Another vintage project from Great Britain, target Speed Week 2011

[thefrenchowl]

Hi, 38flattie or Jeff,

I'm as far as you can get from being an engineer...

While I understand fully the concept of overlap and its effects on normally aspirated engines, I've got some difficulties grasping LSA... What are the effects of various LSA on the same engine???

Lars, I had a better look at the AMR500 today, needed to do all the drawings for the mounting brackets... I think I will leave it as is and do not wish to split it. As you mentionned, small differences in the ball bearings and they are not in my otherwise complete SKF catalogue... So I will spin it reverse...

The one on the driver lobe is 17 x 52 X ? probably 15 wide, while the one on the driven lobe is 16 x 47 x ? probably 12 wide... Oddest sizes I've seen in a while, last time I experienced anything like that was on a Swiss Motosacoche D 50 OHV race engine from the 30s!!!

So I've drawn a main bracket that will fix it directly onto the cast steel rear engine mount, it's got 4 bolts on top of the gear box, plus a straightener on the other side where I will locate an iddler/tensioner as on yours. So I will not need to mod the frame for that purpose...

So quite a few bits to machine in the near future, so long,

All the best from Patrick

[38flattie]

Patrick, I'm far from an expert myself! I've done a lot of research, simply because there is virtually no info on the blown Cadillac flathead I'm building. Here is the simplest answer I've found:

The LSA is the mumber of degrees between intake and exhaust lobe centerlines. The LSA can be fine tuned.. By narrowing the LSA, you can increase Cylinder pressure and higher rpm potential by allowing the intake to close earlier and the exhaust to open later. This increases the amount of time that the piston has to travel before exhausting, but may increase the potential for detonation..
Widening the LSA can be tuned to decrease the chance of detonation and improve low end and idle quality..

The duration of the cam must be adjusted for any major rpm range changes..

Decreasing lobe separation:
1. narrows the powerband
2. moves the powerband lower
3. makes the idle choppier
4. makes more power
5. pumps up the midrange

Increasing lobe separation
1. widens powerband
2. makes the idle smoother
3. takes away from the midrange
4. produces less maximum power

Racers usually use tight lobe separations. The only exceptions are Pro-Stock, where 500+ ci are revved to the moon with cams so HUGE, tight LSA's produce too much overlap, and nitrous/blower/turbo applications where overlap sends all that extra fuel mixture out the tailpipe! You may experience this, and may want a wider LSA because of it.

Tight lobe separations increase overlap and can help increase velocity in overly huge intake ports. This will pump up the midrange, and make the engine feel less "lazy". Some 351C drag race cams have lobe separations as low as 102-104 degrees. Automatics generally need a tighter lobe separation for extra midrange.

Small engines with big ports LOVE tight lobe separations, large engines with small ports work better with wider angles between the lobes.

A tighter lobe separation also allows you to use a slightly larger cam in a lower rpm range. If you want maximum valve timing without revving the engine to the moon, a tighter lobe separation can make it happen

Panic is far more technical than I am, and can probably give some good advice here. I'm curious to hear his answer.

In addition, there is a LOT of experience on this board. I'm sure you'll receive some advice based on experience, rather than theory. I'd take the actual, over the theoretical experience, every time!

Good luck on this!

[thefrenchowl]

 Hi, 38flattie,

Thanks for the interest and answers!!!

As I want to bring all the bits to my machinist next Friday, I'll have to pull the empty engine of the frame one of these next evenings after work, if I find the energy!!!

I will then record the std valve timing and do the graphs, degrees vs lift.

One thing I've always been curious at, the tappets are not at all in line with the cams, sort like an offset cylinder to crank shaft, which is found a lot on old european vintage engines, Guzzi and Motosacoche come to mind...

This must surely skew up the actual cam timing when it translates into valve motion and make it even more assymetrical than on the cams (these roller tappets KHK cams have the opening lobe convex for higher acceleration while the closing ramp is normal, concave for smoother desceleration, with quite a long "full opening" in the middle, might be tricky to find the centre of the lobe, I'm pretty sure it won't be as expected in the middle of the cam timing!!!)

