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Miscellaneous Small Engine Repairs and Garden Tractor Pulling Tips & Tricks
(Information that don't fit in any other category.)

Inspiring Small Engine, Lawn & Garden, and Garden Pulling Tractor Enthusiasts Since 1996. Where Science and Common Sense Come Together for Safety and Improved Engine/Tractor Performance
A-1 Miller's Performance Enterprises - Parts & Services Online Catalog

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Identification and Torque Specifications for the Most Commonly Used Grades of Bolts

How To Professionally Cut New Threads

Various Drill and Tap Charts

Fractions, Numbers, Letters, Decimals and Metric Equivalents

Useful Formulas, Conversion Charts, etc.

Sheet Metal Thickness Gauges

Using a Quality-Made Pulling Hitch with an Adjustable Drawbar on a Competition Cub Cadet Garden Pulling Tractor or Small Wheel Mini-Rod [Top of Page] (Updated 9/25/21 with more clarified information.)
First of all, when a pulling association's or club's sanctioning rules state that "the tractor shall have no more than a 13" hitch height", this wording is not accurate! It should read: "The tractor shall have no more than a 13" drawbar/hitch height." The "drawbar" is a separate part that's supported by the framework on the rear of the tractor. But if the drawbar is non-adjustable and is fastened, welded to or part of the tractor/vehicle frame, then it's called the hitch, as in receiver hitch, to tow a trailer.

Anyway, if you can keep from doing so, don't use a non-adjustable, bolted-on-solid or welded-on hitch. It's not that the weld may break, but if you have to change the height height, or pull with another club that require a different hitch height, or if you were to change tire size, deflate/inflate tire pressure, change the diameter of the front tires, the hitch height can't be changed (lowered) for legality of the club's pulling rules. Therefore, with a fully adjustable drawbar, you can easily and quickly reset the drawbar height according to the club's rules. This will give your tractor a better advantage with the competition, and not be disqualified due to the hitch being too high (above 13" or whatever the club's rules allow).

To be truly competitive, always run the highest drawbar height your clubs' rules allow. But if the driver of a tractor is a large person, then lower the drawbar height to 12". Doing this will place more weight toward the front of the tractor so the driver will have better control while going down the track. And the further rearward the drawbar is located, the more weight must be placed on the front of the tractor. But if the drawbar is too close to the rear axle, it'll be hard to control the front end from rearing up and down uncontrollably at times. Therefore, the best position for the drawbar is 6-1/2" to 8" rearward from the center of the rear axle. This should allow the front of the tractor to rise gently (if the tractor is weighted correctly), which should give the driver full control of the tractor. This measurement applies to all makes and models of garden tractors and for all classes of pulling tractors, from a basic stock to a fully modified.

Information Concerning Strength and Safety of the Pulling Hitch with an Adjustable Drawbar Ê

When certain pulling club's sanctioning rules state something like, "the pulling point may not be more than 3/4 inches in depth," what they actually mean is, on the drawbar, there must be no more (and no less, for strength) than 3/4" of metal between inside rear of the hole and outside rearward edge of the drawbar.

Also, for strength and safety, and because most rules don't bother mentioning this, the drawbar itself should be made of minimum 1/2" thickness steel, and not aluminum!

But the upper and lower angle brackets should be made of either minimum 1/8" thickness mild steel or minimum 1/4" thickness 6061 aluminum.

How to Construct a Professional Pulling Hitch with an Adjustable Drawbar Ê

FYI: This entire assembly is called the HITCH. The adjustable flat bar where the hook goes is called the DRAWBAR.

This type of garden tractor pulling hitch with an adjustable drawbar is the most common and strongest ever used. It's low-cost and looks nice, too. It's the design that most professional pullers use, plus it's NQS legal. It will adapt to virtually any garden tractor as long as two pieces of angled steel can be fastened on the rear.

Specifications are:

Identification and Torque Specifications for the Most Commonly Used Grades of Bolts [Top of Page]
NOTE: Use Standard Torque Settings When Specific Values Are Not Specified. (C) = Coarse thread, (F) = Fine thread
Hardness of Bolts è No lines = Grade 3

No lines = Grade 3 bolt

 3 lines = Grade 5

3 lines = Grade 5 bolt

 6 lines = Grade 8

6 lines = Grade 8 bolt

 Stainless Steel or
Special Alloy
Stainless Steel / Special Alloy bolts
Bolt/Thread
Size
â		 Material: Low Carbon Steel. Tensile Strength: 85,000 P.S.I. (Low Strength) Material: Medium Carbon Steel, Tempered. Tensile Strength: 120,000 P.S.I. (Medium Strength) Material: Medium Carbon Alloy Steel, Quenched and Tempered. Tensile Strength: 150,000 P.S.I. (High Strength) 18-8 [304] Stainless Steel 
 1/4-20 (C)
 1/4-28 (F)
5/16-18 (C)
5/16-24 (F)
 3/8-16 (C)
 3/8-24 (F)
7/16-14 (C)
7/16-20 (F)
 1/2-13 (C)
 1/2-20 (F)
9/16-12 (C)
9/16-18 (F)
 5/8-11 (C)
 5/8-18 (F)
 3/4-10 (C)
 3/4-16 (F)

 70 in. lb./ 6 ft. lb.
 85 in. lb./ 7 ft. lb.
150 in. lb./13 ft. lb.
165 in. lb./14 ft. lb.
260 in. lb./22 ft. lb.
300 in. lb./25 ft. lb.
 35 ft. lb.
 45 ft. lb.
 50 ft. lb.
 70 ft. lb.
 75 ft. lb.
100 ft. lb.
110 ft. lb.
140 ft. lb.
150 ft. lb.
200 ft. lb.

