Difference between a 1970 5.0 vs 1990 5.0 302

[Acgallen]

Little backstory, I'm looking to buy an engine rebuilt kit for my 1989 Bronco 5.0 but cant seem to find a kit that has everything I need. I was looking for a kit that provides hypereutectic pistons, cam, timing, lifters and the gaskets/bearings. I come to find that kit exists but the specs say its for a "1963-1968 289 SBF Ford Engines and 1968-1982 302 SBF Ford Engines". I did some research and the main difference between the years is the stroke changed to 3.000 inches and the shorter connecting rods of 5.090 inches. The engine also came with flat tappet lifters and cam. If that's the only change to the engine I don't see why there are year specs on the rebuild kit if it doesn't include rods. Link to the kit: Rebuilt Kit. Any help would be greatly appreciated!

 

[97RangerXLT]

I do believe that the 1990 SBF 302 had roller cams on it... that was something that Ford did in the 80s.

AJ

 

[racsan]

The only thing I can think of is roller camshaft & efi.

 

[19Walt93]

There are a lot of differences. The 70 engine will have fulcrum style rockers, the 89 has pedestal mount. The 70 had the old heavy block, the 89 is the newer lighter one. The70 has a 2 piece rear main seal, the 89 is a much improved one piece. The 70 crank has a 28.2 oz/in imbalance and the 90 is 50 oz/in. The 70 uses a flat tappet cam and the 89 is a roller. The lifters to convert a 70 to roller cam are about $400- 4 times stock rollers, and the 89 block already has a cam plate compatible with a roller cam. The 70 heads might have smaller chambers(not sure) but the 89 heads have far superior ports and better quality iron. The stroke and rod length are the same- 289's had a shorter stroke and slightly longer rods, all 302's have the same stroke and rod length. If you're 89 is a Mustang engine it has forged pistons. The 89 has low drag piston rings that are thinner. The 70 had a "silent" timing chain that was prone to stretching out in 40k or less, the 89 is a double roller. I've had great luck with Summit racing, very few problems with the parts and excellent customer service if a problem occurred. Internal engine parts are not pieces to shop by price, if you save a few bucks and have to rebuild it again it isn't cheaper.

 

[Acgallen]

There are a lot of differences. The 70 engine will have fulcrum style rockers, the 89 has pedestal mount. The 70 had the old heavy block, the 89 is the newer lighter one. The70 has a 2 piece rear main seal, the 89 is a much improved one piece. The 70 crank has a 28.2 oz/in imbalance and the 90 is 50 oz/in. The 70 uses a flat tappet cam and the 89 is a roller. The lifters to convert a 70 to roller cam are about $400- 4 times stock rollers, and the 89 block already has a cam plate compatible with a roller cam. The 70 heads might have smaller chambers(not sure) but the 89 heads have far superior ports and better quality iron. The stroke and rod length are the same- 289's had a shorter stroke and slightly longer rods, all 302's have the same stroke and rod length. If you're 89 is a Mustang engine it has forged pistons. The 89 has low drag piston rings that are thinner. The 70 had a "silent" timing chain that was prone to stretching out in 40k or less, the 89 is a double roller. I've had great luck with Summit racing, very few problems with the parts and excellent customer service if a problem occurred. Internal engine parts are not pieces to shop by price, if you save a few bucks and have to rebuild it again it isn't cheaper.

Thanks for the info! The 89 bronco engine I have is flat tappet, probably should have mentioned that. So I would need the one piece rear seal instead of the 2 piece? The only reason I'm avoiding summit is they don't have kits with cam and lifters included with pistons. I can definitely buy the timing set separately, any recommendations on a kit?

 

[Acgallen]

The only thing I can think of is roller camshaft & efi.

Forgot to mention my bronco engine had flat tappet.

 

[Acgallen]

I do believe that the 1990 SBF 302 had roller cams on it... that was something that Ford did in the 80s.

AJ

Forgot to mention my engine had flat tappet in it already. The engine can be switched both ways, correct? I plan on doing roller rockers later but at the moment don't have the money and would rather get the car functional lol. Thanks for the reply!

 

[19Walt93]

Forgot to mention my bronco engine had flat tappet.

I believe you'll still have the tall lifter bosses and threaded holes in the valley to bolt down the spiders, I'd encourage you to use a roller cam to avoid having to buy high zinc oil or a ZDDP additive. My son had a Crane cam fail shortly after a rebuild and the metal particles in the oil scored the crank and cylinder walls. Not to mention, roller cams have less parasitic drag and roller lifters can tolerate faster ramps so you can squeeze more power out of it than a flat cam with the same specs. Also keep in mind- if you have a flat tappet cam and switch to a roller you'll need a compatible distributor gear and cam plate. Everything 82 and after has the one piece rear seal so you're all set there.

 

[Bracket racer]

Gee Walt, I was going to list all the things and you beat me to it!

I’ll add the water pump goes backwards with the serpentine belt as opposed to the earlier v belts.
Did you mention the heads flow better?

 

[19Walt93]

Gee Walt, I was going to list all the things and you beat me to it!

I’ll add the water pump goes backwards with the serpentine belt as opposed to the earlier v belts.
Did you mention the heads flow better?

I just said they were better heads. They were struggling to meet the emissions standards in the 70's, they dropped compression, retarded ignition and cam timing, and leaned out the mixture, each step trying to fix the problems caused by the one before. By 75 the exhaust ports were so small my thumb wouldn't go in to the first knuckle. It was cheaper to cast the thermactor passages into the heads instead of having external tubes and that killed the flow.