1962 McCulloch Kart Racing Fuel Data ..............

1962 McCULLOCH KART RACING
modification info sheet

Fuel Data.

1. Boiling Point

A. Methanol 149 F
B. Propolene Oxide 80 F
C. Nitomethane 214 F

2. Nitromethane; Slow burning ( slower than methanol ).

Methanol; Slow burning; requires starting, lighting, and stabilizing
factions for best results.

3. Nitromethane is concidered a " thermalcharger" fuel. It's chemical
formula is CH3NO2, and it is approximately 50% oxygen by weight. In
burning, the NO2 group splits and the two oxygen atoms are released for
combustion.

4. Air / Fuel ratio - for combustible mixture - is narrower than for gasoline.

A. Methanol requires approximately twice the volume of gasoline.
B. Nitromethane requires approximately 1/3 again as much as methanol.

5, Cold plugs are definate requirements. Start with HO-3, and watch tips
carefully. Pre-ignition will come on fast if plug is too hot. Do not overlook
racing or side electrode plugs.

Racing fuels release more heat - thru power - than does gasoline. To avoid
pre-ignition, polish head ( internally ) to remove sharp edges, ridges, etc.

Acetone is excellent for cleaning oily plugs.

6. Ignition; Start with 25 degree's BTDC, But watch for detonation and pre-ignition.

A. Mavrick spark advance will advance firing point by six to eight degree's.
A1. If necessary slot laminations and move assembly to control maximum Mavrick advance.
A2. If detonation is present at low RPM, retard spark 2 to 3 degrees for low end operation.
Pick up maximum possible maverick advance - short of detonation - by retaing lamination position, or by advancing 2 to 3 degrees,
A3. If cutout switch is not used, set point spring minimum tension to bring mavrick spark at lower RPM range.

7. Mixing ; Nitro blends may be mixed and stored without deterioration. Moisture,
from condensation, if not excessive, will frequently improve performance.

A. Do not exceed 15% nitromethane for McCulloch engines, except at own risk.
Recommend starting with a 105 nitro mix, and work up.

8. Storing; Nitromethane blends are corrovise.
A. Carburetor and engine must be flushed after running, using gasolene base
fuel mixture. Run at least a quart through the engine.
B. Do not store nitro blends in metal containers. Glass or grock-type
containers must be used, as corrovise action will eat out metal
comtainers.

Page 2.

9. Handling; Use normal caution when handling nitromethane and methanol. They
are not explosive; Nitro burns slowly, with luminous flame.
Methanol burns with invisible flame.
A. For user protection
A1. Wear goggles (glass( when mixing fuel blends.
A2. If racing, flameproof clothing is recommended, ( With methanol you can be on fire and you won't know it until your clothing chars or it starts to hurt, By then it's too late !
Flameproof coveralls are the simplest answer.
A3. Generally, nitro and methanol are not harmful to the skin.
( Some, however, will be allergic to fuels.)

Propolene oxide does, and will harm (burn) the skin. Wear good,
solid non-absorbent gloves, of the gauntlet type when handling.

10. Compression Ratio;
A. Little is gained with fuel if stock compression is used.
B. Recommended ratio's are;
9-1 ..... 10-1 .... 11-1 ...... 12-1.
Do not exceed 12-1, except at risk of engine separation.

11. Exotic fuels have solvent action on seals and gaskets and most plastics.
Service life of such components will be considerably reduced and only answer
is to replace as neccessary.

12. Other fuel additives
A. Benzol - A high octane ( 108 approx. ) hot - burning petroleum product.
Although benzol will auto-ignite, it serves as a coolant when added to the
fuel mixture ( 10% by volume).

B. Ether - A highly questionable racing fuel. Although generally used as an
igniter, it serves best - if used - as a starter fraction.

C. Acetone - Used generally as an igniter to boost top and RPM and
acceleration. Has strong solvent action on plastics.
Acetone is also used as a blend stabilizer, plus a water tolerance
booster ( methanol blends, with 1% to 3% of distilled water added to
mixture).

