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Overview
What does it take to make 400 horsepower out of a 302? Sure, a supercharger or nitrous will do it, but we're talking naturally aspirated. In this two-part series we will show you that a well built 302, for no more money than a standard performance rebuild, can make 400 or more horsepower at the crank.

In Part One we will detail the short block preparation and assembly, including our cam selection. In Part Two we'll install the heads and intake, and figure out some details for dropping the late model block into an early Mustang project car. Finally we'll get it on the dyno and to the track.

Our motor will be carburated and run a single plane intake, which is going to push the power band pretty high in order to make the ponies we are after.

Block and Crank
We started out with a high-mileage 1989 5.0L block out of a daily driver

Seasoned 1989 5.0L "roller" block.
Mustang. We paid $50 for the short block. You should have no problem getting your hands on a used block for a similar price. We used the late-model roller-block simply because they are abundant, and have more power potential due to the roller cam.

Having 80-90 thousand miles on the engine we know the iron is "seasoned" and ready to work hard. Most engine builders will tell you that used cast iron blocks and heads are much more reliable than brand new castings because they have "settled" by going through many heat cycles.

Our objective was to make this a "budget" rebuild. Although we didn't set out with a specific dollar limit, the goal was to limit as much machine work and new parts expenses as possible.

The cylinder walls still had a nice cross-hatch pattern and showed no signs of damage, indicating
we may be able to get by without boring the cylinders. We had the machine shop

New cam bearings and oil galley plugs.
measure the bores, and they came up with 4.0015", at maximum taper. The piston had another 0.001" of skirt wear. Assuming the honing process would take the bore to 4.002", the block was still within factory tolerances (4.000"- 4.002") They also hot tanked the block to clean it out, and installed fresh cam bearings, freeze and oil galley plugs. This cost us $100 even.

The crank was within factory tolerances for main and rod journal diameters and runout. These are measurements which you should let your machine shop check unless you have the proper micrometer and dial indicators. We got away with a simple crank polish and cleaning for $50.

Pistons and Rods
The initial plan was to use the stock pistons. In 1988 and 1989 Ford put forged TRW pistons in the 5.0L. However, when we mocked up the heads and cam in order to check piston to valve clearance we

Stock 1989 Ford (TRW) Forged piston.
realized the larger intake valve would interfere with stock piston. (See Measuring Piston to Valve Clearance in the Fundamentals section of the Tech Department.) This put a literal bind in our plans to build this motor dirt cheap. Our options were to have the pistons "flycut" (a machining process which grinds larger and deeper valve reliefs into the piston), or to buy new pistons. In terms of cost, it was a wash. Flycutting requires the pistons be removed from the rods, so the labor cost would be $100, plus another $80 for cutting larger reliefs.

Machining the piston makes it neccesary to rebalance the motor; another $200 expense. The final result would
be a piston that is weaker, and still has a limit as to how large a cam we can run. On the other hand, a new set of aftermarket pistons, already cut with large valve reliefs, cost about $200. We'd still have to spend for balancing and getting the pistons pressed on, but at least we'd have the peace of mind that the pistons are good and strong and can accept larger cams in the future.

We decided to go with the Keith Black 281 piston. It's a lightweight flat-top piston which weighs 505 grams, with a 102 gram pin, together this is over 100 grams lighter than a stock piston. A lighter rotating mass translates to less parasitic loss and thus more horsepower. Additionally

Jacks Engines in Oakland,CA handled the machine shop duties.
the KB pistons all come with valve reliefs large enough to accept oversize valves as large as 2.10" and 1.80" intake and exhaust respectively.

Expect to pay between $150 and $200 for a complete balance job. You
will need to bring to the shop your crank, rods, pistons, one set of rings and rod bearings, as well as your harmonic balancer and flywheel or flexplate. If your car is a manual transmission, bring in your clutch pressure plate. A good machine shop will balance the pressure plate separately and give you all the balance specifications so if you need to replace something down the line you can reproduce the balance of that component.
 
