Why are you dead set on an aftermarket crank for if all you want is 500hp? Good pistons and rods, balance the rotating assembly, done.

 

I got a stock crank engine making over 750

 

If you are dead set on a 454 I have the stuff to convert it to run on the stock pcm you have. but have to use a gen VI block

 

DART GEN VII 8.1L Iron Big Block - Technical Notes
Deck Height ................................................ 10.232” (259.89mm)
Bore ................................................ 4.250" thru 4.600" unfinished
Main Bearing Size ................................................ Standard BBC
Main Caps ................................................ All 4 bolt - Steel or Ductile Iron
Weight ................................................ 4.250" bore = 295lb / 4.350" = 280lb
Largest Recommended Bore .................................. 4.625”
Camshaft Bearing Diameter .................................. Standard BBC
Camshaft Position .................................. Standard BBC
Cylinder Wall Thickness, min. .................................. ..300” @ 4.625" bore
Deck Thickness, min .................................. Adequate for all applications
Torque Specs - Main Caps 1 - 5 1/2" bolts 100 ft lbs
W / CMD# 3 2 - 4 1/2" splayed 100 ft lbs
Dart’s inner head studs 3/8” – 7/16” stepped 50 ft lbs
Standard BBC oil filter is used.
Standard GEN VI / 8.1L timing chain, timing cover, and gears can be used.
Actual deck height will be .005"- .010" taller for additional machining requirements.
Standard 8.1L metric oil pan and bolt pattern can be used.
Cam bearing OD should be deburred before installation.
When removing main caps initially, the caps & block should be deburred before reinstalling. This will insure that correct
main size is maintained.
Metric thread & pitch 8.1L head studs or bolts may be used.
Head stud holes are blind. They do not go into the water jacket.
A sealant/antiseize must be used on the head studs. Loctite # 620 is recommended.
Studs should never be torqued into block. They should only be lightly snugged.
It is preferred that a bullet be machined on the end of the head stud where it bottoms in the block to center the stud before
tightening.
.350” OD x .150" Deep
Press-in freeze plugs are provided.
Press-in cam plug dia = stock 2 7/32" 2.215".
Machined for GM 8.1L reluctor wheel pick up. Standard BBC distributor can be used depending on manifold.
Note: Standard BBC distributor can be used with Dart manifold. Be sure to check distributor to oil pump shaft clearance
with distributor, intake manifold and oil pump installed on the block.
oil galley from filter to main galley is 5/8". The main oil galley is stepped 9/16" - 1/2" - 7/16" to insure an adequate oil
supply to the main bearings.
Lifter bores are lengthened .350" for greater lifter support.
Roller Lifters should be Gen VI / 8.1L type which are .300" longer than Mark IV.
Oil pump dowel pins should be .250" OD. Stock GM pins are only .246" OD.
We recommend using Fel-Pro 8.1L head gaskets with the Big M block Gen VII 8.1L
DRY SUMP SYSTEM
If a dry sump oiling system is used you must plug the oil inlet hole in the rear main cap or in the block, underneath the rear
main cap.
Block has threaded inlet for dry sump oil feed in rear of block.
Stock oil filter can be used with a dry sump system.
5/4/2012
PRIORITY MAIN OIL SYSTEM
Oil is directed to the main bearings first, then to the cam bearings.
The lifter galley is fed only from the front.
The lifter galley is threaded for 1/4" NPT restrictors.
NOTE: Due to the extended cylinder walls and variations in distributor and gear dimensions from numerous
manufacturers make sure to check clearance between bottom of distributor gear and block. If it is not adequate, machine
.040" off the OD of the bottom section (w/o gear teeth) of the gear and chamfer the bottom end also.
NOTE: Due to variations in lifter sizes and clearance preferences, most of our Engine Builder customers prefer the lifter
bores sized on the small end of the specification. Sometimes these bores will need to be lightly honed.
NOTE: The two oil filter adaptor attaching bolts should be 1 1/4" (1.250") O.A. length. This will allow 1/2" (.500") of
thread into the block. This is shorter than the stock Chevrolet bolts. This MUST be adhered to.
SPECIAL NOTE: With a multitude of different crank, rod and piston combinations available it is important to check
clearance of all moving parts, especially crankshaft counterweight and connecting rod to block. All parts must be checked
before any type of machining or assembly is attempted.
It is good engine building procedure to ALWAYS check the fit of the distributor before any machining or cleaning is done.
5/4/2012
Dart BBC Big “M” 8.1 L Block
Part # 31253754
Material: Superior Iron Alloy
Bore: 4.250” thru 4.600”
Bore & stroke: 4.625” x 4.750” (max recommended)
Cam bearing bore ID: 2.120” Std.
Cam bearings: Coated, grooved, w/3 oil holes PN# 32210030
Cam bearing O.S. +.010”, +.020”, +.030”
Cam bearing press: .002”
Camshaft position: Standard
Cam Drive: Timing chain, Gear drive & Belt drive
Cam Plug: Standard BBC 2.215” diameter
Cubic Inch: 638 ci (Max Recommended)
Cylinder Wall Thickness: .300 Min @ 4.625” bore
Deck Height: 10.232” (259.89mm)
Deck Thickness: Adequate for all applications
Dist. Tap Hole Valley: Yes
Fuel Pump Boss: None
Fuel Pump Pushrod: None
Freeze Plugs: Std. Press in cup plugs 1 5/8 “dia.
Head Bolt Pattern: Std. GM
Inside Head Studs: None
Lifter Bores: .8427” - .8437” Machined for Gen 8.1L GM Hyd. Roller
Main bearing size: Std. BBC
Main bearing bore: 2.937” – 2.938”
Main caps: Ductile Iron 4 bolt (Steel option available)
Oil system: Wet or Dry Sump - Main Priority Oiling
Oil Galley, main: Stepped, 9/16” – 1/2” – 7/16”
Oil Cooler Holes: None (Can use aftermarket inline)
Oil Galley, filter main: 5/8”
Oil Filter: Stock oil filter location
Oil Pan: 8.1L Metric bolt pattern and oil pan
Rear Main Seal 1 piece, NO gasket groove Fel-Pro 2920
Hyd. Roller Provisions: Yes
Serial No. On main caps / Front passenger side below deck
Starter: Mounts in standard location
Stud & bolt holes: Blind tapped
Tapped Holes: Metric Thread & Pitch
Timing chain / gears: Std. BBC Gen VI / GM 8.1L
Timing Cover: Gen VI stock 6 bolt cover or GM 8.1L
Torque Specs: All ½” bolts – 105 ft lbs
Weight: 4.250” bore (295 lbs)
4.350” bore (280 lbs)
Block Prep Option: Available for additional fee (Call)
5/4/2012
Honing Procedures for
 HONING OIL Sunnen MAN 845-55
 SPEED & FEED CK-10 (C&E) Pulleys
CV-616 185 rpm 50 strokes per minute
 HONING 1) Rough .003” from size Sunnen C30A-25
2) 220 to size Sunnen C30A-55
3) 280 3 strokes Sunnen C30J-65
4) 400 3 strokes Sunnen C30J-85
 REHONE (deglaze) 1) 220 3 strokes Sunnen C30A-55
2) 280 3 strokes Sunnen C30J-65
3) 400 3 strokes Sunnen C30J-85
 RA should be 10 - 24
 SHOE ASSEMBLY TECHNIQUE
Titanium or hard shoe (part# CK-3570) from Sunnen on one side of honing head.
Delron (hard nylon) attached to brass shoe holder & trimmed to size on other side.
(Delron bars can also be purchased from your local plastic supplier)
*** DO NOT use bronze shoe ***
 FRESH OIL IS CRITICAL
These are only recommended procedures we have developed through our Pro Stock
program. Some engine builders have their own procedures for honing our blocks.
All supplies from Sunnen Products
5/4/2012
This Block should be assembled only by experienced, professional engine
builders.
INSPECTION
Upon receiving this block it should be thoroughly inspected for shipping damage.
Prior to machining and assembly please inspect the following items:
Cylinder bores - Oil passages - Deck surfaces - All threads
MEASURING & MACHINING
 All initial measuring should be done before any machining has begun.
 Decks are CNC machined to standard deck heights. If you need a particular
deck height always measure before machining.
 Main journals are finish line honed to the low to middle of the specification.
They should be measured for your preference. If you have need for a different
diameter you must realign hone this yourself.
 Crankshaft & rod clearance should always be checked before any machining is
started. You need .060” clearance for rotating counterweights and rods.
 Due to variations in OD dimensions of the numerous lifter manufacturers, lifter
bores are finish honed on the tight side of the tolerance to leave room for lifters
that are larger than the standard.
WASHING
 Final washing should be very thorough, paying particular attention to all oil
galleys. Use hot soapy water and rinse with hot water first, followed by cold
water which helps reduces rust.
IMPORTANT
5/4/2012
5/4/2012

