Butler Performance 407ci (3.905" Bore) Balanced Rotating Assembly Stroker Kit, for 350 Block, 4.250" str.

Our longrod assemblies offer the ultimate in durability and performance!

These assemblies utilize the lightest, strongest pistons and pin design available. We use only the highest quality ROSS Pistons in all of our long rod assemblies, not the cheaper pistons that many retailers sell at a similar price. Our ROSS pistons have the best weight to strength ratio on the market, and use our own proven Butler Performance designs. Nitrous Safe.

• New Cast or Forged Crank 4.250" Stroke
• 3.905" (.030 over) Forged Butler Pistons in Flat Top or Dish
• Specify Desired Compression Ratio
• Aftermarket 990 wrist pins
• Bushed /Full Float H-beam 6.800" rods
• Pin Fitted
• Total Seal Classic Race Rings
• • Rod Bearings are selected based on proper clearance- this clearance is checked and verified by our shop at no additional charge. 
  • Main bearing clearances depend on crank journal size, bearing brand, and main bore finished size. This is not able to be verified in our shop because it requires the bearings to be torqued into the block. We will be glad to return/swap for -1 or X bearings if needed as long as they are in new condition. Buyer responsible for shipping charges on bearing exchanges.
  • Butler Process- Balanced Internally

All assemblies are internally balanced and require a neutral balanced flexplate or flywheel and harmonic balancer. All our assemblies come standard with Total Seal Classic rings. Our assemblies can be upgraded and customized to your project.

CRANKSHAFTS

We offer crankshafts from leading manufacturers such as Scat, Eagle, RPM, and Ohio. These crankshafts come in cast steel or 4340 forged steel.

Cast crankshafts are an excellent alternative to O.E. Cranks. These crankshafts are new cast pieces made with modern material and casting processes to be a great alternative to 30 year old factory cranks. Recommended for use in street engines without power adders. Many factory cranks we check have stress cracks, so even though your crank has not broken yet, you may have a problem developing that could destroy your engine.

Butler Performance also offers Pontiac 4340 forged cranks from from many of the same manufacturers in a variety of sizes, and include the latest in oiling technology. Forged Cranks offer a tremendous advantage in strength and durability over cast cranks. This is very inexpensive insurance to protect your engine and even if its not needed at your current horsepower level now. Upgrading to a forged crank to build a solid bottom end will give you the option to safely upgrade performance and increase horsepower without having to worry about costly breakdowns in the future.

Most cranks offer standard oiling while some may offer Straight Shot Oiling. (noted in crank description)

BORE SIZES

3.905" (.030" over 350)

We recommend having the pistons in hand when machining piston bores to ensure you set the proper clearance based on actual net diameter of the actual piston.

RINGS

Butler Performance uses Total Seal piston rings in most of our engines and assemblies. The main reason for this is their ability to build ring sets for us using rings from most of the major ring manufacturers as well as their own rings. This gives us a huge selection and Total Seal will custom build ring sets for almost any application if it's not an in-stock part. We offer Total Seal rings in several different styles: 

• Classic Race (CR) sets are traditional, non- gapless sets using plasma-moly top rings. 
• AP Advanced Stainless Top Ring (CS) are manufactured from 440B stainless steel and use a C33 face coating which cylinder wall wear. Stronger, Longer life and Most Precise Tolerances
• Gapless Top (M) sets use a 2 piece gapless top ring. These are the latest design by Total Seal and were made possible by the better ring materials developed over the last few years. The top gapless sets are designed to prevent trapping pressure between the top and second rings.

We also offer TNT, stainless, dykes, and diamond lapped sets from Total Seal. If you don't see what you need, contact us and we can get it for you.

Std Rings- The rings are normally "Drop-In" Style rings. These still may require additional filing for your application.

File Fit- The rings are usually .005" over the desired bore size so they can be filed to fit.

Example; Total Seal CR, .030 Over, File Fit, 4.150+5 Bore
This is a Total Seal brand, Classic Race Series ring used in a .030" over bore application. The stock bore is 4.120" plus the .030" making it a 4.150" bore size. The ring will actually measure 4.155" so that there is an extra .005" so it can be filed to fit the desired ring gap.

PINS

We offer a wrist pin upgrade for all rotating assemblies and short blocks. Standard wrist pins that come in our rotating assemblies are rated up to 800hp naturally aspirated. Standard Pins are Ross Racing 5115 Chromoly, .150" Straight wall/128 gram.

Upgraded wrist pins are Ross Racing Bearing Steel .220 Straight Wall Bearing Steel /195 gram. Rated for use in higher horsepower applications.

RODS

We offer rods from several major manufacturers such as Scat, Eagle, Callies, Compstar, Oliver, and more.

Most rods in our rotating assembly's are high tensile 4340 Forged H-beam or 5140 Forged I-Beam. All rods are full floating, bushed unless otherwise noted.

Most rods come with stock ARP8740 rod bolts are rated at a tensile strength of 190,000 psi. Upgraded ARP2000 rod bolts rated at 220,000 are also available.

MAIN & ROD BEARINGS

Our rotating assemblies come standard with bearings included.

• Rod Bearings are selected based on proper clearance- this clearance is checked and verified by our shop at no additional charge. 
• Main bearing clearances depend on crank journal size, bearing brand, and main bore finished size. This is not able to be verified in our shop because it requires the bearings to be torqued into the block. We will be glad to return/swap for -1 or X bearings if needed as long as they are in new condition. Buyer responsible for shipping charges on bearing exchanges.

We recommend having the crank and main bearings in hand when machining the main bores so that proper clearance can be achieved based on actual parts you have chosen. 

Most Forged crankshafts require narrowed Performance or Race bearings because of the larger radius’s on the cranks main and rod journals.

• Federal Mogul (FMP)- M series main bearings
• Federal Mogul (FMP)-CH series rod bearings
• Clevite (C77)- P series main bearings
• Clevite (C77)- HN series narrow rod bearings

The Butler Process

All rotating assemblies sold by Butler Performance, regardless of brand, are balanced in our shop by our experienced machinists.

We don't take anyone else's word when it comes to the parts we stand behind. We put all rotating assemblies through the Butler Process for quality and performance. Our internal balancing process ensures each part of the kit is put through a multi-step inspection process. We then weigh and pin fit the rods and pistons as needed. We computer balance the crankshaft to the rest of the assembly. This process ensures that all the parts of the assembly are matched to form a "Butler Performance" worthy assembly. We then document all weights and information on a balance card that ships with the assembly.