PREPARING/BUILDING A FACTORY STOCK 5.0/302 FOR FORCED INDUCTION
The following are the steps that I think should be taken and the parts I think should be used whenever you are considering adding forced induction of any kind to your stock 5.0/302 engine.
I know that a lot of people have "gotten away" with doing very little or sometimes nothing to their bottom end and using forced induction. Just remember they are the "exception" to the rule and not the norm. For the best results and longevity you should really consider the modifications and parts recommended.
At very low boost levels, say 5-6 pounds, you probably can get by with all stock components as long as you don't go wild abusing the car. For peace of mind though, follow the recommendations below.
The block should be properly prepped, machined, cleaned and sonic checked for cylinder wall thickness and core shift. The block deck should be checked for flatness and machined to a suitable surface finish so it will hold a head gasket under the increased cylinder pressures. From what I have researched, the MLS (Multi-Layer Steel) head gaskets, such as the Cometic head gaskets
will hold up the best, as long as the deck surfaced is flat and finished properly. Always use new head bolts or studs.
I would also add a Main Support System
& Valley Girdle Pro
to the engine block assembly to further stiffen and strengthen the relatively weak and flexible 5.0/302 factory block. Another worthwhile block strengthening mod is to replace the side freeze plugs with threaded cast iron pipe plugs. I believe the size is 1 1/4" MIP for the plugs. All that is required is purchasing the 6 plugs and drilling or reaming & tapping out the freeze plug holes.
For better engine oiling, I remove all of the oiling system plugs and oil filter adapter. then I use small sandpaper rolls and lengthened rods to polish the oil passages and round off any sharp corners in the system as best as I can. Polishing the lifter galley of the block and oil return holes therein will help return the oil to the pan faster too. If that is too much trouble you can use Glyptal Engine Sealing Paint
to coat the lifter galley and other unmachined surfaces inside the block for better oil return.
The engine rotating assembly is primarily comprised of the pistons, rods and crankshaft. All of these parts should be of good quality and forged components to be able to stand up to the additional stresses of forced induction. A number of Mustangs in the 79-95 year range have forged pistons from the factory, but the rods and crankshafts are of standard cast iron material used in many factory engines. They are not designed for nor were they ever intended to hold up under the rigors of forced induction. The final part that should be upgraded in the rotating assembly is the Harmonic Balancer. To cope better with the forces induced from a belt driven supercharger the factory cast iron balancer should be replaced with a Steel
or Billet Aluminum
Note: I am not, nor have I ever claimed to be an expert on this subject. The information presented here is what I have gleaned from researching the subject many times and over many years. I present it to you to be used as a guide and used at your own risk and discretion. I will take no responsibility for any failures or mishaps you may incur. That being said I believe the information I have presented is accurate and reliable as I can make it at this time and I wish you all the best in your modifications and builds.
If anyone sees any mistakes, errors or information that needs updating, please do not hesitate to let me know. You can PM me or post the info in the 79-95 Mustang forums and address it to me. I would also greatly appreciate any further knowledge or experience on this subject that anyone would wish to share.
More horsepower, torque and tire smoke for all,