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ToyotaChevrolet Big Block Main Stud Installation Guide (1965–2000, 2-Bolt) — MP885
This guide covers installation of the XOTIC PERFORMANCE™ MP885 main stud kit for 1965–2000 Chevrolet big block engines with 2-bolt main caps. Prefer a printable copy? Download the PDF manual.
Two-bolt mains only. MP885 is specified for the 2-bolt main big block. Four-bolt blocks use a different fastener count and layout — check your caps before ordering, not after the pan is off.
Why a big block needs main studs
The Mark IV big block makes torque the way few engines do, and torque is exactly what loads a main cap. A 454 with a healthy cam and good heads is producing peak cylinder pressures that arrive at the crank as a hammer blow on every power stroke, and the two-bolt block gives the cap less to hold onto than a four-bolt does. Main cap fasteners are what keep the crankshaft bearing bores round and located under that load.
Studs do 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 gives more consistent, more accurate preload — the tensile force in the fastener that becomes clamp force in the joint — which is what stops cap walk on a two-bolt block. XOTIC PERFORMANCE™ main studs are manufactured from our premium XOTIC 7200 steel alloy and backed by a lifetime warranty.
What's in the MP885 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 MP885 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 Chevrolet big 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 1/2"-13 chaser (CS315), 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 numbered sequence shown in the manual's torque diagram, tighten the nuts through the three stages below.
- Check the bores. Check the main bores for size and roundness before the crank goes back in, and align hone if necessary using the final assembly fasteners and lubricant at the specified torque.
Chevrolet big block main stud torque specs
| Stage | Torque |
|---|---|
| 1 | 47 ft-lbs |
| 2 | 93 ft-lbs |
| 3 (final) | 140 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 Chevy big block?
47 ft-lbs, then 93 ft-lbs, then a final 140 ft-lbs — three equal steps, following the numbered sequence in the manual.
Does MP885 fit a four-bolt main block?
No. This kit is specified for 2-bolt mains. Check your caps before ordering.
What thread chaser does the big block take?
The 1/2"-13 chaser (CS315). Chasing is not tapping — a chaser cleans existing threads without cutting new material.
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.
Building the whole big block?
See our big block head bolt guide (XP980) and the 12-point big block head bolt guide (XP984).
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: 2025.05.21 (web edition 2026.08).
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