These bushings are for the serious enthusiasts who wants the maximum air flow through their engines. Port matching heads to the intake manifolds is quite easily done since one can look into the plenum and see any miss-match. Porting the heads to the exhaust headers is another matter. The professionals who do this for a living have the confidence and experience to pin the header to the head by drilling into the head and not hitting a water passage while installing the pin. These bushings were engineered for the turbo enthusiasts who like to work on their cars but lack the confidence and experience of the professional engine builder.
Stock headers are manufactured with oversize and elongated header flange bolt holes to facilitate easy installation of the header bolts into the head and to allow the header to expand when heated. The extra movement of the header around the header bolts allows the header to move front to back 1/16 (.055) of an inch, and up and down 1/8 (.140) of an inch. The problem with all this movement is one never gets the header back in the same position once it is removed. Consequently locating the header precisely on the head every time is virtually impossible making port matching the head to header a waste of time and money. Any offsets in the port matching causes the exhaust gas flow to tumble, thereby restricting the flow. Using the T-R Stock Header Porting Bushings is a simple method to precisely locate the header in the same exact position every time the header is installed.
With these exhaust header porting bushings installed in the header flange (2 bushings per flange) you can effectively port match the header to the head since the bushings allows the header to move less than .010-inch in all directions. Three of the four precision machined stainless steel bushings are press fit into the existing header flange holes and prevent movement of the header around the bolt. The fourth larger bushing requires elongating an existing round hole in the flange to permit the header to expand when heated. These bushings allow the header to expand from the lower center bolt hole in the flange in all directions when the header gets hot. The only tools necessary for installing these bushings is a round file, flat file and vise.
Exhaust Port Matching Procedure
After the bushings are installed in the header flange, smear a light coat of Permatex non-drying prussian blue or similar compound around the exhaust ports on the head. Be careful not to get any compound on the inside of the port. Install the header on the head and snug up the bolts so the compound is transferred to the header flange. Remove the header and observe the outline of the head exhaust port shape on the header flange. With a tapered burr and die grinder, remove the metal on the flange to where the compound begins. It is acceptable to have the exhaust port in the head slightly smaller than the header port. Now every time the headers are re-installed on the heads, they will be port matched perfectly.
The exhaust header porting bushings align the exhaust header to the head in the exact position every time. These bushings are a MUST for Buick owners whose engines have port matched intake manifold to head ports and want the exhaust head ports matching to the headers to obtain the maximum horsepower from their engines.
Price $20.00 plus $3.00 shipping & handling |
