P71–Some breathing for the Road Trip car

Chris at ADTR.net has been extremely helpful in terms of guidance and as a source for parts to improve the car that I purchased from CM AutoWerkz.  The car itself has been great and the preparation work done by the guys at CM AutoWerkz  really provided me with a real head start.

In addition to some excellent suspension mods ADTR supplied me with the Stainless Works headers and exhaust that really allowed this Crown Vic to feel some power.  My next call to Chris ended up with my ordering a ported plenum and a set of underdrive pulleys.

The Plenum starts out as a factory Ford casting and is an aluminum elbow between the throttle body and the intake manifold.  Then it is ported and polished to provide a very smooth pathway for the fuel/air mixture on its way to the cylinders.


The job of swapping it out for the factory unit was fairly simple.  I disconnected the hose between the air cleaner and the throttle body and then broke loose the two bolts holding the EGR valve to the plenum.  Then the four bolts that held on the throttle body followed by the five that held on the plenum itself.  Prior to that I had several hoses to disconnect.


Pulling the old plenum off and comparing the two showed just how much work was put into the new piece.  It was substantial. And impressive.



The gaskets were in fine shape and so it was a matter of bolting things back into place starting with the EGR connection.  Once all the bolts were tightened down (very little torque required) and the hoses reconnected I fired up the 4.6 liter engine.  It was fine.  No problems at all.


The underdrive crank pulley replaced the factory harmonic balancer with another, high quality Steeda unit that also was a harmonic balancer, just smaller and with some very nice timing marks.  I used a puller designed for the job as well as an installation tool to ensure that the new one went on properly.  I put on a light coat of anti-seize and when it was seated in place I put a dab of silicone seal on the keyway before tightening the new ARP bolt to hold it in place.  Then it was four small bolts to take off the waterpump pulley and install the new one from the kit.

Chris advised me not to use  the alternator underdrive pulley as, at idle under load, it would not provide the power that might be needed.  Not a problem.  On went the serpentine belt and I fired up the engine again.  Even at idle with the A/C on max the coolant temperature stayed right where it should and everything was good.

Now I was expecting some modest power gain, and I didn’t expect a lot, but what really surprised me was how much smoother the car was especially in terms of the automatic transmission shift points.  If I hadn’t known what had been done I would have assumed that the transmission computer had been re-programmed.  It was that nice.

Thanks again to Chris for the suggestions and advice.  If you have a P71, ADTR.net is the place to check out for mods that improve.

This entry was posted in Automobiles, Car Stuff, Cars, Life and Cars, Modifying Cars, Road Trips and tagged , , , . Bookmark the permalink.

2 Responses to P71–Some breathing for the Road Trip car

  1. Judy Knell says:

    Thanks Jim, any and all improvements made to “my car” are appreciated. 🙂

  2. Linked from ADTRs facebook. Keep up the good work!

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