[74stang2togo]

Just completed this today. The long out-of-production Dynomax Blackjack headers for our cars were the best-fitting design available at one time.

Because they fit the best, does NOT mean they are the easiest to install.

If you happen to score a good used set, or God-willing, a new-in-box set from somewhere; here's what you'll need to know to install them.

(Before you begin, you will want to remove your battery and battery tray, and the smog hoses running along the engine on the passenger side, if present.)

1. Remove your factory exhaust manifolds: If they're anything like mine, they've been in there a long time. I recommend using a 1/2-drive ratchet to break each bolt loose at the head, and an impact wrench for the two holding each flange on. The driver's side manifold is quite easy to remove. The passenger-side manifold is tricky for several reasons. On the passenger side, you'll be best off cutting the downpipe from the manifold off before removing the bolts to the head. Then you will want to lower the manifold down to where you can get to the head of the bolt that goes through the manifold flange with a wrench for removing the pipe. After THAT, you'll find a small metal plate bolted to the firewall. You'll need to remove that to lift the manifold out, it will catch on it otherwise.

2. Remove the remaining exhaust system (unbolt and/or cut hangers as necessary, cut the over-the-axle pipe if needed; this only applies if you're not going to re-use any of the existing system.)

3. Remove the two bolts that hold the passenger-side motor mount to the engine, and the motor-mount through-bolt on the driver's side.

4. Jack the front end of the car up a MINIMUM of 3 feet (yes, 3 feet, you'll need a truck jack and truck jackstands for this one!)

5. Using an engine hoist, lift the engine up at least 3 inches. It may help to remove the radiator hoses (drain coolant first) and loosen up the transmission mount bolts.

6. The driver's-side header goes in from UNDER the car. To ease installation you can remove the steering shaft, but re-installing it after getting the header through there probably won't be easy. If your headers are simply painted, or already rusty, you can shove this one up there with some grunt-work and an accomplice to help guide it's path from above. Having a BIG pry bar to rock the engine back and forth a little also helps. This side is the EASY side if you have an automatic.

7. The passenger-side header goes in from above OR below the engine, either way at a steep angle. If you have an automatic transmission, the bellhousing will be in your way either way. If you grind the slightest bit off of one of the corners of the exhaust flange on the header, it will help with clearance (had already been done to mine, purchased used on Ebay) Grunt work will be needed here too to shove it down through there.

8. Lower the engine back into place, watching the headers as you do so to avoid damaging them (this is NOT an experience you will ever want to repeat at this point, these suckers are NOT easy to get in there!)

9. Bolt everything up, replacing any and all removed components from the car with the exception of the exhaust manifolds and exhaust system.

My dad and I did the bulk of the work on this project this morning on my 1976 Ford Mustang II 5.0/Automatic. It took us approximately 6 hours overall. Your experience with this installation may vary based on your car's year, options, powertrain combination, modifications, and condition.

Recommended tools are as follows:

1/2-drive impact wrench
1/2-drive ratchet
3/8-drive ratchet
3/8-drive extensions (various lengths)
1/2-drive extensions (various lengths)
1/2-drive socket set (SAE, deep and shallow)
3/8-drive socket set (SAE, deep and shallow)
hacksaw, sawzall, air cutoff tool, tailpipe cutter (something to cut tailpipe with!)
Large Prybar
1/2-drive flex joint
3/8-drive flex joint
Hydraulic jack with at LEAST 30" of lift range (will need to be either a shop-style floor jack or an SUV/Truck jack)
Properly-rated jack stands with 30" or more in height
Engine lift

[Matt12192]

what causes aftermarket headers not to fit in the mustang II?

[nigel]

They make headers just for the II's. That fit without having to do all of that and go on in about 30 minutes.

[74stang2togo]

Originally Posted by nigel

They make headers just for the II's. That fit without having to do all of that and go on in about 30 minutes.

These WERE Mustang II specific headers.

None of the Mustang II headers install easily because there is no room in the engine compartment to spare.

The Heddman headers are by far the easiest, taking only a few hours (Not even a small-block Chevy in a pickup can be done in 30 minutes from removal of manifolds to installation of headers.) but I'm not a fan of a slip-fit primary tube that runs under the crossmember and is prone to leaking or getting bent if you hit a bump in the road.

The Dynomax headers were among the harder to install designs, but once in there, offered the BEST in ground clearance, fitment (not too close to anything, no rubbing, no issues at all, even with the automatic tranny), and offered great performance.