Project 666: Nasty 427 Build Part 1 – The Short Block

For naturally aspirated power it is hard to beat cubic inches. Sure, you can slap on a blower or turbo and get great boosts in torque and horsepower, however doing it with raw compressed air is much more challenging. The challenge for Project 666 was to build a power plant that could not only make 675 plus horsepower, but also be able to hold together at redline through every shift and every quarter-mile trek. Getting this kind of power out of a small block Ford based engine means you need to have big displacement, good compression, and the right list of matched components to make it all happen smoothly and reliably.

Here at Pro Power, we specialize in putting together the right combination of components to meet our customers’ goals, so it was no surprise that the crew working on Project 666 contacted us right away with their needs. My years of experience working with a wide variety of small block Ford engines have given me an opportunity to peruse the aftermarket parts and choose each component specifically for any given application. For this project, we were looking to strike a good balance between displacement, RPM range, longevity, and the right horsepower and torque.

The complete engine build is going to be covered right here, so you can see every detail of the 427 build. Part one will consist of the short block build (block, crank, rods, pistons…etc.), part two will cover all of the top end parts and completion of the long block, and part three will go over the results of the chassis dyno after the engine is bolted in our Project 666 Mustang. So, let’s get started with the short block and everything I did to start our monster 427 Windsor engine!

Aluminum Dart Hits the Target

The basis for any engine project starts with the main component – the engine block. There are a lot of choices out there for blocks, but the list shortens when you are looking for good power and reliability. Dart Machinery has been manufacturing racing engine components for many years, and their line of Ford blocks is top notch. After reviewing our needs, I decided to go with their Virgin 355-T61 Aluminum block for this build.

We started with the Dart aluminum 9.500” deck bare bones block mounted on the engine stand. Specialties Machining had previously done all of the machine work, thoroughly checked the block, and removed the billet steel main caps, so it was ready for assembly. Note the Chrome-Moly main studs that come standard, as well as the threaded freeze plug holes.

The Dart block allows us to go up to 4.165” in bore and up to 4.250” in stroke, and this is important because are looking for 427 inches. Additionally, the Dart block has billet steel four-bolt caps on all five mains, which are dowel pinned and registered with the desirable 351 SVO Cleveland size of 2.750” for less friction and bearing heat. The Dart is available in 9.200” and 9.500” deck heights, to fit many different applications. With additional features such as pressed in dry sleeves, upgraded true priority main oiling, threaded freeze plugs, and coated main bearings, choosing the ultra light 93 pound block for the center of our project was virtually a no-brainer.

The Dart Aluminum block uses four-bolt billet steel caps on all five main cap positions. They are doweled for a precision alignment and held in place with studs (included from Dart), which are a great improvement over standard bolts. Ronnie noted that the mains were perfectly machined right out of the box from Dart.

I wanted to ensure that we not only had a good block for our engine project, but that it could fit the parameters of our requirements. With a naturally aspirated engine, you have to try to get the engine to breathe as easily as possible, since you aren’t forcing the air in. That means you have to think about bore size. Dart offers their blocks in two configurations for bore: 4.000” and 4.125”. This is a critical choice that must be made based on what you are trying to do with the engine. We weren’t trying to fit into any rules or keep the cubic inches low, so the 4.125” was definitely the way to go. Not only does it add cubic inches, but the large bore allows the heads to flow more air. How? Well, with a smaller bore, large valves, and a lot of lift, the edges of the valves end up very close to the cylinder wall when they are fully open. This blocks air from flowing around the valve on that side and restricts air flow. By using the larger bore, the air can move all the way around the valve head, and you can typically see about ten percent more air flow through the same head and valves with the larger bore size.

Crank it Up

Having chosen the block, I moved on to the crankshaft. I had to look at what we were doing with the engine and pick out a stroke and a crank that would work flawlessly. I have used numerous Lunati Pro Series crankshafts over the years, and I thought it would be a perfect fit for our naturally aspirated engine.

The Lunati Pro Series crank is a superior part in every way. Not only do all four rod journals have one angle lightening holes, the mains come center gun drilled. Additionally, the counterweights have Lunati’s exclusive contoured wing design to direct oil around the crank at high RPM.

The Lunati cranks are forged from the highest quality 4340 steel alloy, and have been successfully used in 1500+ horsepower engines without failure. They are made right here in the USA, and are micro-finished on the journals with extra wide radii for ultimate strength. The Pro Series crank is a perfect fit for high horsepower and/or high revving engines, and really can’t be beat for finish and quality. They also feature lightening holes in all of the rod throws, so they can easily spin up to maximum RPM.