115 in. lb./10 ft. lb.
140 in. lb./12 ft. lb.
250 in. lb./21 ft. lb.
270 in. lb./23 ft. lb.
 35 ft. lb.
 40 ft. lb.
 55 ft. lb.
 75 ft. lb.
 80 ft. lb.
105 ft. lb.
125 ft. lb.
165 ft. lb.
180 ft. lb.
230 ft. lb.
245 ft. lb.
325 ft. lb.

165 in. lb./14 ft. lb.
200 in. lb./17 ft. lb.
350 in. lb./29 ft. lb.
 30 ft. lb.
 50 ft. lb.
 60 ft. lb.
 80 ft. lb.
105 ft. lb.
115 ft. lb.
165 ft. lb.
175 ft. lb.
230 ft. lb.
260 ft. lb.
330 ft. lb.
350 ft. lb.
470 ft. lb.

 14 ft. lb.
 17 ft. lb.
 29 ft. lb.
 35 ft. lb.
 58 ft. lb.
 69 ft. lb.
 98 ft. lb.
110 ft. lb.
145 ft. lb.
160 ft. lb.
200 ft. lb.
220 ft. lb.
280 ft. lb.
310 ft. lb.
490 ft. lb.
530 ft. lb.

How To Professionally Cut New Threads [Top of Page]

IMPORTANT! New threads in a drilled hole (of the correct size) should ALWAYS be made with a (preferably new) TAPER hand tap to prevent the possibility of breaking the tap off in the hole! (This can be a nightmare, especially with an expensive and/or non-replaceable part!) Taper taps are self-aligning, cut new threads easily, much quicker and require less effort than plug taps. Then deeper threads can be made with a PLUG or BOTTOM tap. (Care should still be taken whenever cutting new threads, especially with smaller size taps.) Most hardware stores do not stock taper (or bottom) hand taps. They keep mostly plug taps in stock. Therefore, taper taps will need to be purchased online, such as eBay or Amazon. And the only threading dies with tapered threads available are for NPT pipe threads. These have a different pitch than any straight bolt threads.

For best thread cutting results, use WD-40 when cutting new threads in aluminum, and when cutting new threads in cast iron or [mild] steel, use thread cutting oil, automatic transmission fluid (ATF) or power steering fluid (which is 10 weight hydraulic oil).

  1. To professionally create new threads, start the [taper] tap perpendicular, and not crooked (over to one side), with the hole. If a taper tap is mistakenly started crooked in the hole, in most cases, it'll straighten itself out with the hole as the cutting process continues. A plug tap may not do this.
  2. For a blind hole with right-hand threads, gently rotate the tap clockwise about 1/2 turn to cut the threads, then back it off counterclockwise about 1/4 turn. This will loosen and somewhat dislodge the metal cuttings from the flutes in the tap (open spaces between the cutting teeth). If the tap is difficult to back off, DO NOT FORCE IT, especially a small tap! Instead, with the tap in the hole, use (150± psi) compressed air to clear out the majority of the metal cuttings from the hole (wear safety glasses!), then GENTLY rotate the tap counterclockwise until it rotates freely and comes out of the hole. Again, use compressed air to clear out the metal cuttings from the hole.
  3. Gently and carefully cut the remaining threads until the tap bottoms out in the [blind] hole. Repeat step #2 several times for better results with a bigger tap, and less chance of breaking off a smaller tap in the hole. Use less muscle and more patience when working with smaller taps!
  4. Use caution and be aware of the depth of a blind hole when the tap bottoms out! If it's a shallow blind hole, judge by the hole's depth to determine where the tap will bottom out.
  5. Then use a (preferably new) PLUG hand tap, and repeat the 1/2 turn clockwise and 1/4 turn counterclockwise until the new threads are cut all the way in or through the hole.
  6. Refer to the Drill and Tap Chart below to find the correct size drill bit to use for any particular hole to be threaded.

Removing a Broken-Off Bolt from a Hole - As far as removing a broken-off bolt in an engine block or cylinder head for an exhaust flange is concerned, I have never had any luck with tapered spiral-fluted screw extractors. In my experience, all they do is thread itself deep into the drilled-out broken-off bolt and expand the bolt, making it harder, if impossible, to remove. Instead, what to do is grind flat any protruding metal of the broken-off bolt/stud, then precision center-drill into the broken-off bolt/stud with a short length drill bit or a centering bit (to prevent wobbling of the bit) as a pilot hole, then bore into the bolt/stud with the appropriate size drill bit, then re-thread the hole with a TAPER hand tap of the appropriate size, and then finish re-threading it with a PLUG tap.

