DART BLOCK BIG BLOCK CHEVYS
The use of Dart Blocks provides for stronger, larger, more powerful Big Block Chevy combinations.
The cost of these engines is higher than using a GM block, and you might choice to also use more expensive stronger internal parts such as the crankshaft and pistons.
I do use the GM 502 block costing $1700, but it is my opinion that the relatively small price
increase for a Dart block is a wise investment.
While I could list a number of partial or complete engine with their prices, I will instead show the cost of various parts that you can add together to figure out an approximate cost for a variety of engines you might build.
My goal in building these engines is to provide you an alternative to the GM 572 crate motor.
There is no doubt that the GM ZZ572 620BHP Street Engine is a great buy for the price of $13,000, after all I provide these engines as well. I sell them at approximate $100 over cost. Some GM dealers sells them at approximate $200 over their cost. Other dealers sell them at List. Buying one of these engines at $13,000 is a good deal, but keep in mind these are mass production engines, not engines buit by high performance specialist.
If you are less concerned about the convienance of buying one of these cookie cutter engines and would prefer something even more powerful for around the same price, then using aftermarket heads, blocks, cranks, pistons etc can do that for you.
If you every line up next to a ZZ572, it would be nice to know you can beat it.
So if you like the ZZ572, I'll supply one to you for about $13,000 plus freight,
or I'll build you a more powerful engine, start it up, break it in, dyno test it,
and pay the shipping to get it to you.
Now let's take a look at what it all costs.
The Block.
I like to use the Dart Big M Block.
These block are far stronger than GM blocks and have a number of performance improvement
features, such as the oiling system.
DART BIG M BILLET CAPS
| 31263344 |
9.800 |
4.250 |
STD |
STD |
$2230 |
| 31263354 |
10.200 |
4.250 |
STD |
STD |
$2230 |
| 31263444 |
9.800 |
4.500 |
STD |
STD |
$2300 |
| 31263454 |
10.200 |
4.500 |
STD |
STD |
$2300 |
DART BIG M DUCTILE CAPS
| 31273344 |
9.800 |
4.250 |
STD |
STD |
$1870 |
| 31273354 |
10.200 |
4.250 |
STD |
STD |
$1870 |
| 31273444 |
9.800 |
4.500 |
STD |
STD |
$1950 |
| 31273454 |
10.200 |
4.500 |
STD |
STD |
$1950 |
These blocks are available in two bore sizes, 4.25" or 4.60.
The maximum recommended bore size is 4.625" which leave the cylinder wall thickness
at .300". However for a street application motor where RPM, and cylinder pressure,
both from the expanding intake charge and piston to wall physically loading are not as
great as in a hard core racing engine, 4.70" is acceptable leaving a wall thickness of .263".
A 4.750 is .243" That is really pushing the limits.
The real challenge is finding rings in the larger diameters.
Rings are readly available in 4.680" - 4.705" - 4.735" - 4.755"
The blocks are also available in either standard 9.800" or tall 10.200" deck heights.
The taller deck allows the use of longer connecting rods, which reduce piston to
cylinder wall loading by keeping the rod rotation angles less serve. Less loading means
less fiction resulting in less horsepower loss. This feature is increasing valuable as the
stroke length is increased.
However these taller blocks will move the valve covers higher and possibly closer to
the brake booster. The intake manifold will either need to be a custom unit, or
the use of two spacer plates will be required.
The camshaft height remain in the STD location, however word is that Dart may
add an optional taller spacing to increase the rod to camshaft lode clearance,
as they have done with the Small Block Iron Eagle block.
Finally these block are available with either Ductile Iron or Billet Steel 4 bolt Main Caps.
The iron caps are plenty strong, with the steel being more desirable for racing applications.
The price for these blocks is as follows.
4.25" Iron Cap $1900
4.25" Steel Cap $2100
4.60" Iron Cap $2000
4.60" Steel Cap $2200
There is no price difference between STD and Tall blocks.
The cost to bore and torque plate hone these blocks is as follows:
+.020" to .040" $250
+.060" to .100" $320
up to .200" over $400
To cut the deck height to establish piston to deck clearance: $120
To grind in stroker crank clearance: $120
632cid
If you want a big CID motor, but withouth all the extra weight I recommend a BRODIX ALUMINUM BLOCK. Not cheap, but at $5600 they are only $1000 more than an aluminum SBC and will make a lot more power for the extra $3000 you'll spend for the block, heads and rotating assembly. I think it's good value.
Donovan Blocks are also Avaliable to build Monster Engines
Crankshafts:
There are a wide variety of crankshaft choices today,
from cast iron street performance cranks
to billet steel racing cranks.
Stroke lengths vary from 3.76" to 4.750"
As a generally rule, the longer the stroke, the more cubic inches the more torque is
produced, and at a lower RPM.
Because a longer stroker drags the pistons and rings further, and at a higher speed,
top end horsepower is reduced. Therefore a balance must be found, and a choice made
as to the ideal length stroke. Increased bore size also increases friction, but with less
power loss than with stroking.
For a street motor, very long strokes do work well, as high speed operation is
not as necessary as with racing. Also trucks will benefit from a monster engine.
