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Discussion Starter #1
I’ve been following some older threads on DIY 8 rib conversion using parts for a navigator. I ordered all the parts from the thread.
Item (Ford motorcraft P/n) 4.6L 8-Rib Conversion Pulleys Name Ford Part Number Cost Alternator pulley GP-720 $20.84 Power steering pulley XL3Z-3A733-AA $16.63 A/C Clutch pulley YB-522 $71.48 Tensioner 1L3Z-6B209-AA $42.30 Crank pulley XL3Z-6312-CA $60.82 Idler pulley YS-250 $19.66 Water pump pulley F6TZ-8509-AA $18.05
I’m having multiple problems getting everything to fit. First off the tensor listed, the bolt holes don’t line up. I understand going 8 rib all the pull-ups will be wider but nothing seems to fit not even close. You can see the comparison of parts how different they are. Does anyone have any pointers in getting the 8 rib set up besides ordering a $600+ kit? This is a 98 cobra
 

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So update. I got the crank pulley, a/c pulley, water pump pulley, power steering pulley all together, installed with no modifications. You will need to use a crank pulley/installer rented at pep boys, you will need a power steering puller and installer rented at pep boys. Use an impact gun for the water pump bolts or loosen when the belt is still on otherwise good luck. For the ac pulley, that was a nightmare but you figure a way to remove the center bolt, the face will pull out, then you need a c-clip Remover/installer tool to remove the c-clip (bought at Walmart or any hardware store) and the pulley comes out and just reverse everything to install. I ordered the belt tensioner with the provided part number at the beginning of the thread and the bolt holes didn’t line up, after reading it’s meant for a different car, so I removed the pulley on the new tensioner and just bolted it to my existing tensioner. My stock tensioner is aluminum and I’ve read that they can bend/break with added power, I was looking at the steel ones but can’t find them anywhere. Anyone know where one could be purchased at? How strong are the stock aluminum ones good to? I’ll be shimming the supercharger pulley out .280” with aluminum spacers. The vortech idler pulley that originally came with the kit measures 2.5”(63.5mm) that is meant for a 6 rib belt. I’ve read how others used that pulley with an 8 rib belt but it’s a little risky. Vortech doesn’t offer a 8 rib pulley in 2.5”, the smallest they offer is 3.0” which I bought a 3.0” 8 rib idler pulley from advance auto and it was too big when I installed it. So I looked up some pullies made by dayco and part number 89175 is a 2.75” (70mm) pulley that fits up to 7 rib belts so that should be okay. Now for engine idler pulley (not the supercharger idler pulley) the part number provided at the beginning of the thread was too big. I ended up just buying another tensioner 8rib idler pulley from advance auto and drilled out some washers so the pulley wasn’t rubbing on the engine cover. Now my last issue that I need help with is the alternator pulley. I purchased the gp720 pulley and it sticks out too far. I read where someone said the gp720 pulley is the correct replacement part for the navigators, if you go to a salvage yard and pull an alternator pulley off one the the 5.4 motors that it will bolt right on and no modifications will need to be done. Since I already have the gp720 pulley, how do I get it to fit properly? I saw on one thread that it needs to be cut 4.12mm but didn’t specify where it needs to be cut and 4.12mm seems a little too much. Any input on the alternator pulley? The black is the gp720 and gold is the stock
 

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Dave @ BGG Performance might be able to help you out, he specializes in 8 rib setups. Dealing with all the headaches an 8 rib setup can be when you piece it together is challenging. Sometimes your time is more valuable to just purchase the kit and be done with it.
 
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