Lunati offers these cranks in several choices of stroke: 3.500”, 3.625”, 3.750”, 3.900”, and 4.000”.

After looking over the choices, I decided that the big boy, four inches of stroke, was best suited for this project. With the 9.500” deck height and a reasonable rod length, there was plenty of room to fit a reasonable piston compression height that would not be too unstable at high RPM. That put our cubic inches right at 427, which was perfect.

The crankshaft is designed with the matching 2.750” Cleveland sized main journals, and uses typical industry standard 2.100” large journal Chevy throws, giving us a lot of options for connecting rods.

The Lunati crank is also designed to be internally balanced, which is perfect for a high horsepower engine. OEM Ford engines are designed to be externally balanced from the factory – that’s where all of the counterweights are on the balancer and flywheel. However, it’s not really a good idea in a higher performance environment, as the weights are way out at the ends of the crank, adding extra flex and wear on the front snout and rear journal. The Lunati crank has all of the extra material built into the counterweights, so the weight is distributed evenly throughout. This helps stability in the crank and provides for better bearing durability.

Making the Right Connection

The rods were next on the agenda. I wanted to make sure that we could design the pistons to work correctly within the deck height and utilize the 4.000” stroke, so I had to run some calculations. I needed to see what piston we would come up with so I could pick a rod length based on all of the numbers.

First, I had to consider the crankshaft itself. Most cranks are designed with counterweights to clear a specific minimum rod length, and the Lunati crank was set up to clear a minimum length of 6.125”. That meant I could use any Small Block Chevy rods in popular lengths 6.125” or longer, including: 6.200”, 6.250”, or 6.300”.

Next, I had to consider the piston and think of all the variables: valve relief depth, skirt length, room for rings, etc.. I have learned from previous experience that a compression height around 1.350” typically works best for big cams and ring room. I calculated that on a 9.500” deck height, with 4.000” stroke and a 1.350” height for pistons, a 6.125” rod would work beautifully.

For maximum naturally aspirated power and less rotating mass, we used this really trick set of Lunati 4340 Fully Machined Superlight rods. They weigh in at a very light 609 grams and have small block Chevy dimensions to fit our Lunati crank. These rods resist pulling apart because Lunati uses 7/16″ ARP2000 material rod bolts, instead of the 8740 bolts typically found in most aftermarket rods.

So, now I knew that we were looking for a 6.125” Chevy connecting rod for a street driven, naturally aspirated, high revving, high compression engine. Again, I looked no further than Lunati and their 4340 Superlight I-Beam connecting rods. The rods are great for power, since they are forged and machined here in the USA from aircraft grade 4340 steel. They are shot peened, individually magnafluxed, and bolted together with extremely strong ARP cap screws. Since we were going to drive this car on the street, we had to stay away from aluminum rods, yet we needed a rod that could hold up to the RPM and horsepower of our nasty 427. Plus, these rods barely tipped the scales at 609 grams, which meant less weight our crank had to spin at 7500 RPM’s.

Slugging it Out

I always prefer to have the exact piston for the job. This means that I can’t simply open up a catalog and pick one out, especially when looking for compression, low drag, and durability. Therefore, custom pistons are the way to go. I know a lot of people are afraid of custom pistons, but I am here to tell you they are not scary at all. In fact, I think just about every engine should have custom pistons. It just makes more sense, because each engine is unique in its application and uses, and should be optimized for power. Custom pistons allow you to tailor the piston to your needs and they typically take only a few weeks to make.

For high quality pistons, I turned to none other than the legendary JE Pistons. JE offers custom pistons, just what we needed for our 427, so I went over the specs with them to build the best piston possible. They offer pistons in any dome, dish, or valve relief configuration, you just need to have all of the information handy when you are ready to place your order. Quite often, these specs will be provided by the engine builder, or in this case, the engine designer.

Fortunately, when you need a specific piston for a special engine, you can turn to JE Pistons for a custom forged 2618 piston made exactly how you need it. These pistons have the small .070″ dome for our desired compression ratio, in addition to a lot of unique features. The ring grooves were machined for our low tension 1.2mm top, 1.2mm second, and 3mm oil JE rings, and we had them add in lateral gas ports to allow more pressure to help seal the top rings. The valve pockets were machined to our cam and head specs, and with weight in mind, these came in at a very light 470 grams.