Removing a Broken-Off Hand Tap from a Hole - A threading tap that has broken-off in an engine block or metal casting can be very difficult to remove. A HSS annular cutter could be used because these have a hollow center hole that can cut around the broken-off tap, Use an annular cutter with the same size center hole as the [broken-off] tap. Then the [bored] hole can be welded up, drilled and new threads made. Or Google: removing broken tap from hole, or have an experienced and reputable machine shop remove the broken-off tap. [Return To Previous Paragraph or Website]

Various Drill and Tap Charts (More Listed Below) [Top of Page]

Drill and Tap Chart for Inch Sizes
To Tap These Size Threads Use This Size Drill Bit Closest Fractional or Number Size Decimal Inches
3-48 UNC #47 5/64" .0785"
3-56 UNF #45 - .0820"
4-40 UNC #43 3/32" .0890"
4-48 UNF #42 3/32" .0935"
5-40 UNC #38 - .1015"
5-44 UNF #37 - .1040"
6-32 UNC #35 7/64" .1100"
6-40 UNF #33 - .1130"
8-32 UNC #29 - .1360"
8-36 UNF #29 9/64" .1360"
10-24 UNC #25 5/32" .1495"
10-32 UNF #21 11/64" .1590"
12-24 UNC #16 11/64" .1770"
12-28 UNF #14 3/16" .1820"
1/4-20 UNC #7 13/64" .2010"
1/4-28 UNF #3 7/32" .2130"
5/16-18 UNC F 17/64" .2570"
5/16-24 UNF I - .2720"
3/8-16 UNC 5/16" 5/16" .3125"
3/8-24 UNF Q 21/64" .3320"
7/16-14 UNC U 23/64" .3680"
To Tap These Size Threads Use This Size Drill Bit Closest Fractional or Number Size Decimal Inches
7/16-20 UNF 25/64" 25/64" .3906"
1/2-13 UNC 27/64" 27/64" .4219
1/2-20 UNF 29/64" 29/64" .4531"
9/16-12 UNC 31/64" 31/64" .4844"
9/16-18 UNF 33/64" 33/64" .5156"
5/8-11 UNC 17/32" 17/32" .5312"
5/8-18 UNF 37/64" 37/64" .5781"
3/4-10 UNC 21/32" 21/32" .6562"
3/4-16 UNF 11/16" 11/16" .6875"
7/8-9 UNC 49/64" 49/64" .7656"
7/8-14 UNF 13/16" 13/16" .8125"
1-8 UNC 7/8" 7/8" .8750"
1-12 UNF 59/64" 59/64" .9219"
1-1/8-7 UNC 63/64" 63/64" .9844"
1-1/8-12 UNF 1-3/64" 1-3/64" 1.0469"
1-1/4-7 UNC 1-7/64" 1-7/64" 1.1094"
1-1/4-12 UNF 1 -11/64" 1-11/64" 1.1719"
1-3/8-6 UNC 1-7/32" 1-7/32" 1.2188"
1-3/8-12 UNF 1-19/64" 1-19/64" 1.2969"
1-1/2-6 UNC 1 -11/32" 1-11/32" 1.3438"
1-1/2-12 UNF 1-27/64" 1-27/64" 1.4219"