Patrick

[panic]

All H-D (well, 1929-1999?) have the tappet center advanced vs. the cam base circle etc. by about 1/8" to be under the rising lobe, which reduces side thrust. Yes, the accel and decel rates are different, and the max lift point isn't centered in the duration, which makes the nominal CLs and LSA academic as to actual function.
They're still useful to compare among cams for the same engine (but not other engines) since the same type of asymmetry exists in all.

[thefrenchowl]

Hi All,

Been a bit busy yesterday evening! Did have this degree wheel for about 5 years but never made an adapter for it!!!

So, all installed, find TDC, old reliable method, screw inside cylinder, rotate one way, then the other and TDC is in the middle...



Then got on with the magnetic base and dial...



Results, with 5 thou tappet clearance on both valves, front cylinder, I might do the rear tonight!!!:

Exhaust opens 52 deg before BDC
Exhaust closes 47 deg after TDC
Max lift .379
Duration 52 + 180 + 47 = 279 deg
Max lift at 85 deg after BDC, 3 deg off centre

Inlet opens 28 deg before TDC
Inlet closes 71 deg after BDC
Max lift .373
Duration 28 + 180 + 71 = 279 deg
Max lift at 70 deg before BDC, 2 deg off centre

Max overlap is at about 20 deg after TDC

Std KHK graph (never done that before on a spreadsheet, took a while to get the wanted display...)



Moded the data on the graph to get the idea, 20 deg advance on the exhaust cam (not the 25 deg from the 28 teeth gears, will actually advance the exhaust cams later to measure for real!!!)



All the best from tired Patrick!!! Was still thinking about all this at 3 am...

[38flattie]

Outstanding! And very little overlap to boot!

I always thought these had a tremendous amount of overlap, so I'm surprised!

Having owned a Harley continuously since I graduated high school in 1981, sometimes as many as 6 at a time, this build really intrigues me. Add to the fact that the FlatCad is running custom heads designed by us, with a modified KR chamber, and I'm really intrigued. I've owned Knuckles, Pans, Shovels, and Twins, and always replaced the cams with Leineweber performance cams. Out of curiosity, I contacted them about your build.

And yes, in the contact I said 'I'm" building it, but it doesn't change the info!

I  hope this info is somehow helpful!



    I have a 1954 KHK, that I'm putting a AMR 500 lobe supercharger on, and plan to
    run methonal. I believe the cams are high lift cams, .375. I would like to get
    the cams worked to get the most power out of the setup I can. I think it may
    have too much overlap for the blower? What can you do for me, and what is the
    cost?




Dear Buddy,

Mr. Leineweber has the following comments:

The cams you have are low overlap cams for racing flatheads.  You probably do
not have too much overlap, and it will probably run pretty good with the set up
you have.

He suggests you put the bike together with the components you have, run it and
then call him and talk to him about your results and what you would like to
change.  He also needs to know what boost and carbueration you are running?

He can be reached most mornings 8-9 am at 760-364-4432.

Warmest regards,
Norma Wheeler for Jim Leineweber


Patrick, I hope I didn't step on any toes here! I just really loves builds like yours and Lars's (Octane)!

[thefrenchowl]

Thanks, 38flattie!!!

I'll have to put your name on the seat cowl as adviser supremo!!!

Std overlap is 75 degrees which is not low by any standard!!!

If I advance the exhaust cams one tooth, 25.7 degrees on the crank, overlap will reduce to 49.3 degrees and sort of center it more around TDC which is more "normal" in me eyes, peak will be about 5 deg after TDC, me thinks I'll stick to that for the moment.

Maybe the std overlap peak being so far after TDC is due to long stroke and rods, I can't believe the piston "inaction" at the top of the bore, it's really left to the exhaust gases to draw the 1st bit of the mix in...

I also measured the piston pop up. The piston sticks .060 above the deck while the head recess is .120, so .060 of squish. Don't know where, I can't remember reading it in the KR booklets, but the factory was looking at .030 to .040 squish, will probably ask my machinist to skim a bit off my cylinder bases to get that .040 figure.

