Beware the bolt-on!
For fifty years we car enthusiasts have been subjected to myriad claims of “bolt-on” horsepower. Most of the time, carefully tuning and perfecting the OE equipment would have produced better numbers on the dyno than the “hopped up tornado torque cube.” Some products definitely help, and it is hard to argue with a solid aluminum intake that can reduce weight and maybe pick up a few horses. Headers have long been a part of the hot rod recipe, but they are subject to far more installation woes than an intake, and once on they are liable to leak, loosen, and at best make the engine compartment plenty hot. For your trouble you can pick up horsepower, torque and even mileage if the header suits your combo. Certainly for racing a well tuned header is the clear choice no matter what the fitment issues may be. On the street the choice is no longer so clear.
For the street driven car the fitment issue becomes a top priority as well as a safety concern when it comes to tube proximity to brake lines. Aside from the occasional passing move or onramp romp the street car rarely goes over 3500 rpm. I wonder what the real difference is between a header and a set of factory manifolds connected to a well constructed 2 1/2” system below 4000 rpm? I began to really question the validity of street car headers when a particular 1964 Dart entered my life.
The owner of the car had seen an article wherein a new set of full tube in the chassis headers were installed on a ‘64 ‘Cuda. After reading the article the owner bought the headers, took ‘em down to the person doing the six-to-eight conversion and that person said “enough is enough” and sent the hapless customer packing. That is how it landed in my lap.
Now, most of us know that what you see in the magazine might differ significantly from real life and this scenario is no exception to that rule. The magazine mechanics popped these headers into their ‘Cuda in what seemed like a few hours and with little trouble. To the layman it looks like a no brainer -- finally all the horsepower your 360 can pump out can be extracted without resorting to fenderwell tubes. Surely this couldn’t be bad. The magazine article gave helpful tips and even showed how much room there was between the fender apron and the tubes. Wait, did you catch that? Between the fender apron and the tubes, a little room here is good, but what about down below where it really counts? This was my first clue. I kept looking at the photos; they were nearly all taken from above. No good look at the all important area where the tubes come together known as the collector, which is supposed to happen next to a starter, a brake tee, torsion bars (which do indeed MOVE) and a pair of stub frame rails.
This is where things get complicated. The second I saw that the torsion bars as well as the steering column pierced the header I knew trouble could easily arise. Trouble did.
After completely re-routing and bending up a fresh set of brake lines I had clearance and the worst spot was where the stock tee fitting attached to the frame rail. There is just over 1/2” of clearance there. Despite using the recommended mounts and measuring carefully, both headers were resting against the frame rails. I swallowed a fit and kept going. With a careful pull against the collector I got an eighth of an inch on the frame rail. Clearly solid motor mounting was now in order. I installed a Chrysler mini starter with no trouble other than skinned knuckles. Sending the wires to the starter relay by routing them rearward was the only modification. Oh yes, it is tight. One eighth of an inch is all we have from the tube to the starter motor. I wonder how long the starter will last as there is no room for a heat shield.