Budget FE Power! - Part 1 in a Two-Part Series
JGM Motorsports and Summit Racing Equipment Get Together to Build Performance into Ford's Venerable Big-Block
From the April, 2008 issue of Modified Mustangs & Fords
By Jim Smart
Photography by Jim Smart
Have you ever had an engine built, only to find yourself unhappy with the result? Our budget FE 390 project was one of those disappointing engine-building experiences. Although it was built by a reputable machine shop, it had a hideous amount of vibration and wasn't performing well--proof that even the best machine shop is only as proficient as its weakest link. All it takes is one person having a bad day to send an engine build into a tailspin.
Because our confidence in the builder was shaken, we decided to visit one we trust--JGM Performance Engineering in Valencia, California. It may surprise you to know JGM Performance Engineering doesn't see very many Ford FE big-blocks. The engine JGM works on most these days is the small-block Ford in low and tall-deck versions in all kinds of displacements.
We're passionate about FE big-blocks and here's why. There remains no replacement for displacement and shear size--that raw, nasty, rotund mass thing that dates back to Roman chariots of yore. Size really does matter and always has. You can have a stump-pulling 427-inch Windsor small-block that makes heaping, helping amounts of torque and horsepower, but does it fill the engine room?
It's always interesting to tear into a fresh rebuild to see what went wrong. We're convinced something was amiss during dynamic balancing, hence the vibration. However, our 390 goes further than that. It's a study in what happens when we have an unhappy combination of parts combined with marginal building technique. Perceived vibration may not have been dynamic balance at all, but rather cylinder-power balance, inconsistent compression, and cylinder pressure between bores. It may also have been improper cam selection and degreeing.
Our 390 FE project demonstrates just how little some builders know. It's easy to hang up a shingle and call yourself an engine builder. We jokingly call them engine "assemblers" because they tend to overlook what's most important in a rebuild. It takes a real engine architect to plan and build an engine properly. For one thing, you can't approach an FE big-block in the same way you would the average small-block. The FE big-block is an old-school, skirted, Y-block design, with all kinds of potential for making big power. However, a street-driven FE should be built for reliability as well as power. To get power for the long haul, you need reliability, and we'll show you how to get it.
Next month, we'll wrap up our Budget FE project with top-end assembly and dyno testing.
Our '67-'68 vintage 390 high-performance...
Our '67-'68 vintage 390 high-performance engine was retrieved from a junked Cougar and turned over to a machine shop in Arizona for rebuilding. Excessive vibration along with poor performance made it necessary for us to bring this engine to JGM Performance Engineering. JGM's Ryan Peart gets started on disassembly.
This ridge on a low-mileage...
This ridge on a low-mileage engine, not to mention cylinder-wall pitting in the crosshatch, has us baffled. Heavy carbon atop the piston indicates excessive idling and a filthy rich mixture.
What Is Blueprinting?
Every engine build should be a blueprint, which means you've got to have a plan. We don't know who first used the term "blueprinting" in the world of engine building, however it's appropriate because you want to plan your engine build, not approach it with reckless abandon. Blueprinting means you're going to check anything and everything that can be checked; then you're going to act on these findings.The first phase of blueprinting is inspection. Even brand-new parts must be inspected and measured thoroughly. Need some good examples of why you should inspect new parts?
- Core plugs found inside a new engine block's water jackets
- Oil-pressure relief valve stuck in a new pump, causing oil filter to explode all over a dyno cell
- Water-pump seal leak in a new water pump
- All 16 valveguides out of parallel in a pair of new aftermarket performance heads, discovered by JGM Performance Engineering during a small-block buildup
- Valve stem to guide clearances too tight in another pair of aftermarket performance cylinder heads, which means valves would have seized when we fired the engine
- Severe core shift in a new block to where boring and honing would have taken us into the water jackets (we returned the block)
- Water-jacket passageway not drilled through on a '70 vintage 351W cylinder head, which would have caused the head to run hot.
- Misdrilled oil-galley passages in main bearing saddles, causing oil starvation at main bearings (this was a Ford block)
The next phase of blueprinting is improvement. Improvement begins with machine work on the block and cylinder heads. Even if you have new cylinder heads, they should be disassembled, inspected, and machined as necessary. This is why we had Edelbrock send us bare castings for our 390. We didn't need Edelbrock's valvesprings and retainers. We had Crane's. We did have Edelbrock send us 16 valves. JGM machined the heads to its specs.