Drill and Tap Bit Chart for Inch, Special Inch and Metric Sizes [Top of Page]
NOTE - There's three different type of drill bits - fraction, number and letter. Actually, there's four, including metric. Use the one that's closest to the size hole that needs to be drilled.
To Tap These Size Threads Drill This Size Hole
0-80 UNF 3/64" / .0469"
1-64 UNC #53 / .0595"
1-72 UNF #53 / 1/16" / .0595"
2-56 UNC #50 / .0700"
2-64 UNF #50 / .0700"
3-48 UNC #47 / 5/64" / .0785"
3-56 UNF #45 / .0820"
4-36 NS (Special Size) #44 / .0860"
4-40 UNC #43 / 3/32" / .0890"
4-48 UNF #42 / 3/32" / .0935"
3-.060mm 2.5mm / .0984"
1/8-40 NS (Special Size) #38 / .1015"
5-40 UNC #38 / .1015"
5-44 UNF #37 / .1040"
6-32 UNC #35 / 7/64" / .1100"
6-36 NS (Special Size) #34 / .1110"
6-40 UNF #33 / .1130"
6-48 NS (Special Size) #31 / .1200"
4-0.70mm 3.4mm / #29 / .1338"
4-.075mm 3.4mm / #29 / .1338"
8-32 UNC #29 / .1360"
8-36 UNF #29 / 9/64" / .1360"
8-40 NS (Special Size) #28 / .1405"
3/16-24 NS (Special Size) #26 / .1470"
10-24 UNC #25 / 5/32" / .1495"
3/16-32 NS (Special Size) #22 / .1570"
10-32 UNF #21 / 11/64" / .1590"
5-.090mm (fine) 4.2mm / .1653"
5-.080mm (coarse) #16 / 4.3mm / .1693"
12-24 UNC 11/64" / .1770"
12-28 UNF #14 / 3/16" / .1820"
12-32 NEF (Extra Fine) #13 / .1850"
14-20 NS (Special Size) #10 / .1935"
1/4-24 UNC #7 / 13/64" / .2010"
14-20 NS (Special Size) #7 / .2010"
6-1.00mm (coarse) 5.2mm / #5 / .2047"
1/4-20 NS (Special Size) #4 / .2090"
1/4-28 UNF #3 / 7/32" / .2130"
1/4-32 NEF (Extra Fine) 7/32" / .2188"
1/4-40 NS (Special Size) #1 / .2280"
7-1.00mm (coarse) 6.1mm / 15/64" / .2401"
5/16-18 UNC F / 17/64" / .2570"
8-1.25mm (coarse) 6.9mm / 17/64" / .2716
5/16-24 UNF I / .2720"
8-1.00mm (fine) 7.1mm / .2795"
5/16-32 NEF (Extra Fine) 9/32" / .2812"
9-1.25mm (coarse) 7.9mm / 5/16" / .3110"
3/8-16 UNC 5/16" / .3125"
9-1.00mm (extra fine) 8.1mm / .3189"
To Tap These Size Threads Drill This Size Hole
9-0.75mm (fine) 8.3mm / 21/64" / .3268"
3/8-24 UNF Q / 21/64" / .3320"
10-1.50mm (fine) 8.7mm / 11/32" / .3425"
10-1.25mm (coarse) 8.9mm / 11/32" / .3503"
10-1.00mm (Spark Plug Threads) 9.1mm / .3583"
7/16-14 UNC U / 23/64" / .3680"
11-1.50mm (coarse) 9.7mm / .3818"
7/16-20 UNF 25/64" / .3906"
12-1.75mm (fine) 10.5mm / .4133"
12-1.50mm (coarse) 10.7mm / 27/64" / .4212"
1/2-13 UNC 27/64" / .4219
12-1.25mm (Spark Plug Threads) 10.9mm / 27/64" / .4291"
1/2-20 UNF 29/64" / .4531"
1/2-24 NS (Special Size) 29/64" / .4531"
14-2.00mm (coarse) 12.2mm / .4803"
9/16-12 UNC 31/64" / .4844"
14-1.50mm (fine) 12.7mm / 1/2" / .4999"
14-1.25mm
(Common 14mm Spark Plug Threads)		 12.8mm / 1/2" / .5039"
9/16-18 UNF 33/64" / .5156"
5/8-11 UNC 17/32" / .5312"
16-2.00mm (coarse) 14.2mm / 35/64" / .5590"
5/8-18 UNF 37/64" / .5781"
16-1.50mm (fine) 14.7mm / .5787"
11/16-11 NS (Special Size) 19/32" / .5938"
18-2.50mm (coarse) 15.8mm / 39/64" / .5220"
11/16-16 NS (Special Size) 5/8" / .6250"
3/4-10 UNC 21/32" / .6562"
18-1.50mm (Spark Plug Threads) 16.8mm / .6614"
3/4-16 UNF 11/16" / .6875"
20-2.50mm (coarse) 17.8mm / 11/16" / .7008"
7/8-9 UNC 49/64" / .7656"
7/8-14 UNF 13/16" / .8125"
22-1.50mm 20.9mm / .8228"
7/8-18 NS
(Special Size / Spark Plug Threads)		 53/64" / .8281"
24-3.00mm 21.4mm / 53/64" / .8425"
1-8 UNC 7/8" / .8750"
24-2.00mm 22.3mm / .8779"
1-12 UNF 59/64" / .9219"
1-14 NS (Special Size) 15/16" / .9375"
1-1/8-7 UNC 63/64" / .9844"
1-1/8-12 UNF 1-3/64" / 1.0469"
1-1/4-7 UNC 1-7/64" / 1.1094"
1-1/4-12 UNF 1-11/64" / 1.1719"
1-3/8-6 UNC 1-7/32" / 1.2188"
1-3/8-12 UNF 1-19/64" / 1.2969"
1-1/2-6 UNC 1-11/32" / 1.3438"
1-1/2-12 UNF 1-27/64" / 1.4219"

Drill and Tap Chart for National Pipe Tapered (NPT) Threads | NOTE - Recommended tap drill to use for 75% thread depth. [Top of Page]
To Cut This Size Pipe Threads Use This Size Drill Bit / Closest Fractional / Decimal Inches Outside Diameter of Pipe
1/16-27 NPT D / 1/4" / .246" 0.313" (5/16")
1/8-27 NPT R / 11/32" / .339" 0.405" (13/32")
1/4-18 NPT 7/16" / .4375" 0.540" (35/64")
3/8-18 NPT 37/64" / .5781" 0.675" (43/64")
1/2-14 NPT 45/64" / .7031" 0.840" (27/32")
3/4-14 NPT 59/64" / .9219" 1.050" (1-3/64")
1-11 1/2 NPT 1-5/32" / 1.1562" 1.315" (1-5/16")
1-1/4-11 1/2 NPT 1-1/2" / 1.500" 1.660" (1-21/32")
1-1/2-11 1/2 NPT 1-47/64" / 1.7344" 1.900" (1-57/64")
2-11 1/2 NPT 2-7/32" / 2.2188" 2.375" (2-3/8")

