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Old 07-28-2021, 12:26 AM
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heinke heinke is offline
MetalShaper of the Month Jan 2018
 
Join Date: Nov 2009
Location: Prescott, AZ
Posts: 487
Post Alternator Belt Routing

In working through wire harness routings, it became clear that I needed to figure out the placement and mounting for a central component of the electronic system, the alternator. The original Miura had a somewhat quirky, non-standard element to the alternator in that it used a toothed, Gilmer style belt to drive it. For my Miura, I have no choice but to go with something non-standard as there just isn’t any space to mount even the smallest of alternators in a standard arrangement. Given the EFI fuel pump, electric cooling fans, electric water pump, ECU/Ignition/VVT controllers and A/C, this configuration requires a high output alternator and thus the alternator itself will be decent size and need some mounting space.

I decided to start with the alternator that came with the Coyote engine from the Mustang GT. It’s a Nippondenso unit, put out 140 amps when tested and there’s a 200 amp version in the same case if the one I have doesn’t have quite enough output. Given the lack of space, the only choice is to mount and run the alternator backward so the first modification was to swap out the clutch drive pulley it had with a solid pulley so the alternator could be spun counter clockwise.

The Coyote engine is typically configured with 2 serpentine belts having the alternator located on left side which is the forward bank of cylinders. To fit the engine in the chassis, I had to remove the front belt drive off the crank damper pulley, so the engine is now only single belt capable. So to determine potential belt routings, I had to source a belt tensioner that fits on the right side of engine where the idler pulley needs to be right next to the engine front. I also had to add an extra idler pulley so the belt would clear the newly added belt tensioner.





It’s all very compact and tight with only one belt rubbing issue but I think it can be made to work (pulley at top is simulating the alternator pulley). Out of the two possible belt routings, this one seems to be best. The other potential routing has the belt going around the coolant intake neck. While that routing would enable placing the alternator higher (providing more clearance between it and chassis tube), I don’t like the notion of needing to dump coolant and removing a hose to do a belt change.

Here’s the rubbing issue.



The timing chain case drops down and touches the belt just upstream of the idler pulley. I removed just a bit of metal from the timing chain case where it rubs and ended up with a hole. The casting is maybe 1/8” thick where I thought given the shape it would be thicker. I put a cotton swab through the hole and poked it around. I felt only solid walls and it came out dry without any sign of oil on it. Best case, it’s only a hollow cavity and no repair is needed. Most probably, I’ll need to pull the timing chain cover off and weld some metal in behind it.

So question out to anyone who’s torn down a Coyote engine; what’s in that part of the timing chain cover? Is this a space that is somehow connected to the windage part of the engine?
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Joel Heinke
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