14 Tips For Windsor Small-Block Ford V-8s
Considering a small-block Ford V-8 project or a vehicle with one under the hood? Here’s the info you need when you’re shuffling through the swap meet aisles or scrolling through online classified ads. From identifying parts to addressing common issues, this guide will help you become a Ford Windsor small block V-8 expert and avoid unpleasant surprises!
How to tell a 302 Ford from a 351
302 or 351? The differences between a 302 and a 351 are minimal. Most parts are interchangeable, which makes differentiating between the “little” small block and the “big” small block difficult at first glance. The 351 gets its displacement advantage from a taller deck (8.2” for the 289/302 and 9.5” for the 351). The real question: 8.2” deck or 9.5” deck? The easiest way to identify a 351 block is look at the interface between the coolant passage boss and the deck on the left side of the block. A 289 or 302 will have no gap, where a 351 will have 1.3” of extra deck material.
What is a 9.2 Deck Height Windsor?
9.2 Deck 351: To make things confusing, there’s also an aftermarket “short deck” version of the 351 block, called the “9.2” block. Rather than a 9.5” deck like production 351s, the 9.2 block features a slightly shorter deck for lower displacement builds to bring everything closer to the centerline of the crank and reduce rotating assembly mass. This aluminum Ford Performance Parts block is offered in both 9.5” deck height (M-6010-Z351) and 9.2” deck height (M-6010-Z35192).
Understanding Ford Engine Casting Numbers
Casting Numbers: Making sense out of Ford’s alphabet soup casting numbers isn’t as cryptic as you’d think. When identifying castings, this handy guide will help you identify what you’re looking at.
Ford Windsor Firing Orders
Firing Order: The 289/302 and 351 have a different firing order…but in typical Ford fashion, there is an exception to this rule: the 302 “HO” engine used the 351 firing order. This was done for a bunch of reasons, but it can make things confusing. Quick rule: if the 302 has a factory hydraulic roller cam, it has the 351 firing order.
Windsor Head Bolt Hole Sizes
302 vs 351 heads: While 289/302 and 351 cylinder heads are essentially the same, there is one small difference between production versions. 351 blocks use 1/2″ head bolts, while 289/302 blocks use 7/16” head bolts. As such, the holes in the heads are smaller on production heads designed for a 289/302. Most aftermarket heads have 1/2” head bolt holes, so special washers are required when installing aftermarket and 351 heads on a 289/302 block. This head stud kit from ARP (P/N 154-4005) has 7/16” studs with special reducing washers for the larger, 1/2″ holes in a 351 cylinder head.
4-Bolt or 2-Bolt Main Ford Windsor Blocks
4-Bolt Mains: Aside from the 1969-1970 BOSS 302, all Ford 289/302 engines have 2-bolt main bearing caps. Experience has shown that the mains aren’t a small block Ford’s weak point anyway. Many beefier aftermarket blocks have 4-bolt mains.
Ford Windsor Block Strength
Block Power Limit: Most modern 302 blocks can split right down the middle when putting out over 600 lb-ft of torque. If you’re planning on building a small block Ford for something over that power level, invest in a beefier aftermarket block.
Selecting the right externally balanced flywheel for a Ford Windsor
Balance (or Imbalance): The 289/302 crankshafts were cast with heavier counterweights and used 28-oz imbalance factor. With the 255/302 engine in 1981, Ford built lighter crankshafts that required 50-oz imbalance flywheels and harmonic dampers to make up the difference. Therefore, 1981 and later engines require different flywheels and harmonic dampers compatible with the different imbalance factor. All 351 engines use a 28-oz imbalance factor. Some aftermarket flywheels, like this aluminum unit (P/N 24-209) from Hays, includes bolt-on counterweights to work with different crankshafts.
Ford Windsor Rocker Setups
Stud or Pedestal Rocker Arms: Ford small blocks made before 1978 featured stud-mount rocker arms, while post-‘78 small blocks used a bolt-down, “pedestal” rocker arm setup. Aftermarket cylinder heads either utilize the later pedestal setup or use screw-in studs with pushrod guide plates. The latter require hardened steel pushrods compatible with the guide plates but are the preferred option for high performance builds. Heads with pedestal-mount rockers have mounting pads that are higher than those designed for screw-in studs, so converting to a stud-mount rocker setup requires different heads or machining the pads down. Valvetrain geometry is a minefield of variables, so be sure to check geometry and never assume “it’s fine!”
Ford Windsor Factory Camshaft Styles
Flat Tappet and Roller Cams: 1985-up Mustangs with 5.0L “High Output” engines featured a factory hydraulic roller camshaft. The design allowed more aggressive camshaft profiles for higher performance while maintaining a smooth idle. Ford’s factory hydraulic lifters are heavy, but extremely robust. A fork-shaped guide kept the lifters aligned and a spring-steel “spider” held the forks in place. Roller blocks have tapped bosses in the valley to accept the spider. Aftermarket roller lifter conversions exist to use roller lifters in an earlier flat-tappet block. The camshaft used will also determine the distributor gear needed. Flat tappet cams require cast gears, steel gears are for roller cams, and bronze gears work with both.
One-Piece vs 2-Piece Ford Windsor Rear Main Seals
Rear Main Seals: Ford small blocks made before 1982 used a two-piece rear main seal, and 1982-later engines have blocks and bearing caps designed for a one-piece rear main seal. Rear main seal leaks are a common issue with all Ford small blocks, regardless of the seal type.
Ford Windsor Cast vs Forged Pistons
Cast and Forged Pistons: 1987-1992 5.0L H.O. engines came factory-equipped with forged pistons, and other engines used hypereutectic cast pistons. In theory, the factory forged pistons were more robust than the cast slugs, but in practice the results are mixed. Regardless, using aftermarket forged pistons are the best bet when building a small block Ford.
Ford Windsor Oil Pump Driveshaft
Oil Pump Drive Shaft: The oil pump drive shafts on small block Fords can twist and fail—especially when driving a high-volume pump. Ford Performance Parts offers heavy-duty replacements for the 289/302 and the 351.
Ford Windsor Valve Cover Styles
O-ring Gaskets: Modern engines use O-ring seals on most sealing surfaces, but “vintage” engine designs like the small block Ford V-8 utilize traditional gaskets. These gaskets leak over time, especially if they’re old and exposed to synthetic oils. Toward the end of the small block Ford’s production, Ford used steel-reinforced rubber gaskets on the valve covers and oil pan. These factory gaskets are no longer available, but there’s aftermarket versions. They do a good job of keeping the oil inside the engine and are reusable to boot.