ICON Premium Forged Big Block Chrysler 383 "B" 433ci / 491ci Piston Flat Top 4.290" Bore

Name: ICON Premium Forged Big Block Chrysler 383 "B" 433ci / 491ci Piston Flat Top 4.290" Bore
Brand: UNITED ENGINE MACHINE
SKU: 648-IC689.040-1
Price: 198.37 USD
Availability: InStock

^$198³⁷

Ships on 11/05/2026

Lowest Price Guarantee

Chrysler "B" 431ci / 489ci

Flat Top Pistons

431ci Use w/ 6.768" Connecting Rods & 3.750" Crank Stroke

489ci Use w/ 6.535" Connecting Rods & 4.250" Crank Stroke

Big Block Chrysler "B" 433ci / 491ci Forged Piston

Flat Top

4.290" Bore (+.040'')

433ci - 6.768" Rod & 3.750" Stroke; C/R 10.9/75cc; 10.4/80cc; 9.7/88cc

491ci - 6.535" Rod & 4.250" Stroke; C/R 12.3/75cc; 11.7/80cc; 10.8/88cc

1/pkg.

Technical Notes:

For use with 383 "B" blocks
Stock standard 383 cylinder bore is 4.250" with 3.375" crankshaft stroke
4.290" Bore + 3.750 Stroke = 433ci
4.290" Bore + 4.250" Stroke = 491ci

Technical Specs:

Alloy: Premium High Ductility 2618
Bore: 4.290"
Crankshaft Stroke: 3.750" (433ci); 4.250" (491ci)
Connecting Rod Length: 6.768" (433ci); 6.535" (491ci)
Deck Height: 9.980" (B)
Compression Height: 1.318'
Pin Size: 0.9900' x 3.000"
Pin Location: Centered
Flat Top: 2 Valve Reliefs
Effective Head Volume: 4.5cc
Intake Valve Relief: 0.218' Depth / 2.300' Diameter
Exhaust Valve Relief: 0.199' Depth / 1.880' Diameter
Top Landing Height: N/A
Ring Grooves: 1/16' Top; 1/16' Middle; 3/16' Bottom
Gram Weight: N/A
433ci Compression Ratio: 10.9:1 w/75cc Heads; 10.4:1 w/80cc Heads; 9.7:1 w/88cc
491ci Compression Ratio: 12.3:1 w/75cc Heads; 11.7:1 w/80cc Heads; 10.8:1 w/88cc

United Engine and Machine Company is proud to introduce their new Icon line of forged pistons. Icon brings the same quality and performance you've come to expect from other United Engine brands while adding a new lightweight forged design. No matter your high performance application, there is an Icon piston for you.

Features:

High ductility 2618 alloy
Perfect for Nitrous, Turbocharged and Supercharged Apps
Dual forced pin oiling on most applications

Lateral gas porting on higher compression ratios
Fully machined with deep valve pockets
Second land accumulator grooves
Top land mini groove technology
Diamond finished skirts
Triple wound spiral locks
Spacer rings included in short compression heights that intersect the wrist pin bore

Part TypePiston

Product LineUEM Pistons Icon Premium Forged Series Big Block Chrysler Pistons

BrandUNITED ENGINE MACHINE

Package Height4.3

Package Width4.5

Package Length4.6

Weight1.47 PG

Part CategoryPerformance Parts

Part FitmentSemi Universal

Vendor Part NumberSIC689.040

Package Qty1

Package TypeEA