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The motor Im working on is a Gen VI I believe. I need to check and see about that for sure. Its a Mercruiser 502 MPI out of a 87 Baja.
 

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B.A.M aka "Black Azz Mike
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I have a BBC 4 bolt main block. I believe it's a GEN 4, 30 over 502.
Bore X Stroke = Cubic inches


a 30over bore is a 4.280 bore

a 502 block has a stock 4.468" bore and a 4.000" stroke(crank)
 

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B.A.M aka "Black Azz Mike
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2,925 Posts
here is a handy lil chart :)


Big block Chevy bore and stroke



Engine Size Stock Bore +.060"-over Stock Stroke
366 3.935" 3.995" 3.760"
396 4.094" 4.154" 3.760"
402 4.125" 4.185" 3.760"
427 4.250" 4.310" 3.760"
454 4.250" 4.310" 4.000"
Mrk5-502/Mrk6 4.468" 4.530" 4.000"


454 Engines 3.760" 4.000" 4.250" 4.500" 4.750" 4.875"
Stock bore = 4.250" 427" 454" 482" 511" 539" 553"
Bored .030" =4.280" 433" 460" 489" 518" 547" 561"
Bored .060" =4.310" 439" 467" 496" 525" 554" 569"
Bored .090" =4.340" 445" 473" 503" 533" 562" 577"
Bored .100" =4.350" 447" 476" 505" 535" 565" 580"
Bored .125" =4.375" 452" 481" 511" 541" 571" 586"


502 Engine 3.760" 4.000" 4.250" 4.500" 4.750" 4.875"
Stock bore = 4.468" 472" 502" 533" 564" 596" 611"
Bored .032" = 4.500" 478" 509" 541" 573" 604" 620"
Bored .062" = 4.530" 485" 516" 548" 580" 612" 629"
Bored .092" = 4.560" 491" 523" 555" 588" 621" 637"


Brodix, Dart & Merlin Blocks 4.000" 4.125" 4.250" 4.375" 4.500" 4.625" 4.750" 4.875" 5.000"
4.500" bore 509" 525" 541" 557" 572" 588" 604" 620" 636"
4.530" bore 515" 532" 548" 564" 580" 596" 612" 628" 645"
4.560" bore 523" 539" 555" 572" 588" 604" 621" 637" 653"
4.590" bore 530" 546" 563" 579" 596" 612" 629" 645" 662"
4.600" bore 532" 548" 565" 582" 598" 615" 632" 648" 665"
4.625" bore 537" 554" 571" 588" 605" 622" 638" 655" 672"


To calculate the displacement of an eight-cylinder engine: bore x bore x stroke x 6.2832

Cubic inches x 16.387 = cubic centimeters. Cubic centimeters x .061 = cubic inches
 

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B.A.M aka "Black Azz Mike
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I retyped all the 3 times and it wont keep it in a chart from:mad::mad:
 

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here is a handy lil chart :)


Big block Chevy bore and stroke



Engine Size Stock Bore +.060"-over Stock Stroke
366 3.935" 3.995" 3.760"
396 4.094" 4.154" 3.760"
402 4.125" 4.185" 3.760"
427 4.250" 4.310" 3.760"
454 4.250" 4.310" 4.000"
Mrk5-502/Mrk6 4.468" 4.530" 4.000"


454 Engines 3.760" 4.000" 4.250" 4.500" 4.750" 4.875"
Stock bore = 4.250" 427" 454" 482" 511" 539" 553"
Bored .030" =4.280" 433" 460" 489" 518" 547" 561"
Bored .060" =4.310" 439" 467" 496" 525" 554" 569"
Bored .090" =4.340" 445" 473" 503" 533" 562" 577"
Bored .100" =4.350" 447" 476" 505" 535" 565" 580"
Bored .125" =4.375" 452" 481" 511" 541" 571" 586"


502 Engine 3.760" 4.000" 4.250" 4.500" 4.750" 4.875"
Stock bore = 4.468" 472" 502" 533" 564" 596" 611"
Bored .032" = 4.500" 478" 509" 541" 573" 604" 620"
Bored .062" = 4.530" 485" 516" 548" 580" 612" 629"
Bored .092" = 4.560" 491" 523" 555" 588" 621" 637"


Brodix, Dart & Merlin Blocks 4.000" 4.125" 4.250" 4.375" 4.500" 4.625" 4.750" 4.875" 5.000"
4.500" bore 509" 525" 541" 557" 572" 588" 604" 620" 636"
4.530" bore 515" 532" 548" 564" 580" 596" 612" 628" 645"
4.560" bore 523" 539" 555" 572" 588" 604" 621" 637" 653"
4.590" bore 530" 546" 563" 579" 596" 612" 629" 645" 662"
4.600" bore 532" 548" 565" 582" 598" 615" 632" 648" 665"
4.625" bore 537" 554" 571" 588" 605" 622" 638" 655" 672"


To calculate the displacement of an eight-cylinder engine: bore x bore x stroke x 6.2832

Cubic inches x 16.387 = cubic centimeters. Cubic centimeters x .061 = cubic inches
Thanks for the good info.
Speed-O-Motive has alot of engine math on thier website.
 

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Have a (never used) new GM factory 502 short block sitting in the garage, been sitting for 5 years or so, How bad do you want it $$$
 
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