Stroker engine packages are a popular option because the Ws can retain their stock appearance, but with the increased displacement, pack far more potent punch than a stock engine. After all, we’ve all seen sleeper cars and trucks that look like restored vehicles but run like race cars. A stroker engine has had the original dimensions of the bore and/or stroke changed to alter the displacement and, of course, that is all done internally. Increasing the stroke of the engine’s crank- shaft and in some cases, increasing the bore of the cylinder is a route to higher stroker performance.
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Strokers are built to increase dis- placement, and while horsepower is increased, a stroker engine benefits from the increased torque. The added torque comes from the longer stroke. That, coupled with the additional cubic inches, usually yields a more powerful engine. In the case of 348 and 409 engines, their original size and unique design created a fair amount of torque to begin with and stroking these engines can often make more.
As covered in the first chapter, the bore of the cylinder is one dimension in the equation of cubic inches. Another is the stroke of the pistons, or up and down movement within the cylinders. By changing the bore and/or the stroke of an engine, the cubic inches changes. For reference, the actual formula for calculating cubic inches is the bore squared multiplied by the stroke then multiplied by the constant of 6.2832.
Cubic Inches = bore2 x stroke x 6.2832
The bore is squared to get the total volume of the bores while the stroke does not get squared because that measurement is not about volume as much as it’s about the movement of the piston inside that bore volume.
For example, the 348 has a standard bore of 4.125 inches and a stroke of 3.25 inches. Here’s the math:
(4.125 x 4.125) x 3.25 17.015625 x 3.25 55.300781 x 6.2832 347.46586 rounded up = 348 ci
Another example is a 409 with the stock bore of 4.3125 and a stroke of 3.50 inches. Using the formula above, here’s the math:
(4.3125 x 4.3125) x 3.50 18.597656 x 3.50 65.091796 x 6.2832 408.98477 rounded up = 409 ci
Using this formula, you can see how the simple two specifications of bore and stroke can be easily manipulated to change the cubic-inch out- put, or as hot rodders and racers have called it for years, stroking an engine.
Here are the specifications Chev- rolet used to change from 348 to 409: A stock 348 has a bore of 4.125 inches while a 409 has a bigger bore of 4.3125 inches. One half of the move from 348 to 409 was an increase of .1875 inch in the cylinder bore. The other half was the stroke change that went from 3.25 to 3.50 inches for a net gain of 1/4 inch. Together, the new bore and stroke gained those 61 ci. Remember that those specifications are for each cylinder and the advantages gained are times eight for the total of all the cylinders.
Although some engine blocks do not require clearancing, the 348 and 409s blocks do require clearancing in most cases. With the bigger crankshafts needed in a stroker—and that includes the circle of the bigger counterweights as well as the throw, or distance the rod is moving up and down via the rod journals—more clearance is needed for rotation. The longer throw of the rods need to safely clear the block or the rods will impact the block in their rotation.
The 348 block did not have the proper clearance to accept a longer stroke crankshaft, so the 409 was made from basically the same block but with more crankshaft bed clearance cast into the new 409 block cores. With more room in the crank- shaft bed area, more stroke could then be added. When the 348 grew into the 409, part of enlarging the engine included an increase in the bore, too. So Chevrolet increased the clearance for the bigger crankshaft and the distance between the bores to keep the engine running at safe street and long-distance temperatures, and thus the 409 was created. Early on, it was discovered that a 348 could not be overbored to 409 because the cylinder walls became too thin. As a result, the blocks would overheat. Chevrolet avoided that by recasting the 348s into 409 blocks. Unless they are actually building a new block, today’s stroker builders can’t really go beyond some additional machining mostly to ensure parts of the rotating assembly don’t impact the block and increasing the bore.
You also need a compatible oil pan for your stroker build. The oil pans from 348 and 409 engines are interchangeable, yet they are different. The 348 oil pan is slightly narrower, and therefore cannot be used for a 409 stroker engine. The answer is to use the wider 409 oil pan, or as Joe Jill from Superior Automotive says, “notch the 348 pan.” With today’s generous amount of repro- duction 348/409 parts available, a factory reproduction 409 oil pan can be easily found at Show Cars. Racing oil pans for W engines can be found at Stef’s Performance Products.