Drill and Tap Chart for Metric Threads [Top of Page]
Tap Size Drill This Size Hole Drill This Size Hole Basic Major Millimeter Diameter Basic Major Inch Diameter Millimeters Per Thread
M1.6 x 0.35 #55 1.25mm 1.6mm .063" .35
M2 x 0.4 #52 1.6mm 2mm .0787" .4
M2.5 x 0.45 #46 2.05mm 2.5mm .0984" .45
M3 x 0.5 #39 2.5mm 3mm .1181" .5
M3.5 x 0.6 #32 2.9mm 3.5mm .1378" .6
M4 x 0.7 #30 3.3mm 4mm .1575" .7
M5 x 0.8 #19 4.2mm 5mm .1969" .8
M6 x 1 #8 5mm 6mm .2362" 1
M8 x 1.25 H 6.8mm 8mm .315" 1.25
M8 x 1 J 7mm 8mm .315" 1
M10 x 1.5 R 8.5mm 10mm .3937" 1.5
M10 x 1.25 11/32" 8.8mm 10mm .3937" 1.25
M11 x 1.5 3/8" 9.5mm 11mm .433" 1.5
M11 x 1.25 U 9.75mm 11mm .433" 1.25
M12 x 1.75 13/32" 10.2mm 12mm .4724" 1.75
M12 x 1.25 27/64" 10.8mm 12mm .4724" 1.25
M14 x 2 15/32" 12mm 14mm .5512" 2
M14 x 1.5 1/2" 12.5mm 14mm .5512" 1.5
M16 x 2 35/64" 14mm 16mm .6299" 2
M16 x 1.5 37/64" 14.5mm 16mm .6299" 1.5
M18 x 2.5 39/64" 15.5mm 18mm .7087" 2.5
M18 x 1.5 21/32" 16.5mm 18mm .7087" 1.5
M20 x 2.5 11/16" 17.5mm 20mm .7874" 2.5
M20 x 1.5 47/64" 18.5mm 20mm .7874" 1.5
M22 x 2.5 49/64" 19.5mm 22mm .8661" 2.5
M22 x 1.5 13/16" 20.5mm 22mm .8661" 1.5
M24 x 3 53/64" 21mm 24mm .9449" 3
M24 x 2 7/8" 22mm 24mm .9449" 2
M27 x 3 15/16" 24mm 27mm 1.063" 3
M27 x 2 1" 25mm 27mm 1.063" 2

- Metric Equivalents to Decimals of an Inch - 
      Decimals of |        Decimals of   |       Decimals of
 MM     an inch   | MM       an inch     | MM      an inch
------------------+----------------------+--------------------
  .1 =  .00394"   |  1.  =  .03937"      | 15.  =  .59055"
  .2 =  .00787"   |  2.  =  .07874"      | 16.  =  .62992"
  .3 =  .01181"   |  3.  =  .11811"      | 17.  =  .66929"
  .4 =  .01575"   |  4.  =  .15748"      | 18.  =  .70866"
  .5 =  .01968"   |  5.  =  .19685"      | 19.  =  .74803"
  .6 =  .02362"   |  6.  =  .23622"      | 20.  =  .78740"
  .7 =  .02756"   |  7.  =  .27559"      | 21.  =  .82677"
  .8 =  .03149"   |  8.  =  .32496"      | 22.  =  .86614"
  .9 =  .03543"   |  9.  =  .35433"      | 23.  =  .90551"
10.  =  .3937"    | 12.7 =  .500"        | 24.  =  .94488"
11.  =  .43307"   | 13.  =  .51181"      | 25.  =  .98425"
12.  =  .47244"   | 14.  =  .55118"      | 25.4 = 1.000"