In This Article:
We go through the steps and details required to achieve greater than one horsepower per cubic inch from our 302 motor. Part 1 details the parts selection and short block assembly. Part 2 deals with the top end assembly and leads in to the dyno results.


Part I Short Block
Part II Induction
Part III Installation
Part IV Dyno Testing
 


Short Block Assembly
After receiving a hot tanking and cylinder hone, our seasoned '89 5.0L block was back from the shop. We were now ready to begin assembly of our 400hp 302."

Don't count on your machine shop to thoroughly clean the block and crank after they've worked on it. Use hot water and soap, and then go over the machined surfaces with carb cleaner to get off any remaining dirt.
 
We finished up with cleaning the oil passages in the block and crank with rifle brushes, and wiping the bores with carb cleaner. Spray some oil over the machined parts to keep them from getting flash rust.
     

Begin assembly by checking and gaping the top rings. KB recommends running 0.0065" per inch of bore, so for a standard 4.00" bore, we calculated a 0.026" gap. This is larger than traditional convention, which is 0.004" per 4.00" bore, so follow the piston manufacturers recommendations.
 
Use a piston upside down to square the ring in the bore and to lower it down the cylinder. Check the gap with a feeler gauge. The bottom of the bore is typically the tightest area due to taper, so check there. If your engine has been bored oversize, the bores should be equal diameter from top to bottom.
     

We are using file-fit rings from Hastings. To open the gap draw one end of the ring against a file. File only in one direction, from inside to out. Check the gap after a few strokes, as material removes easily.
 
Once you've finished a ring, organize it so that it goes back into the cylinder it was gapped for. We simply tacked them to the wall in the shop and marked the corresponding cylinder.
     

Install the rings on the pistons. Begin with the three piece oil rings. The wavy "expander" ring goes first, then the lower oil ring followed by the upper. The rings are "spiral cast" on to the piston, meaning you carefully put them on with your fingers from one end to the other as shown.
 
The second and top rings go on with an expander tool. Note that we have marked the piston tops with their cylinder numbers and an arrow to designate the front of the piston. This helps us remember to stagger the rings correctly.

 
 


Short Block Assembly (continued)

We're using ARP main studs for added strength. Studs are considerably stronger than bolts because they are not "twisted" when torqued to spec. Thread them in hand tight, do not torque the bare stud down.
 
Prior to installing the crank and main bearings, we recommend checking main and rod bearing clearances. Refer to our article Measuring Bearing Clearances in the Fundamentals section of the Tech Department.
     

Lay a bead of silicone sealer in the seats for the rear main seal. Once this is done the crank can be set down and torqued to specification. If you are using studs, or ARP bolts, be sure to use their torque ratings.
 
On late-model 5.0L the rear main seal is one-piece. Coat the seal with a little oil and then slip the seal over the crank. The expander spring in the seal faces towards the front of the block.
     

Place some moly on the crank side of the main bearings, then carefully place the crank in place.
 
Load the main caps with their bearing shells, use moly on the crank sides only.
     

After installing the main caps and torquing to specs (we used the specs provided by ARP.) The next step is to seat teh thrust bearing. Use a large screw driver against the counterweights, and pry the crank forward and backward a few times. Then torque the thrust bearing cap with the crank leveraged forward (towards the front of the engine.) It may seem like the crank is going no where, but you can check for thrust end-play, as described in the next frame...
 
With a dial indicator zeroed against the end of the crank, and base secured to the block, pry the crank back towards the direction of the flywheel and note the total end-play. Then pry it forward and note the endplay. Add the two values to obtain total crank endplay. Acceptable values are between .004-inch and .010-inch. If the endplay is not enough, the thrust bearing flanges can be "lapped" across sand paper to increase play. In the rare case of too much clearance, you'll need to consult with a machine shop, as the crank may be excessively worn.

 
 

Short Block Assembly (continued)

Install the rod bearings, and moly the crank side of the bearings. Cut a couple 2" pieces of 5/16" hose and place them over the rod bolts, this will prevent scarring the bore or crank when installing the rod and piston.
 
