrace and accept it.

The plan should still be to measure what we need to and gather the information.   Then start making decisions and ordering parts.

This "journey" will be different, no blind spots, eyes open all the way.

 
Kufupandaboy

I guess I need to start working on the simulations for output, eh? ?

[fordboy628]

Chris,
I assume you are aware of the following.  Seems to have a lot of useful information on the K-series.  Apparently some people have been down this road before...

http://kengine.dvapower.com/

IO,

Thanks.   Already been using that site for research.   DVA has built a couple of 1700cc engines producing 250 bhp and 152 lbs/ft tq.   BTW, this was on a "rolling road", so this is rear wheel bhp/tq.   These numbers may be a bit optimistic.

At a similar build specification, at 1 liter that scales down to:  147 bhp and 89 lbs/ft tq.

I think it is reasonable to have a goal of 85% of those numbers as a goal for the first permutation of the 'K' build.

That would be:   125 bhp and 76 lbs/ft tq.   Should be able to achieve the bhp and perhaps do a bit better on the tq, say 83 lbs/ft, because:

Currently the "Grenade" makes 99.1 bhp and 75.8 lbs/ft tq,

and I, for one, think we can be a bit more "efficient" with 8 ports and 4 valves per cylinder.

And, I've built LOTS of Cosworths . . . . .
 
Fordboy

[fordboy628]

Okay, a die cast head -



Huge tappet surface –




Cam girdle/ladder –




I didn’t just fall off of the turnip truck, but gut level, if I were to have designed this engine, I think I’d have gone with a different surface for cam bearings than just the die cast aluminum itself – Maybe this is the way it’s done today, but I don’t much care for it -


I’m seeing some wear in the bearing surfaces on the ends – they don’t quite pass the fingernail test, but the cams look fine.  Maybe a surface machining of the head and the girdle and an align hone?  Or maybe not worry about it.




I’ve got to figure out how to bypass the hydraulics in the tappets to get some accurate valve to piston measurements.

midget,

Stop whining.  Even Cosworth runs the cams right in the cam carrier, on the aluminum.

We are not going to measure the valve to piston clearance with the cams installed.   Head with valves & light checking springs only, degree wheel on the crank.  Lots of measurements, lots of calculations.

The stroke (and possibly bore diameter) is going to be changed, so why measure the existing geometry? ? ? ?

The only thing that is important to the new build is existing valve clearance notch depth, how much lift can be tolerated at and around TDC, and how much more will be required.   This time around we are not going to be "scraping the bottom of the barrel" for compression ratio.  The 'K' is getting a domed, 4 notch piston with adequate piston dome thickness so that the piston dome can be machined to reduce the C/R to what we want, NOT what can we get.   We are not going to leave this to "check later" or "see how it works out".    This is going to be "built in".    It's called planning ahead.    Or the term I like: "Engineering".    Verstehen sie?
 
Masterpoboy

P.S. 75mm bore x 56.5mm stroke = 998.4cc's   Vs   original 75mm bore x original 79mm stroke = 1396cc's   OR  whatever.   We get to decide.

[Milwaukee Midget]

R-E-L-A-X. . . .

Wow - large Packer-green fonts.

Geez, buddy, guess I'd better grab some Octoberfest and make a drive across the Cheddar Curtain.   

[lsrjunkie]

Chris, no reason for concern on where the cam rides in the cylinder head. Being in the automotive repair business, I can't recall seeing an overhead cam engine where the camshaft doesn't ride directly on the aluminum of the head. IMHO the only down side to your head is the headache of valve adjustment. Just be glad they didn't design it with a rocker arm that lives below the cam ie; Ford 5.4 and 4.6 V8s, as well as the Dodge 4.7 V8. I'm sure there's many more... Just seems like too many moving parts to me.

[Milwaukee Midget]

Chris, no reason for concern on where the cam rides in the cylinder head. Being in the automotive repair business, I can't recall seeing an overhead cam engine where the camshaft doesn't ride directly on the aluminum of the head. IMHO the only down side to your head is the headache of valve adjustment. Just be glad they didn't design it with a rocker arm that lives below the cam ie; Ford 5.4 and 4.6 V8s, as well as the Dodge 4.7 V8. I'm sure there's many more... Just seems like too many moving parts to me.

Thanks, lsrjunkie.

I've never had an OHC head apart, so I really didn't know what to expect.

I will continue to post my observations and the questions they raise - despite Fordboy's admonition to stop whining and relax.  I'm not afraid to share my ignorance, because what I've found is that by doing so, I'm often asking the questions others are wondering about, but don't have a forum to express, or sometimes are too embarrassed to ask.

Philosophically, I'm still a student - a status I intend to maintain.  I don't want to necessarily become an expert, but I do want to have a solid understanding of what's going on.

I guess I shouldn't be surprised by the construction.  On early versions of the A-series BMC, there was no cam bearing on the back cam journal - it just spun in the cast iron bore, centered by the oil pump drive.  Granted, it was right by the oil pump, and plenty of oil was provided to prevent a seize-up, but as I look at the oil passages on the cam ladder on the Kettle, I'm seeing lots of flow available.

And seeing as a lot of bearings are aluminum alloy these days, it's not unreasonable to expect that a traditional bearing surface wouldn't be required.

This is what happens when you jump from 1940's technology to 1990's technology - things change, and one is enlightened and/or surprised. 

[RichFox]

My V4 engines all have the cam running in the iron bore. 88 years old and still doing OK. So it makes me wounder if cam bearings ever were necessary.

[Buickguy3]

  Rich,
   I've wondered the same thing. If you never lose the "oil wedge" there should be little or no wear.
   Doug 

[Jack Gifford]

... a lot of bearings are aluminum alloy these days...

Umm... I guess "these days" means the last half-century? GM high-performance bearing (Moraine M-400) overlays were mostly aluminum; first available about 1960.

[Milwaukee Midget]

... a lot of bearings are aluminum alloy these days...

Umm... I guess "these days" means the last half-century? GM high-performance bearing (Moraine M-400) overlays were mostly aluminum; first available about 1960.

Jack, I'm an old soul in a lot of ways.