


While the primary 14mm head studs get all the attention in a "bulletproof" build, the small M8 bolts located under the valve cover—often referred to as the inner row or top row head bolts—are a critical part of the 6.0L sealing system. The ARP 250-4206 kit replaces these often-overlooked factory bolts with high-strength 8740 Chrome Moly hardware.
When installing a set of ARP2000 or Custom Age 625+ main head studs, completing the job with this M8 bolt kit ensures that the entire cylinder head receives uniform clamping pressure, preventing oil and coolant leaks in the upper portion of the head.
High-Strength 8740 Material: Heat-treated to a tensile strength of 200,000 psi, providing a significantly higher safety margin than the factory Grade 10.9 fasteners.
Uniform Clamping Force: Designed to work in conjunction with ARP main head studs to ensure the cylinder head is compressed evenly across its entire surface area, not just around the cylinders.
Prevents Top-End Leaks: Replacing the aging factory bolts prevents the minor head-to-block movement that can lead to external oil or coolant weeping near the intake manifold and valve cover areas.
J-Form Rolled Threads: Threads are rolled after heat treatment, giving these bolts superior fatigue life and making them far less likely to stretch or snap during installation or thermal cycling.
Direct OEM Replacement: Specifically sized for the M8 locations on the 6.0L Powerstroke cylinder head, requiring no modifications for installation.
Many 6.0L owners make the mistake of reusing the factory M8 bolts when installing head studs. However, these small bolts undergo the same heat cycling and stress as the larger fasteners. If the inner row bolts are fatigued, they can lose their tension, compromising the overall seal of the head.
The ARP 250-4206 kit is the "finishing touch" for any professional 6.0L engine build. By using these alongside your ARP head studs, you are ensuring that your top end is secured by the best hardware in the industry from edge to edge.
Professional Note: This kit is an essential addition when you have the heads off for a gasket job. It includes 10 high-strength bolts and precision washers to replace the entire inner row for both cylinder heads.
PLEASE READ AND FILL OUT THE WARRANTY REGISTRATION FORM TO ACTIVATE THE WARRANTY.

Supplied with every engine is a complete copy of our warranty with an attached warranty registration form. This form can also be found here. Once filled out:
Then email a copy of each document within 45 days from the time of purchase to warranty@choateperformance.com. You should also retain a copy for your records as it may be required to assist with a warranty concern.
MODEL C STANDARD WARRANTY
1 Year / Unlimited Miles

THIS WARRANTY IS WITH THE PURCHASE OF THE INSTALLATION PACKAGE AND IS FOR THE ENGINE/WORKMANSHIP ONLY. NO LABOR PAYOUTS.
EXTENDED COMMERCIAL WARRANTIES ARE NOT AVAILABLE ON WORKHORSE, CASSQUATCH RACE SERIES, OR MODEL C ENGINES.
Remanufactured Heads — 6 Months
PARTS ONLY

Cylinder heads are warranted to be free from defects in material and workmanship. This warranty does not cover cylinder heads that are damaged due to improper installation, overheating, abuse, or accident.
Short Block Engines

Warranty coverage for Short Block engines does not include labor payout. We do not cover fluid leaks on any Short Block builds.
DAILY DRIVER WARRANTY
5 Year / 100,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
Labor rate for PREFERRED DEALER ONLY is a higher shop rate using Mitchell flat rate time.
WORKHORSE SERIES ENGINE
5 Year / 100,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
Labor rate for PREFERRED DEALER ONLY is a higher shop rate using Mitchell flat rate time.
YOUR CASSQUATCH RACE ENGINE
6 Months / 3,000 Miles
PARTS ONLY

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
CHOATE ENGINEERING PERFORMANCE COMMERCIAL WARRANTY
1 Year / 20,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
Labor rate for PREFERRED DEALER ONLY is a higher shop rate using Mitchell flat rate time.
CHOATE ENGINEERING PERFORMANCE EXTENDED COMMERCIAL WARRANTY
3 Year / 60,000 Miles

THIS WARRANTY IS NOT A FULL COVERAGE WARRANTY. PLEASE REVIEW YOUR WARRANTY CAREFULLY.
WARRANTY COVERAGE DETAILS
This warranty will cover remanufactured Short and Long-Block engines that are built by Choate Engineering Performance unless otherwise stated. From this page on, engines will be referred to as “unit(s)” and/or “engine(s)” unless otherwise stated. Fuel pump, injectors, and turbo warranties, and warranties on all accessories, are covered by the supplying manufacturer’s warranty.
FOR PREFERRED DEALERS ONLY: LABOR RATE IS SET AT A HIGHER RATE PER HOUR UP TO A MAXIMUM OF $2,500, NO EXCEPTIONS.
THE LIMITED WARRANTY WILL BE VOID AND WILL NOT APPLY TO DEFECTS OR FAILURES CAUSED BY THE FOLLOWING:
BUYER ALSO ACKNOWLEDGES THAT PROPER MAINTENANCE PROCEDURES ARE REQUIRED TO KEEP THE UNIT IN PROPER WORKING ORDER. CHOATE ENGINEERING PERFORMANCE WILL NOT ASSUME ANY RESPONSIBILITY FOR THE COST OF THIS ROUTINE MAINTENANCE.
Buyer acknowledges the following:
This warranty will not cover damages caused by the following for remanufactured engines:
Choate Engineering Performance limited warranty will end after the expiration of time or mileage from the date of the original invoice. Any repairs or replacements will not extend the warranty. The buyer shall be responsible for all defects thereafter, regardless of cause. Choate Engineering Performance limited warranty is in lieu of all other warranties expressed or implied.
The buyer agrees Choate Engineering Performance will not be responsible for:
TO QUALIFY FOR THE 5 YEAR / 100,000 MILE WARRANTY YOU MUST FOLLOW ALL INSTRUCTIONS AND REPLACE ALL PARTS SPECIFIED.
THIS WARRANTY IS TRANSFERABLE THROUGH PRIVATE SALE AND CHANGE OF OWNERSHIP ONLY ONCE IF CERTAIN CRITERIA ARE MET.
CHOATE ENGINEERING PERFORMANCE LIMITED WARRANTY FOR THE WORKHORSE AND CASSQUATCH SERIES ENGINES IS IN ADDITION TO ALL ITEMS LISTED IN THE STANDARD WARRANTY PACKAGE AND SUPERSEDES ALL MILEAGE REQUIREMENTS.
The Limited Warranty specifically does not cover the following:
FREIGHT / SHIPPING CHARGES

CHOATE ENGINEERING PERFORMANCE SHALL NOT BE RESPONSIBLE, NOR SHALL IT PAY ANY FREIGHT/SHIPPING CHARGES.
ADDITIONAL INFORMATION

As consideration for the above warranties, the buyer agrees they will take no action, statement, characterization, or implication regarding Choate Engineering Performance that may in any manner be interpreted as disparaging to Choate Engineering Performance or the reputation of Choate Engineering Performance. Any violation of this is a material breach, entitling Choate Engineering Performance to void any warranty.