Chevy 427

This is the best “displacement week” of the year in our opinion. We get the click off some of the best engines the big three ever produced in this one series of days. Other than the 426 Hemi, there is not a more mythical or vaunted cubic inch displacement than 427ci. Both Ford and Chevy slayed the competition in the 1960s with big block engines measuring out to 427ci.

It would be an argument to last the ages in trying to settle which 427 is better, the Ford or the Chevy. Certainly, Ford took their platform to the technological end with the SOHC program and Chevy’s 427 has been a terror on the drag strip since the moment it rolled off of the Tonawanda assembly line in 1966. The SOHC engine that Ford built was intended for NASCAR but the sanction ankled in the rules it before ever seeing it compete. The Chevy 427 certainly lived a longer service life than the Ford variant which was phased out for the 428 by 1968.

Let’s look at the Chevy first!

The Mark IV 427 debuted in 1966 in Corvette and in full-sized Chevrolet cars. The L36, 390hp engine had a bore and stroke of 4.25 × 3.76, a two bolt main block, a cast crank, a set of small port heads, and a hydraulic cam. It had 10.25: 1 compression and a Q-Jet on top. 1966 was also the year the L72 was released. This engine had a horsepower rating of 425, used a four bolt main block, 11.0: 1 compression, a solid lifter cam, aluminum intake manifold, better heads, and a Holley 4bbl carb. The L68 came out in 1967 and was available until 1969. That engine had a tri-power carb setup and a 400hp rating. Basically it was the 390hp engine with improved induction. Continuing on the L71 engine had all the good parts of the L72 plus the tri-power for a rating of 435hp. Then there was the L89 which was the L71 with aluminum heads.

The bad daddy in all of this was the L88. Exorbitantly expensive and covertly hidden with its 430hp rating, the engine was a 500hp piece all day long. Maybe more than that. All the high performance pieces you could want, aluminum heads, and aluminum high rise intake manifold, and a Holley 850CFM carb. The ZL1 was the exotic all aluminum 427 that is worth huge money these days.

Then there was the original LS1. Seriously. In 1969 there was an LS1 427 that was a low horsepower, cast iron intake, two bolt block, small cam, small headed, 10.25: 1 engine that made 335hp.

Now let’s check out the many faces of the Ford 427 FE big block

Like the Chevy 427 the Ford is one of those engines that everyone remembers fondly. When you hear a car has a 427 in it, you know it is serious business. The 427 at base is a bored out high performance 390. 4.23 × 3.78 are the bore and stroke numbers for the engine. Being largely over square, the engine was great for high RPM operation. As many people know there were three main versions of the engine. There was a low, medium, and high riser. There was also the amazing SOHC version as well and the truly beast like Tunnel Port engine.

The low riser version of the 427 was around in 1963 and 1964. The block was the same used for the 390 and 406. The engine had a cast iron crank and a solid lifter camshaft. The 1963 engines had heads with 2.04 ″ intake valves while the 1964 engines had 2.09 ″ valves in the heads. Weirdly those heads would later be used on the 428 Cobra Jet engines! Some of these engines used cross-bolted mains that used the deep skirts of the engine to help promote bottom end stability and strength. The single carb low riser engines were rated at 410hp. The dual quad version made 425hp. The 11.5: 1 compression was shared with both engines.

The medium riser engines were produced from 1965-1967 and it was basically a solution to the fitment problems caused by the tallness of the high riser engine. High riser equipped cars needed a bubble or a scoop to allow the engine to properly fit but with intake ports that were shorter by nearly half an inch, the Medium Riser was an easier fit. The ports were not fresh designs. In fact, the dimensions were the same as those found on 390 engines from the early 1960s. The medium riser heads have big valves in them. 2.195 ″ on the intake side and 1.73 ″ on the exhaust. The engines used forged cranks and cap screw connecting rods. A solid lifter cam opened the valves. Medium riser engines used the side oiler block which was the best of the bunch. Despite all this stuff the medium riser was rated at the exact same horsepower levels as the low riser engine!

1964 was the year that the high riser showed up with its special heads and induction system. The 2.72 × 1.34 inch ports were the tallest found in the FE engine. The valve sizes were 2.195 ″ on the intake and 1.73 ″ on the exhaust side. The tall ports and intake were there so that the air would have a nicer path to the valve. The plan worked. These engines made loads of power between 5,000 and 7,000 RPM. Once again, the bones were the same as the other engines with the old 390/406 block, the iron crank, cross bolted mains, solid lifter cam, and a pair of different intakes that only fit the high riser heads.

The 427 tunnel port engine is one for the books. Technically not their own engines but rather cylinder heads that could have been bought over the counter, the round ported heads had ports so big that the pushrods passed through them in protective tubes. There were different intake manifolds available that only fit the TP heads, and the 2.25 ″ valves on the intake side were more than willing to swallow as much air as the engine shoveled at them.

Last but not least is the awesome “90-day wonder” Ford’s SOHC 427 that was designed for NASCAR and then sent to the drag strip when NASCAR threatened to hang so many restrictions on the cars running the engine that they would be competitive.

The heads are the story here. Cast out of aluminum and using fully hemispheric combustion chambers, they also had big round ports on the intake side and D-shaped ports on the exhaust side. 2.25 ″ intake valves were backed up with 1.90 ″ exhaust valves. (Pssst… these valves also fit Boss 429 heads. Fun fact to know and share). The left and right heads on a cammer cannot be swapped. Weirdly the right head has six cam bearings and the left has five. Because of this the cams are side to side specific. The there’s the legendary six foot timing chain that spins the whole works’ round. There were both single and dual carb intakes. Ford rated it at 615hp with a single four barrel. The only other weird thing about the cammer is that the block has a couple of oil drain back bosses in it which are not supported by wedge heads so if you have an actual “cammer” block you’ll know it.

These engines made tremendous power on nitromethane fuel and with blowers on them in dragster and a limited number of funny cars but they were very temperamental. As quick as they were and as much fear as they struck into the hearts of racers running Chrysler hemi engines they were never reliable enough to be a longterm threat.

Both engines live on as examples of Detroit’s horsepower wars of the 1960s. While they were not the ultimate engines produced, they certainly have the greatest aura. Below are videos of these engines roaring on the dyno!

Leave a Comment