Cylinder-head improvement includes:
- Before you machine, check head castings (even new ones) for cracks
- Machine (or replace) valveguides to proper stem/guide clearance
- Three-angle valve job (perfect for street because this improves flow, yet allows for adequate valve cooling)
- Machine decks to true (always--even new ones)
- Remove risers (high spots) in chambers that can become hot spots
- Install hardened exhaust valve seats (when not equipped in old iron heads)
- Screw-in rocker-arm studs and guideplates (stud-type rocker arms only)
- Chamfer oil drainback holes to improve return flow
- Port-match (match intake and exhaust gaskets) to improve flow
Peart checks deck height with...
Peart checks deck height with a dial indicator because we want to know what this engine is right off the truck. This is not only a teardown--it's a fact-finding mission. We want to know why this engine build failed.
A lot of trash in the Cobra...
A lot of trash in the Cobra T-pan indicates oil contamination with finite metal particles. Some of this is moly-based assembly lube, but there's more. We're convinced piston-to-cylinder wall clearances are excessive. Our 4.050-inch bores have already been punched 0.030-inch oversize. We'll have to take it 0.010 inch more because we're on the high side of 0.030 inch.
Although these C3AE-A rods...
Although these C3AE-A rods have been reconditioned, workmanship is disappointing. Rod bolts were not replaced when they should always be replaced. Large ends are egg-shaped. Side clearances are within factory specifications.
We don't have a cam card from...
We don't have a cam card from the previous build, but we do know this is a high-performance, flat-tappet, hydraulic camshaft. Peart determined lift to be 0.325 inch intake and 0.325 inch exhaust (at valve, 0.572 inch). Duration is 236/236, with 108-degree lobe centers. This is an aggressive flat-tappet hydraulic street cam with a lumpy idle. We'll tone it down with a hydraulic roller cam.
We were surprised by the condition...
We were surprised by the condition of this aftermarket balancer, which had been forced onto the crank. Luckily, there was no damage to the crank. We had to throw this balancer away.
Because we're going to 0.040...
Because we're going to 0.040 inch oversize, JGM wants to be sure our block sports proper cylinder-wall thickness. Although we've seen our share of FE big-blocks (except 427) go to 0.060 inch oversize, iron can sometimes get thin in places. Peart sonic-checks all eight cylinders--top, middle, and bottom primarily on the thrust side. The thinnest we found was 0.162 inch, or shy of 1/4 inch thick.
Peart measures all crankshaft...
Peart measures all crankshaft journals and makes a determination about machine work. Crank journals will need to be polished and oil passages chamfered. We were surprised to see oil holes that weren't chamfered.
JGM Performance Engineering...
JGM Performance Engineering put our block through an extensive cleaning process that makes old iron look like new. Peart checks the line bore and finds main bearing saddles out of alignment. We check line bore to see if our crank sits in the saddles nice and straight. If it doesn't, we eat up main bearings, for starters. When the crank and block are out of alignment, everything is, from crank to piston crown.
When resizing the line bore,...
When resizing the line bore, we begin with main bearing caps, shaving a couple thousandths off where caps meet the block to perfect mating surfaces. This, of course, makes the main journal passage smaller. We are also machining the sides to get them true.
If you've ever wondered why...
If you've ever wondered why machine work is expensive, consider setup time. To line-hone this block, Peart has to set up the machine, which takes a lot of time if it's being done properly. He installed our ARP main studs, which will have to be modified to clear the Cobra T-pan. Here, he dresses each stud with molybdenum lube and torques the main caps.
We line-hone main saddles...
We line-hone main saddles for much the same reason we hone cylinder and lifter bores: to get them straight and true. What's more, we're crosshatching bearing contact surfaces, which makes the bearing more secure. Factory-production machining tolerances aren't as precise as a machine shop's because there's no time for it. When we blueprint an engine, we're checking and machining everything, which frees up power and improves reliability.
As Peart line-hones, he checks...
As Peart line-hones, he checks dimensions; then he installs the main bearings and measures inside dimensions as a result of bearing crush. We want proper crush (and not too much of it) to where we achieve perfect journal clearances with the crank installed.
The block decks are machined...
The block decks are machined to achieve perfect cylinder-head mating surfaces. Peart makes two passes on each side and shaves 0.010 inch off the decks. We couldn't help but notice the previous machine shop never cut the decks.
One pass of the milling machine...
One pass of the milling machine shows this irregularity--deck warpage. One more pass will eliminate irregularities. Doesn't this tell you something about why cylinder-head gaskets blow on fresh engines because someone didn't check and mill the decks? Light areas are low spots--areas where coolant and/or compression could leak through.
Because our 390 block is already...
Because our 390 block is already bored 0.030 inch oversize, we didn't bore to 0.040 inch over. Instead, we'll hone the additional 0.010 inch. We do this because boring creates excessive heat we don't want. We'll take a slower path to 0.040 inch over. JGM begins with coarse stones, then finer as he hones. Here, he tapers cylinder bores for smoother access.