Because I had already done all of the legwork, I had the information needed to give JE the proper numbers to build our special pistons. We needed a 4.125” bore. The compression height of our piston would come out to 1.365”, which puts our piston .010” in the hole. Although a max effort engine would probably be zero deck, I prefer a little cushion when building custom pistons. That way, if we need to deck the block, the pistons are still usable. The Lunati rods use the standard .927” pin, so I chose the 52 series JE pins, and because we had a big bore, went with the 2.750” length for better pin engagement. These would be held in the piston with the standard double spirolox.

Our JE pistons are equipped with double spirolox, to retain the pins in the pin bores for a full floating piston and rod arrangement. After sliding the pin through the rod and the piston, the clips are installed. Ronnie showed us that the trick to putting these in, is to stretch them out and then wind them into the grooves slowly and carefully.

As far as compression ratio goes, I knew we needed to be around 13.5:1. We wanted this engine to be able to rev and breathe at high RPM’s, so that meant we needed some compression. With the Trickflow heads we would be using, JE calculated that we needed a small dome, about .070” tall. Giving them cam specs and valve sizes also allowed them to put the proper valve reliefs in the pistons, so we wouldn’t have an issue. At this point, I had not picked out a cam, but I had a general idea of the specs, and I typically guess larger when giving specs for valve reliefs. I knew that we would be somewhere around 270 @ .050” and .700” lift, so I told JE we would be using a cam 285 @ .050” with .770” lift. This is something I always do on custom pistons, to ensure that the valve reliefs are not only deep enough, but can also accommodate a larger camshaft down the road.

The pistons were then designed for our naturally aspirated engine by the JE engineers. That meant that the ring lands were a little tighter and higher than a boosted engine, with the top land coming out at .200”, the second at .150”, and the third with a thickness of .080”. The pistons also came out pretty light, weighing in at 470 grams, and were clearanced at .005” on the skirts.

Sealing the Deal

Rings would be a very important issue in this engine. I wanted to make sure we had rings that would hold in the compression and reduce drag, so I picked out a trick set of rings from JE that I have used in the past. The rings are thin for less weight and lower resistance at 1.2mm width top, 1.2mm second, and 3mm oil. The top ring is a steel chrome that has great sealing and wear. That, coupled with the latest 3mm oil ring design, would maximize our power for the Windsor.

For bolting everything together in our engine, we simply pulled out our ARP catalog. ARP makes a wide variety of fasteners for most common engine builds. Our 427 is held together with ARP oil pump bolts, timing cover bolts, cam bolt, oil pan bolts, and they even make a heavy duty oil pump shaft.

Some Assembly Required

At this point, I contacted Ronnie Wilson at Specialties Machining in Pompano Beach, Florida about screwing our package together. Ronnie has been building engines for over twenty years and is very familiar with high horsepower Fords. You may recognize his name from all of the Fun Ford Weekend Championships that he has collected over the years, racing his Ford powered Mustang.

Ronnie was excited about the project, and Specialties Machining has all of the equipment necessary for getting the job done correctly. They have the machines for boring and honing, measuring tools, and Ronnie hand assembles each engine that leaves the shop. They also do all of their own balancing in-house, and have plenty of experience working with aluminum blocks like the Dart that we were using for this engine.

Ronnie got the Dart aluminum block and was impressed with its finish and quality. After setting the sleeves according to Dart’s instructions, he checked all of the block’s dimensions and found them to be perfect. The line hone was on the money, the lifter bores were properly sized – all that he needed to do was finish hone the sleeves to 4.125” with the proper stones for our steel rings.

Designing the Perfect Beastly Cam

While Ronnie was working on machining the block, I got to my computer and started designing the camshaft. This is a crucial decision and should not be left to an amateur. Typically, if you are using a blower or turbocharger, the camshaft design can be a little forgiving. The boost tends to make up any slight errors you may have made in design. However, since our goal is to make a lot of power naturally aspirated, the camshaft has to be perfect in every way.

Many factors came into play in choosing the camshaft. We were originally thinking hydraulic roller, but after looking at the complete engine, a mechanical roller would be the better choice without too many down sides. The solid lifter would allow us to rev the engine up to 7500 RPM’s and make more torque and horsepower throughout the usable RPM range.

This is what a big Comp Cams mechanical roller camshaft looks like. The lobes are aggressive and rounded for maximum “area under the curve.” The roller lifters allow the lobes to open the valves and reach higher lifts faster, moving more air in and out of the engine. A nice feature on the Comp Cams billet cores is the pre-drilled dual dowel holes. These are really necessary when you are running extreme spring pressure and don’t want the timing set to try to break the weaker single dowel pin. The best part? This cam was custom made right in the Comp Cams factory in just a few days.