The most infamous stroker of the 348/409 family has to be the Holy Grail of W engines, the rare Z11, 427- ci engine. It’s also a good example of how stroker methodology actually works. To make the Z11, 427, Chevro- let actually used a standard 409 block with its standard bore of 4.312 inches. Because the W was basically capped at that 4.312-inch bore and could not physically go much larger, any additional cubic inches had to come from increasing the stroke. Chevrolet did just that and added .150 inch to the stock 409 stroke of 3.500 inches for a result of 3.650 inches.
Using the formula on page 103, the Z11 math looks like this:
(4.312 x 4.312) x 3.650 18.593344 x 3.650 67.865705 x 6.2832 426.41379 rounded up = 427 ci
Just that simple change in the stroke yielded the 18 ci desired to hit the vaulted 427 number. Note this and pretty much any other stroker operation can be done without any changes to ancillary parts such as heads or intakes. Likewise, the compression ratio of the pistons doesn’t factor into the cubic inches of a stroker. It’s all done with the stroke and bore of an engine. The added cubic inches then have the potential to make more horsepower and smart builders exploit as many components and assemblies on the engine as they can to do just that. Chevrolet did exactly that on the Z11 by making a brand-new set of Z11 heads and intake manifold to take advantage of the extra cubic inches, thus making it one of the more powerful engines of its time.
Along the lines of Z11 specs, Lamar Walden tells us a homemade version of the famous Z11 short block can be simply made by using a 3.650- inch stroke crankshaft in a stock 409 block with stock bore sizes. No extra crankshaft clearance work is needed on the block and all the bearing sizes are the same so it becomes what is known as a drop in. The final results yield a 427-ci short block. As for the famous Z11 heads and all the power they can provide, see the chapter on heads for information on reproduction Z11 heads that are available from Walden.
Bore and Stroke
The limitations of the OEM block are big drawbacks to designing a stroker engine. Depending on the intended use of the to-be-stroked engine, the thickness of the cylinder walls is critical. Typically, a slight overbore of .030 inch is safe while merely doubling that to .060 can possibly invite overheating problems and possibly failure. A .060- inch overbore on an engine used in drag racing is usually not a problem because of the short running time. However, on a road race or oval track, the engine spends a lot of time running at wide-open throttle, causing the cylinder’s heat and stress to become a problem.
A stroker is created by the combination of bore and stroke, so you must maintain that balance. To maintain the best proportions of bore and stroke, stick with an accepted stroker kit or use engine-design software. The software allows you to confirm that you’re not exceeding the physical limitations of the block. Software is used to see just what those options can be and even to help figure out what kind of power characteristics the new stroker design will deliver. Then it’s just a matter of finding the parts from off the shelf inventory or having them custom made.
Cam and Head Selection
When selecting a cam for a stroker engine, the same basic info as any cam selection prevails. Stroker engines produce more torque, and choosing a cam to take advantage of that is necessary. The same holds true
for the additional cubic inches. With the changes created by the difference in power (from the bore) and torque (from the stroke), a new power band exists and the cam needs to complement that.
With a stroker build, you’re adding displacement or cylinder volume. In order to maximize the performance potential of the heads, you need increased head flow to match the increased cylinder volume. Again, the bigger bore can take advantage of better-breathing heads and help deliver all that power the stroker develops. The basic premise of stroking an engine is to make it bigger and stronger, so why choke it down with heads that can’t do the job?
Four-Bolt Main Bearing Conversion
All W engines came with only a two-bolt main bearing system, and that includes the Z11. Four-bolt mains are desired, especially as 600 hp is surpassed. Virtually all racing engines and all of the new, aftermarket aluminum and iron blocks use them on the center three mains. A qualified machine shop can install four-bolt mains on a 348 or 409 block’s three main journals. The process involves precisely locating the main caps on the journals and drilling and tapping the main journals, but this requires experience. You don’t want to make a mistake and ruin the block, so this is best left to professionals.
Pro Gram Engineering and several other companies make four-bolt main bearing cap kits for the W in straight or splayed configurations. In fact, Pro Gram makes three products. One is with the extra bolts being added in a straight pattern, another locates them in a splayed pattern and the third is a new front cap with four bolts that are straight only. Having the extra strength of four-bolt mains in a deeply stroked engine is good basic engine building and is strongly recommended. These kits fit both the 348 and 409 blocks as the crankshaft is the same diameter for the two.
From a monetary viewpoint, going the stroker route can be done two ways. One is for the builder with an unlimited budget who pays for custom made parts such as a new crankshaft, rods, and pistons. The economical way is to find out which of those parts are already in stock. Sometimes, companies have com- pletestrokerkits consisting of the hard parts such as the crankshaft, rods, and pistons in one package.
