KG4 RPM limit of Points? Or different cam lobe profile?

[mikesea]

Hi Guy’s
Anyone run our point assembly on a distributor machine or live testing to find out what rpm the points sign off? Seems the only cam lobe not listed is for the H20. This leads me to believe the H20 might have a better cam lobe profile extending the rpm limit @ the same point spring tension. Also which points are the ones to buy? Better condensers?
Always thanks,
Mike

[mikesea]

Anyone have a H20 apart please look at the point cam lobe and see if it has a identifying number. A picture would be good too. I would think it has a longer closing ramp to set the point down gently so it does not bounce. I like the stop they built onto the point so if it was over revved the point could return sooner than later without the stop. Just great USA engineering best materials and thinkers.
Updated Iron Ore 11.02.2017
After 1963 the change in Iron Ore for making steel in the USA took the first step down hill. This lower grade Iron Ore had to be refined 2-3 times to be as good as Pre-1963. The next down grade of the Iron Ore I forget the year maybe be 1969 it had to be refined 7 times to be as good as pre-1963 Iron Ore that is what finished us off as biggest supplier.
Sorry got off track.
Mike

[foot_doctor]

What model is H20? If you mean MK20H, the cam is an integral part of the crankshaft, and exhibits a gradual closing ramp. It shares this configuration with the MK25 Mercury crankshaft. I can assure you that at 7000 plus RPM at racing trim, the Phelon Mag. was up to the task. When I had my mag testing machine, we commonly tested those mags at 8000 plus RPM with no discernable points float. R.T.

[Pete]

Did you happen to measure the movable arm point spring force when opened to point gap on the 20H and MK25?

[foot_doctor]

The only tool we had at the time for measuing the spring force was meant for use on the 4 cyl. mags, and the direction of rotation was counter to that of the 4 cyl. mags. Since then I have obtained a different style of gauge that can measure either style. However, I always formed the springs on the Phelon points to exhibit the most cosed-points pressure, and saturated the lube felt with pure bees wax in order to limit camfollower wear. Unlike the Bendix-Scintilla mags that worked best with .009" point gap, the Phelons worked best with .018 to 020" gap. Just like the book says. R.T.

[Pete]

quote foot_doctor:

The only tool we had at the time for measuing the spring force …………………. However, I always formed the springs on the Phelon points to exhibit the most cosed-points pressure …………………….. R.T.

So you hand bent the spring on the movable point arm for more force, and no tool to judge amount just experience ❓

[foot_doctor]

YUP! R.T.

[mikesea]

R.T. Thanks for your learned information, just what I thought about the cam lobe ramp shape. As a newbie to outboards. For years I too had a Sun Dist machine fun times 50 years ago. I also mounted a Sun scope with a row of adjustable air gaps to tune Vertex mags using plug customers cap, rotor and wires. Checking the Big picture I am really enjoying this forum and will help with what I have learned over my life time but learning about the outboards. Wish I could setup a Dyno for my KG4 & KF7 or KE7 Lighting I forgot E or F already LOL have to go look I am old now Ha
Mike

[foot_doctor]

My Mag machine had the ability to test 4 and 2 cylinder magnetos. It was capable of spinning the mag at 10,00 RPM, but none of the mags we used at that time functioned at that speed. The motive power was supplied by a 3/4 hp DC motor and a variable output DC power supply. The energy required to spin the mag was displayed on an ammeter. Some required more energy than others at the same RPM. The High voltage outputs were coupled to a set of spark plugs with .040" gaps that were in a sealed chamber that had a window that allowed the sparks to be observed. The chamber housing the spark plugs had a pressure regulated air supply that was varied between 0 and 130 PSI. The mags that produced the most consistant output at the highest pressure, RPM and lowest motor amperage were the ones we selected for racing. Mercury and Fairbanks Morse 4 cylinder mags create sparks with alternate polarity. Two positive, two negative per revolution. The strongest positive sparks were needed as the negative sparks more easily passed from the heated center spark plug electode in a running engine. The 2 cylinder Phelon mags created negative sparks, and when we reversed the polarity of the aluminum rotor Bendix Scintilla rotors those magnetos actually outperformed the Phelons. They did require .009" point gap as opposed to the suggested .018’". All of my best "A" motors sported Bendix Scintilla mags with the thin and light racing flywheel. R.T.

[mikesea]

Nice, I remember a machine that that would allow psi to plugs in a sealed section. I liked the amp reading required to turn the mag.R.T. are you the foot specialist that people have mentioned? If so Its a pleasure to meet you. I would love to talk sometime as being retired I have time to BS and continue my learning. I love to learn about everything we can use on or in our engines. I have had access to steels, coatings, oils, heat treat, Cryo treat and vibrate table. Along with what people find on the Dyno vs. real world in the water, water system mods and the combustion space process. Have done a lot of A-B-A testing in my first 25 years. Later much better documented testing that proved or dis proved what I was thinking.

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