[496 vs 427 tall deck]

i have 427 tall deck truck #473478 and #353049 head, weiand stealth 454 intake if i want stroke to 496 with flat top piston i know need .060 bore + 4.25 crankshaft, and spacer intake kit.

 

but what rod length and piston type should i use?

[building a TALL DECK 496 stroke BBC]

i have 427 tall deck truck #473478 and #353049 head, if i want stroke to 496 with flat top piston i know need .060 bore + 4.25 crankshaft.

what rod length and piston type should i use?

 

got a truck block? want a 496 vs a 427

if you have or can purchase a tall deck 427 bbc engine..there are potential mods you can make..

 

now Im well aware most of you may not ever use a bbc engine, but if you do...heres some info

IF the rest of the basic engine is servicable,Id rebuild it with a mild port clean up,a valve job,a re-ring and new bearings, plus the tall deck block allows you to use longer connecting rods and a 4.25" stroke crank, to build a 496 displacement 10:1 cpr engine ,youll need the block bored and honed at .060 over(4.310 bore) done very easily,just the increase in displacement and compression (with the correct, crank, rods and pistons) matched to a reasonable cam will make a very noticable power increase

kits like this are available for the standard 9.8" blocks

 

http://www.sallee-chevrolet.com/Sca...embly_Kits.html

 

crank rods. pistons, ballanced for about $1400

add a cam like this

http://store.summitracing.com/default.as...p;x=29&y=14

 

and with no other changes to the basic engine youll have a noticable power increase

Id expect to spend under $3000 and have a reasonably effective street combo

 

but since your useing a tall deck block youll want to purchase all the parts seperately

 

chevy has produced two comon bbc block heights, the comon pass car 9.8" deck block and the taller less comon 10.2" truck block, truck blocks allow more clearance but they move the heads further appart so spacers or differant intakes and a few other parts are necessary, I personally PREFER truck blocks as they tend to be thicker and cheaper, as fewer people want to use them

 

it should be OBVIOUS that youll need to do a MINIMUM of homework BEFORE ordering parts for a 496 bbc stroker kit to fit a tall deck block

 

here this calculator will help

http://kb-silvolite.com/calc.php?action=piston_comp

 

the standard BBC has a 9.8" deck height, the TALL block has a 10.2" deck thats .400 taller, so youll want to use standard 454 pistons to keep the cost low and make up the differance in connecting rod length for a better rod/stroke ratio.

keep in mind youll want to use longer rods and lighter pistons for a better rod/stroke ratio WITHOUT getting into CUSTOM parts

the comon longer than stock,bbc rod lengths available are 6.385",6.585",6.8"

 

BUT ,look a standard 454 bbc has a 4" stroke, 6.135 rod and a 9.8" deck so the pistons got a 01.665" pin height the same block with a 3.76" stroke crank from a 427 would use a 01.785 pin height, neither will work in a 4.25" stroke 10.2" deck block application

 

these pistons below have a 1.27 pin height

 

http://kb-silvolite.com/performance...ls&P_id=358

 

the tall deck with its 10.200 deck and a 1.27" pin will require a 6.8" rod

 

http://store.summitracing.com/default.as...p;x=35&y=14

 

1.27"piston pin height, + 6.8" rod length + 1/2 of 4.25" stroke(thats 2.125") equals 10.195" or .005 below the 10.2" deck on a tall deck block

thats a 1.6:1 rod/stroke ratio, or close to the 1.63:1 a 350 chevy has and better than the original 454s 1.53:1 ratio, even thought the strokes been increased

 

a combo like that should exceed 550 ft lbs and 500hp easily