Model A & B

Ford Garage

Snap-on Cylinder Head Nut Wrench

This Snap-on cylinder head nut obstruction wrench is the perfect wrench to use on the Model A and Model B engine!

This obstruction offset style wrench has a 1/2 inch square drive and an 11/16 inch twelve point box end. It has the drive end located exactly over the box end, and it is used with a 1/2 inch torque wrench directly with no offset correction needed. The torque is applied exactly in line with the stud and nut axis.

The dogleg in the wrench gets around the water hump on the top of the head, as well as accessing the nut under the distributor without disturbing or removing anything.

This wrench also accesses all the intake and exhaust manifold nuts, with carburetors installed, including aftermarket Weber carbs and manifolds, and downdraft manifolds shown on other Ford Garage pages. Not exactly inexpensive, but an amazingly useful quality tool!

These genuine Snap-on forged alloy steel offset obstruction wrenches are far superior to the crude fabricated wrenches intended to do the same job and sold by some of the Model A reproduction parts suppliers.

These obstruction offset wrenches are found in two sizes. The original and the 'A' suffix are both about 8-1/2 inches long, while the 'B' suffix is about 7-1/4 inches long. Both lengths work fine on a Model A.

There is also an identical version obstruction offset wrench made by Bonney which is about 8-1/2 inches long, and equal in quality to the Snap-on.

For Sale:
These 11/16 inch cylinder head nut wrenches have been out of production from Snap-on for quite a few years now, but I often have a couple of nice used ones available for sale for $60 each.
I also currently have two NOS Bonney's for $45 each.

Bonney on the left, Snap-on on the right.


Beware of Repro Catalog Wrenches!

For your further entertainment and information, here is the currently available repro catalog wrench being touted by a couple of persons on the Model A internet message boards as being a good and cost-effective alternative. (Not!).

On a recent internet thread, I recommended the Snap-on wrench shown at the top of this page. Based on my post, another person countered with the virtues of the lower cost mickey mouse repro catalog wrench shown directly above and below.

It did not turn out so well for the person buying the repro catalog wrench over the Snap-on. This is what happened after applying 55 ft-lbs of torque to a wrench that is not up to the task!

After applying torque to only four studs, the repro wrench cracked and broke. The buyer then contacted me asap to see if I still had any more Snap-on wrenches available. I priority-mailed him one in time for his July 4th (2017) activities, and in return, he sent me this failed repro so it could be featured here as a warning to others!

It is unfortunate that the repro catalog wrench was designed and made by someone who had no engineering education or basic mechanical aptitude, and even more disappointing that the catalog companies sell this junk to unsuspecting Model A owners.

The reproduction catalog wrench is water jet (I believe) cut from of low carbon mild steel plate and bent into final shape. The actual socket ends are pitifully designed with insufficient section size in the corners and large stress risers.

It would seem that any tool designer with any engineering education or relevant mechanical experience would predict failure due to insufficient raw material strength and elevated stress levels caused by poor product design. Apparently not!


Professional grade tools enable professional results!

Quality OEM Snap-on and Bonney wrenches are forged from chrome-vanadium alloy steel, are sized for adequate strength and durability in use, and are designed per sound engineering principles.


More related information on Ford Garage:

  1. For more Model A & B related information, use the Site Search box at the top or bottom of this page.
  2. Model A & B Cylinder Head Gasket Guide comprehensive listing
  3. Model A & B Cylinder Head Compression Ratios
  4. Model A & B Cylinder Head Nut Tightening Sequence
  5. Model A & B Cylinder Head and Distributor Pullers by Ron Cloat
  6. Model A & B Cylinder Head Stud Removal Tools
  7. Model A & B Broken Cylinder Head Stud and Bolt Removal

April 2003