Fractions, Numbers, Letters, Decimals and Metric Equivalents [Top of Page]
NOTE: There's three different type of drill bits - fraction, number and letter. Actually, there's four, including metric. Use the one that's closest to the size of hole that needs to be drilled. 
Fraction/|         |        | Fraction/|         |       | Fraction/|         |
 Number/ | Decimal |   MM   |  Number/ | Decimal |  MM   |  Number/ | Decimal |  MM
 Letter  |         |        |  Letter  |         |       |  Letter  |         |
----------------------------+----------------------------+----------------------------
  1/64"  =  .0156" =   .396 |  #20    =  .161"  =  4.089 |  T      =  .358"  =  9.093
  1/32"  =  .0312" =   .795 |  #19    =  .166"  =  4.216 | 23/64"  =  .3594" =  9.129
  #60    =  .040"  =  1.016 |  #18    =  .1659" =  4.214 |  U      =  .368"  =  9.347
  #59    =  .041"  =  1.041 | 11/64"  =  .1718" =  4.366 |  3/8"   =  .375"  =  9.525
  #58    =  .042"  =  1.067 |  #17    =  .173"  =  4.394 |  V      =  .377"  =  9.576
  #57    =  .043"  =  1.092 |  #16    =  .177"  =  4.496 |  W      =  .386"  =  9.804
  #56    =  .043"  =  1.092 |  #15    =  .180"  =  4.572 | 25/64"  =  .3906" =  9.921
  #55    =  .0465" =  1.181 |  #14    =  .182"  =  4.623 |  X      =  .397"  = 10.084
  3/64"  =  .0468" =  1.191 |  #13    =  .185"  =  4.699 |  Y      =  .404"  = 10.262
  #55    =  .052"  =  1.321 |  3/16"  =  .1875" =  4.763 | 13/32"  =  .4063" = 10.320
  #54    =  .055"  =  1.397 |  #12    =  .189"  =  4.801 |  Z      =  .413"  = 10.49
  #53    =  .0595" =  1.511 |  #11    =  .191"  =  4.851 | 27/64"  =  .4219" = 10.716
  1/16"  =  .0625" =  1.588 |  #10    =  .1935" =  4.915 |  7/16"  =  .4375" = 11.113
  #52    =  .0635" =  1.613 |  #9     =  .196"  =  4.978 | 29/64"  =  .4531" = 11.509
  #51    =  .067"  =  1.701 |  #8     =  .199"  =  5.055 | 15/32"  =  .4688" = 11.908
  #50    =  .070"  =  1.778 |  #7     =  .201"  =  5.105 | 31/64"  =  .4844" = 12.304
  #49    =  .073"  =  1.854 | 13/64"  =  .2031" =  5.159 |  1/2"   =  .500"  = 12.700
  #48    =  .076"  =  1.930 |  #6     =  .204"  =  5.182 | 33/64"  =  .5156" = 13.096
  5/64"  =  .0781" =  1.984 |  #5     =  .2055" =  5.22  | 17/32"  =  .5312" = 13.495
  #47    =  .0785" =  1.994 |  #4     =  .209"  =  5.309 | 35/64"  =  .5469" = 13.891
  #46    =  .081"  =  2.06  |  #3     =  .213"  =  5.41  |  9/16"  =  .5625" = 14.288
  #45    =  .082"  =  2.083 |  7/32"  =  .2188" =  5.558 | 37/64"  =  .5781" = 14.684
  #44    =  .086"  =  2.184 |  #2     =  .221"  =  5.613 | 19/32"  =  .5938" = 15.083
  #43    =  .089"  =  2.26  |  #1     =  .228"  =  5.791 | 39/64"  =  .6094" = 15.479
  #42    =  .0935" =  2.375 |  A      =  .234"  =  5.943 |  5/8"   =  .625"  = 15.875
  3/32"  =  .0937" =  2.383 | 15/64"  =  .2344" =  5.954 | 41/64"  =  .6406" = 16.271
  #41    =  .096"  =  2.438 |  B      =  .238"  =  6.045 | 21/32"  =  .6563" = 16.67
  #40    =  .098"  =  2.489 |  C      =  .242"  =  6.147 | 43/64"  =  .6719" = 17.066
  #39    =  .0995" =  2.527 |  D      =  .246"  =  6.248 | 11/16"  =  .6875" = 17.463
  #38    =  .1015" =  2.578 |  1/4"   =  .250"  =  6.35  | 45/64"  =  .7031" = 17.859
  #37    =  .104"  =  2.642 |  E      =  .250"  =  6.35  | 23/32"  =  .7188" = 18.254
  #36    =  .1065  =  2.705 |  F      =  .257"  =  6.528 | 47/64"  =  .7344" = 18.654
  7/64"  =  .1094" =  2.779 |  G      =  .261"  =  6.629 |  3/4"   =  .750"  = 19.05
  #35    =  .110"  =  2.794 | 17/64"  =  .2656" =  6.746 | 49/64"  =  .7656" = 19.446
  #34    =  .111"  =  2.819 |  H      =  .266"  =  6.756 | 25/32"  =  .7813" = 19.845
  #33    =  .113"  =  2.87  |  I      =  .272"  =  6.909 | 51/64"  =  .7969" = 20.241
  #32    =  .116"  =  2.946 |  J      =  .277"  =  7.036 | 13/16"  =  .8125" = 20.638
  #31    =  .120"  =  3.048 |  K      =  .281"  =  7.137 | 53/64"  =  .8282" = 21.034
  1/8"   =  .125"  =  3.175 |  9/32"  =  .2813" =  7.145 | 27/32"  =  .8438" = 21.433
  #30    =  .1285" =  3.195 |  L      =  .290"  =  7.366 | 55/64"  =  .8594" = 21.821
  #29    =  .136"  =  3.454 |  M      =  .295"  =  7.493 |  7/8"   =  .875"  = 22.225
  #28    =  .1405" =  3.569 | 19/64"  =  .2969" =  7.541 | 57/64"  =  .8906" = 22.621
  9/64"  =  .1406" =  3.571 |  N      =  .302"  =  7.671 | 29/32"  =  .9063" = 23.020
  #27    =  .144"  =  3.658 |  5/16"  =  .3125" =  7.938 | 59/64"  =  .9219" = 23.416
  #26    =  .147"  =  3.734 |  O      =  .316"  =  8.026 | 15/16"  =  .9375" = 23.813
  #25    =  .1495" =  3.797 |  P      =  .323"  =  8.204 | 61/64"  =  .9532" = 24.209
  #24    =  .152"  =  3.861 | 21/64"  =  .3281" =  8.334 | 31/32"  =  .9688" = 24.608
  #23    =  .154"  =  3.912 |  Q      =  .332"  =  8.433 | 63/64"  =  .9844" = 25.004
  5/32"  =  .1563" =  3.970 |  R      =  .339"  =  8.611 |     1"  = 1.000"  = 25.400
  #22    =  .157"  =  3.988 | 11/32"  =  .3438" =  8.733 |
  #21    =  .159"  =  4.039 |  S      =  .348"  =  8.839 |

Small Screw Size and Maximum Diameter of Threads (For drilling mounting holes for screws) [Top of Page]
Thread Size Actual Outside Diameter of Threads

Closest Drill Bit Size
2-56 .086" #44 / 3/32"
3-48 .099" #39 / 7/64"
4-40 .112" #33 or #34
5-40 .125" 1/8"
6-32 .138" 9/64"
8-32 .164" 11/64"
10-24 .190" 3/16"
10-32 .190" 3/16"
12-24 .216" 7/32"

Useful Formulas, Conversion Charts, etc. [Top of Page]

It's best to use a handy calculator here, have pencil and paper available, or have JavaScript enabled in your web browser.

To calculate the cubic inch displacement (CID) of an engine:
Bore x Bore x .7854 x Stroke x Number of Cylinders = Cubic Inch Displacement.
Example: (for a 4.3L Chevrolet V6 engine) 4.000 (bore size) x 4.000 (bore size again) x .7854 x 3.48 (stroke) x 6 (number of cylinders) = 262.37 CID.