I have another Excell sheet with supercharger calcs, I put a link since it's a bit big...

http://www.harleykrxlrtt.com/images/supcalcs.jpg

The yellow line is the max "safe" setting!!! (now, where did I hear that before??!!!)

Carb will be the moded 1"7/8 MGAL S&S I've shown earlier in photo...

By for now, Patrick

[38flattie]

Just a few thought's here, not that they amount to much.

I see you're 'safe' limit is 12lbs boost @12356 supercharger rpm's, so you're 'over spinning' the supercharger.

Could you mill the heads to up the compression, use the head gasket thickness to insure the .040" squish area, and drop to  11lbs boost @ 11893 rpms, keepng the supercharger within factory recommended rpm's?

[thefrenchowl]

Hi, 38flattie

The ARM 12000 rpm limit is for cars, while sucking pure air, getting hot and such, as gas is injected after in the plenum runners. They do say you can run them faster "for a while".

I'll haver the carb before the AMR, hence vaporizing plenty of methanol, that should cool the AMR plenty!!!

No head gasket on any K, KR and KH, just silver paint on both faces, let dry till just sticky and assemble. That ensure the squish is consistent I suppose...

Patrick

[38flattie]

Ah, very good!

[thefrenchowl]

Hi all,

Had a bit of a cold recently, so not much progress, again...

Still, took 1/2 a day of work to bring most of the engine to the machine shop, B&E Engineering in Crewe. I'v' been using their skills for the last 20 years when they were just 2 partners in a cramped unit, Eric and Brian... Eric retired last year so there's just Brian now, with about 10 employees these days in much bigger premises. That's Brian:



And you can see now what I look like!!!:



So, plenty of bits on the table!!!







And a long list of drawings and notes to get the following done:

Dual plug the heads
Mods to right hand side case and timing cover for iddler gear and front magneto fitting
Skim cylinder bases to get the squish band to 40 thou, it's about 60 thou at present
Make supercharger drive and support brackets, plus inlet and outlet flanges for carb and plenum chamber connections, and last, new belt pulley
Make supercharger drive seal and bearing holder, to be welded on primary cover, but I have not yet decided if I'm using the tin cover or the cast alloy K one...

Don't know how fast I can get the bits back, so, for now, that's all, folks!!!

Patrick

[thefrenchowl]

Hi All,

Another Friday, another visit to my fav machinist and quite a few bits done.

Front magneto and iddler installed but I forgot to take photos, most of the seance was talking about the supercharger drive!!! Decided to use the tin cover and fit no bearing on the drive shaft, just a seal...

Moded crank sprocket with refaced inner and drive rollers:



1/2 finished (way too long!) drive shaft:



Assembly:



See you all soon,

Patrick

[thefrenchowl]

duplicate...

[thefrenchowl]

Hi All,

I was a bit busy today, trip to Walesby in the Nottingham Forest (Robin Hood...) to check rally site and a committee meeting of our national Harley-Davidson Riders Club of G.B., but managed to go and see Brain 1st thing to check progress... The man has been real busy, I'm in debt!!! With any luck, the engine will be back in the garage within 2 weeks so the rest of the built can progress further...

Front magneto is all done, iddler an'all, it follows the lines of the KR/XLR/XR layout but not quite, just a bit simpler and did not require mods to the timing cover:





The supercharger bracket is also finished, it sandwitches between the body and its gear cover and bolts on the rear engine mount, totally independant of the frame:









The supercharger drive is also finished, alloy seal holder with a little back plate inside the tin cover to bolt on, I will just have to trim it a bit on the rear to be able to fit the std tin oil filler cover:



The O ring seal/clamp pieces for the end of the plenum chamber are well on their way:



Brian also found the time to do 2 flanges to mate the carb manifold and the plenum chamber to the supercharger:



And, last but not least, the heads are now dual plugged!!!:





Plenum chamber will be made out of 2"1/2 stainless steel thin wall tubing, just need to source a wide 90 degree bend...

So quite a busy week really!!!

All the best from Patrick

[panic]

Excellent!
How much are you going to shorten the spark setting (original is 36°?)?
Given any thought to what effect (if any) the blower will have on convection air around the rear cylinder?