A number of suppliers make complete or partial stroker kits for 348 and 409 blocks. A stroker kit is an easier route to take with a stroker build because all of the components are complementary. If you choose to buy a stroker crank, rods, and pistons separately, you must make sure all the parts are dimensionally correct and compatible with one another. There- fore, if you buy a complete stroker kit, you do not have to fit, balance or machine the parts to work with one another. A complete kit usually consists of a crankshaft, rods, pistons, wrist pins, rings and bearings, while a partial kit may only include the crankshaft, rods and pistons.
Show Cars offers its popular 409 4-inch stroker kit that is complete with Eagle crankshaft, Ross forged pistons (with pins), GM big-block Chevy rods, Clevite main and rod bearings and chrome-moly ring set.As it stocks many different stroker kits, the sizes and components vary. Another kit it offers has a 3¾ stroke and coupled with bore sizes that are .030, .040, and .060 inch over the combinations are numerous. Using Keith Black pistons, the overbores available are somewhat different at .038, .048, and .068 inch in 11:1 compression. The 348s have not been left out, as it offers the same 3¾ stroke and overbore sizes.
Lamar Walden Automotive also offers stroker kits for 409s. One is a 450-ci model and the other is a 482 cubic incher. Both include forged pistons, a steel crankshaft, H-beam connecting rods, rings and bearings. Walden can balance these assemblies as well. To create a 482 kit, Walden overbores the cylinders to 4.375 inches and uses a Chevy 454 crank. He mills the stock 2.750- inch main journal to 2.500 inches, and as a result, stroke length- ens from 3.500 to 4.000 inches. The billet rods are matched to arrive at 482 ci.
Scat Crankshafts also makes stroker kits and its two kits start with 409 blocks and are available in 434- and 472-ci versions. Both use a 4.00-inch-stroke crank, with the 434 using a 4.155-inch bore and the 472 using a 4.340 bore size. You have a choice of H- and I-beam connecting rods. The kits include crankshaft, rods, pistons, rings, and bearings and are available with different bal- ancing packages. The 4340 forged standard-weight crank has a 4.00- inch stroke and all of Scat’s top- quality features such as pendulum counterweights, ground and pol- ishedjournals, and gun drilled main line and lightening holes. Both I- and H-beam rods are 6.135 inches in length. The stronger stroker H-beam rods come with 7/16-inch ARP cap screws, Formula 1 lightening hole, and special doweled cap.
For those who want to piece together their own kits, Eagle Rods and Crankshafts makes a 4-inch stroker crankshaft for 409s and sells the rods to go with it. It’s not a full kit but a number of piston manufacturers sell W-engine stroker pistons.
While the new aftermarket blocks seductively offer amazingly bigger engines, using stock 348 or 409 blocks is still a good basis for a stroked W engine. In fact, there are a surprisingly large number of com- binations possible. Automotive journalist Steve Magnante has reported on quite a number of W stroker builds. He’s allowed me to review some of those builds to consolidate the facts into this quick reference collection. Here, for the very first time, are the bulk of 348/409 stroker recipes he has documented.
When Edelbrock was develop- ing its aluminum 409 heads, Mag- nante was allowed into the top secret engine assembly and dyno departments to observe. This was before any of the newer aftermarket blocks were available so Edelbrock used a 1964 truck 409 block with the cast- ing number 3857656. The crankshaft came from the same engine as did the six quart truck oil pan. Edelbrock gave the engine a .060-inch overbore for a final bore size of 4.375 inches with the stock 3.50-inch stroke crank. The combination ended up at 421 ci with 9.6:1 compression so it could run on 91 octane fuel. The base unit developed 466 hp and 461.9 ft-lbs of torque. That in itself is quite an engine and with just the .060-inch overbore work and stock 409 heads. If a W engine with even more punch is desired, Magnante says to take that same stock, 409 truck block and, “Step up to a 470-plus-cube stroker kit, add a point of compression, swap on a set of 750-cfm carburetors and do a little porting and you’ll nudge 600 hp for sure.”
It’s important to note that the truck block used had the large machined reliefs that increased the size of the combustion chamber and reduced the stock compression ratio to 7.75:1. To counteract that, Edelbrock’s builders used 9.6:1 compressionJ&E pistons. Another after- market part used for the buildup was Pro Gram Engineering’s billet steel, four-bolt cap conversion kit. And as seen later in this chapter, some of these strokers use bigger crankshafts on bigger builds so four-bolt mains are almost a must.