Calculate Engine Cubic Inch Displacement

Enter Cylinder Bore:
Enter Crankshaft Stroke:
Enter Number of Cylinders:
= Engine Cubic Inches:

To convert CID into Cubic Centimeters (CC): (1 Cubic inch = 16.3870641 Cubic centimeters)
Multiply the CID by 16.39 = Cubic Centimeters.
Example: 262.37 (CID) x 16.39 = 4300 CC.
To convert CC back into CID: 1 Cubic centimeter = 0.0610237 Cubic inches.

1 Cubic Inch = 16.39 Cubic Centimeter

Enter Cubic Inches: = CCs:

To calculate engine cubic centimeters (CC) for the approximate horsepower, first convert the CC's into the cubic inch displacement (CID) by dividing the CC's by 16.4, which will show the approximate CID. Then for a flathead engine, divide the CID by 2.45, which will show the approximate HP of the engine @ 3,600 RPM. And for an OHV engine, divide the CID by 1.45, which will show the approximate HP of the engine @ 3,600 RPM.

To convert CC's into Liters: (1 Cubic centimeter = 0.001 Liter)
Divide the Cubic Centimeters by 1000 = Engine Liter Size.
Example: 4300 ÷ 1000 = 4.3L.

231 cubic inches = 1 US gallon

Enter Cubic Inches: = Gallon:

Finding the Correct Piston Compression Height -
(Piston Compression Height is the distance from the wrist pin centerline to the top of the piston.)

Enter Deck Height: (From main bearing centerline to top of block. The deck height on the OEM Kohler 10hp through 16hp engine blocks is 8.625")
Enter Crankshaft Stroke: (OEM Kohler is 10hp = 2.875", 12hp, 14hp & 16hp = 3.25")
Enter Rod Length: (from wrist pin hole centerline to rod bearing hole centerline. OEM Kohler is 10hp is 5.558. 12hp, 14hp & 16hp = 5.3")
Enter Piston Compression Height: (OEM Kohler is 10hp is 1.63", 12hp, 14hp & 16hp is 1.7")
= Deck Clearance: (0 meaning flush w/cylinder)

Rod Length Divided by Stroke = Rod Stroke/Ratio

Enter Rod Length:
Enter Stroke:
= Rod Stroke Ratio:

1cc = .061 cubic inches

Enter CCs: = Cubic Inches:

How to Calculate the Compression Ratio of a Flathead or OHV Engine -

  1. Acquire a flat piece of Plexiglas slightly larger than the cylinder head, and drill a small hole in it where the combustion chamber of the head is.
  2. Acquire a large test tube with cubic centimeter increments.
  3. Fill the test tube with brake fluid.
  4. Make a note of how much brake fluid is in the test tube.
  5. Seal the Plexiglas over the cylinder head with the head gasket that's going to be used on the engine. (Use silicone sealer)
  6. Fill the combustion chamber with the brake fluid through the drilled hole.
  7. Make a note of how many cubic centimeters of brake fluid it took to fill the combustion chamber.
  8. Now calculate the cubic inches of the cylinder in the engine. Convert that figure into cubic centimeters.
  9. Finally, divide the cubic centimeters of the cylinder by the cubic centimeters in the combustion chamber. This should give the exact compression ratio.

1 cubic foot = 7.48 US gallons

Enter Cubic feet: = Gallons:

Sheet Metal Thickness Gauges (All dimensions in inches.) [Top of Page]
Gauge Standard Steel Galvanized Steel Aluminum Gauge Standard Steel Galvanized Steel Aluminum
3 0.2391" - 0.2294" 20 0.0359" 0.0396" 0.0320"
4 0.2242" - 0.2043" 21 0.0329" 0.0366" 0.0285"
5 0.2092" - 0.1819" 22 0.0299" 0.0336" 0.0253"
6 0.1943" - 0.1620" 23 0.0269" 0.0306" 0.0226"
7 0.1793" - 0.1443" 24 0.0239" 0.0276" 0.0201"
8 0.1644" - 0.1285" 25 0.0209" 0.0247" 0.0179"
9 0.1495" 0.1532" 0.1144" 26 0.0179" 0.0217" 0.0159"
10 0.1345" 0.1382" 0.1019" 27 0.0164" 0.0202" 0.0142"
11 0.1196" 0.1233" 0.0907" 28 0.0149" 0.0187" 0.0126"
12 0.1046" 0.1084" 0.0808" 29 0.0135" 0.0172" 0.0113"
13 0.0897" 0.0934" 0.0720" 30 0.0120" 0.0157" 0.0100"
14 0.0747" 0.0785" 0.0641" 31 0.0105" 0.0142" 0.0089"
15 0.0673" 0.0710" 0.0571" 32 0.0097" 0.0134" 0.0080"
16 0.0598" 0.0635" 0.0508" 33 0.0090" - 0.0071"
17 0.0538" 0.0575" 0.0453" 34 0.0082" - 0.0063"
18 0.0478" 0.0516" 0.0403" 35 0.0075" - 0.0056"
19 0.0418" 0.0456" 0.0359" 36 0.0067" - -

Click Here for Detailed Illustrated Plans on How to Construct a Professional Pull-Back and Self-Propelled Garden Tractor Pulling Sled (Available Soon)

To place an order, send your parts for repairing, and/or for customer service assistance, and FREE honest and accurate technical support, please contact: A-1 Miller's Performance Enterprises | 1501 W. Old Plank Rd. | Columbia, MO (Missouri) 65203-9136 USA | Phone: 1-573-256-0313 (shop) | 1-573-881-7229 (cell; text or when leaving a voice message, please speak slowly and clearly). Call in your order or email us a list parts you need. Payment Options. Please call Monday-Friday, 9am to 5pm, Central time zone, except holidays. If no answer, please try again later. (When speaking with Brian on the phone, please be patient and understanding because I stutter.) E-mail: pullingtractor@aol.com.

