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Butler Performance Custom Short Block, Aftermarket IAII Block, 505-541 cu. in. (Assembled)


  • Customized Butler Performance Short Block
  • Choose Bore Size, Stroke, Crank, & Rod
  • Choose 4.250" or 4.500" Stroke
  • Create a custom package tailored to you
  • All short blocks undergo the "Butler Process"

Please Call for Availability
Availability: Contact sales@butlerperformance.com for current availability.


505 - 541 CI short block
(Aftermarket Block)
  • Assembled by a Butler Engine Specialist
  • NEW IA II Aftermarket Block -sonic tested, completely deburred, bored and honed with torque plate - line honed, deck squared, cam bearings,and brass freeze plugs ready to assemble
  • New Crank 3.25" Mains 4.250" to 4.500" Stroke
  • Ross Pistons- Choose Bore
  • H-Beam Rods or with optional ARP 2000 bolts ($90)
  • Pin Fitted
  • File Fit Rings
  • FM/CL Racing Rod and Main Bearings
  • Balanced Internally
  • Can be upgraded with various options
505 - 541 CI short block with 4340 Forged crank
Contact Us
505 - 541 CI short block with billet crank
Contact Us


The above short block(s) may be upgraded with parts such as:

Add any of our Butler Performance cylinder head packages- Aluminum or Cast Iron

Add these items to the cart to complete your kit;
Oil Pan
Timing Chain
Timing Cover
Stainless Steel Bolt Kit
SFI Damper
Total Seal Gapless Ring
Oliver Rods
Flywheel or Flexplate
Rear seal / Gasket set

Add questions or details to the order notes in the checkout and we will contact you to finish customizing your short block before processing


Images for display purposes only and could show optional parts. Contact us for a custom quote for your application and specifications


These blocks can be used in almost any application from street use (fully water jacketed) to all out racing engines.

**Price Does Not Include machining/bearings for 50MM or 55MM cam

Cast Block Features:
Standard with every IA II block**

Siamese Cylinders: 4.170" Bore but can be bored up to 4.350"

All steel registered main caps: With splayed four bolt pattern on the three center mains which adds rigidity

Block cast: Allows clearance for 4.750 stroke crank.

Main webs: Strengthened to maximum width possible.

Cam tunnels: Reinforced.

Wider pan rails: Provides better oil pan gasket sealing and gasket retention.

Thicker deck surfaces: Provides added strength and aids in cylinder head sealing

Solid lifter galley: With drilled oil returns that prevents lifter bore breakage and adds strength

Improved oiling: Front main oil feed, which adds longevity and helps prevent front main bearing "starvation".

Bottom of the block: Is solid to the bend, above the pan rail, for added strength

IA II Blocks have Redesigned Block Cooling Passages: Improves cooling to all cylinders.

Provisions for external cooling: 1/2" NPT holes provided at the rear of the block. Gives you the option to dry deck the block.

Dual bell housing bolt patterns: For both Pontiac and "corporate" housings.

Lifter bores are deeper to allow the use of standard type "corporate" lifters.

Bottoms of cylinders: Are notched to clear strokes up to 4.75". A 5.0" stroke is possible with some grinding.

Head bolt bosses: Are tied to cylinder walls and the exterior block walls are thicker for added strength.

Oil filter passages are threaded for easy remote filter mounting. Oil pump passages have corner plugs at 90-degree turns to reduce flow restriction. (Plugs are included with kit.)

Threaded front external oil passage: for lubricating superchargers or turbos. The IA II Block uses standard Pontiac 5 bolt Motor mount pattern.

Standard deck height: IA II Blocks are available with 3"

Threaded freeze plug holes: For safety and wall rigidity. This lessens the chance of the engine blowing out a freeze plug.

* Drilling is required to match your heads water holes. Estimated drilling time; 10 minutes.
There is no longer a material alloy surcharge!

Our IA II blocks are machined by one of the best aftermarket engine machine shops in the country. All blocks are checked out on a CNC coordinate measuring machine with-in process probing during manufacturing. We pressure test and sonic check every block. IA II Blocks come with a full warranty for material and workmanship.

ALL Blocks are shipped DRY DECK*

Included reusable engine cradle


  • BP-SB-505-541
  • BP-SB-505-541
  • Butler Performance
  • Contact sales@butlerperformance.com for current availability.
  • New

Shipping Information

  • Item Requires Shipping
  • $395.00

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