Why Use a Torque Plate?
Even though an engine block looks like a big, invincible chunk of machined iron, it's sensitive to virtually everything, including heat and stress. Install and torque a pair of cylinder heads and your block "moves" to that shape and union. Think about it--when you torque cylinder heads, you're "moving" bolt holes, decks, and cylinder bores. These elements change shape and dimension. We fire the engine and they change yet again with heat.
Connecting rods are reconditioned...
Connecting rods are reconditioned the same way we line-hone. Peart disassembles each rod and removes the rod bolts. He shaves the caps first, and then hones large ends as shown. This gives rod bearings a nice crosshatch pattern to hang onto. The large end, if reconditioned properly, should have a crosshatch pattern and provide adequate bearing crush. New ARP bolts are installed in each rod before honing.
Summit Racing Equipment provided...
Summit Racing Equipment provided us with new Speed-Pro 0.040-inch oversize forged-aluminum pistons with coated skirts for reduced friction. These C3AE reconditioned Ford rods offer plenty of strength for our 390 street engine and will take a six-grand blast. Rods are bushed for floating pins.
When your machine shop finish-hones cylinder bores, they must be the same shape they would be with the cylinder heads torqued in place. That's why reputable machine shops use torque plates that are torqued to specs for honing operations. This allows the cylinders and block to conform to the installed shape. Savvy machinists also understand there needs to be a cooldown period between honing phases because honing generates heat, which alters cylinder dimensions. Jim Grubbs hones a little, then checks dimensions top, center, and bottom before and after cool down.
Even if you're building a stone-stocker, you should always be thinking about oiling-system improvements. All oil passages should be chamfered to reduce fluid turbulence and improve flow. Pressure is important, however volume is more important to not only lubrication, but also to heat transfer. Did you know oil does more than just lubricate? It also carries heat away from hot engine parts. Improving return oil flow to the pan is just as important. Chamfer oil-return holes and use red GE Glyptal paint in all oil flow areas--valley, heads, timing set region in front, even the inside of your oil pan. Before application of GE Glyptal, surfaces must be hospital clean or it will peel off. You can find GE Glyptal at Eastwood.
Rear main seals don't have...
Rear main seals don't have to leak. Peart locates the seal parting gaps offset from the main-bearing cap contact surfaces to reduce or eliminate risk of leakage. Use Permatex's The Right Stuff sparingly in seal grooves, with a dab at the gaps.
We're installing Crane's 349521...
We're installing Crane's 349521 hydraulic roller camshaft to reduce internal friction and improve valve-timing events. Both will improve performance. A roller cam allows for a more aggressive profile without sacrificing idle quality and hammering valvesprings. Peart gave our Crane stick generous helpings of engine-assembly lube. Never, ever use moly-based lubricants on cam journals. Use moly coat only on flat-tappet cam lobes, which aids in the break-in process.
We set the cam first due to...
We set the cam first due to improved access. With the crank in place, it would be harder to set the cam. Peart coated both main journals and bearing with assembly lube, which is better than engine oil thanks to its sticky consistency. It doesn't go away if an engine has to sit for a while.
Here's a cross-section of...
Here's a cross-section of the crank/bearing/seal area. We studded the mains with ARP studs for support. This makes our 390's bottom end more bulletproof for those occasional six-grand, wide-open-throttle experiences. Peart has only hand-tightened these studs. They get torqued when we run down main caps.
FE big-blocks have a number...
FE big-blocks have a number 5 main bearing cap that's quite involved and leak-prone if you don't install it properly. In addition to main bearing seals, there are also side seals. Peart applies a light application of The Right Stuff between the side seals and main cap before setting main cap in place. He also applies The Right Stuff between the main cap and block in the corners. Don't forget to lube all main bearings and journals with assembly lube.
Main stud nuts are torqued...
Main stud nuts are torqued in third values--ultimately to 85 ft-lb. Begin at the number 3 cap at 28 ft-lb, then number 2, then number 4, then number 1, and finally number 5. Come back with 56 ft-lb in the same order, and then finally to the 85 ft-lb. Be smooth in your application of torque--no jerking the torque wrench. Be sure to check the crank for freedom of movement (turning) with each cap. If you encounter resistance, clearances must be checked. It means you have improper bearing crush and tight clearances. Peart checks crankshaft endplay using a dial indicator. Endplay should be 0.004-0.0010 inch. Ours is 0.006 inch.
We have an interesting theory...
