Clearance for Valve Covers
An Article by Tim Ronak
Preface: Tim Ronak has prepared a fine article for those who are having difficulty with valve cover/firewall interference, when removing or replacing the valve cover. This can be caused by thicker valve covers, such as aluminum castings, thicker gaskets for higher roller rocker arms, and/or the thicker aluminum head replacements. The original LAT Tiger lettered valve cover, as supplied in LAT-2 and LAT-8, had the rear fins removed in the casting mold, as opposed to the ""COBRA" lettered version, or the Ford "Motorsport" version, to prevent interference with the firewall in a stock installation, except for access to the attach bolts. But if you have asuch a problem with your valve covers, thicker gaskets, or the aluminum heads that are generally a good deal thicker than cast iron originals, here is a solution. Sunbeam Specialties has the original LAT valbe cover molds, and produces them as the original, without fins in the rear.
How to Build Clearance to Easily Remove the Aluminum Valve Covers
For the strong of heart there is a way to improve the clearance around the valve covers for easy removal of the covers with the engine firmly affixed. Originally I had decided to modify my car only with bolt on bits. Unfortunately after the installation (fitting) of my new engine with the aluminum covers and TFS Twisted Wedge Heads, it was impossible to remove the cover on the Drivers side due to the increased height of the Posi locks and Comp Cams Roller Rockers. The clearances were TOOOO tight even for the tin covers. See Figure 1 Because I intend to drive my car a lot, I want to also be able to service it easily. For this reason and this reason only I decided to modify the firewall. I also won't deny that the fact that the engine was already completely assembled, also played a part in my decision. This article is definitely NOT for the purist and originally I was only going to cut the areas immediately above the valve covers. Instead I decided that the 2 notches would be more noticeable, more work and more unsightly than if I was to do a clean modification across the entire opening. I really feel this is what the Jensen factory should have done in the first place.
If you look carefully at the Tiger tunnel picture (Figure 2) it is unmolested except for some massaging of the firewall (beating with a hammer) off on the right (Drivers Side) where I tried the mallet clearance method (apparently used on the assembly line) to no avail. Remember I did this to allow for Twisted Wedge Heads, which are about 3/8 of an inch taller than stock heads along the valve cover rail with all other external dimensions unchanged from stock. While this extra height in the valve-cover mounting rail reduces clearance to the firewall with the cover installed, it has no bearing on the serviceability. Serviceability is only limited due to the obstruction created by the internal mechanisms like rockers and Posi-locks given the close quarters you have to work in to raise the valve cover off of the engine. My clearance issues were with interference from the rocker arm and retaining nut in trying to REMOVE the valve covers. If you plan on running 7/16th studs and posi locks AND the Tiger aluminum covers this extra clearance may be a good idea for you as well. It is important to note that with some slight dinging around the motor mounts the Headers from Rick at SS seem to fit great.