While it may appear the rods are symmetrical on each side, they are not. The large end has two different bevel cuts. The larger radius (right) must face towards the outside of the crank journal, other wise the rod will bind against the journal.
     

Stagger the ring gaps, and load the piston into a suitable installer. Install the piston using the wood handle of a hammer to tap it down. Make sure the rings are not caught up on the edge of the bore, or that the rod bolts aren't hitting the crank.
 
Lube the rod bolt threads and nuts with moly, and torque to 25 lb.ft. for stock rod bolts, or 30 lb.ft. for ARP fasteners.
     

While the motor is still upside down, we install the oil pump and pickup. We used a rebuilt stock oil pump.
 
With all the pistons and rods installed, we turn the motor right-side up. We'll install the cam and timing chain next.
 
 


Camshaft and Lifters

Overview
For a carburated 302 to make 400 naturally aspirated horsepower it is going to take a cam which is extremely efficient in the 4000 to 7000 rpm range. We'll be using
World Windsor Sr. heads which are up to the task of flowing well at high rpms, but we need a cam to match. We turned to Crane Cams to help us select a cam that will support the power range we are targeting.

Crane recommended a solid roller cam from their Powermax series . We ended up going with a complete valve train assembly from Crane. We've always found the best results when you stick to the cam manufacturers recommended springs, retainers, lifters, etc. This not only guarantees everything is going to go together right the first time, but also that all the parts have been engineered to work together. This is extremely important when you are building a high revving race engine which cannot tolerate any amount of valvetrain instability.

Crane's mechanical roller-tappets (part no. 44542-16) The link bar design eliminates the need for stock retainer hardware.

Selection
The Crane S238 is a mechanical roller cam with 238 degrees intake duration and 246 degrees exhaust duration, with 110 degrees lobe

We'll use an aggresive profile solid-roller cam.
separation. Lift is .560" and .579" respectively. As with any solid cam (flat tappet or roller) you have to account for the valve lash, which in this case is .020". This means that in terms of operating specs, the cam will have .540" lift intake and .559" lift exhaust. Because of the .020" lash, duration drops roughly 10 degrees to 228°/238° respectively.

While some folks may think this is a big cam, we think it is really not all that big. In fact it should be just right for what we are after! The basic
rpm range is from 3000-6500 rpms, and with the good heads and single plane intake, we should be able to stretch out the peak to near 7000 rpm. The advantage of a mechanical roller cam is two fold. First of all roller cams make more power being that the roller tappets generate less frictional losses as compared to flat tappets. However the real performance benefits to roller tappets is that their base is of infinite diameter. A flat tappet lifter has a machined base which can only "ride" the cam lobe for so long, whereas the wheel of a roller tappet can follow very aggressive lobe lift and ramp rates. Finally, the benefit to mechanical lifters, be it roller or flat tappet, is that they have a higher rpm potential over hydraulic tappets. A mechanical tappet has no valving which can "pump up" and create power loss during high rpm valve float.

Installation
Some engine builders prefer installing the camshaft in the block before

Installation for roller cams requires only oil.
the pistons and crank go in. It doesn't really matter, so long as you do it right! The key is to slide the cam in slowly so as to avoid nicking the cam bearings or cam lobes. Using a long bolt as a handle helps ease cam installation. Roller cams do not require a break-in period so really all you need is to generously oil the lobes and slide it in. Moly is not necessary, but wont hurt. Flat tappet cams, however, do require moly lube due to the high friction during the initial break-in of the lifters to the cam lobes.

Due to the link bar design of Crane's solid roller lifters, there is no need

Linkbar solid-roller lifters are installed with engine lube.
to use the stock guide bars and retainer. The lifters must be installed with the link bar facing the center of the block. We dipped the lifters in oil, and coated the lifter bore with a little moly prior to installation. If you are going to run a flat tappet cam, be sure to use plenty of moly on the lifter face.

