Powerbuilt Piston Ring Compressor Set with Ratcheting Pliers — 6-Band Kit 2-7/8"–4-3/8", steel bands & carrying case

Powerbuilt's Piston Ring Compressor Set with ratcheting pliers (940387) is a six-band kit that lets you compress and install piston rings on pistons from 2-7/8" to 4-3/8" quickly and without ring damage.

When installing new pistons, controlling the piston rings is the difference between a smooth rebuild and repeated rework. This Powerbuilt kit combines six adjustable steel bands, a ratcheting clamping plier, and a heavy-duty carrying case with laminated instructions so you can compress rings evenly and reinstall pistons with confidence. It's designed to handle a broad range of piston diameters commonly found in automotive and light-duty engines.

How does the ratcheting plier improve piston ring compression?

The ratcheting lock plier lets you tighten the selected band in controlled, incremental steps so the rings close uniformly around the piston. The ratchet mechanism holds tension without slipping, which reduces the chance of ring splaying or catching during installation.

• Ratcheting action provides incremental tightening and secure hold.
• Locks at target diameter to free your hands for alignment.
• Reduces ring distortion compared with manual squeezing.

What piston sizes does this set cover and how do I pick the right band?

The kit includes six bands that together compress pistons from 2-7/8" (73 mm) up to 4-3/8" (111 mm), covering many stock and aftermarket applications. Choose the band whose diameter range contains your piston outer diameter, attach it to the plier, tighten until snug, and the band will hold the rings in place for cylinder insertion.

• Band ranges: 2-7/8"–3-1/8", 3-1/8"–3-3/8", 3-3/8"–3-5/8", 3-5/8"–3-7/8", 3-7/8"–4-1/8", 4-1/8"–4-3/8".
• Select the band that fully encompasses piston diameter for even compression.
• Use the ratchet to tighten gradually and check ring end gaps before installation.

Can this kit protect piston rings and speed up engine assembly?

Yes — by keeping rings evenly compressed and aligned, the kit lowers the risk of ring nicking or misalignment that can occur when forcing a piston into a bore. The reusable bands and stable clamping help speed repetitive installations during multi-cylinder engine builds.

• Prevents ring catching and tangling during insertion.
• Reusable steel bands for multiple rebuilds.
• Speeds up multi-piston jobs with consistent results.

What does the case include and are instructions provided?

The molded heavy-duty case stores all six bands, the ratcheting plier and features laminated instruction sheets that are permanently attached for immediate reference. The instructions include step-by-step photos and guidance developed by a professional repair manual writer to help you use the tool correctly the first time.

• Durable storage case keeps parts organized and protected.
• Laminated, permanently mounted instructions with photos.
• Kit engineered for shop use and repeated service cycles.

Who this is for: This Powerbuilt Piston Ring Compressor Set is aimed at professional mechanics, home engine builders, and hobbyists who need a dependable, wide-range compressor for automotive and light-engine piston installation. If you frequently work on multi-cylinder rebuilds or want to protect new piston rings during assembly, this kit offers the coverage and control to make installations faster and more reliable.