 

Part# 15400170
Material: Superior cast iron alloy
Comb Chambers: 107cc
Intake Valve Dia: 2.190” or 2.250” option
Intake Port volume: 320cc
Intake Port Dim: Factory 8.1L GM
Int Port Location: Factory 8.1L GM Location
Intake Gasket: Factory GM 8.1L Gasket or Felpro # QMS96057
Exh Valve Dia.: 1.880”
Exh Port volume: 128cc
Exhaust Port Dim: 1.530”T x 1.800”W
Exh Port Location: Raised .050” from factory location
Exhaust Gasket: Factory GM 8.1L Gasket or Felpro # QMS95840
Flow, Intake: 341cfm @ .600” lift
Flow, Exhaust: 252cfm @ .600” lift
Flow Wet: N/A
Freeze Plugs: Dart PN# 32860000B 1 3/8 dia. Brass
Head Bolts: Factory GM head bolts + .270 Dowel Holes
Head Studs: N/A
Manifold: Factory GM or Dart
Milling: Min. 100cc .005” = 1cc flat mill only
Push Rod length: Must be measured / Factory GM 8.1L
Push rod Guide Plate: Dart Adjustable PN# 27001230-4
Retainers: 1.250” or 1.550”
Spark Plug: .750” Reach tapered seat
Spring Pockets: Inner step 1.265” outer step1.550”
Springs: 1.250” Dia. w/ Rotator & 1.550
Valve Length: Intake: 5.235” OAL Exh: 5.425” OAL
Valve Stem Dia: 11/32”
Valve Train: Factory GM valve train
Valve Guides: Integral guides
Valve Guide length: N/A
Valve Guide clearance: .3435” I.D (.002” w/ .3415 dia valve stem)
Valve Guide Spacing: Factory GM 8.1L
Valve Seats: Integral intake seat & Hardened ex. seat.
Valve Seat dia. 2.450” Int. & 2.000” Exh.
Valve Seat angles: 45°
Torque: Use factory GM torque procedures
Intake Manifold (M6 x 1) = 106 in lbs Rocker studs (M10 x 1.5) = 37 ft lbs
Valve Cover (M6 x 1) = 106 in lbs
Weight: 75.5 lbs ea.