The advantages of using a 351W vs a 5.0 (302):
FIRST, you get an extra 49 cubic inches of displacement. As the saying goes, there is no replacement for displacement. Second, the webbing in the lower half of the block is thicker, making the block stronger. Third, the crank has bigger main and rods journals, making the cranks more durable than their 302 counterparts.
FACTS: What you need to know/consider when you swap a 351W into a Fox platform chassis:
A 351 block is very similar to the 302. That means that almost all parts swap between a 302 and a 351. This includes: Heads, cam, lifters, timing chain, timing chain cover, water pump, engine mounts. The bellhousing bolt pattern is the same as a 302, so all trannies that bolt to a 302 will bolt to a 351.
Swap Parts Needed:
1. The oil pan is different. You can also get an oil pan of of an early eighties 351W LTD Crown Vic. If you go the junkyard route, remember you also need a oil pan pickup tube, and a special main bolt that the pickup attaches to. The FRPP pan is a pretty good deal, and if you shop around, which comes with the dipstick, bolt, and pickup tube.
2. The internal balance of a 351W is the same as pre-81 302's (28.2 oz). The 5.0 HO has a 50 oz. unbalance, which means you cannot use the flexplate/flywheel or the harmanic balancer off of an HO engine. You have to get the correct pieces from a Parts Store or junkyard.
3. The deck height is higher and wider, which means you need a 351W Intake Manifold.
4. Also, a higher deck height means that the accessory bracket will need to be replaced. FRPP sells the new bracket for about $50.
5. The higher deck height means the headers sit up higher than in a 302 powered Mustang. A special set is required for a 351 (BBK or MAC makes really nice headers) 302 WILL NOT WORK!
6. You mayl need a cowl hood for your car or you can space your K-Frame down to clear your stock hood.
7. The distributor has a larger oil pump driveshaft. You can obtain one from a 351W powered FI truck (if you are using FI) or if running a carb, any late 70's/early 80's car using the 351W and a Duraspark system.
Those are the major differences. As you can see, for about $1000 you can put a 351W in your Mustang. This is cheaper than a stroker, plus you wind up with a more reliable engine.
Tips: There are several things to look out for to ensure that your swap to a 351W is easier and more successful. They are as follows:
1. A high volume oil pump WILL NOT clear the FRPP pan. If you want to run an HV pump, you must either modify the pan or buy a Canton or similar pan, for many dollars more. The modifications just include cutting down the front drain bolt, and welding on a corner to the pan to clear the pump housing.
2. Get new motor mounts. The additional weight of the 351W will make old 5.0 mounts go bad in a hurry. Recommend are the 87-93 convertable mounts, which will work in any 79-93 Mustang K-Frame (4, V6 or V8 stlye)