Merc 20H CD ignition

[Mike 41P]

This is an update from the thread I started exactly one year ago. I have adapted the Sidewinder type OMC ignition to my 20H and I am very happy with it. I ran it at Crystal Lake and many 20H'ers saw it and I think everyone felt it was an OK thing to do, a way to make the ignition reliable so our old motors can go on for lots more years.

The key item is the cast steel flywheel which is the 9.9/15 HP brother to the 6/8 HP wheel used by Ed Runne for the Sidewinder. My flywheel was prepared by Fast Rods (Cooper Jess). The flywheel weight meets the old 20H spec. The other thing is a simple adapter ring to mount the stator, just as we do now for our Hot Rods.

This is legal for 350 and 400 Mod, but not for 250 Mod or Stock Classic current rules. I have shown it to Jeff Williams, Tom Sutherland and Jeff Brewster and they all are open to the idea of accepting this change if the rest of stock and mod commissioners agree. If you support this idea please tell your stock and mod commissioner you want them to vote yes on a proposal for this at the next national meeting.

I will give the commissions the details of the conversion and when it is approved I will publish it here. Maybe either Fast Rods or Sidewinder could do a conversion kit.

[DeanFHobart]

Mike 41-P,

Very nice.

[bh/]

-to the same end, this M20 'cottage racer' powerhead was converted to 12v battery ignition from the troublesome Bendix-Scintilla. Simply throw out the coils , re-wire the points,
install 2 small external coils, and a 12v drill battery. He says he picked up revs.
With 12v on board, Hall-Effect triggers could replace the points.
What would APBA say,
Just don't tell them.
Pics from Old Mercs site .

[rumleyfips]

Christner said that the magneto and rings cost 8 %. It takes horsepower to generate electricity no matter how you do it.
Look at lawn tractor pulling for crank trigger impulses : both optical and proximity are available.
Inductive systems produce a longer duration spark than CD's do, sort of a poor man's multiple spark.
Want more spark voltage ; use a 14 volt drill battery.

[Mike 41P]

My thread a year ago brought up several possibilities like this but I used this OMC system for several reasons.

1. I want to use a system that is familiar and readily available to racers. This system is used on the OMC A's, Hot Rod's and Sidewinder's and many OMC 400 MODS. APBA and CBF still view the 20H as a 'stock' motor and this ignition update is to a current 'stock OEM' system that anyone can get. This is what will probably make this OK for APBA and CBF.

2. I want to keep my 20H in a configuration that I feel is true to its roots, which I think this does.

3. I am not looking for any performance advantage, however small or large that might be. Back to number 1, this is a 'stock' system equivalent to but more reliable than the original.

Also, no way does a magneto draw 8% of the engine power to create the spark. Yes the spark does get its power from the engine. I have no idea what fraction of the engine's power is taken by the drag the coils put on the flywheel. My guess is that it is more like 0.08%.

If one wants a wide open field to try any of these other ideas, in APBA we can do that in 350 or 400 Mod. The 20H is in both and in those classes you can use ANY ignition system that you can dream up. As I said at the start I am looking here for a reliability update for APBA 250 MOD and B CLASSIC. And hopefully also CBF.

[dwhitford]

Considering the unavailability of replacement Phelon parts for 20H (and other Merc-engine magnetos) and the high price of so-called equivalent replacement parts from overseas, I, as a Merc engine restorer applaud Mike's innovation. If such innovation can keep some 60+ year-old engines running well, especially if ''under the covers'' for restorations, Mike's innovation is a good thing.

I hope the S.O.R.C and other rules-making parts of APBA see my point of view the same way. If we're going to still keep running such old engines in the Stock and Mod categories, we need some rules bending to facilitate the process.

By the way, replacement magneto parts for Bendix-Scintilla (KE-7, KF-7, & KG-7) are even pricier or more unavailable. The Scintilla coils are notorious for cracking their outer hulls beyond repair with age, even in good storage conditions! I've tried repairing some of these with both epoxy and silicon sealant without success.

Bravo to Mike!

[rumleyfips]

Christners 8% parasitic drag included the rings. I have seen 3% elsewhere but can't remember where.

[madstork]

Mike,

Nice job. I have seen your stuff at the races and it is all first class. I look forward to seeing your 20H at Franklin next year.
I am building a KG-7 for a cottage racer and wondering if this set up could replace the old scintilla mag.

Again, Nice !!!

Sincerely,

Doug Follett 87-P

[Mike 41P]

2016 update --- the conversion was accepted by the Mod Commission, it is now waiting for 250Mod racers to vote
Please vote yes if you are in 250Mod
If you are 100% on top of your Phelon ignition you do not need this
But if you have one of those that stutters and hick-ups or just plain won't start this may be good for you
Ed Runne is the sole approved machinist for the flywheel work.
If this passes I will start a new thread with all details
Mike T

[skip baker]

Mike Is the ignition from a 9.9 and 15 and what years can we use? Thanks Skip

[Mrs blueskyracer]

bump for those who couldn't find it!

[STEVE FRENCH]

BUMP !

[Mike 41P]

There is a different later post in here somewhere that has the drawings and instructions

[25xs]

There is a different later post in here somewhere that has the drawings and instructions

Right here: https://hydroracer.net/forums/forum/m...ion-conversion

[STEVE FRENCH]

Mag adapter Availability ?