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Main Stud Kit - 1955-1968 Chevrolet Small Block 2-Bolt Small Journal Engines
PART # SKU MP884
Original price
£39.00
-
Original price
£39.00
Original price
£39.00
£39.00
-
£39.00
Current price
£39.00
Availability:
in stock, ready to be shipped
These are main studs, not head studs. Main and head studs serve different purposes—selecting the right one is crucial.
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.
Disclaimer: Designed to secure crankshaft main bearing caps. This is NOT a head stud kit.
INSTALL GUIDE
This guide covers installation of the XOTIC PERFORMANCE™ MP884 main stud kit for 1955–1967 small-journal Chevrolet small blocks with 2-bolt main caps. Prefer a printable copy? Download the PDF manual.
Small journal, 2-bolt — confirm both before ordering. Chevrolet moved to the large-journal crank for 1968, and four-bolt main blocks use a different fastener count entirely. MP884 covers the early small-journal two-bolt block only. If your block has four-bolt centre caps, see the MP889 kit and guide instead.
Why an early small block needs main studs
A 283 or a 327 that's still in service today is doing something it wasn't originally asked to do — a hot cam and a four-barrel, a stroker crank, or a supercharger on a build where the block is the only original part left. Main cap fasteners are what keep the crankshaft bearing bores round and located under that load, and the factory two-bolt main bolts were specified for output figures from the Eisenhower era.
Studs handle it 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 produces more consistent, more accurate preload — the tensile force in the fastener that becomes clamp force in the joint. On a sixty-year-old casting whose main threads have been in and out more than once, that consistency is worth real money. XOTIC PERFORMANCE™ main studs are manufactured from our premium XOTIC 7200 steel alloy and backed by a lifetime warranty.
What's in the MP884 kit
- 10 × main studs (XOTIC 7200 alloy)
- 10 × hardened parallel washers
- 10 × nuts
- 1 × socket
- 1 × allen wrench
- 1 × fastener assembly lubricant
Before you start: verify first
Confirm that part number MP884 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 an early 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. Loctite may be used for permanent stud installation, but the fasteners must be fully torqued before the Loctite sets.
- 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 sequence diagram, tighten the nuts through the three stages below.
- Check the bores. Upgrading from factory bolts to high-strength studs increases clamping force, which can alter main bearing bore geometry. Check the bores for size and roundness, and perform an align hone if necessary using the same fasteners and lubricant that will be used at final assembly, at the specified torque.
Chevrolet small block 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 small-journal Chevy small block?
30 ft-lbs, then 60 ft-lbs, then a final 90 ft-lbs — three equal steps, following the sequence in the manual.
How do I know if my block is small journal?
Small-journal blocks were built through 1967 and use a 2.30" main journal; from 1968 Chevrolet moved to the 2.45" large journal. Measure the crank or check the block casting before ordering.
Do I need to align hone after installing main studs?
Check first, then decide. The added clamp load from studs can move the main bores. Measure them for size and roundness, and if a hone is needed, do it with the same fasteners and lubricant you'll use at final assembly, torqued to spec.
What about a four-bolt main block?
Different kit. Four-bolt centre caps take sixteen studs — see the MP889 guide.
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: 2025.05.20 (web edition 2026.08).
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