We have an interesting theory on piston-ring selection. Not everyone shares this opinion, so get ready. There's a developing belief that you should use gapless rings in the top groove and conventional rings in the second groove. This helps cylinder sealing while keeping oil travel and friction where they belong. We invite all theories. Peart checks ring-end gap, which should be 0.010-0.031 inch (ideally in the middle of this range) for top rings and 0.010-0.020 inch (again in the middle) for secondary rings. Ring gaps are adjusted on a special grinder. Did you know only the top ring is a compression ring? Secondary rings are actually oil rings, which carry oil up the wall. Bottom rings wipe oil down the wall.
Our Sealed Power forged pistons...
Our Sealed Power forged pistons from Federal-Mogul and Summit Racing Equipment have free-floating wristpins. Because Summit doesn't sell a lot of forged pistons for 390s, these pistons have conventional C-clips. Peart checks the clip installation thoroughly to be sure each is seated firmly in the groove. The wristpins and rod bushings are lubricated with assembly lube.
Oil wiper rings are next....
Oil wiper rings are next. Install the expander first, making sure ends do not overlap. They must meet head-on, without overlap. Peart rolls his rings on like this. End gaps should be positioned 180 degrees opposite.
Top and secondary rings are...
Top and secondary rings are installed using an expander tool. Never roll these rings on, which will distort the ring. Gaps should be 180 degrees opposite and 45 degrees from each oil ring gap. All ring gaps should be 9, 12, 3, and 6 o'clock. And yes, rings will move during operation.
A Word About Bearings
There are a lot of misconceptions about bearings. That little tang on main and rod bearings isn't there to keep the bearing in place; it's a reference tool to ensure proper bearing positioning. Never use engine oil or assembly lube between bearing and rod, or bearing and block. Contact between bearing and rod, and bearing and block must be bone-dry for security purposes. Crush and crosshatch keep a bearing secure; so do dry contact surfaces. Be sure to use generous amounts of engine assembly lube (do not use a moly-based lube) on journals and bearings. Make sure the bearing is properly centered and secured. Check the oil hole alignment of the bearing where applicable.
Peart bathed the cylinder...
Peart bathed the cylinder walls with assembly lube. It's also OK to use engine oil here instead of assembly lube. Piston rings and grooves should get engine oil or assembly lube to ensure lubrication on startup. Use rod-bolt boots to protect cylinder walls and rod journals from being nicked. When securing the rod and tightening the nuts, inspect bearing security as well.
Peart checks piston deck height....
Peart checks piston deck height. Another important item to check early in the going long before this step is chamber volume and piston-crown volumes. These elements, coupled with deck height/compression height, help you determine compression on each bore. Deck height is zero.
The cam retainer plate is...
The cam retainer plate is next, along with a Cloyes Hex-Adjust dual roller timing set. Peart opts for dead-center timing because he didn't find any irregularities in our Crane roller cam. An adjustable timing gear enables you to advance or retard valve timing depending on expectations and cam-timing events.
Blueprinting is the process of leaving no stone unturned in an engine build. Blueprinting means sweating details others tend to miss. It's one thing to call your build "balanced and blueprinted" and quite another to actually do it. When we degree a camshaft, we're examining the most important details of an engine build--rotating assembly and valve timing events.
Because there's no such thing as perfection in mass production, you must always believe in failure potential. Assume the worst and hope for the best. New parts right out of the box aren't perfect. Like the best of machine shops, there are going to be factory workers who are having bad days--inattentive to things they should be attentive to, apathetic, careless, sloppy, eager for lunchtime or beer-thirty. Are you willing to gamble hard-earned dollars and your engine to this kind of carelessness? We didn't think so.
When we degree an engine, we're checking two things if it's being performed properly. First, we're checking for true TDC (top dead center) on all eight cylinders. Reputable builders will check for true TDC on the No. 1 cylinder and see if it jibes with TDC on the harmonic balancer. Most of the time, it won't. When it doesn't, good builders will mark true TDC on the balancer--and degree the balancer for pinpoint timing. True TDC is dead-middle of the top-dead-center crank journal rollover when the piston dwells at the top of the bore.
Wise builders will find true TDC on all eight cylinders more for curiosity's sake than anything. The truth is, true TDC will vary with even the best 4340 steel crankshafts. In a perfect world, we would have identical TDC on all eight cylinders, but this isn't a perfect world. Factory machining tolerances vary enough that you're not going to have eight cylinders that smack TDC with identical consistency; however, it's always good to know exactly what you have before buttoning up.
Once you've established true TDC on the No. 1 cylinder, you're free to degree the camshaft. Degreeing a camshaft allows you to compare the cam card and camshaft. You're establishing valve-timing events and lift as they relate to crankshaft travel. If you're unhappy with valve-timing events, this is the time to make changes either with the existing cam or opting for another one.