From 1962-1981, all Ford 221-260-289-302 small blocks used the 28.2oz imbalance. From 1982-2001, the 5.0 (302) used the 50oz imbalance. In 1985, the 5spd 5.0 Mustangs used a roller cam 5.0, and from 1986, until the end of 5.0-prowered Mustang production in 1995, all Mustangs used the ‘roller motor’, and by 1986, 5.0s with EFI were using ‘roller motors’. This information is written assuming that you want a ‘roller’ motor and have a small block car or all of the small block parts. Most 5.0s have a serpentine belt in place of the traditional V-belts. 5.0s also use a 4-bolt crank pulley, which complicates things more This leaves you with several choices, keep the serpentine setup, switch to V-belts and find a 4-bolt crank pulley, or use a conversion damper and bolt up the stock 3-bolt pulleys. If you want to stay with the serpentine belt setup, you would be able to keep the late model alternator which is a plus. The 5.0 timing cover will accept any style water pump (except the ones for 289s that dont need a backer). The 5.0 timing covers and timing chain sets accept the eccentric to drive the mechanical fuel pump. If you want an electric fuel pump, go to the junkyard and look at F150s with EFI. These trucks should have a frame rail mounted electric fuel pump that you can use in a classic car (take the brackets and related items). To fix the waterpump outlet problems encountered when using a ‘70 or later water pump on a pre ‘70 car, you can buy a special radiator, have yours modified at a radiator shop, or find a hose that you can trim down and use for the lower hose (a stock upper hose should fit fine). You will need to relocate your oil dipstick to the front of the motor. To do this you could buy a new cover, use your old cover, or drill a hole in the 5.0 cover (‘86-93) to put the dipstick in front. Don't forget to put a plug in the old dipstick hole on the side of the block (the hole just needs tapped for a 1/8in NPT brass plug.) You will need to reuse your original oil pan. ************************************************** **********************
The Mustang HO 1985 was the first year for the ‘roller’ 5.0, which was used in ONLY 5spd cars. 1986 Mustang 5.0 HOs had E6AE truck heads, cast pistons with no valve reliefs, Speed Density EFI, roller cams, and are generally considered the ‘worst’ 5.0 HO in stock form. 1987-’88 Mustang 5.0 HOs had E7TE heads, cast pistons, Speed Density EFI, and roller cams. 1988 Calif. Emissions Mustang 5.0 HOs had E7TE heads, forged pistons, Mass Air EFI, roller cams, and are generally considered the ‘best’ stock 5.0. The MAF EFI responds well to modifications, and the forged pistons are extremely durable and tolerate high-lift cams. For 1988, ONLY Calif. Emissions cars had Mass air, the rest were speed density. 1989-1993 Mustang 5.0 HOs had E7TE heads, forged pistons, Mass Air EFI, roller cams, and are generally considered the ‘best’ stock 5.0. The MAF EFI responds well to modifications, and the forged pistons are extremely durable and tolerate high-lift cams well.
EFI, Man, the EFI conversion is a whole ‘nother can of worms on top of the 5.0 swap. This just piles on another list of issues and parts. I’ll try to present as complete a list of possible. One problem is that the air filter on K&N style and factory setups interferes with the stock battery location. There are several things that you could try. One idea is to mount the intake like on non-HO motors, where the upper intake is reversed so that the air intake runs down the left side of the motor, out of the way of the stock battery tray. You could also re-locate the battery to the driver’s side or the trunk. Another dilemma is that all of the forms of shocktower bracing (stock, Monte Carlo bar, and Export brace) interfere with the EFI intake, necessitating an aftermarket support designed specifically for EFI-equipped classics. Another big issue is the wiring. Here you can go cheap and, using a wiring diagram for both the donor car and your Mustang, integrate the 5.0 harness with your original wiring, eliminating the extra wires along the way. The other wiring option is to buy a premade EFI conversion harness from (about $600) and drop everything right in. Here's some info courtesy of Lightning from the VMF: “If you use the EFI EGR spacer, you'll run into shock tower clearance issues on 65-66's. 1994 and newer 5.0 EFI motors use totally different connectors for the wiring and none of the sensors are compatable with an ‘87-’93 harness, plus they have some features built in the the ‘94-5 EEC that make them less desirable. Only HO motors use 19lb injectors, passenger cars use 14lb, so bolting a non-HO EFI setup on a motor that’s performance oriented is going to require some upgrades: Mass Air, and larger injectors. Ford motorsport sells 4 bolt v-belt pulley sets (crank, water pump, and alternator) that are very nice. www.fordfuelinjection.com
IMO is the best site for figuring out how to do yor own wiring and getting the pieces to build your own harness, or buying a pre made harness. He has a very nice harness building kit for $60 that includes a 4 fuse block w/fuses that elimnates the fuseable links in the harness, it also includes all necessary relays, shrink tube, high temp wire sleeves, 2 rolls of harness wrap and plenty of corregated harness covering, in addition he has just about any pigtail you could imagine. Of course to do your own you need to know how to solder and how to read a simple 1 line schematic. In addition I constantly see new custom EFI harnesses on Ebay for $250. I’d never, ever fork out the $$ that Ron Morris, Painless or Windsor Fox ask for their harnesses. It’s not that difficult to figure out yourself if you understand the basics of an engine’s needs and have a whole lot of patience. Its very rewarding to start that car for the first time after you just wired it yourself. I realize that’s not for everyone but regardless theres no need to fork out $600 for a harness