Ever since it was first introduced in 1963, the 289 High-Performance V-8 has been the subject of myth, legend, and folklore. Enthusiasts get fired up over the 271hp Hi-Po due to its adrenaline-inducing sound, mechanical tappets, throaty exhaust, and high-revving personality. It was the 289 Hi-Po that earned new respect for Ford on racetracks and road courses worldwide in the 1960s thanks to talent at Shelby American, Holman & Moody, and Ford Motor Company. However, for all the hoopla over the Hi-Po engine, there's not much mystery to the power making capability of one of Ford's most legendary engines. According to Steve Karst of Karst Engineering in Mesa, Arizona, you make power and design in reliability with a Hi-Po the same way you would any other Ford V-8.
The 289 High-Performance V-8 is an up-rated 289 with a hot cam, wider main journal caps, heavy-duty connecting rods with 3/8-inch bolts, slide-on crank counterweight, wider harmonic balancer, hand-picked nodular iron crankshaft and flywheel, dual-point distributor, and cylinder heads designed for valvetrain stability at high rpm. The 289 High-Performance V-8 makes additional power via a mechanical camshaft with more lift and duration-along with that wonderful chatter at idle.
Here's the casting number...
Here's the casting number on Paul Calvisi's '65 289 High Performance block. But don't get excited if you see the C5AE-6015-E casting number behind your Mustang's starter. It doesn't mean you have a Hi-Po block. It means you have a 289 block. What makes it a Hi-Po block is its wider main caps. This C5AE-E block was cast on February 25, 1965-date coded 5B25.
So what is it that makes the 289 High-Performance V-8 so extraordinary? And how do you make the Hi-Po engine better without disturbing authenticity? Much of it centers on old hot rodding tricks along with the infusion of stealthy new technology no one will know is there but you.
The 289 High-Performance employs the same block as any other 289 V-8 of the era. If you check the Ford Master Parts Catalog, you'll see that the 289 Hi-Po block was given its own part number because it came with wider main bearing caps. There are quite a number of different 289 block castings beginning in 1963 and ending in 1968. For example, '63-'64 289 blocks have five-bolt bellhousings. From '65-'68, they are six-bolt to improve noise, vibration, and harshness. There are also '67 289 engines with C8OE '68 302 blocks. Ford used a lot of 302 blocks for late '67-'68 289 engines. The 302 block has slightly longer cylinder skirts (.015 inch) to allow for the 302's .013 inch of additional stroke. You can use the 302 block for your 289 project if a 289 block is unavailable.
Hi-Po-Build It Better
Are you tired of being told that oil spots on the floor are just part of the old Mustang experience? Try these internal Hi-Po modifications designed to keep your garage floor dry. The 289 High-Performance came from the factory with a two-piece rear main rope seal retained with a steel pin in the No. 5 main bearing cap. Rebuilds have always gotten two-piece rubber seals that eventually leak. And if the builder forgot to remove the rope-retaining pin, it distorts the new seal and leakage happens immediately. If you must have the original two-piece rear main seal, stagger the seal end gaps away from main cap-to-block gaps, which minimizes the chance of leakage. Put a dab of Permatex's The Right Stuff at the seal end gaps and main cap-to-block gaps, which will prevent leakage.
Wider main bearing caps make...
Wider main bearing caps make a 289 Hi-Po block the real thing. While the footprint is the same as a regular 289 main cap, they have wide shoulders to provide improved journal support at high rpm. Look for the red paint blotch on Hi-Po parts. These wider main caps are also common to all Mexican block 289s and 302s. They are numerically identified differently on Mexican block engines.
If you're ready to move into the 21st century, have your Hi-Po block and "1M" crankshaft machined for a late-model 5.0L one-piece rear main seal. It's worth the expense and you can count on lifetime leak-free service. While you're at it, opt for Fel-Pro's one-piece oil pan gasket with plastic installation pins in the kit for easy installation.
By the way, if you have a manual transmission, replace the old clutch pilot bushing with a full roller bearing for smooth operation. Bearings cost more, but are worth it in what you gain in improved performance.
Here are other internal improvements you can make to your Hi-Po to improve power and reliability.