Cylinder pressure plays a big role in deciding the cam specs, so with 13.5:1 compression, I could choose some pretty good sized lobes to reach our RPM goal, without losing too much pressure in the bores. Also, the heads we would be using, (Trickflow high ports that will be covered in part two), would flow air up to .700” lift, so I wanted to make sure that we had a good amount of lift to use all of the available airflow.

Comp Cams has an extensive list of lobe designs to choose from and an excellent history of providing custom cams in a timely fashion. After studying their lobe list, I settled on the designs we would need for this engine. The intake lobe would come out with 272 degrees of duration at .050” lift with a .435” lobe lift. The exhaust lobe would be slightly larger, at 279 degrees at .050” with a lobe lift number of .420”. That would give us a net lift with a 1.6 rocker ratio of .696” intake and .672” on the exhaust. The lobe separation would be put right at 112, to give us a little broader RPM range and flat torque curve. The cam would be ground on a billet blank right at Comp on standard sized journals, as the Dart block was set up to use regular sized cam bearings. This cam would work well with our intended stick shift setup and give us peak power at the desired 7500 RPM range.

The roller thrust plate from Comp Cams is what we use for all higher RPM roller cammed engines. The needle bearing rollers reduce friction, and it is a more durable upgrade from the cast piece that Ford uses.

Bearing the Load

With the cam in hand, Ronnie Wilson was able to dry assemble the engine and check all of the clearances. I provided him with our preferred bearings of choice, which were made by King. King manufactures high performance bearings made from Alecular, which I have found to be a superior choice over familiar tri-metal bearings. The Alecular material is embeddable, holds up to higher heat, and they are precision matched for clearance.

Ronnie snapped the King bearings into the block and then carefully dropped in the crank. He then assembled the pistons and rods to slip them into the block. It turns out that the rod and main bearing clearances were perfect on the Lunati crank with standard bearings, even though King offers a variety of extra clearance and tighter bearings on the shelf.

Ronnie has installed all of the rings. After assembling all eight connecting rods onto the JE pistons, Ronnie sets them up on his bench and gets them ready to go into the short block. Here, he has already snapped the King High Performance bearings into place in the rod and cap, and indexed the dome on the pistons to align correctly with the chamfer on the rods. (The chamfered side goes toward the radius of the crank journal.)

Highest Level of Clearance

With the pistons and rods loosely in the bores, Ronnie went ahead and checked for interference with the block, piston to crank, and oil pump assembly. Some minor grinding was required to clearance the block and the oil pump, then Ronnie could move on to checking the valve reliefs and dome fitment.

Even though we aren’t covering the top end in this story, the heads were required for finishing up the short block. Ronnie slipped the heads into place with the timing set and cam in the block. Before getting too far, Ronnie noticed that the heads were hitting on the domes a little, so he marked the heads and the domes in order to modify them prior to balancing.

Before Ronnie was ready to assemble, all clearances and specs were triple-checked. Ronnie laid the main bearings in the bare block and rested the crank into place. It is a good idea to “dry assemble” an engine before you do any final balancing or assembly. A whole list of necessary modifications may come up: Switching bearings for less or more clearance, polishing the crankshaft, machining the counterweights or pistons for clearance, dome modifications, oil pump clearance, block clearance, etc.. By doing a dry assemble, you make the changes before you balance the rotating assembly. Fortunately for Ronnie, this engine only needed minor clearancing.

Ronnie then mocked up the lifter, pushrod, and rocker assembly to check piston to valve clearance. JE and I had done a good job with the valve reliefs, because Ronnie noted that we had “miles” of clearance. This is a good thing, in case we ever want to up the rocker ratio or go to a larger camshaft. If the valves had not had enough clearance, Ronnie would have had to flycut the pistons for minimum clearance – that’s why you do the dry mock up before assembly and balancing. However, in this case, Ronnie could just move on with minimal clearancing on the pistons.

After checking all of the clearances and modifying everything, the rotating assembly was chucked up into Specialties Machining’s balancing machine. Ronnie was happy to report that the crank internally balanced beautifully, with no major work required.

The Right to Assemble

With the block honed and clearanced, the oil pump machined, and the domes of the pistons massaged, Ronnie could now start assembling the engine. The rings were oversized by about .002” and Ronnie went ahead and filed them to the proper end gaps for our naturally aspirated engine. With the crank back in place and torqued, he went ahead and laid the engine on its side (which he prefers) to start dropping in the pistons and rods.

The rings are squeezed by a ring compressor for installation into the bores, then the rod caps are torqued to spec around the crank journals. Note that the Lunati rods use a stronger 7/16” diameter ARP2000 material cap screw design, rather than the OEM style bolt and nut assembly. Following the manufacturer’s torquing instructions with a high quality torque wrench and proper lubricant is mandatory for this step.

