One of the best mods on my Mustang 3.7L engine
July 19, 2014
It gives my Mustang better low end torque, better throttle response, better sound, and better engine bay appearance. I have to say it is one of my favorite mods so far.
The first set of BBK headers I received had uneven flanges, but AM sent me a new set to get it right. Below are my install instructions in case you find them useful.
I bought the OEM gaskets from Ford dealers ($9.50 each at whole sale price). To make things easy, I also removed the strut tower brace, CAI, battery and tray, the starter. I heard many stories about how hard it is to take off bolts connecting the exhaust manifolds with mid-pipe, so I sprayed some WD40 one night before, then it became a piece of cake. The tool I used are a 20 inch long extension, coupled with a swivel joint, and a 15mm deep socket. I used jack stands and some wood to support the mid pipe after they are disconnected from the exhaust manifolds.
Taking off the stock manifolds is a 20 minute job. Some of the studs came out with the nuts. After all the studs and nuts come out, I socked them in WD45, took the nuts off by using a 5mm socket and 13mm wrench. Then I installed all of the bolts back to the engine block.
For the passenger side, the only headache is the lower rear bolt. The issue is that after the header is installed the top of the bolt is only about 1/4 inch away from the header tubes. What that means is that if you tighten it up all the way using a box end wrench, you would not be able to get your wrench out. What I did is to just hand twist other nuts to the bolts, leaving the header hanging loose. I used my 13mm gearwrench to tighten up about 2/3 length of that bolt, then took out the gearwrench before it is too late. I then tighten up all of the other 5 bolts from above the engine bay by using the 13 mm gearwrench. The lower rear bolt was tightened up with a 13mm open end stubby wrench.
I torqued them up in the order of upper middle, lower middle, upper rear, lower rear, upper front, lower front. I used a 13mm line wrench to get this done, and made them as tight as I cold. My hand strength is not as great as that of a gorilla. :-)
The driver side is a whole lot easier. The only thing is to maneuver the header to the bolts. I had to disconnect the steering column shaft by removing the bolts towards the firewall in the engine bay. You can use gearwrench for all of the 6 bolts all the way. For the lower rear bolt, I used a stubby 13 mm gearwrench from beneath the car.
The correct order to tighten the four mid-pipe bolts on two sides are: lower right, lower left, upper right, upper left. First tighten all of them to 89 lb-in, then increase by 89 lb-in until you reach 30 lb-ft. That's how the service manual says in order to align the exhaust system.
The toque for the bolts on the connector between the mid-pipe and the pipe connecting the muffler is 35 lb-ft. Starter bolts: 35 lb-ft. Steering column shaft bolt: 18 lb-ft. Strut tower brace bolts: 26 lb-ft.
I am very happy with the results. So far there is zero leak.