An interesting & Funny Story

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Scott Kneisel
Posts: 464
Joined: Mon Mar 24, 2008 7:48 pm
Vintage Karting items owned: '63 Rupp Grand Prix, 66 Rupp Chappy, Mc6's, Mc8, Mc10's, Mc20's
Lotsa' other Macs
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Location: Farmington, NY

An interesting & Funny Story

Post by Scott Kneisel » Fri May 08, 2015 1:54 pm

A funny story…..
So this winter I built this fully modified Mc8 intended to run in sportsman rear this season. I mounted it up last week on my ’63 Grand Prix and started her up and did some initial tuning on the block. Figured I was ready so I shut down until Wednesday. Went to Avon for a vintage practice day with three other vintage karters in the area.

Unloaded my stuff and at 11:00 (When we can start the engines) I suited up, fueled up, oiled the clutch and chain and started it on the block. It kicked back a bit but fired up right away. Seemed a little sluggish but I figured it was just cold. I took the kart off the block, got in and hit the gas!!

Funny thing is that instead of racing ahead, it raced backwards right into my block and starter. I was a little shocked at first and it didn’t really register in my brain that the engine was actually running backwards. I always thought that was impossible for a Mac but no longer!!

You see I installed a PVL ignition system which fires off the flywheel magnets so it will apparently generate a spark in either direction. I am sure the timing was off a bit and that was why it was sluggish.
Must be during that kick back it started in reverse. I restarted it and it was fine for the rest of the day.

So this opens up a new realm of possibilities for Left and right McCullochs.
Just thought I would share that.

Gene Luzader
Posts: 62
Joined: Fri Jun 15, 2007 6:04 pm
Vintage Karting items owned: 1963 Simplex Challenger Twin West Bend 820's
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Location: Monroeville, PA

Re: An interesting & Funny Story

Post by Gene Luzader » Fri May 08, 2015 3:04 pm

Scott
That happened to me with one of my WB 820s but it only
ran real slow backwards.
Gene Luzader

REAR
Posts: 946
Joined: Sat Jun 16, 2007 10:19 am

Re: An interesting & Funny Story

Post by REAR » Sat May 09, 2015 6:52 am

Scott,

How did it run once you figured out which way was what, any better then a oem coil ?

R.E.A.R.

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Scott Kneisel
Posts: 464
Joined: Mon Mar 24, 2008 7:48 pm
Vintage Karting items owned: '63 Rupp Grand Prix, 66 Rupp Chappy, Mc6's, Mc8, Mc10's, Mc20's
Lotsa' other Macs
User Agreement: Yes
Location: Farmington, NY

Re: An interesting & Funny Story

Post by Scott Kneisel » Sat May 09, 2015 2:34 pm

In the correct direction it definitely feels pretty hot, good low and high end so I think I got the porting just right on this one for a variety of tracks. I have a bench fixture (calibrated engine) where I can spin it and measure the dynamic timing. The PVL ignition fires at 30 BTDC with a standard mac flywheel, 35 BTDC or so with a 5 degree flywheel. This engine sports a standard uncut flywheel and Mc6 high compression head with 0.015" crush. Running on 93 octane gas/mix it had no pre-ignition and peaked out at 312 degrees after many hot laps. I am going to put on the alky carb, a cut 5 degree flywheel and run it on Alky next time and see how it feels. Will test it out at Cuddyback at the end of the month.

I have also been experimenting with some Phelon ignition modules on a Mac lamination. They fire at 35 degrees with a standard flywheel and 40 degrees with a 5 degree. I have not track tested them yet but have it on a good source (PND) that the spark trails off on those after 12K RPM but I still want to try them since I bought 10 of those little beauties :-)

Anyway I am having fun doing this. The down side of the electronic ignition is that there is no maverick spark effect but firing at 35-35 degrees is what you get with maverick anyway. The advance timing didn't seem to hurt the low end on this engine, even with a 5K dry clutch.

Ernie Shores
Posts: 47
Joined: Fri Jun 15, 2007 7:42 pm
Vintage Karting items owned: Lots of Fox Karts!!!
Location: Ft Walton Bch. Fla

Re: An interesting & Funny Story

Post by Ernie Shores » Sun May 10, 2015 7:36 am

Scott:
It seems like you have started a trend to get more karters interested in running the Sportsman Rear class with the your forward thinking modifications on the older Mac engines. Keep coming up with new ides to make them run and survive.

You have built me some great running large block saw engines which I enjoy running. They are like the energizer bunny, they just keep going and get better with each run. I'll be running them at Newcastle and we should have a good diverse class of engines running.

Ernie

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