Serpentine Belt Solution

Dropping a late-model 5.0L motor into a early Mustang or other 60’s and 70’s Ford has become the norm for restomoders. It makes good sense – the 5.0L motor is in abundant supply, it drops right in to the early Mustang engine bay, it offers the option of fuel-injection, and so on. But one of the challenges guys run into is how to setup the pulleys and belts, especially if you simply want to run nothing but the waterpump and alternator – no air, no power-steering and certainly no smog pump. It’s confusing and we found no shortage of internet forums filled with guys scratching their heads. So we figured we’d try to resolve it once and for all in this FordMuscle tech article.

This is the goal - a serpentine belt running the 5.0L waterpump and alternator. No AC, no power steering, and definitely no fugly OEM brackets.

This is the goal – a serpentine belt running the 5.0L waterpump and alternator. No fugly bulky OEM brackets.

The reason the serpentine accessory drive belt presents an issue for 5.0L swaps into early Mustangs is several fold. First,most guys do not plan to use all or any of the 5.0L accessories – e.g. the late-model smog pump, power steering pump, and AC compressor. So these components get stripped off, leaving the big and bulky mounting brackets that come on Fox-body Mustangs, Explorers and other late-model Fords. Guys don’t want these brackets uglifying their vintage engine bay, so they come off too. This leaves an alternator and belt tensioner, and the question of how and where to mount it such that it works with the serpentine crank and waterpump pulleys.Let’s pause right here – for guys that ARE going to run A/C and/or power steering in their vintage Mustang, the rest of this article wont apply to you because we are dealing with the simple scenario of how do you run a serpentine belt on a 5.0L, in an early Mustang with only the alternator as the belt driven accessory. Believe it or not, this is a very common scenario for early Ford owners – they aren’t running A/C because the vehicle never had it, and they have ditched the old power steering for a modern electric of rack and pinion unit, and of course no one is running a smog pump. If you are using a 5.0L motor and do have A/C and/or a power steering pump, chances are good you’ve already figured out how to drive those accessories with either modified late-model brackets or custom brackets.

So picking it back up – you’ve got a 5.0L motor dropped into your early Mustang, Falcon, Maverick or whatever, and you have no idea where to mount the alternator let alone how to route the serpentine belt between the crank, waterpump, alternator pulley and belt tensioner.  On the surface it seems simple – why not just route a belt around all three pulleys and pull the alternator along a channeled bracket to tension the belt? After all this is how the vintage single v-belt system would have worked. Well, for one big reason – the 5.0L engines use a reverse rotation waterpump! That means the waterpump pulley has to spin in the opposite (counter clockwise) direction of the crank and alternator pulleys. The way that is achieved is the waterpump pulley is driven by the backside of the serpentine belt. On a 5.0L engine the belt tensioner

To further compound the issue, the 5.0L pump inlet pointed to the driverside, requiring the radiator to have the lower hose connection on the driver side. Many companies now offer new radiators with staggered inlet and outlets just for this reason, and this is a simple solution – and so is simply taking your radiator to a radiator shop and having them move the lower radiator outlet.

This is where most of the heartache comes in. Many guys think the solution to the belt routing and also to the radiator issue is to bolt on the original vintage Mustang waterpump back on. They soon find out, after the engine overheats, that the timing cover on a 5.0L is different than that of a early small block Ford. You need to change that too to make it work. But, when you do that, the pulley mounting face on the water pump is now setup for a V-belt, not a serpentine belt, and won’t align with the 5.0L crank pulley and harmonic balancer. And you can’t just bolt on a single V-belt crank pulley because it is likely 3-bolt, not 4-bolt as are late-model 50oz harmonic balancers. It end’s up being a chain of events that becomes quite frustrating.

So what is the solution if you are dropping a 5.0L engine into your vintage Ford with the 5.0L reverse rotation waterpump and want to run only an alternator? There are outrageously expensive solutions in the form of billet brakets and pulleys and so forth; but the simple solution is to use the March 1465-09 kit. This kit solves both the alternator mounting issue and also the belt tensioning issue, allowing you to run a short serpentine belt and maintain the late-model timing chain, reverse rotation water pump, and standard 5.0L pulleys.

The March kit mounts the alternator on the passenger side cylinder head and the short serpentine belt wraps around the crank and alternator pulleys, with the back side of the belt turning the 5.0L waterpump in the correct reverse-rotation. The belt is tensioned via a heim-joint rod. It’s slick, clean, and best of all cheap…under $75.

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