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The installation of headers on any of the 1963-1966 early A-bodies can be a very daunting task. Anyone who has done it can attest to the pain, cursing and knuckle busting it takes to get them into these tight fitting engine bays. This article hopes to describe the installation of Doug’s Headers into my 1966 Plymouth Valiant.
The Valiant has a warmed over small block LA 360 engine and later 70’s model 4-speed transmission and bell housing. The stock 273 exhaust manifolds were causing some major constipation for this motor. Corked up horsepower and torque was dying to be unleashed with the addition of these Doug’s headers.
I tried to take as many pictures as possible to show how these headers fit and the clearance issues that may arise depending on your engine setup. The Doug’s instruction sheets are pretty straight forward and it would behoove you to follow them closely. Getting ahead of yourself and not following them will cause you some major frustration and set backs. This was all done with common automotive tools in my backyard. The actual installation time for me was about 10 hours due to some fitment issues that will be described later.Let’s get started with the disassembly. Pictured is the engine with the stock 273 manifolds.