My question is, what are the specifics of my 302 in my 94 I am purchasing. I have the general ideas on the 302's, but I haven't paid as much attention to them as I have with the 300's to now, which the 300's changed even less.

Is it a roller as opposed to flat tappet valvetrain? Would it be MAF as opposed to SD? Different internals, intakes, etc? I really don't know alot about the internals on the 302, especially things that have changed from year to year. Thanks! Sorry, I'm sure this type of post has been posted before but my search earlier yielded little help.

 

Join the club. There's a lot of confusion concerning the truck and regular pass car motors from this era. 94 especially, was a year of transition for these motors. Therefore, it may be either speed density, or mass air, and it may, or may not, have roller tappets. One thing about mass air; a mass air motor, will have the mass air meter on the original installation, between the air filter box, and the throttle body, and the wiring harness will have leads that go to the mass air meter.

95 and 96 truck 5.0's have roller tappets and mass air.

Now HO type 5.0L's from Mustangs, Cobra's, Lincoln LSC, and to some extant the Explorers are fairly well known. HO's had a high tourqe roller tappet cam, with the 351w firing order from 85 up. 85 HO's used a Holley 4 bll carb. 86 HO's are speed density EFI, but used E6SE heads and had no valve reliefs on the pistons. 87 and 49 state 88 HO's are SD. 88 California Ho's are mass air, as are all HO's from 89-up. 85-93 HO's had forged pistons. 93-up HO's used hypereutectic pistons.

Both the regular truck 5.0L, and the HO, use E7TE heads from 87 up, Cobra's used GT40 heads, and Explorers used GT40P heads. Pass car 5.0L's from this era, use the E6 (or E9) SE swirl heads.

95 and 96 truck 5.0's use the 351w firing order, same as the HO's, but most others use the old 289/302 firing order, regardless of flat or roller tappets.

The truck upper intake manifolds looks very different from the typical car intakes. It's like long narrow cast tubes from the throttle body/plenium to the lower intake. The car upper intakes are laid over the engine for a low profile. 5.0 HO, intakes have throttle bodies on the passenger side, while crown vic's ect.. had them on the drivers side. Although the car intakes look similar, the Mustang HO versions flow better with larger plenium volumes and larger runner cross sections from 87 up. The best intake was the GT40 tig welded tubular intake, originally only available after market. It looks kind of like a bundle of snakes. This intake was used on the Explorer 5.0's. The Cobra intake was a cast version of the GT40 intake.

94 engines ofton have the spout connector hidden, rather than coming from the dizzy. The Computors on 94's seem to resett the timing to de-fault, regardless of how you set the timing manually. It seems to have been an OBD II experiment or something. They did away with this afterward on the 95 and 96 motors. You seem to have to have chip burned, to modify the parameters on 94's.

 

What about the bottom end? What are the internals probably?

What do I need to know about this motor? What would I need to do with this motor to make it happier?

 

The bottom ends on stock 302's are pretty much trouble free, provided the RPMs are kept below 6,200, and they are not abused, and they see proper maintance. Expect about 150,000 on well kept 302's, before any brass starts showing on the bearings. The rings also hold up well. I've never torn down a 302, and found I needed to ridge ream the cylinders to get the pistons out. Usually, even at 200,000 miles, you can't feel a ridge.

Detonation may cause oiling problems with number 8 cylinder. Number 8 will see a lean condition before the others, and also any cross fire from faulty plug wires, between wires 7 and 8, will cause a pre-ignition in number 8. Numbers 1 and 5 will also somtimes see leaner mixtures on the EFI 302's. Keep the fuel pump and fuel system in good shape, and you shouldn't have any problems. Pay attention to the health of the fuel pressure regulator, and if it has dual tanks the-switching system. The in tank electric fuel pumps will get weak with age, so occasionally monitoring the fuel pressure is a good idea, to stay on top of when they should be replaced.

The timing chain will probably wear out before the bottom end internals. If it has more than 130,000 miles, I would probably plan on replacing the timing chain set, before too long. Since it's half tore down at that point, you may want to just go ahead and re-ring and re-bearing, with new gaskets. The rear main seal usually starts leaking around 100,000 miles.

The pistons on 85-92 HO's are forged. The post 92 HO's, and probably the truck motors, are hypereutectic. Hyper E pistons are much tougher than plain old cast pistons, but will still not tolerate nitrious oxide injection, or 20 pounds of turbo boost. Forged pistons are needed for that. If you don't want to spray it with N2O, or use a turbo, then the non-forged; hyper or cast pistons are fine. The lighter hyper E pistons don't grow as much when hot, as forged pistons, so tighter clearances are used. This allows quieter, smoother operation, with even more miles between overhauls.

The stock truck cams are fairly wimpy. If you have mass air fuel injection, then replacing the cam may be a good idea, at some point. Something similar to the HO cam is good.

Roller cams require a special steel distributer gear, so if you have a roller, then the gear on the dizzy you use, needs to be steel. If you don't use a roller cam, then the gear must also be compatiable to a flat tappet cam. So any cam replacement down the road should be done in this light.

 

At what we think was about 240k miles we had to put a crank in our 302, the rest of the motor wasn't bad enough to warrant doing anything to. The biggest thing you can do is help it breath, open up the exhaust, and put a good high flow air filter in it. That will get you some free hp, well cheap anyway.