Marc Nagley; Gun Barrel City, TX: I have two 454 four-bolt main blocks and would like to know which one would be the best for a buildup—something like the Blue Collar 454.
Block L: Casting Number 10114182
Block R: Casting Number 12550313
I also have a set of heads casting number 10114156. Would this set be good for my Blue Collar buildup? Several notes: Block R has six bolts for the timing cover and a mechanical fuel pump boss and a one-piece rear seal. Block L has a 10-bolt timing cover and a one-piece rear seal.
Also, will I be able to use the larger Manley valves, 2.19/1.88, and have the minor back cutting done to increase the flow with the above mentioned heads? The Ask Anything column is outstanding. I read it every issue. Keep up the good work. Wish I had half the knowledge you have. As the old saying goes, "You have forgotten more than most people know."
Jeff Smith: Well, Marc, we'll attempt to live up to your expectations! First, I had to check to make sure there really is a town called Gun Barrel City, Texas—and there is! My guess is that liberal Democrat Representative Nancy Pelosi (she is the House Minority leader) has never visited.
We'll go into more detail, but it appears these two blocks are very similar so choose the one that looks like it has been abused the least. Our pals at Jim Grubbs Motorsports tell us they rarely get a big-block Chevy in for machine work that does not need to be align-honed, so you might inspect both closely to see if one looks better. Try measuring the housing bore diameters of each main, but even that won't tell you if they are properly aligned. These are both Gen V blocks that are still the standard 4.25-inch bore that combined with a 4.00-inch stroke makes a 454. I am not aware of any real differences between the two blocks, except, as you mentioned, the 10114182 block has the 10-bolt timing cover. Most of the Gen V and VI blocks came with either a cast or plastic six-bolt timing cover. The most significant change for the GEN V/VI conversion was the one-piece rear main seal. This obviously requires a one-piece rear main seal crank that's not interchangeable with the older, MK IV two-piece rear main seal cranks. We found a cast, 4.250-inch stroker nodular iron crank from Ohio Crankshaft for $295 for a one-piece rear main seal engine that's incredibly affordable and adds a bunch of displacement for the same cost as a standard stroke crank. Another big change with these blocks was moving the main oil galley from the MK IV‘s position alongside the oil pan rail, to the Gen V placement parallel to the cam bore. This also creates a priority main oiling system, which is far better for higher-rpm lubrication to the mains and rods. Also, keep in mind that these blocks will require a specific Gen V/VI oil pan and gasket. Gen V blocks eliminated the mechanical fuel pump mount that was reinstated with the Gen VI version block.
This is Marc’s 12550313 Gen V 454 block. This is a four-bolt main block that uses a one-pi
Perhaps the biggest area of concern with the Gen V/VI blocks is the altered water jackets. Even more so because these cooling jacket holes in the block are different for Gen V and Gen VI. Both your blocks are Gen V and often a stock MK IV head like a stock iron casting may not work. The changed configuration of the upper water jacket holes creates a very thin area for the gasket to seal. Most current aftermarket big-block heads are now designed to accommodate both the Gen V and Gen VI (the Gen VI upper coolant holes nearest the lifter valley are different than the V) version blocks. Before purchasing a set of new heads, it would be wise to check with the manufacturer to ensure the head you choose is compatible with a Gen V block. We found several Fel-Pro head gaskets that will work with the Gen V block, including the PN 1047 gasket that is a 0.039-inch-thick composition gasket that is relatively affordable. I spoke with Fel-Pro's Greg West, who offered this great explanation: "The problem is with the head and block castings themselves. The oblong-shaped coolant openings located toward the valley side of the Gen V and VI blocks are cast holes and there can be quite a variation between castings, so they don't always match up to the corresponding coolant holes in the Gen IV heads. There is sufficient material on the gasket to cover the outer contour of both the heads and block, but the hole mis-match in the two castings doesn't provide enough land area to properly compress the gasket. I suggest laying pieces of carbonless paper on the deck of the block on the valley side. Tighten down the head on the block without a gasket. Remove the head and look at the impression left on the carbon paper around the water openings. If the impression on the paper around the water ports is less than a 1⁄4-inch, it is likely that water will leak into the valley."
Another feature of the Gen V/VI is that it is designed to accept a factory hydraulic roller camshaft. The front of the cam is stepped to accept a bolt-on cam limiter plate so you don't have to screw around with adjusting camshaft endplay with cam buttons. The lifter bores are also taller on these blocks to give more support to the hydraulic roller lifters. What all this means is that a hydraulic roller cam is much cheaper to install because you can use stock replacement lifters instead of the more pricey aftermarket retro-fit lifters.
Next thing to look at is the heads. If you are on a budget, you can retain the stock heads you mentioned. All the modifications are easy to do, but before you get too deep into these castings you need to know about the net lash valvetrain. Because setting lifter preload requires significant time on the assembly line, GM went with the net lash system, where a bolt tightens down the rocker to a set point that also preloads the lifter to its proper depth. For these newer big-blocks, GM used a small 3⁄8-inch bolt to retain the rocker arm instead of the typical big-block 7⁄16-inch adjustable stud. The problem is that tiny 3⁄8-inch bolt will not hold up against decent performance camshaft spring pressure. Plus, the net lash does not allow custom lifter preload, except through custom pushrod lengths. There is an alternative, however. Crane makes a conversion stud kit that uses a 3⁄8x16 lower portion stud that screws into the head with a 7⁄16-inch top thread that allows the use of big-block rocker arms. The Crane conversion kit is PN 99152-16 ($104, Summit Racing) and this would allow you to run roller rockers like the Crane Classic big-block rocker PN 13774-16 ($312, Summit Racing). If you stick with a mild hydraulic roller cam, the conversion rocker studs will work just fine. However, if you are considering running a big cam and spring pressure, that small 3⁄8-inch internal stud probably will not withstand a lot of spring pressure. With a bigger cam, have a machine shop do the compound angle drilling and tapping for a 7⁄16-inch stud. Just to cap this off, do a little more research because by the time you invest in machine work for larger valves, machining the rocker stud bosses for a 7⁄16-inch studs, a valve job, and the inevitable new guides, you will be quickly approaching the cost of a set of Edelbrock aluminum heads that are also considerably lighter. A pair of ready-to-bolt-on Edelbrock oval-port aluminum heads from Summit (PN 50459) will run $1,799.
Crane Cams; 866/388-5120; CraneCams.com
Edelbrock; 310/781-2222; Edelbrock.com
Federal-Mogul (Fel-Pro); 810/354-7700; Federal-Mogul.com
Ohio Crankshaft; 800/333-7113; OhioCrank.com
Chris Carter; via CarCraft.com: How do mass airflow meter modifiers work? I have a 2006 5.3L truck engine I'm about to swap into an older car. Rather than pay someone to tune my engine, I am thinking of modifying the engine, maintain the stock OE computer and wiring harness, and add a mass airflow modifier.
This is a Granatelli mass airflow (MAF) meter. All current GM MAFs now work off of frequen
Jeff Smith: All engines with mass airflow meters (MAF) measure the amount (mass) of air that enters the engine. This allows the EFI to be more accurate because the MAF tells the ECM exactly how much air the engine is ingesting, making a quick and easy calculation for the proper air/fuel ratio. The other version of EFI is called Speed Density where there is no MAF. Without a MAF, the ECU must use input from the manifold absolute pressure sensor (MAP) to determine load and then combine that with the throttle position sensor (TPS) and engine rpm to determine the amount of fuel the engine needs based on a predetermined estimate of the amount of air the engine is ingesting at that given load. Both MAF and Speed Density also rely heavily on the feedback from the oxygen sensor. While speed-density systems are easier to work with and cheaper because they don't use a MAF, they are also less accurate. It might be worthwhile to take a look at how MAFs work so you understand what's involved.
Original MAF sensors used a thin wire stretched across the meter's inlet. A current was applied to the wire, and the amount of voltage and current required to maintain a given wire temperature would change as the mass of air passing over the wire increased. More modern meters divert a small amount of air through a channel and measure the drop in voltage as airflow increases across the meter and use that to calculate mass flow. Early meters delivered a specific voltage output curve that the computer used to determine the amount of airflow. According to Lingenfelter Performance Engineer Jason Haines, GM computer systems after 1994 began using a frequency based output instead of voltage because it offered more accurate information and control at idle and low engine speeds. Now, let's say you've modified your engine and that stock MAF is now a restriction to airflow. This means you need to install either a larger OE MAF or an aftermarket MAF to plug into the inlet system. The problem with using a non-OE MAF is that it may not communicate properly with the existing factory computer. This is where the MAF modifiers come in.
Haines told us that modifiers for late-model GM engines really aren't necessary since all the GM software from companies like HP Tuners and EFI Live (the two biggest) allow you to tune the ECM directly, including MAF frequency. The most popular MAF modifiers were designed for Ford applications that did not have easy tuning access to the OE Ford ECM.
I also spoke to Andy Wicks, who runs DynoTune Speed and Performance in Watertown, South Dakota (DynoTuneUSA.com). Andy is the guy who for years ran the chassis dyno for us at the Car Craft Summer Nationals. Andy has tons of experience tuning all kinds of late-model fuel-injected engines. Andy says the typical GM MAF sensor actually has quite a bit of room for power and that, for a normally aspirated combination, the stock MAF can handle as much as 480 to perhaps 500 normally aspirated horsepower without any changes. He also said the MAF modifiers were actually good for the older Ford systems that still used a zero-to-5-volt scale, where you could use a MAF modifier to increase the voltage reading. For example, you could increase the part-throttle 0.10-volt reading to 0.11 and increase fueling by 10 percent. The down side to this approach is that it sacrifices part-throttle resolution. A far better approach is to go into the computer and adjust the base fuel map tune to compensate for the changes.
This is the JMS mass airflow modifier (MAM). It offers several tuning advantages, includin
To address your specific example, let's say you want to increase the performance on the truck 5.3L engine with a camshaft, ported cylinder heads, headers, and either a passenger-car LS6-style intake, or an aftermarket intake manifold. With all these modifications, you may want to add larger injectors to match the additional airflow generated by the engine's new heads and intake. If you add larger injectors, the original base fuel map will have to be adjusted to compensate for the greater amount of fuel flow. For example, if you added injectors capable of 30 percent more flow, then the fuel map will need to be reduced in pulse width by the same 30 percent to create the same amount of fuel flow at part throttle. The engine will have to be tuned because that simple compensation will not really create the proper fuel curve. Andy told us that his company offers a simple "startup" tune service (for $150), where you send him your stock ECU, along with the specs for your engine, and he will disable the VATS (vehicle anti-theft system) so the engine will start and run, and then a basic file that will allow your engine to run and drive. More than likely, your application will still require further tuning to get the last improvements and better driveability, but this is an inexpensive way to get the car running.
The bottom line is that while the mass air modifier has its place, tuning the ECU's specific fuel and spark maps is still the best procedure for your GM performance application.
EFI Live; +64 (9) 534 1188; EFILive.com
Dyno Tune Speed and Performance; 605/753-1101; DynoTuneUSA.com
HP Tuners; HPTuners.com
JMS Chip & Performance; 601/766-9424; JMSChip.com
The next time you see one of those tree-hugging "zero emissions" electric cars on the freeway, educate them with this little bit of wisdom. In the state of California, roughly 70 percent of all electricity is generated by coal-burning powerplants.
COIL SPRING CALCULATIONS
John Wade; Stafford, England: Some years ago you published a formula for calculating the spring rate of a spring using wire diameter and number of coils. This was in a reply to a question from a reader. I meant to but never did make a note of the formula. Do you have easy access to it in your back issues/tech notes, and if so could I please ask for it again?
A coil spring with more active coils (left) tends to offer a lower spring rate than short
Jeff Smith: It's always fun to get tech letters from outside the U.S., this time from England! This is a relatively easy one, and we just got this formula off the Internet from someone with engineering expertise. The formula is somewhat simple but requires some specific engineering information—namely something called torsional modulus of the spring wire. Don't worry, we had to look up the definition so we'll save you the time. Basically, this relates to torsional rigidity, which is a material's resistance to twisting, or more accurately the ratio of the amount of force (torque) required to twist a given bar to generate a given amount of angle or twist at the end of the bar. So the variables would be the properties of the steel, the diameter of the bar, and its length. One property of carbon steel relates to its elasticity—or its ability to bend without breaking and also to return to its original shape. This is a very important factor for a spring that's constantly twisted. Now let's take a steel bar and bend it around a mandrel to create a coil spring. The length of the bar relates to the number of active coils in the spring. An active coil is defined as one that does not touch an adjacent coil. The overall spring diameter plays into this equation as does, of course, the diameter of the wire that makes up the spring. A larger wire diameter increases the spring's resistance to being compressed. The formula uses what is called "mean coil diameter," which is basically the outside diameter (OD) plus the inside diameter (ID) divided by two. For a 5.5-inch OD spring with a 0.625-inch diameter wire, this number is 5.185 inches.
A spring's ability to resist compression is called the spring rate. This is expressed in terms of pounds per inch. As an example, if we stand a coil spring on end and apply 500 pounds of load to the top of the spring and it compresses exactly 1 inch, then this spring has a rate of 500 pounds per inch. Note that this is not 500 pounds per square inch. That is a pressure reading (such as air pressure inside a container) where force is applied equally in all directions. A spring has a rate of force that is applied in a linear direction.
The one engineering concept we need to include in our spring equation is the torsional modulus of a steel spring wire. This is given as 11.25x10^6 (10 to the sixth power), or 11,250,000. Now that we have this number, we can apply the formula:
Spring Rate = G * D^4 / 8 * N * D^3
G = torsional modulus of steel: 11,250,000
D = wire diameter: 0.625
N = number of active coils: 6
d = mean coil spring diameter: 5.185 inches
Now we can plug in the variables. Let's solve D^4 and d^3 first:
D^4 = (0.625 * 0.625 * 0.625 * 0.625) = 0.1525
d^3 = (5.185 * 5.185 * 5.185) = 139.39
Spring Rate = 11,250,000 * 0.1525 / 8 * 6 * 139.34
Spring Rate = 1,715,625 / 6688.3
Spring Rate = 256.5 pounds per inch (lbs/in)
Now if we reduce the number of active coils from 6 to 4, the formula tells us that the rate will increase. This means the new denominator (the number below the line in simple division) will be a smaller number: 8 * 4 * 139.39 = 4,460
Spring Rate = 1,715,625 / 4,460
Spring Rate = 384 pounds per inch
A simpler way to measure coil spring rate is to use a scale to measure the actual load created by the spring. Let's place a coil spring on a scale and compress the spring 1 inch. Let's assume the scale reads 500 pounds—this isn't the rate, this is just the initial load. We need to preload the spring to get a more accurate reading. Now compress the spring another 2 inches and the scale now reads 1,800 pounds. Subtract the initial load of 500 pounds from the total (1,800 – 500 = 1,300 pounds). Now divide that 1,300 pounds by 2 because we want to know the rate in pounds per inch, so 1,300 / 2 = 650 lbs/in.
These calculations can be used for any type of coil spring, such as a valvespring. Let's say you want to reduce the installed height of a valvespring by 0.100 inch and you'd like to know what the new closed and open valve spring loads will be. If you know the spring rate, the calculation is easy. Let's say the installed height was 1.850 and the original load was 90 pounds. With a spring rate of 415 lbs/in, decreasing the installed height to 1.750 means a change of 0.100 inch. The math will be 415 x 0.1 = 41.5 pounds of load increase on the valve all the way through its entire lift curve—assuming it's a constant-rate spring. Now let's toss a variable into the works. A beehive spring is tapered at the top, which means the overall spring diameter is not constant, which makes this a variable-rate spring. This means the above calculation will not be accurate since the rate will change as the spring is compressed. This also assumes that no coils touch, which will affect the spring rate because now we have fewer active coils. In terms of a quickie eyeball evaluation of any coil spring, shorter springs offer a higher rate as does a thicker wire diameter. Longer springs with more active coils will reduce the spring rate. I hope this helps you with your spring calculations.
Art Carr is the man behind California Performance Transmissions, and by the date on this NHRA Competition license, he's been doing this stuff for a long time. This license was issued to him in 1966 to drive a AA/Altered to speeds of up to 170 mph. That was bad fast back in the day.
Jerry Phelps; MGYSGT USMC Ret., Newport, NC: I really liked your article on the 305 buildup using the Vortec heads. I'm in the process of doing the same thing to my 1985 Monte Carlo SS L69. Did you mill the Vortec heads, and what thickness head gasket did you use?
Jeff Smith: First of all, the alphabet soup after Jerry's name stands for Master Gunnery Sergeant, United States Marine Corps, Retired. My father was a career Marine aviator (and a Mustang, an enlisted man who became an officer). My dad always had the greatest respect for the Master Sergeants—he said they were the ones who really ran the Marine Corps. Hopefully, this answer will warrant an acceptable "fit rep," Gunny.
Over the years, Car Craft has done several 305ci small-block Chevy builds, so I'm not sure which specific engine build you referenced, but it doesn't really matter since this information will be mostly the same. Unlike the early '67–'69 302 engines with their 4.00-inch bore and 3.00-inch stroke, the issue with the 305 is a really small bore. The standard configuration of a 305 is a 3.736 bore and a 3.48-inch stroke, and the L69 version used in Monte Carlos and early third-generation Camaros had 9.5:1 compression, which was aggressive for the day. The engine was rated at 190 hp, while the lower performance version LG4 was between 150 and 170 hp. The L69 also used a slightly longer-duration camshaft than the lower compression versions. Both engines used the same iron head with a 58cc combustion chamber size. You can use the Vortec iron small-block head on the 305 because they came with 1.94/1.50-inch valves, which will clear the small bore. However, the Vortec chamber is larger at 64 cc than the 58cc 305 engine chamber. This can be rectified by milling the head to reduce chamber volume. The general rule of thumb is to remove 0.006-inch deck surface to reduce the combustion chamber volume by 1 cc. So this would require milling roughly 0.036 inch off the heads to trim the chamber down to 58 cc. That's assuming the heads have not been previously milled. I plugged a 58cc chamber into a stock-bore-and-stroke 305 with a flat-top piston equipped with four valve reliefs (roughly 8 cc) with a 0.015-thick shim head gasket and the piston below deck height 0.020 inch will produce a static compression ratio of 9.5:1.
The 0.015-inch head gasket thickness is equal to a stock-style steel shim gasket, which is the thinnest gasket you can run on these engines. The above situation is based on the piston being below the deck by 0.020 inch. It's possible that the pistons might be slightly closer, which will raise the compression. If the engine has been rebuilt and the machine shop has milled the deck and brought the pistons up to, let's say, 0.005 below the deck, then a thicker composition head gasket will be required both to keep the compression ratio around 9.5:1 but also to maintain a minimum of 0.038 to 0.040 inch of piston-to-head clearance. With cast pistons that run a tighter piston-to-wall clearance, this will reduce piston rocking, which should be minimal anyway, considering the small diameter. It's best to keep the piston close to the head to tighten the quench volume, which enhances combustion efficiency. Piston-to-head clearances beyond 0.050 inch tend to minimize the effect of quench, which can cause detonation problems. And this is something you'd like to avoid, since the 305 engines tend to be very detonation sensitive. This should get you in the ballpark for compression and help wake up that little 305.
Removing this much material from the deck surface of the head may cause problems when mounting the intake manifold. This tends to push the bolt holes in the head down toward the bottom of the mounting holes in the intake manifold. The best solution is to mill the intake, as well. The suggestion there is to remove 0.12 from the intake flange for every 0.010 removed from the cylinder heads. This means if you removed 0.040 from the heads, you'd need to mill 0.048 inch from the intake manifold flange and about 0.060 from the intake endrails. Or I'd suggest test-fitting the intake. As long as the endrails don't touch the china wall on either end of the block, you might be able to just elongate the intake manifold bolt holes with a file to make the intake fit. This might also create a slight mismatch at the port opening, but we've found through testing that this rarely affects horsepower, even when the intake opening in the head is smaller than the intake manifold's outlet port.
Federal-Mogul (Fel-Pro); 248/354-7700; Federal-Mogul.com
We had so much fun with our first 496 ("707 HP for $6,720," Mar. 2007) that we are building another complete with a Ohio Crankshaft stroker kit, good H-beam rods, and a set of JE pistons. There's also rumor of a set of excellent oval-port AFR heads that promise big-time power. Stay tuned.
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