I just spent most of the day messing with the single and two barrel versions, with some interesting results.
First, the single barrel:

Exhaust timing duration- 130
Intake timing duration- 130

Completely stock-
Easy hand starts
7300 on APC 16x10
2000 idle

APC 16x8-
7300 (?)
2000 idle

MA 13x6
9200
2200 idle

Echo GT carb block and WA-167 carb-
Starting ok
7400 on APC 16x8
2200 idle
Poor transition

Stock + widen exhaust port
No change

Stock+ exhaust to 140
No change

Stock+ .005 cylinder gasket replaced original .020 (exhaust back to 130)
7500 (16x8)
6200 on Pro Zinger 20x6 (!)
Starts excellent
1800 idle

Two barrel:

Completely stock-
Easy hand starts
7600 on APC 16x8
1900 idle
Great transition

This engine seems to be (port) timed to make power around 7000. My plans include trying to find the bottleneck...



I checked the ignition timing, as the magnet position indicated it should be firing about 30 degrees after TDC!

WE HAVE AN AUTO ADVANCE MAGNETO!
Apparently, the coil picks up the impulse very early, like 330 degrees early.
It then delays the spark, depending on engine speed. Awesome!
Here's what I got:
At 2000 RPM, it fires at 20 BTDC.
As RPM increases the timing advances smoothly and proportionally, to 30 BTDC at 7400!!!

The stock carb is amazing too. Although there are no means to adjust mixture, it did well with 13x6 thru 20x6 props!

More to come...


Joe Petro