Useful Formulas, Conversion Charts, etc.

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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 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 a 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:

- Identification of Most Commonly Used Grades of Bolts -

Use Standard Torque Settings When Specific Values Are Not Specified.
(C) = Coarse thread, (F) = Fine thread

Hardness 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 /
Special Alloy
Stainless Steel / Special Alloy bolts

Bolt 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.

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- Threading Tap to Drill Bit Chart -

---------------------------------------------------------------
 Tap Size  | Drill Bit Size       |  Tap Size  | Drill Bit Size
----------------------------------+----------------------------
   0-80 NF ---------------- 3/64" | 5/16-18 NC - letter "F" or 17/64"
   1-64 NC ---------------- #53   | 5/16-24 NF - letter "I" or  9/32"
   1-72 NF ---------------- #53   |  3/8-16 NC ---------------- 5/16"
   2-56 NC ---------------- #50   |  3/8-24 NF --------------- 21/64"
   2-64 NF ---------------- #50   | 7/16-14 NC ---------------- 3/8"
   3-48 NC ---------------- #47   | 7/16-20 NF --------------- 25/64"
   3-56 NF ---------------- #46   |  1/2-13 NC --------------- 27/64"
   4-40 NC --------- #43 or 3/32" |  1/2-20 NF --------------- 29/64"
   4-48 NF ---------------- #42   | 9/16-12 NC --------------- 31/32"
   5-40 NC ---------------- #38   | 9/16-18 NF --------------- 33/64"
   5-44 NF ---------------- #37   |  5/8-11 NC --------------- 17/32"
   6-32 NC --------- #35 or 7/64" |  5/8-18 NF --------------- 37/64"
   6-40 NF ---------------- #33   |  3/4-10 NC --------------- 21/32"
   8-32 NC - #29(.136") or  9/64" |  3/4-16 NF --------------- 11/16"
   8-36 NF - #29(.136") or  9/64" |  7/8-9  NC --------------- 49/64"
  10-24 NC - #25(.150") or  5/32" |  7/8-14 NF --------------- 13/16"
  10-32 NF - #21(.157") or 11/64" |    1-8  NC ---------------- 7/8"
 1/4-20 NC -- #7(.201") or 13/64" |    1-14 NF --------------- 15/16"
 1/4-28 NF -- #3(.213") or  7/32"
 ----------------------------------------------------------------------------

- National Pipe Tapered (NPT) Tap Chart -

----------------------------------------------------------------------------
 1/8" NPT -------------- 21/32"   |   3/4" NPT -------------  59/64"  
 1/4" NPT --------------  7/16"   |     1" NPT ------------- 1-5/32"
 3/8" NPT -------------- 37/64"   | 1-1/4" NPT ------------- 1-1/2"
 1/2" NPT -------------- 23/32"   | 1-1/2" NPT ------------- 1-47/64"
----------------------------------------------------------------------------
14mm x 1.25 pitch (spark plug) use 15/32" or 12mm drill bit.

Click here to print out the above chart. (Opens new
web page.)

- Fractions, Numbers, Letters, Decimals and Metric Equivalents - 

-------------------------------------------------------------------------------------
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 |

NOTE: There's three different TYPEs drill bits - fraction, number and letter. Actually, there's four, including the metric ones. Use the one that's closest to the size of the hole you need to drill.

Click here to print out the above chart. (Opens a new web page.)

- 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"

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