- Hardened exhaust valve seats
- Hollow stem stainless steel valves (less weight, more power)
- Viton valve seals (stay away from old umbrella seals)
- Fel-Pro Print-O-Seal head and intake manifold gaskets
- PowerHeads CNC porting to improve power with stock heads
- Larger 1.94/1.60-inch valves
- Mechanical roller tappet camshaft and steel distributor drive gear
- Lightweight Comp Cams Magnum roller rockers (If rollers are too expensive, use '78-up 5.0L stamped steel rocker arms with Boss 302 fulcrums, screw-in studs, and polylocks/self-locking nuts
- One-piece pushrods
- Hypereutectic pistons
- Gapless piston rings for better cylinder sealing
- PerTronix Ignitor I or II electronic ignition
- Extrude Hone intake manifold, cylinder heads, and exhaust manifolds
- Fine tune the crank machining process to improve oil flow, yet reduce friction
- Blueprint oil pump, checking clearances and relief valve
- Heavy-duty oil pump shaft
- Brass freeze plugs
- Screw-in oil galley plugs
- Block drain petcocks on both sides for proper routine maintenance
- Centerforce Dual Friction Clutch for ease of pedal operation
- Intake manifold gasket port match
- Remove all stress risers (high spots from casting and forging) to minimize cracking risk and personal injury
- Massage oil drain back passages to improve return flow
- Screen oil drain back passages to keep trash out of the oil pan
- Never use rail style rocker arms on a Hi-Po engine, even with the longer valve stem - some people have had catastrophic results because rails can dig into spring retainers
The 289 High-Performance engine...
The 289 High-Performance engine is the sum total of its limited production parts-heads, mechanical camshaft, connecting rods, cast flattop pistons (yes, cast pistons), nodular iron "1M" crankshaft, special four-blade fan, dual-point distributor, cast iron 4V intake manifold, and 600-cfm Autolite 4100 carburetor with manual choke and 1.12-inch throttle bores. Very few elements separate the Hi-Po from its standard two-barrel and four-barrel brethren.
Hi-Po connecting rods aren't...
Hi-Po connecting rods aren't much different than standard 2V/4V rods except for additional meat at the large end along with knurled 3/8-inch bolts. Cast pistons were original equipment in 289 High-Performance engines including Shelby GT350. The best upgrade for an old Hi-Po rod is new ARP bolts.
If you're building a stock...
If you're building a stock 289 High-Performance engine, you don't need expensive and temperamental forged pistons. For Paul Calvisi's Hi-Po engine, we went with .020-inch oversize (4.020-inch bores) cast pistons from Federal Mogul's Speed Pro Division with ductile iron rings. Builder Steve Karst of Karst Engineering gently rolled the rings on, lubricating ring grooves and rings with SAE 30 weight engine oil for proper break-in.
Even if you've specified pre-gapped...
Even if you've specified pre-gapped piston rings, always check ring end gaps. Top compression rings and center oil rings have specific ring end gaps based on location. The top ring will have a wider gap than the center ring because it's a lot hotter on top. Another misconception is ring terminology. Only the top ring is a compression ring. The second ring is an oil control ring. What are traditionally called the oil rings are oil wiper rings in the bottom groove. The oil control ring carries oil up the bore and the oil wiper rings clear cylinder walls.
What you use for assembly...
What you use for assembly lubrication on cylinder walls is determined by how long the engine will sit before firing. If it's going to sit a long time, use engine assembly lube. If for a short time, use SAE 30 weight engine oil. Piston rings need direct contact with cylinder walls for exceptional seating.
Here's a close-up of a Hi-Po...
Here's a close-up of a Hi-Po main journal. Make your Hi-Po more reliable by giving main and rod journals closer scrutiny. Because journal temperatures can reach upwards of an oil-cooking 350 degrees F at high rpm, oil distribution is crucial. Oil passages must be clean and openings chamfered to improve flow. It isn't just about pressure, but also flow. This means bearing clearances must be spot on for the right balance of flow and pressure. Hi-Po main bearing clearances should be .0005 to .0028 inch. Ideally, you will have clearances in the middle of these two numbers.