Posted on: March 27, 2009

by Phil Lindsay
Originally printed 3/80

When your Tiger is crawling along in slow traffic, the under hood temperatures can go out of sight. All of the engine cooling aids such as aluminum intake manifolds, header pipes and extra large radiators depend upon dumping their heat into the engine compartment. What’s needed is an under hood cooling system to remove this heat build-up when there is insufficient road speed to pull the hot air out of the bottom of the engine compartment.

There are several ways to do the trick, ranging from the obvious hood louvers to exotic exhaust fan systems. Since I try to keep my Tiger stock in outward appearance, I choose to provide cooling ports without the addition of hood or fender louvers. With the aid of a chassis punch (the cup and die type used in the electronics industry), I made a series of 1 1/4″ diameter holes in the wheel well area.

Although a hole saw would also work, the limited access might be a problem unless the engine compartment was stripped clean. The chassis punch provides a very smooth edged hole that will work well with a rubber grommet plug. The diameter of the hole should match the grommet size. I was able to locate grommet plugs with a 1 9/32″ diameter so I selected a hole punch with a 1 1/4″ diameter. Obviously, if you don’t drive your Tiger much in the rain, you don’t need the plugs. I use the plugs only during the heavy rainy season (November – April).

The number and location of the cooling ports probably isn’t important as long as the hot air can escape. I have approximately 16 holes on each wheel well and in order to avoid weakening the wheel well, I spaced the holes at least an inch apart.

Try not to place the holes directly in line with the electrical connections on the generator voltage regulator or starter solenoid. After using this set-up for over 2 years, I am convinced it works.

Lots of hot air can be felt around the front wheel wells when the Tiger idles. I doubt that the ports are effective at highway speeds due to the air turbulence created by the tires. Although the wheel well cooling ports are easy to do and don’t change the stock appearance of the car (at least from the exterior), the approach is a bit messy and may not appeal to everybody.

The punch and rubber grommets may be obtained from the following:

Punch: Model 730 Round Radio Chassis
Greenlee Tool Company
2136 12th Street
Rockford, IL 61101

Grommet Plugs: 1 3/4″ diameter
AA Rubber and Plastics
2960 25th St.
San Francisco, CA 94110
415-826-3740

Model 963 Rubber Grommet Plug
Atlantic India Rubber Company
571 West Polk St.
Chicago, IL 60607

Call or write for current price and availability information.

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