Common Connecting Rod Ratios

Common Connecting Rod Ratios

Connecting Rod ratio is the mathematical relationship between the overall length of the connecting rods and the stroke of the crankshaft. Divide rod length by the crank stroke and you get the rod ratio.


Engine
Stroke
Rod
Ratio
Notes
Ford 144 Six
2.5
5.88
2.35
 
Ford 240 Six
3.18
6.79
2.13
 
(s) Ford 281
2.75
5.7
2.07
destroked 289 crank, 283 Chevy rod
(s) Ford 351W
3.50
6.65
1.90
351M rods, 1.14 pistons
Ford 2800 V6
2.70
5.14
1.90
 
Mopar 383-400
3.38
6.35
1.88
 
Ford 352
3.50
6.54
1.87
 
Ford 221-239 Fl
3.75
7.0
1.87
 
(s) Ford 302
3.00
5.56
1.85
302 crank, 400 Chevy rod, 1.14 piston
Ford 429
3.59
6.60
1.83
 
Ford 3.0 V6
3.15
5.78
1.83
 
Ford 2.9 V6
2.83
5.14
1.82
 
Ford 351M
3.50
6.65
1.80
 
Mopar 413-440
3.75
6.75
1.80
 
Olds 400-425
3.875
7.00
1.80
 
Chevy 283
3.00
5.7
1.80
 
Ford 289
2.87
5.15
1.79
 
Pontiac 326-400
3.75
6.625
1.77
 
Olds 330-403
3.39
6.00
1.77
 
Merc 255 Flat
4.00
7.0
1.75
 
Chevy 327
3.25
5.7
1.75
 
Olds 350 Diesel
3.39
5.85
1.73
 
Ford 4.0 V6
3.32
5.748
1.73
 
Ford 390
3.78
6.49
1.72
 
(s) Chevy 350
3.48
6.0
1.72
6″ rod, 1.26 piston
Ford 460
3.85
6.60
1.71
 
Ford 351W
3.50
5.95
1.70
 
(s) Ford 315
3.076
5.205
1.69
stroked 302 crank, Pinto rod
Ford 302
3.00
5.09
1.69
 
Ford 4.6 Mod
3.54
5.93
1.68
 
(s) Ford 383
3.70
6.20
1.68
stroked 351W crank, Eagle rods
(s) Ford 375W
3.68
6.13
1.67
stroked 351W crank, Mopar rod/piston
(s) Ford 375C
3.68
6.13
1.67
stroked 351C crank, Mopar rod
Ford 2300 Lima
3.126
5.205
1.67
 
Ford 2.5 HSC
3.583
5.99
1.67
 
Ford 400
4.00
6.65
1.66
 
(s) Ford 443
4.03
6.70
1.66
stroked 390 crank, Slant Six rod
Pontiac 421-428
4.00
6.625
1.66
 
Ford 2.3 HSC
3.30
5.45
1.65
 
Ford 2000 Pinto
3.02
4.98
1.65
 
Chevy 350
3.48
5.7
1.64
** let’s use this as a baseline **
Ford 351C
3.50
5.7
1.63
 
Chevy 396
3.76
6.13
1.63
 
Ford 428
3.98
6.49
1.63
 
(s) Ford 525
4.200
6.79
1.62
stroked 460 crank, 240 Six rod
(s) Chevy 383
3.75
6.0
1.60
6″ rod, 1.14 piston
Ford 170 Six
2.94
4.715
1.60
 
(s) Ford 347
3.40
5.4
1.59
destroked 351C crank, Eagle rod
Olds 455
4.25
6.735
1.58
 
Pontiac 455
4.21
6.625
1.57
 
Ford 300 Six
4
6.21
1.55
 
(s) Ford 416
4.06
6.21
1.53
stroked 400 crank, 300 Six rod
Chevy 454
4.00
6.13
1.53
 
Ford 200 Six
3.13
4.715
1.51
 
(s) Ford 406w
4.06
6.12
1.50
stroked 400 crank, 360 Mopar rod
(s) Ford 351
3.50
5.205
1.49
cut down 351C crank, Pinto rod
Chevy 400
3.75
5.56
1.48
 
(s) Ford 430W
4.187
6.13
1.46
stroked 400 crank, Mopar rod
(s) Chevy 427sb
4.00
5.7
1.43
Callies crank
(s) Ford 366
3.60
5.15
1.43
stroked 351C crank, 289 rod, in 289
(s) Ford 454W
4.187
5.85
1.40
stroked 400 crank, Olds Diesel rod
 

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