One more modern amenity was Clevite’s semi-grooved main bearings installed with the grooved half in the block. As this would be a clas- sic stroker build, the crankshaft was sent out to Marine Crankshaft for some work. It was turned .010 under on the mains and .020 inch on the rods, as well as receiving some edge chamfering and nitride-hardening for a longer life.
Attached to that crankshaft were Eagle forged H-beam rods. They were 6.135-inch-long big-block Chevy pieces that fit the 409 crank perfectly. ARP 7/16, 12-point cap screws were installed to be an upgrade from the 3/8-inch bolts Chevrolet used with its original 409 rods. To keep things oiled, a Melling high volume, big-block Chevy oil pump was used and received the typical racing treatment of welding the pickup tube to the pump body to eliminate the parts coming apart from engine vibrations in excess of what would be 6,500 rpm.
Up top, the Crane cam is a hydraulic roller reading .616/.628 lift and 292/296 advertised duration (230/234 at .050 inch). This piece exceeds the factory Z11 cam which was rated at .511-inch lift. As 409s take the equivalent of a small- block lifter, Edelbrock used some of its stock hydraulic roller lifters. The double timing chain set came from Cloyes and was used with a Teflon thrust button. For a little more insurance for the valvetrain, the normally pinned rocker studs on a 409 were replaced with 7/16-inch screw-in studs and capped with Crane 1.7:1 ratio, big-block Chevy roller rockers and Edelbrock 3/8-inch chrome- moly pushrods were used.
At the time, Edelbrock had come out with its own version of a 348/409 water pump so one was used. W-engine crankshaft snouts fit to a small-block Chevy harmonic balancer so an after- market, ATI Super Dampener was used. The intake was an Edelbrock dual-quad aluminum with Edelbrock 500-cfm Thunder AVS carburetors. Also used were a MSD Pro Billet electronic distributor, Champion RC12YC spark plugs gapped at .035 inch, MSD 8-mm Heli-Core wires, and Edelbrock polished cast-aluminum valve covers.Magnante’sEdelbrock recipe yielded these impressive stats: horsepower was 466.1 at 5,800 rpm, a maximum safe engine speed of 6,500 rpm and a recommended shift point of 6,200 rpm.
Another cool combo came from Superior Automotive—another shop specializing in 348/409 strokers. Its stroker takes advantage of the fact there are something like only 100,000 409s out there and the 348 is often thought of as having more than four times as many units made. Because of this disparity and the obvious difference in cubic inches, the smaller W is often overlooked. Superior showed how to really wake up a 348 by stroking it to 434 ci with some great results. It used Edelbrock’s RPM Performer 409 aluminum heads, an Eagle stroker crank and H-beam rods, Ross pistons, an Isky solid roller cam and a new single-plane 4-barrel intake manifold from Lamar Walden.
Technically, the “348 turned 434” stroker drew these stats: 576.8 hp at 6,200 rpm with 516.8 ft-lbs at 5,500 rpm. It started with the most obvious, the bore, where it opened up the stock size of 4.125 inches by .030 to become 4.155 inches. Checking the wall thickness before the bore, it was found to still be a secure .175 aver- age across all the bores. A second boring operation enlarged the crescent found in 348/409 blocks that acts as part of the combustion chamber. That spec is now .060 inch over.
Using billet steel main caps from CRV 409 Parts added more security to the bottom end so 700 hp is safely possible. Superior used ARP 1/2-inch studs on the center of the mains to upgrade the original 1/2-inch bolts. On the outboard and new main bolt holes, it used 7/16-inch bolts. It torqued the main cap nuts to 100 ft-lbs and gave the outboard bolts 65 ft-lbs. In that main bore went a 4340 steel, forged Eagle crankshaft. Its 4-inch stroke is .750 inch greater than the stock 3.25-inch stroke of a 348. Normally, stroking a 348 block requires machining work for more clearance but Eagle reduced the counterweight diameter of its crankshaft, making it a drop in. The pistons are Ross forged 11.7:1 versions and weigh less than the stock pieces. That’s good as the newer rods are heavier and stronger than the originals.
Depending on the manufacturer of the crankshaft, that extra 3/4 inch of stroke may have some con- tact with the 348 block so Superior used its Rottler CNC machine station to machine away the problem areas with a few passes for clearance. As in the case of any stroker, a dry run of rotating the crankshaft with the rods and pistons attached is done to ensure clearance is complete.
The Edelbrock RPM Performer 409 heads are limited to .550-inch maximum valve lift on 348 blocks because the valves are bigger than stock and impact the block if the lift is too much. This is to ensure no valve-to-block contact, so checking with a spring and dial indicator is recommended. When the safe clearance was confirmed, an Isky solid roller cam was installed. The specs on it included .639/.639 lift, 294/294 duration and 260/260 duration at .050- inch lift on a 112-degree lobe center. Isky solid rollers, tie bars and 3/8- inch chrome-moly pushrods were also used. The Isky cam’s movement is controlled by a Cloyes True Roller double timing chain wearing a Man- ley solid aluminum thrust button.
For supplying oil, a W engine can use a small-block Chevy oil pump so a Melling 302 Z/28 high-volume unit was installed. There was some slight clearance grinding needed as the body of the pump touched the number-5 main cap. Up front and outside, a stock 348/409 crank snout fits a small-block Chevy harmonic balancer but relocates the timing mark to render it inaccurate. The new Eagle stroker crankshaft corrects this with the correct keyway position. An aftermarket PRW 6.75-inch balancer makes the rotating assembly inter- nally balanced.
One of the easiest and fastest modifications to a W block is the removal of the stock canister oil filter. Prone to bad sealing and jus being harder to work with, the stock unit was used on all Chevrolet engines prior to 1968 when the switch was made to the easer, spin-on filters. Many aftermarket companies make such kits and Superior chose the one from Trans-Dapt that bolts to the block. This conversion is not only easy but remains very effective for filtering as the stock bypass valve is kept in place. Remote and multiple oil filters are always a possibility but were not used in this build.
If a build like this requires the engine to be a little more polite on the streets, here’s a handy trick Supe- rior used. The Ross pistons in this build have 11.7:1 compression with the .040-inch-thick Victor-Reinz composite head gaskets used. If the builder installs a set of .035-inch- thick Innovative Machine steel shims between the block and the gasket, the compression drops more than one full point to a more pump friendly 10.5:1.
This build went in a differ- ent direction for induction. Lamar Walden and CRW Industries make their single-plane intake that can also be used with one or two 4-barrels or a GMC blower via the intake’s adapt- able plenum. On top of that versatile intake manifold, a Holley 950 double- pumper mixes fuel. Headers for the engine in this application are more for the dyno than actual use. Edel- brock came out with its four-into-one headers for 348s and 409s not long after this engine was built, but have discontinued headers for W engines.
For electrical power, a MSD 348/409 Pro Billet distributor was used. One benefit of this piece is a self-contained control module that eliminates the need for any remote ignition boxes. It fires Champion RC12YC plugs via MSD 8.5-mm Super-Conductor wires.
If taking a 348 and doing a simple stroker job can yield a stout engine, then what can a bigger, 409 block do with a healthy 4-inch stroke and even more overbore? In this case, a crankshaft from a Big-block Chevy is the starting point. The bore was cut a respectable .060 inch over and the results are a 481-ci W. Specifically, the bore would end up at 4.3725 inches with a stroke of 4.00 inches. The details of this Superior Automotive build also include using a Mark IV (two-piece rear main seal) 454 crankshaft from one of the many big-block engines Chevrolet put out between 1970 and 1990. Using any other crankshaft such as from 1991 and up won’t work with a 409 block. In this build, the stroke increases by 1/2 inch and coupled with the bore increase and other work, the results are 532 hp and 542 ft-lbs of torque.
Before that 454 crankshaft can be stuffed into the 409 block, it needs to have its mains turned down .250 inch from 2.748 to 2.498 inches. When this happens, a radius from the crankshaft’s journal to the cheek of the crankshaft is needed to reduce the stress a 90 degree change of direction can create. Besides normal precision balancing, the only other crankshaft machine work involves turning the 454’s crank snout down to 1.250 inch so an externally balanced small-block Chevy 400 dampener can be used.
Joe from Superior points out that many of his builds included extensive crankshaft work. Journals were turned down, edges rounded and chamfered, the counterweights were shaped to be knife-edged, snouts turned down, and many times, the crankshafts needed to be heat treated and even hard coated. Joe says these days, stroker crankshafts are more readily available for builders. Using a dedicated stroker piece is often less expensive and most definitely faster and easier on stroker builds. Another strong selling point is that many newer stroker crankshafts have centralized their counterweights so machining the block for clearance is minimal or sometimes not even needed at all.
