Ford Mustang 302 & 351 Cylinder Head Bolt Size Guide

Posted 8/9/2017 by Tyler Rodriquez

Not sure which head bolts to get for your engine build? We break down the common sizes and explain which bolts you need for your 302/351 motor build!

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Mustang Head Bolt Sizes

Factory 79-95 302 5.0L Motors - 7/16" Head Bolts
Factory 351W 5.8L Motors - 1/2" Head Bolts
Factory 79-95 302 5.0L Motors w/ 351 Heads - 7/16" Head Bolts + Head Bolt Reducers

Mustang 302 Cylinder Head Bolt Size Guide - Mustang 302 Cylinder Head Bolt Size Guide

Mustang 7/16" Head Bolts

1979-95 Mustangs with factory 5.0 302 motors require a 7/16" head bolt when securing cylinder heads to the block. This includes some aftermarket cylinders that are not made specifically for a 351W setup.

Mustang 1/2" Head Bolts

1979-95 Mustangs running a 351W motor will require the use of 1/2" head bolts when securing cylinder heads to the block. The 351W motors featured 1/2" head bolts, unlike the smaller 7/16" bolts found on factory 79-95 302 5.0L motors.

Mustang Step Down Washers & Head Bolt Reducer Kits

Your factory 5.0 engine block takes a 7/16" head bolt. If you're looking to run 351W cylinder heads, you'll need a step down, or reducer, washer for these to work. Most of your aftermarket aluminum performance cylinder heads, like the GT40X head, also use a 351W size 1/2" head bolt hole. Step down washers take up the slack when installing a 1/2" size cylinder heads, on a factory 302 block that has 7/16" bolt holes. There are kits available with just the step down washers, as well as kits with the washers, and new head bolts!

Ford Mustang 302 & 351 Cylinder Head Bolt Size Guide

Mustang Head Bolt Sizes

Mustang 7/16" Head Bolts

Mustang 1/2" Head Bolts

Mustang Step Down Washers & Head Bolt Reducer Kits

Mustang Cylinder Head Bolt & Stud Kits