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Main Stud Kit - 1967-1997 Chevrolet Small Block 4-Bolt
PART # SKU MP889
Verified Reviews
Original price
£55.00
-
Original price
£55.00
Original price
£55.00
£55.00
-
£55.00
Current price
£55.00
Availability:
in stock, ready to be shipped
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Disclaimer:
Designed to secure crankshaft main bearing caps. This is NOT a head stud kit.
Why Main Studs?
Main studs provide superior clamping force compared to main bolts, reducing wear on block threads and assisting with main cap alignment. Unlike bolts, which twist during tightening, studs remain stationary, reducing the chance of main cap walking under high loads. They are especially beneficial in high-performance applications where increased stability and durability are required.
INSTALL GUIDE
This guide covers installation of the XOTIC PERFORMANCE™ MP889 main stud kit for 1967–1997 Chevrolet small blocks with 4-bolt main caps. Prefer a printable copy? Download the PDF manual.
Four-bolt mains only — sixteen studs. MP889 is sized for the four-bolt block. A two-bolt small block takes ten studs and a different kit: see the MP884 guide. Count your cap bolts before you order.
Why a 4-bolt small block needs main studs
The four-bolt main block was Chevrolet's answer to exactly this problem — a cap that stays put under load — and it's still the block people reach for when they're building something serious. But a four-bolt cap is only as good as the fasteners holding it, and the factory bolts were specified around a 350 making 300 horsepower, not a 383 stroker with a blower on it.
Studs do the job 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 — and with sixteen fasteners sharing the work, even preload across all of them is what actually keeps the main 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 MP889 kit
- 16 × main studs (XOTIC 7200 alloy)
- 16 × hardened parallel washers
- 16 × nuts
- 1 × socket
- 1 × allen wrench
- 1 × fastener assembly lubricant
Before you start: verify first
Confirm that part number MP889 is compatible with your application before installing any components. Inspect all package contents for damage and clean as necessary to ensure accurate installation. Report any obvious defects or shipping damage to us before proceeding.
How to install main studs on a 4-bolt Chevrolet small block
- Chase the block threads. Clean the threads in the block with a thread chaser prior to installing the studs, to ensure accurate fitment and precise torque readings. The manual specifies the 7/16"-14 chaser (CS314), available separately.
- Thread the studs in by hand. Screw the main studs in as tight as can be made by hand — no tool necessary, and do not apply torque.
- 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.
- Install the main caps. Set the caps in place and ensure appropriate alignment before any load goes on them.
- Lubricate. Using the fastener assembly lubricant included in the package, lubricate the threads of the main studs and the nuts.
- Hand-tighten the nuts. Thread the nuts onto the studs as tight as can be made by hand.
- Torque in three equal steps. Working in the sequence shown in the manual's torque diagram, tighten the nuts through the three stages below.
- Check the bores. Check the main bearing bores for size and roundness, and consider an align hone if the geometry has moved — done with the same fasteners and lubricant used at final assembly, at the specified torque.
Chevrolet small block 4-bolt main stud torque specs
| Stage | Torque |
|---|---|
| 1 | 30 ft-lbs |
| 2 | 60 ft-lbs |
| 3 (final) | 90 ft-lbs |
A common mistake to avoid: when torquing a fastener, do not stop short of the recommended value — continue in one motion until the specified torque is achieved. If you accidentally stop short, loosen the fastener and re-torque. Stopping short and "topping up" produces unequal preload distribution across the caps and can leave a bore out of round.
Frequently asked questions
What are the main stud torque specs for a 4-bolt small block Chevy?
30 ft-lbs, then 60 ft-lbs, then a final 90 ft-lbs — three equal steps, following the sequence in the manual.
Why check stud height with a straightedge?
Because an unevenly seated stud tells you something is wrong in the hole before it becomes a broken stud in service. A stud sitting proud usually means debris at the bottom or a thread that didn't clean up; a stud sitting low can mean the same thing. Within 1 mm (0.040") across a length group is the target.
Do I need to align hone after installing main studs?
Check first. Measure the main bores for size and roundness once the studs are torqued. If a hone is needed, do it with the same fasteners and lubricant you'll use at final assembly, at the specified torque.
Will MP889 work on a two-bolt block?
No — a two-bolt block needs ten studs, not sixteen. Use MP884 instead.
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: 2026.01.31 (web edition 2026.08).
PACKAGE CONTENTS
VEHICLE FITMENTS
⚠️ PROP 65 WARNING
CALIFORNIA WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov
