Building a Bigger Clevor
Andrew Grubb; Ontario, Canada: I am planning the build of a 351, Windsor-based, 427 stroker engine with around 600 hp that is as streetable as possible. Do you think it is worth spending the extra $2,000 for a Dart block that allows the capability to run a 4.125-inch bore, so that a shorter (less than 4-inch) stroke can be used? Most stroker kits use an excessively long stroke that can significantly reduce engine life, so the extra initial investment of the Dart block may be worthwhile in the long run. Also, would having a shorter stroke and a larger bore create a more high-end power engine (spinning up to 7,000 rpm or so)? What are the main benefits of using Cleveland-style heads, and would it really be worth the effort over a set of say, AFR 205cc (PN 1450) ported heads? I intend to run on pump gas, and the compression will be around 10.5:1 with forged internals.
The car will be light (around 2,500 to 3,000 pounds) and will see mostly street use but an increasing amount of track time (road course). I am going to be putting this into either a Cobra replica and/or a stripped out '66-ish Mustang coupe. I am hoping to spend less than 10K on the engine, $12K if it is a Dart block. If you would like to take a stab at how much horsepower and torque this thing will make, I definitely won't stop you.
Jeff Smith: Wow, Andrew, there's plenty to cover here. It's my opinion that you are always better off with a new, aftermarket block, especially if you intend to spin this engine beyond 6,000 rpm. An original Ford 351W block that is now 40-plus years old may not be durable enough to justify the cheap initial investment considering the amount of money you have to invest in machine work, particularly if you want to convert from two-bolt to four-bolt mains. To do all the proper machine work on a stock block, including adding four-bolt main caps (which cost roughly $325 for the caps), you're looking at spending $1,300 to $1,600. We priced the Dart SHP 351W block from Summit Racing (PN 31365235) at $1,865.41, plus freight. Want more reasons? Don Barrington at Barrington Machine mentioned that the Dart block has a priority main oiling system as compared with the stock 351W orientation, in which one lifter bank also feeds the main and rod bearings. If you were going to use the stock block, Don suggests bushing the lifter bores to reduce the oil-feed size to the lifters, thereby directing more oil to the mains. Plus, the Dart SHP block uses the smaller 2.749-inch Cleveland main-bearing journal diameter compared with the Windsor's larger 3-inch one. This reduces the bearing speed, which cuts down oil shear—a serious consideration for a track-day engine that will see lots of continuous rpm. Based on all these considerations, plus the Dart's inherent strength, the decision appears to be relatively easy. If that's not enough, the Dart block's much thicker cylinder walls allow punching the bores out to a maximum of 4.185 inches. That combined with a shorter 3.85-inch stroke creates a 424ci engine, which is fairly close to the desired 427 ci. You mention you would like to push this engine up to 7,000 rpm, but keep in mind that with a larger-displacement engine, you will be able to make 600 hp at a lower rpm, so you don't have to spin the engine quite that high. A longer-duration camshaft that is necessary to make the power at higher engine speeds also pushes the torque peak rpm higher, which helps produce more horsepower. For example, if an engine makes 400 lb-ft of torque at 4,000 rpm, that amounts to 304 hp. But make that same 400 lb-ft at 6,000 rpm, and you get a much higher 457 hp. So you can see that moving the torque higher in the rpm band is worth horsepower. But in the best tradition of no free lunch, that higher engine speed is also abusive on parts such as connecting rods and especially hard on the valvetrain. Often, a component like a valvespring that will live forever at 6,000 rpm can die a quick death when subjected to near-continuous use at 6,500 to 6,800 rpm.
With that in mind, the answer to the question of bore size is easy: Bigger is always better. Add a cylinder head that flows some air, and you have the basis for an engine that will make outstanding power. In my admittedly conservative approach, it seems wise to choose a shorter-duration camshaft that will maximize torque between 4,500 and 5,000 rpm. You will probably discover that a typical performance engine will spend much of its time in this rpm range. If you are really serious (and it sounds like you are), do some additional research and find a car that races your road course that has a similar engine and drivetrain combination. You could just ask the owner, but I would suggest asking specifically if he has a data logger (Racepak makes a good one, but there are many others) that would allow viewing a log of the engine's rpm curve on a quick lap. What you're looking for is how much time the engine spends in the rpm bands of 4,000 to 5,000, 5,000 to 6,000, and then 6,000 and above. More than likely, the engine will spend a clear majority of its time between 4,500 and 6,000 rpm. If that's the case, I would concentrate on emphasizing power production in that rpm range. For example, if your engine makes more torque it will accelerate the car hard coming off the corner and will carry more speed all the way down the straight as opposed to just making power right before you have to lift to enter the next corner. It's the same concept in drag racing, when torque accelerates the car all the way down the track.
To address your cylinder head question, I think you are on the right track with the AFR 205cc (PN 1458 w/72cc chamber) Windsor heads, since these heads not only flow really well but also offer excellent velocity, which will help make gobs of torque. If you subscribe to the torque concept, these heads are an excellent choice, even for a 427ci engine. AFR makes a larger, 225cc head (PN 1456 w/ 72cc chamber) with some significant flow increases over the 205 head, especially in the midlift flow areas where it might help to make even more power. Valve sizes are the same between the two heads (2.08/1.60-inch dimensions). Another thing to consider is that the exhaust ports are raised on both of these heads, which means bolt-on headers might not fit as cleanly on the Mustang.
If you think you'd still like to spin the engine to the higher speeds to take advantage of the increased horsepower, you might consider the Cleveland-style heads offered by Trick Flow Specialties (TFS). On paper, these canted valve heads produce similar specs to the 225cc AFR inline heads with 2.08/1.60-inch valves, although the TFS combustion chamber is much smaller at 60 cc (PN TFS-5160T005-CO1; $2,749.95 Summit Racing). The basic as-cast heads offer some decent flow numbers. The TFS catalog lists intake flow numbers for the 190cc as-cast Cleveland head as such: 248 cfm at 0.400-inch lift, 286 cfm at 0.500-inch, and 299 cfm at 0.600-inch lift. These are excellent numbers, matched with good exhaust flow numbers that average 76 percent exhaust-to-intake flow. This is really important because the original factory Cleveland castings are notorious for their extremely poor exhaust-port flow that killed any power potential above about 5,000 rpm. Clearly, if you wanted to spend a little more money on the CNC-ported heads, the flow would increase significantly. TFS also shows in its catalog a dyno test of a 383ci small-block Ford using the 190cc as-cast Cleveland heads making 524 hp at 6,500 rpm using a Crane 236/240 at 0.050 hydraulic roller camshaft with 0.621/0.631-inch valve lift. If we take the horsepower per cubic inch of that engine and multiply it by a 427ci engine, we get 595 hp. A larger engine will make the above cam smaller, which means it would probably reach horsepower peak at closer to 6,000 rpm than 6,500. TFS says the 383 made 480 lb-ft of torque at around 4,500, so we can assume the torque would also jump up to around 540 to 550 lb-ft with the larger 427. On deciding between the two heads, keep in mind that you will need to consider which head you will use before ordering pistons, since the canted Cleveland valve angles are completely different from the inline Windsor head. This means the valve reliefs in the pistons will be different depending on the cylinder head. You will probably need a dished piston to run pump gas, since these heads have a 60cc chamber. A 4.185-inch bore and a 3.85-inch stroke, a 20cc dished piston, a deck height of 0.005 inch in the hole, and a gasket thickness of 0.041 inch will produce a 10.6:1 compression ratio.
Finally, you might want to consider how the Cleveland head will physically fit in either of the cars you are considering compared with the Windsor head. The Cleveland package will basically require a custom set of headers, while you might be able to find a set of aftermarket headers that are designed for what would essentially be a 351 Windsor if you went with the AFR heads. It's these little things that can make a big difference in terms of how much the project will cost.
Airflow Research (AFR)
Trick Flow Specialties (TFS)
Billet steering wheels. Do you love them or hate them? Email us at CarCraft@carcraft.com. Yes, this one is sideways.
More On Oil
In the Aug. '11 issue, we did a story titled "How to Break in That Flat-Tappet Cam." In that story, we also tested several different break-in oils for both zinc and phosphorous (commonly referred to as ZDDP), two major antiwear additives that have been reduced in current API SM- and SN-rated oils for late- model cars intended to reduce efficiency loss in catalytic converters. One of the oils we tested came from Brad Penn, and as mentioned in the story, we were surprised to learn the amount of zinc and phosphorous in the company's Break-In Oil was lower than we anticipated, especially because Brad Penn has a very good reputation for providing high-quality lubricants.
Not surprisingly, we heard from representatives from Brad Penn, and they offered an explanation of those particular antiwear additive levels. According to Mike Kozminski, manager of Research and Development, and Richard Glady, VP of Sales & Marketing for American Refining Group Inc., which owns Brad Penn Lubricants, there is more to the story than just the concentrations of ZDDP in the oil.
According to the letter we received, "Brad Penn Break-In Oil is formulated to contain a nominal 1,000 ppm (parts per million) of ZDDP. Because with a ‘green engine' break-in process, it is essentially a controlled component ‘wear-in/run-in' period, the amount of anti-wear additive concentration (i.e. ZDDP) in the break-in oil must be carefully balanced to protect the cam and bearings to take the required ‘set' and at the same time seat the rings properly. Excessive amounts of ZDDP can interfere with these processes and may result in glazing of the cylinder wall, preventing the rings from seating properly. Too little ZDDP may result in bore ‘polishing' where the rings have worn down the cylinder crosshatching, essential for maintaining a lubricant film. The same is true regarding the presence of detergents (i.e. calcium) in break-in oils. Too much or too little of these components can be a source of potential difficulty. In response to Mr. Lake Speed, Jr.'s comments regarding detergents, industry studies and testing have shown that when detergent-type additives were included in oil formulations in properly pre-determined concentrations along with ZDDP, a ‘synergistic' effect was seen. It has been proven that the anti-wear properties of the zinc-containing additive and the oiliness of the detergents act on metal surfaces cooperatively. Under boundary lubrication conditions like those found in the valve train area (cam lobe/flat tappet contact points, etc) the zinc is the main actor. Therefore, when considering a break-in oil purchase, the fact that the oil contains detergents should not be considered a negative factor in the decision. A properly formulated and chemically balanced oil like Brad Penn Break-In Oil that contains both anti-wear and detergent additives will provide excellent engine protection and performance during the normal engine break-in process. In addition, with the unique Penn-Grade base oil cut, it provides tremendous wetability and enhances the performance with both Brad Penn's Break-In Oil and Penn-Grade High Performance Oils."
What is interesting about the Brad Penn lineup of oil is that while the Break-In contains a nominal 1,000 ppm level of ZDDP, it's worth considering the level of ZDDP in the oil that Brad Penn recommends after the engine has established its wear patterns. On Brad Penn's own website (www.bradpennracing.com/Zinc.aspx), the company lists the Penn Grade 1 10W-30 as containing zinc levels of 1,565 ppm, with phosphorous levels of 1,332 ppm, based on testing from Southwest Research, a highly respected research firm. These are figures that our research has indicated are acceptable levels of ZDDP, both in break-in and daily-use conditions. According to Brad Penn, engine builders who use Brad Penn Break-In Oil have had success breaking in flat-tappet cams with valvespring pressures up to 150 pounds of seat pressure and 350 to 400 pounds open. The company also claims break-in success in roller-cam engines with valvespring pressures of up to 450 pounds closed and 1,000 open. Brad Penn says a majority of cam manufacturers recommend Brad Penn Break-In Oil and Penn Grade 1 High Performance Oils to protect their cams. It is also important to note that there are dozens of factors involved with lubrication, especially in a brand-new engine using flat-tappet followers. Focusing on just the levels of ZDDP may not be the whole story. But combined with a historical perspective, it is clear that camshaft lobe failures seemed to spike at exactly the same time that the API-reduced ZDDP levels dropped below 1,300 ppm, and we feel this evidence is the best reason for focusing on these antiwear additives. The bottom line here is that Brad Penn offers several performance engine oils that do an outstanding job. Choosing the proper lubricant for your particular application is still not difficult, once you know more about what goes into each of those bottles of oil. Our goal is to give our readers that information so that they can make intelligent choices regarding the components they use in their performance engines.
The seller wanted $8,500 for this Camaro. The dude in the green shirt was like, "No way, homie!"
Edelbrock offers additional accelerator pump nozzles in a kit that can be used to cover up
Patrick Duf; Freeport, NY: I have been reading your magazine for years (thanks, Dad!), and I am finally writing to receive some advice on my '79 Malibu beater. My Malibu has a 305 Chevy and come next summer will have a 350 in it. My problem is going from idle to wide-open throttle. I recently threw in a Comp Cams XE268 cam (224/230 degrees duration at 0.050, 0.477/0.480-inch lift), a 2,200-2,400-rpm converter, L98 aluminum heads, an Edelbrock Performer RPM Air-Gap manifold, and topped it off with an Edelbrock 1405 carb per Edelbrock's recommendation. The main problem is when I put my foot down, the engine stalls out and does not restart. I checked the No. 1 plug to see if it got wet when the throttle was opened all the way, but it was bone dry. If you have any suggestions on where to start looking it would be greatly appreciated. This is my first engine build.
Jeff Smith: Thanks for taking the time to ask a question, Patrick. We all have to start somewhere, and it appears that yours is a relatively easy fix. The issue is one of combinations. When creating a high-performance parts mix that includes a carburetor, an intake manifold, a camshaft, and a cylinder package, you have to expect to do a little tuning to make the system work properly. It sounds like something as simple as merely increasing the accelerator pump shot, but before we get into that, it's important to ensure that the fuel delivery system is in good shape. Often, what appears to be a carburetor-related problem can be traced to low fuel pressure and/or low fuel volume. We will assume for a moment that you are using a standard, engine-driven fuel pump, since that's the simplest and most common fuel delivery system. Even a stock fuel pump should be able to supply sufficient fuel for a mild performance engine like yours, so check to make sure the fuel line is not obstructed or somehow kinked in a way that would restrict fuel volume. Next, you will need to borrow or buy a good fuel-pressure gauge. Those tiny, inline fuel-pressure gauges that are about 1 inch in diameter are notoriously inaccurate, so locate a larger, more accurate gauge. Ideally, set it up so you can drive the car and have a buddy watch the gauge. We've done a quick test with a T-fitting in the fuel line and taped the gauge to the bottom of the windshield. Make sure you don't have any leaks, then drive the car easy and eventually hit wide-open throttle in Second gear, somewhere safe (and legal—getting a ticket while tuning puts a damper on the process!). You should have a minimum of 4 psi of fuel pressure with a preferred 5 to 6 psi. We can assume from this that the pump is supplying sufficient volume—that's why we test under load instead of just at idle. If the pump cannot keep up with the demand, the pressure will drop as rpm increases. If the pressure drops, it may not necessarily be the pump's fault. In older cars in particular, odd things, such as big dents or twists in the fuel-supply line, can restrict volume. You might also check to ensure the tank is properly vented. The simple way to check is to do the same test with a cap you know is properly vented.
Assuming there is sufficient fuel pressure, the next thing to try is changing the accelerator pump linkage. There is a small arm that connects the throttle linkage to a small vertical pin that is actually the top of the accelerator pump. The linkage will have three adjustment holes, and the hole closest to the carburetor body will produce greater leverage to deliver a little more fuel. That's the no-cost trick. If that helps, but the bog is still there, you will probably have to add a larger accelerator pump nozzle. The stock nozzle diameter for your carb is 0.028 inch. Edelbrock sells a nozzle kit (PN EDL-1465; $12.95 Summit Racing) that includes three squirters at 0.024, 0.033, and 0.043 inch. Try the largest one first, and if the hesitation disappears, try the 0.033-inch nozzle.
Another tuning item that might help is to make sure both the initial and total ignition timing are properly adjusted. I'd suggest setting the initial timing at 12 to 14 degrees. This is what you'll read on the harmonic balancer at idle, using a timing light with the vacuum advance line unhooked. If you add a timing tape to the balancer, you can use a standard timing light to read the total timing at around 2,600 rpm. Again, with the vacuum advance line removed and plugged, you should read around 34 degrees of total timing. Don't advance the timing much more than 36 degrees, because the 305 engines tend to be detonation sensitive, and too much timing can make them rattle—and that's a quick way to both kill power and possibly break a piston. If you find you have other questions related to tuning, you can also call the Edelbrock Tech Line at 800/ 416-8628.
Here's a picture of this month's Horsepower! star, Greg Monroe's '01 Bullitt in his shop, Racer's Edge Tuning (RET). Want a turbo kit installed on your car? Call RET at 562/ 622-2508.
Timing is Everything
Dale Caissie; Kamloops, BC, Canada: I'm having trouble setting up initial timing on my SBC 350. It's a 0.030-over '84 block, balanced Scat rotating assembly, flat-top hypereutectic pistons, Pro Products damper and flexplate, ported Edelbrock Performer RPM heads, Comp XE300HR hydraulic roller cam with matching valvesprings, Crane 1.5:1 roller rockers, Pro Products single-plane intake, with a Holley 750 street HP on top. The ignition is a Mallory Pro Billet PN 8361m with a HyFire digital 6 CD box and matching coil. Here's my problem: Upon trying to dial in initial timing, my advance is way up at 30-plus degrees. This is with an idle speed of 900 to 1,000 rpm with the vacuum advance disconnected. Is my mechanical advance coming in already? How do I compensate for setting that initial advance? I questioned myself on the initial build of a milder combo a few years back that maybe the balancer was for the timing tab to be in the center of the timing cover, not off to the side as most would be, so I double- and triple-checked the location of TDC to the timing pointer, and it's correct. As for tuning, I have out-of-the-box jetting, power-valve and accelerator pump jet. Before I dive into carb tweaking, I've always been told to nail down ignition timing before anything else. Any suggestions?