Degreeing
Anytime you order a custom camshaft it is good practice to check that it was ground to the correct specifications. This verification process, known as "degreeing" is not too difficult to learn and is a must in any performance engine builders set of skills. Our tutorial on Degreeing a Camshaft in the Fundamentals section of the Tech Department will take you through the fairly simple process.

 
 
 
Crane Mechanical Roller Cam
We opted for a slight tweak to the PowerMax catalog P/N 368511. We had the lobe separation changed to 110 versus 112. (P/N after adjustment is 44SR00016.)
Crane Mechanical Roller Lifters
Crane's Pro Series (P/N: 44542-16) link bar mechanical roller lifters will ensure revs beyond 7000rpm.
Other Crane Matched Valvetrain Components
For best results we chose to use Crane springs, retiners, locks, pushrods, and valve seals to match our cam and lifters. For more details on these items see 400hp 302 Part Two Top End

 

 


Oiling, Cooling, and Fuel

Oil Pumps and Drive Shafts

Last month we ended with installing the oil pump. Before we get into the top end of the engine, we'd like to mention a couple points that we didn't get to last time. We had selected a stock pressure and volume oil pump

A hardened oil-pump shaft is highly recommended.
for our motor. Although it has been popular to use high pressure and high volume pumps for performance buildups, it is actually not neccesary, and may do more harm than good. Unless you are running greater bearing clearances or a deep-sump oil pan, you don't need more than the stock pump.Not only does it require more power to drive a high volume pump, it also places stress on the oil pump shaft, distributor gear and bearings. Small block Fords have a notorious problem of twisting and breaking the oil pump drive shafts (see right).
A worthwhile and cheap upgrade is to purchase the ARP/Ford Racing Parts heavy-duty oil pump shaft. We recommend this over the typical "hardended" shafts that are included with most aftermarket oil pump shafts.

Oil Dipsticks


Tap and plug the dipstick hole on 5.0L blocks.
Late model 302/5.0L roller blocks had the oil dip stick in the side of the block rather than in the timing chain cover as on early 289/302 engines. Since we are planning to put this engine in an early model Mustang, using an early style pan and timing cover, we needed to plug this hole. The easiest way to accomplish this is by tapping it for a screw in plug. Some folks simply put a wooden dowel in the hole, but this is the time to do it right. Last thing you want is a gusher upon initial startup!

Windage Tray
We should also mention a few words about oil control. In a wet sump system, the crank swings through the oil sitting in the pan. At high

Windage trays are cheap and easy horsepower.
engine speeds weight of the oil on the crank creates tremendous drag on the crank, which robs horsepower. Any sort of oil control, be it a baffled oil pan, or a crank scraper or windage tray is benefitial. Some engine builders claim windage trays to be worth 10-15 horspower at high rpms. Since we already had one in another motor, we figured it would be worth the trouble to drop the pan and put it on the 302. Note that if you are using main studs you'll need to purchase from ARP special studs with threaded extensions for the windage tray. Otherwise, most trays come with special bolts with threaded heads.

Fuel Pump Eccentrics

Two piece fuelpump eccentric.
There are two types of fuel pump eccentrics for small block Fords, a one piece and a two piece. The one piece centers on the camshaft dowel pin while the two piece has a tab which centers in the dowel hole of the timing chain cam gear. Most new cams come with a short and a long dowel in the box so you can select the appropriate one for your eccentric. However, you only need to worry about eccentrics if you plan to use a mechanical pump. Otherwise you can leave it out.

Water Pumps
Cooling a high horsepower engine is something worth giving serious

High flow waterpump
consideration too. Higher output of power also means higher output of heat. The project car which recieved this motor will get a new three or four core radiator for sure. On the engine itself we have selected an aftermarket high performance waterpump. The FlowKooler waterpump utilizes a modified impelled to achieve an increase in flow of 30% over a stock pump. The pump is also aluminum, which shaves nearly 5 lbs. off the front end compared to an early iron waterpump.
 
 



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