This for Information Only
– there is advantages and disadvantages in using this information : Basically the stroker kits available today (and older versions of this practice ),use a smaller diameter chevy rod bearing after offset grinding the rod journals of a stock (or stock style replacement ) crankshaft to achieve a longer stroke. You can also purchase new crankshafts with these dimensions. Crankshaft Balance FactorsThe long and short of it – Rod length Information
advantages
disadvantages
Cheaper than aftermarket crankshafts
This is a way of resurrecting a badly damaged
but possibly very expensive used crankshaft
Lighter – revs higher
Lighter – breaks easier
(note: I have always disputed this advantage because the stock B/RB Blocks have a real problem here ,
the lifters are angled down , this geometry is corrected in
some aftermarket blocks )
Additional .050 side clearance on rods if the crank isn’t first welded or rods custom made.
( note: new cranks can be made this way also )
The long and short of it: Left – 500 ci – dodge based piston, rod and pin
Rod journal = 2.375″
Wrist Pin = 1.156″ ( thick wall – Tapered )
Weight 2400 g
Note: this will survive a Top Fuel 4 sec pass
( although it usually bends the wrist pins )
and a 5 sec pass in a TAD , shifted at 10,700 rpm ?
Right : 527 ci – B block – Chevy rod
Rod journal = 2.2″
Wrist Pin = .990″ ( thin wall )
Weight 1420 g
Left :
this appears to be a stock Hemi 8 bolt Mopar factory forged crankshaft that has been
1) ground down to “B” engine main journal diameter
2) offset ground to net a 4.375 “
3) then hand ground to clear the pistons and the block
Note: The outside diameter of a Chrysler B crankshaft is 7.3″, RB /Hemi is 7.4″
weld can still be seen here also after cutting from 440 to 400 journal size .125″
Edge of weld can still be seen after
cutting the crank down .175″
The crankshaft above appears to have been an original HEMI shaft because it has an 8 bolt flange. For that reason it has probably been repaired and abused many times over the last 40 years but
when resurrecting a badly damaged used crankshaft you have to make a decision as to when it is cost and time effective.
Crank
shaft
Rod Journal Sizes
Rod Width
Journal Width
Rod Length
Rod Length
Ratio
Main Journal Sizes
Stroke
Bore
Bore Stroke Ratio
counter
weight dia
Wrist Pin Sizes
Race-hemi
500 Fuel
(small bore)
2.375″
1.015″
2.060″
7.0″+
1.55+
2.750″ / 3″
4.5 “
4.187″
.93
7.4″ +
1.156″
Race-hemi
500 Fuel
2.375″
1.015″
2.060″
7.0″+
1.6+
2.750″ / 3″
4.375″
4.25″
.97
7.4″ +
1.156″
Race-hemi
450 TAD
2.375″
1.015″
2.060″
7.0″+
2.750″
4.1(+-)
4.38″
(+-)
1.06
7.4″ +
1.095″
Race-hemi
527 TAFC
2.375″
1.015″
2.060″
7.0″+
2.750″
4.375
(+-)
4.38
(+-)”
1
7.4″ +
1.095″
Race-hemi
572
2.375″
1.015″
2.060″
2.750″ / 3″
4.5 “
4.5″
1
7.4″ +
1.095″
Race-hemi
604
2.375″
1.015″
2.060″
2.750″ / 3″
4.75 “
4.5″
.947
7.4″ +
1.095″ / 1.156
Race-hemi
636
2.375″
1.015″
2.060″
2.750″ / 3″
5.0 “
4.5″
.9
7.4″ +
1.095″ / 1.156
Dodge Hemi *
2.375″
1.015″
2.060″
6.860″
1.83
2.750″
3.750 “
4.250″
1.13
7.4″
1.0321″
Dodge RB-440 *
2.375″
1.015″
2.060″
6.768″
1.80
2.750″
3.750 “
4.320″
1.15
7.4″
.991″
Dodge B-400 *
2.375″
1.015″
2.060″
6.358″
1.88
2.625″
3.380 “
4.340″
1.28
7.3″
.991″
Chevy BB rods on aftermarket crank
2.20″
.995″
2.009″
2.625″
/2.750″
3.380 ” / max 4.75″
4.32+”
7.120 ” +
Chevy BB rods on reground stock
2.20″
1.015″
( ? )
2.060″
( ? )
2.625″
/2.750″
3.380 ” / max 4.15″
( ? )
Chevy BB *
2.20″
.995″
2.009″
6.865″
2.750″
.990″
Chevy SB – 400 *
2.10″
.943″
6.865″
2.650″
.927″
Chevy SB – big *
2.10″
.943″
6.865″
2.450″
.927″
Chevy SB – small *
2.00″
.943″
6.865″
2.300″
.927″
* = stock
Note after market rods may have additional side clearance
Race – hemi/B/RB – not kits – varies from team to team
every part may be custom dimensions
