crankshaft and connecting rod compatability

grumpyvette

Administrator
Staff member

POSTED BY, navygunner08;
"Does it matter what length rod you use with a particular crank? So if a crank is listed for use with 5.7" rods, can you use a 6" rod without modifications? And vise versa? "

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one factor to keep in mind is that rods typically have a side that rides against its matched companion and a side thats BEVELED for clearance on the crank journals radias EXAMPLE
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notice the top rods non-beveled side that faces the matching rod is up, but on the lower rod the the beveled side that faces the crank counter weight is up on the lower rod
Most cranks have counter weights designed to clear a piston skirt a certain distance from the crank center line and use a piston & rod assembly in a certain , set, and limited weight range, crank counter weights can be larger and heavier with the longer 6" connecting rods, in use,.. so you generally can INTERNALLY balance a heavier piston and rod assembly with longer connecting rods that allow the larger counter weights., so you can use either a 6" or 5.7" connecting rod on a crank designed for the shorter 5.7" connecting rods but you might need rather expensive mallory metal inserts to get it correctly balanced.
cranks designed for 6" connecting rods generally can,t be used with the shorter 5.7" rods.
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VERIFYING CLEARANCES GREATLY REDUCES WEAR AND DURABILITY ISSUES

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you might want to read these threads, for a great deal more related info


viewtopic.php?f=44&t=38&p=46&hilit=stroker#p46

viewtopic.php?f=53&t=204

http://garage.grumpysperformance.com/index.php?threads/sbc-spacer-bearings.3058/

viewtopic.php?f=53&t=341&p=417&hilit=stroker+tips#p417

viewtopic.php?f=53&t=253&p=301&hilit=stroker#p301

viewtopic.php?f=53&t=247&p=293&hilit=stroker#p293

viewtopic.php?f=53&t=794&p=1352&hilit=stroker#p1352

http://www.chevydiy.com/1955-1996-chevy-small-block-performance-guide-crankshafts-manual-part-2/#

viewtopic.php?f=50&t=428&p=527&hilit=stroker#p527

viewtopic.php?f=53&t=141&p=772&hilit=stroker#p772

viewtopic.php?f=53&t=510&p=770&hilit=stroker#p770

viewtopic.php?f=52&t=399&p=1499&hilit=stroker#p1499

viewtopic.php?f=53&t=253&p=672&hilit=stroker#p672

viewtopic.php?f=53&t=10213
always accurately measure the crank main journals, and remember the crank and block bearing sizes on a 400 sbc and 350 smc are different as are the early 283-327 sbc
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Chevy Crankshaft Journal Sizes
Chevy V-8 Crankshaft Journal Sizes

There is a lot of misinformation on the internet about these numbers. We have taken the time to verify the data as much as possible. There still may be errors. Please lets us know if you find one.

Journal sizes are factory standard sizes. Your crankshaft journals may have been previously cut down by a machine shop. Make sure the crank you have is matched to your block. Blocks were made with specific journal sizes. Putting a small or medium journal, small-block crank into a medium or large journal, small-block block requires crank bearing spacers or special thick, aftermarket bearings
Chevy Small Block Journal Sizes
Gen. I, Small Journal
C.I.D. Main Rod
265 2.30 2.00
283 2.30 2.00
302 2.30 2.00
327 2.30 2.00
Gen. I, Medium Journal (Includes Vortec 305,350 to 1998.)
C.I.D. Main Rod
262 2.45 2.10
267 2.45 2.10
302 2.45 2.10
305 2.45 2.10
307 2.45 2.10
327 2.45 2.10
350 2.45 2.10
Gen. I, Large Journal
C.I.D. Main Rod
400 2.65 2.10
383, Gen. I, Non-Factory

Gen. I, 400 Crank in a Gen. I, 350 Block. Crank mains cut down.
C.I.D. Main Rod
383 2.45 2.10
377, Gen. I, Non-Factory

Gen. I, 350 Crank in a Gen. I, 400 Block. Spacer or Thick mains bearings.
C.I.D. Main Rod
377 2.10
Gen. II, Medium Journal

Includes: L99 265, LT1 350, LT4 350
C.I.D. Main Rod
265 2.45 2.10
305 2.45 2.10
350 2.45 2.10
302, Gen. II, Non-Factory

Gen. II, 265 L99 Crank in a Gen. II, 350 Block.
C.I.D. Main Rod
302 2.45 2.10
Gen. III

Includes: 1979-05 LS1 Corvette, Firebird, Camaro.
C.I.D. Main Rod
345 2.558 2.10
Corvette ZR1, LT5, DOHC.

Gen. II, 265 L99 Crank in a Gen. II, 350 Block.
C.I.D. Main Rod
350 2.76 2.10
Chevy Big Block Journal Sizes

T = Tall Deck
C.I.D. Main Rod
366T,396,402,427,427T,454,502 2.7488-2.7495 2.20
Chevy 348-409 W Journal Sizes
C.I.D. Main Rod
348,409,427 Z11 2.50 2.20
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http://garage.grumpysperformance.co...-bearing-trashed-in-1-2-hour.5141/#post-71921

http://garage.grumpysperformance.com/index.php?threads/thrust-bearing-wear.619/#post-37676

http://garage.grumpysperformance.co...ed-holes-in-bearings-shells.10750/#post-64733

http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-52466
 
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