On this 409 block, the added swing of the 454 crankshaft counterweights and connecting rods is enough to hit the bottom of the cylinder bores. Cutting small notches creates clearance for the now larger diameter of the rotating assembly. And in a “as long as we’re here” move, Superior also uses the machining time to adapt the block to four-bolt mains. A set of custom machined, billet steel center main caps was used. One more note on pretty much any 348/409 bore job is restoring the famous W-engine reliefs in the upper bores. One good reason is how they impact the compression ratio and another solid reason is the builder has more of a hard time getting the piston rings into the bores without those reliefs.
The rotating assembly has some wiggle room for the parts used. Superior says reconditioned stock 454 rods can be used but opted for new, forged steel, Eagle I-beam rods that are often less expensive. These rods have the usual 454, 6.135-inch measurement and offer wider beams, wrist pin bushings, and use bigger ARP 7/16-inch rod bolts.
This is one of those builds where piston and rod orientation is critical. As used on the later 409s with more compression, piston numbers-1, -4, -5, and -8 have different valve positioning than piston numbers-2, -3, -6, and -7 and that impacts clearances. Installing them incorrectly results in valve contact with the pistons.
In this build, the customer wanted to use his older, and rarer, .060-inch over TRW pistons. A Lovatt hard anodized coating was applied for less cylinder/piston drag. That coating adds .003 inch to the overall diameter of the piston so that had to be calculated into the build list and boring measurements. In the case of older 348 and 409 pistons, manufacturers followed the lead of Chevrolet and created a heavier side of the pis- ton to offset the cylinder’s side load. Superior counteracted that by milling the undersides of the pistons, reducing mass and helping to correct their offset weight. And compression was an issue as the vintage pistons were a race-only, 11.5:1 compression. As this was to be a street engine and use pump gas, a set of .030-inch Innovative steel shims was installed with the Best .045-inch compos- ite head gaskets. The combinations resulted in more streetable 10.006:1 compression ratio.
Superior and other builders don’t use stock replacement 409 cam bearings when the valvespring pressure exceeds 350 psi. If used, they will self destruct. Instead, Superior used modified Durabond 1955–1963 small-block Chevy cam bearings. When using these cam bearings, the first four are a direct install with the fifth one requiring three 1/4-inch holes for oiling and correct positioning. Any cam used must have a grooved rear journal or the flow of oil to the lifter galleys may be reduced.
Oiling capacity needed to increase so a big-block pump was used to supply more oil. With the addition of a Melling oil pump and 3/4-inch pick-up, this is accomplished. The build also used a Mel- ling hardened steel intermediate shaft with a steel collar at the oil pump end. The best part is that these mods still allow for the use of a stock, 409, 6-quart oil pan.
Isky made the RR-639/260 solid roller cam used in this build and it specs out at .639/.639 lift, 294/294-degree advertised duration, 260/260-degree duration at .050 inch and 110-degree lobe center. Else- where in the timing cycle, a Cloyes True Roller timing set with Pioneer cam bolt lock plate and Manley thrust button were used to keep the lobes of the cam and its roller lifters in harmony.
For this build, iron 409 heads were selected. The intake ports received a healthy but basic porting job as well as gasket matching. One more trick to the 690 head castings was the removal of the pins holding the rocker arm studs and drilling and tapping them for screw-in studs. For valves, another relatively easy trick of installing 2.203/1.734, big-block Chevy stainless steel valves was per- formed. It’s an easy upgrade after the seats have been enlarged. When the heads were flow tested after their work, they confirmed the 409 690 head is quite capable of running on 600-plus-hp builds. The modifications to the heads continued with
the addition of Manley springs and titanium retainers, Scorpion big- block Chevy 1.7:1-ratio aluminum roller rockers and a set of retro cast- aluminum valve covers.
Elsewhere inside, the changes continued with Isky solid roller lifters. They are basic big-block Chevy pieces with 409-style tie- bars. Another upgrade was the use of Manton 3/8-inch diameter push- rods measuring 8.750 inches on the intake and 9.275 inches on the exhaust side. For induction, a pair of Edelbrock 750 cfm carburetors was bolted to a port-matched L80, aluminum dual-quad intake manifold. The electricity came from a stock 348/409 distributor that received a Pertronix electronic conversion. AC spark plugs are fed via Taylor Spiro Pro 8-mm silicone wires.
The 409 was an already strong engine. Stroking it up to 481 makes it more fun. In fact, stroking any 348 or 409 is just plain fun.
Written by John Carollo and Posted with Permission of CarTechBooks