Jeff Smith: It sounds like the timing is advanced, because that's where the engine seems to run properly. I'm assuming the problem is that if you try to pull the timing back to somewhere around 14 to 16 degrees initial, the engine won't run. While your friends are correct that you need to set the timing correctly to dial in the carb, it sounds like we have multiple issues. Let's start with the basics. You said you checked the timing marks to make sure they are accurate. The best way to do that is to pull all the spark plugs to make it easier to turn the engine by hand. Install a spark plug–style piston stop and carefully rotate the engine clockwise by hand until the piston contacts the stop. Mark the zero (0 or TDC) timing position location on the balancer, then carefully rotate the engine counter-clockwise until the piston hits the stop and mark the balancer again at the zero timing mark. Never use the starter motor to turn the engine with a piston stop in place. This procedure will produce two locations on the balancer. If the balancer is degreed, then simply record the number of degrees on either side of zero and compare the numbers—they should be the same. If your balancer is not degreed, try this simple trick: Place a piece of tape to straddle both sides of the zero mark on the balancer and mark at zero and at both stop points. Then remove the tape and use a steel ruler to measure both distances from your zero mark. If the distance is the same on both sides of the zero mark on the balancer, then TDC is correct. If the mark is not centered, you will need to move either the indicator or remark the balancer. Frankly, it's easier to create a new indicator. Then double-check your work to make sure you went the right way. With this effort, you now have a true zero mark from which to determine both initial and total timing.
Back to your problem: If TDC is correct, let's look at your combination. With a Comp XR300HR hydraulic roller, the specs are 248/254 degrees at 0.050-inch tappet lift with a 110-degree lobe-separation angle. That, my friend, is literally a bottom-of-the-page camshaft that suffers from minimal idle manifold vacuum. So I'm going to guess that you had to crank open the throttle blades to establish any kind of idle speed and that the engine wants all that timing just to stay running. What you really have to do is richen the idle mixture screws to put more fuel to the engine. By doing so, you will be able to pull the timing back slightly. But more than likely, you will need 18 to perhaps 20 degrees of initial timing to keep the engine running at low speeds. This is especially true if you only have 9:1 (or less) static compression. Let's touch on why more initial timing is necessary.
Overlap is the amount of time in camshaft degrees between the exhaust closing and intake opening points. A long-duration camshaft like yours creates that lumpy idle that everyone wants because of the increased amount of time that the intake and exhaust valves are simultaneously open. But this greater overlap also kills manifold vacuum. We calculated your cam's overlap by adding the exhaust closing point at 0.006-inch tappet lift in degrees before TDC and the intake opening point at degrees after TDC. This number came out to an astonishing 83 degrees. While this number is difficult to relate to by itself, let's compare it with the same Comp lobe family but with a shorter XE276HR cam. The overlap figure for that cam is 59 degrees or (drum roll, please) 24 degrees less. For every added degree of overlap, the idle quality suffers. So my guess is that the Holley is a little too lean to compensate for that much overlap, and that's why it appears you need so much timing. About the only thing you can do to help this situation is to degree the cam to ensure that the intake centerline is actually at 106 degrees after TDC. Assuming the cam was not retarded (which would lower idle manifold vacuum even more), you might consider advancing the cam by 2 to 4 degrees. This will improve idle vacuum slightly, requiring a little less initial timing.
You will also have to make the idle air/fuel ratio much richer with the transmission in Neutral or Park because once the engine drops into gear, it will create more load, and idle vacuum will drop even further. This means the air/fuel ratio has to already be rich in Neutral or Park because the fixed idle-feed restrictor that determines the mixture will not be able to compensate for the reduced signal from the manifold when the transmission is put in gear. This is part of the problem with a carburetor attempting to accommodate a long-duration camshaft with lots of overlap using an automatic trans that changes the idle load. You will probably have to drill holes in the primary throttle blades to allow more air into the manifold. This will allow you to close the throttle blades back down to their intended location so that the idle transfer slot will work the way it was intended. The new Holley HP carbs incorporate an idle bypass feature, located underneath the carb stud, that allows the tuner to leave the throttle blades properly located relative to the idle transfer slot, and adjust the idle speed by varying the air bypassed through that separate circuit. It's slick and it works very well, which means you don't have to drill holes in the throttle butterflies anymore.
Holley Performance Products
Bowling Green, KY
We spotted this SOHC 5.4L Ford engine in the junkyard. The bore size and spacing is the same as a 4.6, but the 5.4 has a taller deck height. You can tell by looking at the distance between the top of the front-facing freeze plug on the driver side of the engine.
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