Mazda / Ford 2.5L KL V6 Main Stud Installation Guide (1993–2002) — MP882

This guide covers installation of the XOTIC PERFORMANCE™ MP882 main stud kit for the 1993–2002 Mazda / Ford 2.5L KL V6 — MX-6, 626, Millenia and Ford Probe GT. Prefer a printable copy? Download the PDF manual.

Why a KL V6 needs main studs

The KL is a compact, high-revving 60-degree V6 with an aluminium block and a bolt-on main girdle — an unusually sophisticated design for a mid-90s family car, and one of the reasons it stands up to boost as well as it does. But everything that holds the crankshaft in a KL passes through that girdle, and the factory bolts were specified for a naturally aspirated engine turning modest power. Turbocharge one, or build a KL-ZE and spin it, and the loads at the main caps go up sharply.

Studs handle that better than bolts for a structural reason. A bolt is torqued into the block, so it twists and stretches at the same time; a stud is threaded in finger-tight and stays still while the nut is torqued against it, loading the stud in pure tension. That gives more consistent, more accurate preload — the tensile force in the fastener that becomes clamp force in the joint. On a girdled aluminium block, even preload across every position is what keeps the tunnel straight. XOTIC PERFORMANCE™ main studs are manufactured from our premium XOTIC 7200 steel alloy and backed by a lifetime warranty.

What's in the MP882 kit

• 16 × M10 × 157 mm main studs (XOTIC 7200 alloy)
• 8 × M8 × 142 mm main studs
• 16 × nuts
• 16 × hardened parallel washers
• 2 × sockets
• 2 × Allen keys
• 1 × fastener assembly lubricant

Before you start: verify first

Confirm that part number MP882 is compatible with your application before installing any components. Inspect all package contents for damage and clean as necessary to ensure accurate installation. You will also need a torque wrench (1/2" and 3/8"), an M8 × 1.25 bottoming tap, an M10 × 1.25 chaser (CS318), ratchets and extensions, RTV sealant such as Permatex Ultra Grey, and brake cleaner or acetone. Report any obvious defects or shipping damage to us before proceeding.

How to install main studs on a 2.5L KL V6

1. Clean and prep the block. The block must be completely clean and dry. Clean the threads thoroughly with brake cleaner or acetone using a brush or swab, blow out every main stud hole with compressed air, and confirm all holes are free of debris.
2. Tap or chase the threads. Use an M10 × 1.25 tap or chaser (CS318) on the main holes, and an M8 × 1.25 bottoming tap on the M8 holes, cutting all the way to the bottom. Add light cutting oil, work slowly by hand, and don't force the tap until it reaches the bottom of the M8 holes. Blow the holes out again afterward.
3. Test-fit the studs (recommended). Hand-thread each stud dry into the block to verify depth and clean threads, then remove them all before you go near the RTV.
4. Install the main girdle. Apply a continuous bead of RTV to the mating surfaces between block and girdle, lower the girdle into place against the dowels, press down evenly, and let the RTV skin over for 5–10 minutes (check your sealant's instructions). Do not disturb the girdle once it's set.
5. Install the studs through the girdle. With the girdle in place, apply the supplied thread lubricant to both ends of each stud and thread it through the girdle into the block by hand. A 3 mm or 4 mm Allen key can be used to lightly run them in. Do not overtighten — finger tight is enough, and seating should be consistent across all studs.
6. Check stud height with a straightedge. Use a straightedge ruler to measure the distance from the mating surface (deck or main cap) to the top of each installed stud. Ensure all studs of the same length group sit level with each other (within 1 mm / 0.040”). Uneven height may indicate debris or incorrect thread engagement. Properly installed studs will bottom out smoothly and show uniform height across all positions. If a stud appears higher or lower than the others, remove it, re-clean the hole, and reinstall by hand. Do not use tools to force studs deeper. Incorrect stud seating can cause off-angle stress, uneven preload, or stud fracture during engine operation.
7. Fit washers and nuts — dry side down. Apply lubricant to the underside of the nuts and to the top side of each washer, with the rounded edge facing up. Do not put lubricant on the flat underside of the washer that contacts the girdle. Place the washers on the studs with the dry flat side down, then thread the 12-point nuts on by hand until seated.
8. Torque in three equal steps. Working in the sequence shown in the manual's torque diagram, bring the nuts up to the final values below in three equal steps.
9. Final inspection. Verify the washers are seated flat with dry undersides, the nuts are fully torqued in the correct order, and the RTV is evenly compressed without excessive squeeze-out.
10. Check the main tunnel. Check the bores for size and roundness. In most cases the block will need to go to a machine shop for an align hone to correct main tunnel distortion — done with the same fasteners and lubricant used at final assembly, at the specified torque.

KL V6 main stud torque specs

Reach both values in three equal steps across the full sequence — not one fastener at a time to final torque. Consistency depends on using the supplied lubricant, applied exactly as described above.

Frequently asked questions

What are the main stud torque specs for a 2.5L KL V6?

62 ft-lbs final on the M10 studs and 28 ft-lbs final on the M8 studs, each reached in three equal steps following the manual's sequence.

Why can't I lubricate the whole washer?

Because a washer that can spin freely against the girdle changes the friction the torque wrench is reading, and you end up with wildly different preload from one stud to the next. Lube the top face and the underside of the nut; leave the flat face that contacts the girdle dry.

Do I really need an align hone?

Plan for it. The manual is explicit that in most cases this block will need one after a stud upgrade — the added clamp load moves the main tunnel. Measure the bores for size and roundness, and if they've moved, hone with the same studs, nuts, and lubricant you'll use at final assembly.

Which cars use the KL V6?

The Mazda MX-6, 626 and Millenia, and the Ford Probe GT, from 1993 through 2002.

Need help?

For technical support, email support@xotic-performance.com. All XOTIC PERFORMANCE™ fasteners are covered by our limited lifetime warranty. Finished your install? Tag #XOTICPERFORMANCE on Instagram for a chance to be featured.

© 2026 XOTIC PERFORMANCE™. This installation guide is an original copyrighted work of XOTIC PERFORMANCE™. Reproduction, distribution, or use of this content in whole or in part without written permission is prohibited. Doc ref: 2025.08.13 (web edition 2026.08).