After tightening all of the cap screws on our Lunati rods, Ronnie slid the camshaft in and retained it in the Dart aluminum block with a Comp Cams roller thrust plate. The timing chain was then slipped on so Ronnie could degree the camshaft into place. The cam was pretty close right out of the box, so Ronnie was able to quickly dial it into proper phasing. In order to do this, he used a deck bridge and dial indicators to note the opening and closing events on the cam lobes. It is always critical for your engine builder to have the right tools when building a high performance street or racing engine.

At this stage, the 427 is starting to look nasty! The JE domes are filling the holes in the block and the camshaft and crankshaft are in time with each other. There are only a few more items left to bolt on before the short block is complete. Then it’s on to the upper end air flow items in part two!

Now that the cam was degreed, Ronnie bolted on our brand new timing cover with the timing cover gaskets and seal already pressed in. The TCI balancer could now be installed onto the snout of the crankshaft. We chose the TCI Rattler to get the ultimate in dampening quality for this project, and it was designed for our internally balanced rotating assembly. TCI also makes a precision billet timing pointer that we bolted onto the front cover so we could time the engine accurately.

Next, we bolted the Melling Select High Volume Oil Pump onto the main cap. The Melling Select pump is very popular here at Pro Power for wet sump applications. It features a geroter set assembled to an extended drive shaft, allowing for additional support in the cover for high RPM engines. The housing and cover are fully CNC machined here in the USA and the pump is phosphate coated for corrosion resistance. The best part about the Melling Select pump is the adjustable pressure relief valve that allows the engine builder to adjust the pressure to where it needs to be.

A Melling Select high performance oil pump will keep the lubrication flowing around the 427. This is the best choice for a wet sump application because the pump has all the improvements for high rpm and severe environments. The pump also includes an adjustable bypass so you can set the pressure where you need it. ARP bolts hold it firmly to the block and to make sure we don’t twist the shaft we dropped in a heavy duty ARP unit.

We used ARP fasteners throughout the short block to bolt everything together. ARP makes bolts for the oil pump, camshaft, balancer, and timing cover. Additionally, we used their heavy duty oil pump drive shaft on the Melling pump to ensure that no twisting would occur under high loads and RPM.

Pro Power’s shelves are stocked with the best gaskets, so sealing everything together was easy. We have a special Viton one-piece rear seal that was installed in the back of the engine, and a Felpro timing cover gasket set was used on the front.

Keeping the crankshaft vibration down is a big job, but not for the TCI Rattler. It was designed for high RPM and racing duty like our 427 will see, and will be perfectly timed with TCI’s billet timing pointer made just for Fords. The TCI billet pointer came with all of the correct spacers and bolts to mount up to our aluminum timing cover. It looks nice, too!

That’s it! The short block was now complete and we were ready to start getting the top end and valvetrain installed to complete the engine. Look for part two of this story to cover the Trickflow heads, Comp Cams valvetrain, as well as the intake that will all supply the air to feed the 427 cubic inches. When we get it all together and back to the Power TV shop, the engine will be completely tuned on the chassis dyno to see how we did. We’ll write that up in part three of Project 666’s engine build up.

It is finally complete! Since we had all of the right parts, the short block was really fairly easy to put together. Because we had not yet decided on an oil pan, we left it for when the engine gets installed into project 666. Look for part two of the 427 build to see the TrickFlow heads and valvetrain parts finish out the long block.

For our short block parts list, with part numbers please refer to the list below:

  • Dart Aluminum Block – 31345235
  • Lunati Crankshaft – IOC11EN
  • Lunati Connecting Rods – 6125FML
  • JE Custom Pistons – CUSTOM
  • JE Piston Pins – 927-2750-15-52S
  • JE Spirolox – 927-042-CS
  • JE Rings – JG3308-4125-2
  • King Rod Bearings – CR848HP – STD
  • King Main Bearings – MB5169HP – STD
  • Comp Cams Custom Camshaft – FW4137/4049 SR112
  • Comp Cams Timing Set – 7138
  • Comp Cams Thrust Plate – 3120TB
  • TCI Balancer – 870010
  • TCI Timing Pointer – 871007
  • Pro Power Timing Cover – TC351E
  • Felpro Timing Cover Gaskets – TCS45449
  • Pro Power Rear Seal – RMS-351WL
  • ARP Oil Pump Shaft – 154-7901
  • ARP Camshaft Bolt – 255-1001
  • ARP Oil Pump Bolts – 150-6902
  • Melling Oil Pump – 10833

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