13. Fuel Blends ( Sample base)
A. Mild blend
Methanol 70% ( main power base)
Benzol     10% ( coolant and extender)
Gasoline 10% (starter)
Castor Oil 10% ( lubricant)

B. Medium Blend
Methanol 70% ( main power base)
Acetone   5% ( igniter)
Gasoline 5% ( starter )
Benzol 10% ( coolant )
Castor Oil 10% ( lubricant)

C. Hot Blend ( can be very wild )
Methanol 55% ( main power base)
Nitro methane 15% ( power additive)
Acetone 5% ( igniter)
Gasoline 5% ( starter)
Benzol 10% ( coolant )
Castor Oil 10% ( lubricant )

Page 3

14. Other fuel formulas

The following are fuel formulas which have been in existence for years, in
fact, some date back to pre-WW1.

A. Methanol 75% castor oil - 10:1
Ether            10%
Water           15%

B, Acetone 35% Castor oil - 10:1
Methanol     35%
Ethyl Acetate   5%
Gasoline        35%

C. Ethyl-methyl
Ketone          35%
Methanol       25%
Ethyl acetate   5%
Gasoline        35%
Castor oil 10-1

D. Diethyl Ketone 35% castor oil - 10-1
Methanol               25%
Ethyl Acetate           5%
Gasoline                35%

E. Methanol 99% castor oil - 10-1
Benzol      0.75%
Nitrone Ether    .25%

F. Methanol   86.6%
Benzol                 5%
Acetone              8%
Sulfuric Ether     .4%
Castor Oil - 10-1 ratio

15. Carburetor and modification.

A. The high latent heat of methanol, plus the very low air/fuel ratio
( 4-1 to 6-1 on track, versus 12-1 to 16-1 for gasoline), results in
a high internal cooling action with a heavy induced air/fuel charge.

B. The average carburater calibrated for metering gasoline will not pass
an adequate volume of methanol. Therfore, carburator modification modification
is required if methanol is to be used.

C. As a rule-of-thumb, the opening of a given passage or jet to a diameter
50% greater than that required for gasoline will suffice, However, under
some conditions of engine modification it will be necessary to calibrate
the carbuator for the individual installation.

D. McCulloch Carburator
P/N 48811 and P/N 48890
Note : See sketch "A" and Sketch "B" for reference.

D1. Enlarge main nozzle (A) TO .0995 inch
D2. Enlarge main pick-off orifice (B) to .085 inch
D3. Enlarge idle pick-off orific (C) to .052 inch.
D4. Enlarge idle adjusting orifice (D) to .052 inch
D5. Enlarge transition orifice (E) in idle cluster to .045 inch.
D6. Thoroughly clean carbuetor body, making certain that all
passages are free of chips and or dirt.

Page 4.

D7. Enlarge fuel pump inlet passage to .152 inch diameter.
( see sketch "B)

D8. I nstall new screen ( capillary seal, P/N 55690B) over main
Jet and then install a new expansion plug (P/N 104407)
over the main jet chamber.

D9. Install new expansion plug ( P/N 102758) over the idle
cluster chamber.

D10. Assemble carburator.
Note when installing needle valve and seat assembly, avoid
overtightening. If the valve body is screwed in too tightly,
the gasket (P/N 55689) may possibly upset and cause displacement
of the valve seat ( P/N 55474). This in turn will result in loss of the fulcrum
arm (P/N 55688) Setting.

D11. When installing the fuel line the use of clamps at both carburator
and tank ends of the line is strongly recommended.

D12. Open both idle and main needles 3 turns off their seats.

D13. Sqirt gasoline into the carburator throat for easy starting.

D14. The Kart should smoke excessively and four stroke under all
conditions of throttle opening .

D15.If engine leans down to a two stroke condition while running
at these mixture settings, stop it and find out why. Pump trouble
or dirty line filters may be the problem.

D16. As the engine warms up it will be found that leaning each
needle ( idle and main ) a little at a time will finally result in a
solid two stroke sound,
Further leaning will result in engine damage if carried too far.

Note A restart on a cold engine will result in four stroking
until the engine is warmed up completely.