A-1 Miller's shop is open to the public Monday-Friday, 9am to 5pm, Central time zone, with an appointment on weekends, except holidays. If you're the kind of person who don't trust delivery/shipping companies (mis)handling your high-dollar and fragile merchandise, you can make the long drive to A-1 Miller's shop to personally purchase parts, or drop off and/or pick up your carburetor, clutch assembly, engine parts, entire engine, transmission, transaxle, entire garden tractor, small motorized vehicle, etc. for repairing and/or rebuilding. Please call, text or email me before coming so I'll be at my shop waiting for your arrival. When you visit our shop, you will be dealing directly with the owner for the best customer service. Directions to our shop | 1501 West Old Plank Road, Columbia, MO - Google Maps or Map of 1501 West Old Plank Road, Columbia, MO by MapQuest. "The road to a [trusted] friend's house (or shop) is never long." Don't sacrifice quality workmanship for distance. [Return To Previous Paragraph, Section or Website]

By the way - As business is booming, we're going to relocate our business later this year at 12091 N. Rt. B, Hallsville, MO 65255 with a bigger, better, fully insulated, heated and air-conditioned building/shop (shouse) so we can provide many more high quality parts and professional services, and hire more help to have our customer's parts orders fulfilled sooner, parts repairs and engine rebuilds performed promptly without delay. We will also provide pick up and delivery service and perform professional repairs for various small engines and lawn & garden equipment! We're also thinking of building competitive garden pulling tractors, and pull-back and self-propelled garden tractor pulling sleds to offer for sale. If you want, ask to be put on our waiting list and we'll contact you when the time comes. Photos during construction of our new building/shop are posted here!

To place an order, please call the number below Ê or send an email with your name, complete and correct postal address and phone number and so I can figure the total with shipping cost and USPS Tracking. For payment options for parts ordered or services performed, or to make a donation to my websites, I accept cash (in person), USPS Postal Money Orders, cashier's checks, business checks, MasterCard, VISA, Discover, American Express (please add 2.5% to the total for the credit/debit card processor's surcharge), Western Union Money Transfer or MoneyGram Money Transfers. (If a part for a specific purpose is special ordered, your debit/credit card may be charged for the full amount or as a deposit right after your order is placed; please do not send your debit/credit card information in email!) Or you can pay A-1 Miller's through PayPal. (My PayPal account name is my email address. And be sure to mention in PayPal a description of what the payment is for.) If sending a money order, please include a note in the envelope with your name, complete and correct postal address, phone number and a description of what the payment is for. My mailing address and phone number are below Ê . I'll make a note of your order, and I may have to order some of the parts, which should take a few days to come in, but I will send the parts to you as soon as I have everything in stock after I receive your payment.

IMPORTANT - When sending your part(s) to A-1 Miller's for rebuilding or repair, package everything securely so the item(s) won't get damaged in shipping and please include a note in the box with your name, mailing address, phone number (in case I have any questions) and a description of what you want done. When shipping heavy parts, it's best to put a slightly smaller box inside a larger box, to double the strength and integrity of the package. Because the clumsy "gorillas" or incompetent and uncaring workers that work for certain delivery services mishandle the heavy packages and don't care. And when the work is completed, I'll either call or email you an invoice with the total including shipping & handling.

Payment Options and We Ship to Canada and Worldwide
Item(s) in a package or cushioned envelope weighing less than 1 lb. is sent by US Postal Service Airmail Letter Post for a 4-7 days delivery. Packaged item(s) weighing over 1 lb. and up to 66 lb. is sent by US Postal Service Airmail Parcel Post for a 4-10 days delivery. I cannot use the US Postal Services' Flat Rate Priority Mail envelopes and boxes to ship outside U.S. territories. Item(s) weighing over 67 lbs. or more is sent by FedEx Ground or equivalent services. We try to keep our shipping cost to customers within reason. Therefore, we don't ship our products in a fancy-looking package with our company name and/or logo on it because most customers will just toss it in the trash after they remove the contents. And being there is no USPS tracking number outside the US, all I can do is make sure I write your address correctly on the customs form and on your package.

My websites are not set up to process orders and accept payments. Therefore, for payment options, I accept cash (in person), USPS Postal Money Orders, cashier's checks, business checks, MasterCard, VISA, Discover, American Express (please add 2.5% to the total amount for the credit/debit card processor's surcharge), Western Union Money Transfer or MoneyGram Money Transfers. If paying with a credit/debit card, please call me at either number below. To make a payment to me through PayPal, please click this link: https://www.paypal.me/PullingTractor. Or to make a payment to me (pullingtractor@aol.com) in the US through the Venmo app, please click this link: venmo.com. Or use Cash App to make a payment to me (pullingtractor@aol.com). And be sure to mention in PayPal, Venmo or Cash App a description of what the payment is for with your full name, postal address, phone number and email address. If sending a money order or cashier's check, please include a note in the envelope with your name, complete mailing address, phone number, email address and a description of what the payment is for. I'll make a note of your order when I have all your information, and I may have to order some of the parts, which should take a few days to come in, but I will send everything on your list to you as soon as I have the parts in stock after I receive your payment.


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