Read­ers' Tech Q&A

Hot Rod - - Everyday - Mar­lan Davis

I have a 1971 Torino fast­back with a tired 302. I would like to pur­chase a junk­yard 5.0L from a newer model ve­hi­cle. I know the oil pan sumps are dif­fer­ent. In­stead of buy­ing a kit, can I use my pan, pickup, tim­ing cover, har­monic bal­ancer, and fly­wheel from my orig­i­nal en­gine? Also, what years and ve­hi­cles should I be look­ing for to get a mo­tor from? I am go­ing to keep the en­gine car­bu­reted.

There’s no re­place­ment for dis­place­ment. Al­ways! I’m as­sum­ing you want to re­place your worn-out, two-bar­rel 302 with a later, more per­for­mance­ori­ented 5.0L en­gine and run a four-bar­rel carb— this is, af­ter all, HOT ROD.

What’s “best” for per­for­mance while min­i­miz­ing the need for ad­di­tional, sep­a­rate bolt-ons? Within these pa­ram­e­ters, if you can find one, the most suit­able late-model can­di­date would be a 5.0L H.O. from a 1985 Mustang. This mo­tor was the first 5.0L with a hy­draulic-roller cam, but still re­tained a car­bu­re­tor—namely an emis­sions-le­gal de­scen­dant of a Hol­ley four-bar­rel carb (but its in­take man­i­fold ac­cepts any per­for­mance-ori­ented Hol­ley 4150/4160-se­ries four-bar­rel). It also has a non-com­puter, large-cap Duras­park II break­er­less dis­trib­u­tor, which al­ready has a dis­trib­u­tor gear that’s com­pat­i­ble with the roller cam (grab the con­trol mod­ule on the driver-side in­ner fender plus the mod­ule-to-dis­trib­u­tor wir­ing har­ness). Be­cause this pack­age was car­bu­reted, it re­tained a me­chan­i­cal fuel pump and the bolt-on camshaft fuel-pump ec­cen­tric.

Af­ter 1985, Mustang 5.0L H.O.’s came with a hy­draulic-roller cam, but stepped up to com­put­er­ized, se­quen­tial elec­tronic port fuel in­jec­tion (SFI). As you’re stay­ing with a car­bu­re­tor, for you they’d be a sec­ond choice, but be­cause they were pro­duced from 1986 through 1995 in a Mustang, avail­abil­ity is ob­vi­ously much greater.

The SFI ver­sions reached their peak with high­er­per­for­mance GT-40 heads on 1994–1995 Mustang 5.0L-H.O. Co­bra en­gines as well as the 1996–1997 Ford 5.0L-H.O. in the Ex­plorer. The 1998 Ford Ex­plorer re­ceived GT-40 heads but with a mod­i­fied spark-plug an­gle, so they won’t al­ways clear older mod­els’ stock ex­haust man­i­folds or ex­haust head­ers.

Ford per­for­mance spe­cial­ists, such as Ad­vanced Engineering West’s Mark Sanchez, also cau­tion you should stay away from the first 1986 SFI Mustang 5.0L en­gines: “1986 is not de­sir­able—it’s junk.

Jump straight to a 1987 or later.”

Other op­tions, less de­sir­able from a per­for­mance point of view, in­clude any non-H.O. Ford 5.0L with a hy­draulic-roller cam. Roller cams were fac­to­ryin­stalled in all 5.0L-equipped cars start­ing in 1986. Roller cams didn’t hit the truck line un­til 1992 (al­though all 1988-and-later trucks should have roller-cam-com­pat­i­ble cylin­der blocks with pro­vi­sions for in­stalling the fac­tory-type roller cam lifter re­tainer and dog­bones).

Fuel-in­jected en­gines use a com­puter-con­trolled dis­trib­u­tor, so you’ll have to trans­fer over the ex­ist­ing points-type dis­trib­u­tor and coil. But who wants points? Now’s the good time to con­vert the points unit to break­er­less. PerTronix is one con­ver­sion kit maker. Or you can buy a new MSD or PerTronix break­er­less dis­trib­u­tor and coil. If re­tain­ing your orig­i­nal points dis­trib­u­tor, you must in­stall a hy­draulic-roller-cam-com­pat­i­ble dis­trib­u­tor gear. This also ap­plies to any new dis­trib­u­tor that doesn’t come with such a gear pre­in­stalled.

You can bolt a car­bu­reted in­take onto any fu­elin­jected en­gine. Fac­tory 302 four-bar­rel in­takes are rare, so you’ll need to get an af­ter­mar­ket Edel­brock or Weiand in­take if get­ting rid of the SFI.

Re­mem­ber that even the “new­est” of these late­model en­gines is more than 20 years old. Un­less you get in­cred­i­bly lucky and find a wrecked car that just hap­pens to have a newly re­built en­gine, your take­out will likely re­quire a ma­jor refresh.

So much for retrofit op­tions, but what other parts must be trans­ferred or mod­i­fied from your old en­gine to the new en­gine so it fits and

[ A 1983–1985 Mustang 5.0L-H.O. had a Hol­ley four-bar­rel and a non­com­puter Ford Duras­park dis­trib­u­tor. Hy­draulic flat-tap­pet cams were used in 1983 and 1984, but the rare 1985s added a hy­draulic-roller cam, still with the Hol­ley carb (block cast E5AE-HA or E6SE-DC). 1986–1995 5.0L-H.O.’s had SFI. Ex­pect to pay $450–$800 at the wreck­ing yard for any of these mo­tors.

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