Below you will find a bunch of engine size combination and their estimated power outputs.
Crankshafts are available in cast iron/steel, 5140 forged steel, like the factory uses,
4140 chrome-moly, 4340 chrome-moly-nickel a little bit stronger,
and 4340 cut from a billet.
Prices will vary dependant on brand. Many of today's cranks are imported,
and are less expensive than American made. These import cranks will stand up to racing,
but once you get to 1000BHP, cutting corners on cost may not prove to be wise,
and so I do recommend the top quality Made in USA cranks.
For street motors up to 700BHP, the cast cranks are ok, but over 600BHP is where
a 4140 is a good investment, with a 4340 being even better, and prudent at 850BHP.
Prices are generalizations, but close.
Cast Iron/Steel $190 to $300
5140 Forged Steel $420
4140 Forged Steel $500 to $900 (dependant on brand and stroke)
4340 Hardened Steel $625 to $1400
Billets $2500 plus
Connecting Rods:
Rods come in 5140, 4140 or 4340.
Aluminum rods are for racing only, intended to absorb high load such as fuel & methanol, blowers, and nitrous oxide, there is no need to use them in a street motor.
Billet rods are for racing and titanium for unlimited budgets.
Rods either come with bolt & nut arrangement or cap screw. 
Rods are available in I-Beam, Light-Weight and H-Beam.
Light weight rods give up strength, H-Beam require a little more clearancing then I-Beam.
Personally I like 4340 I-Beam Cap Screw rods for street motors, but recommend H-Beam
at about 700BHP depending on the brand.
Rods are also made in various lengths from standard 6.135" plus .250" at 6.385,
plus .400 at 6.535" to the ultra long plus .565" at 6.700.
As stroke length is increased it is desirable to increase the rod length.
The limits are enforced by block deck height
and minimum piston compression height (how far you can more the wrist pin up before
going pass the oil ring groove).
Light weigh rods will allow the motor to accelerate more quickly.
This can help offset the reduction in acceleration rates caused by increasing the stroke length.
As with the cranks, the rods are available in import and American.
5140 $250
4340 $300 to $600
Light weight 4340 $480 to $800
H-Beam $500 to $1000
Billet $1100 to $1700
Titanium expensive.
Choose the rod that is strong enough and in your price range.
Pistons:
Cast Hypereutectic. I use these pistons for moderately priced street motors.
They are strong, and offer a useful selection of compression ratio choices.
They do not like heat, which can lead to ring end gap closure,
and they don't like prolonged exposure to detonation.
Forged pistons are more ductile. They will resist being damaged by detonation longer,
and are less likely to crack like a cast piston.
Racing forged pistons require greater clearance for heat expansion,
and as such tend to "click" when cold.
Forged pistons come in three different aluminum alloys.
They can be bought "off the shelf" or custom made to meet specific applications.
Cast pistons are priced between $150 to $500
Forged piston start at $500 and go to about $850 
To complete a short block will require rings $80 to $300, bearings about $70,
balancing $160 and assembly $350 to $600.
I like to include the harmonic balancer $100 $300 and flex plate $50 to $80,
or a flywheel $150 to $300.
Installing the camshaft is extra. Roller camshafts with lifters cost about $700
were as a flat tappet cam & lifters is about $200.
Timing chain set up, $50, Gear Drive $150.
LONG BLOCK
The completion cost of the engine will depend on the cylinder heads,
iron heads are about $1000 to fully CNC ported aluminum heads at close to $3000
Exotic racing heads like Darts Big Chief cost around $4500.
AFR Heads are a very good choice!
Add it the sheet metal, an manifold and carb, ignition, and labor,
and the price speed on a Dart Big Block Chevy spreads from
$9500 to $17,000. Hard core race motors are something else again.
My goal is to provide you the most powerful, reliable engine I can build,
at the most reasonable price.
I keep an eye on the industry and the prices other engine builders are selling at.
I can typically provide a better price for the same level of quality and power.
When choosing a motor, and comparing options, be sure your are getting
the same quality, and are not buying cheaper parts to get a lower price.
However I don't see many respected engine build putting low quality parts
in the Dart blocks. Buy where you feel most confident.
Gentlemen choose your weapon.
These numbers a computer generated.
AFR 305 heads, CompCams XE276Hyd. Roller Camshaft. Dual Plane Manifold.
No other changes were made beyond cid.
Bore X Stroke = CID TQ/RPM BHP/RPM
3.940" X 3.760" = 396 531/4500 570/6500
4.125" X 3.760" = 402 535/4500 573/6500
4.250" X 3.760" = 427 567/4500 587/6500
4.500" X 3.760" = 478 621/4500 614/6200
4.600" X 3.760" = 500 641/4200 619/5800
4.700" X 3.760" = 522 664/4200 629/5600
4.250" X 4.000" = 454 593/4700 597/6000
4.280" X 4.000" = 460 600/4600 600/6000
4.310" X 4.000" = 467 607/4500 603/6000
4.350" X 4.000" = 476 615/4500 606/6000
4.500" X 4.000" = 509 649/4000 618/5500
4.600" X 4.000" = 532 671/3500 626/5500
4.280" X 4.250" = 489 625/4300 603/6000
4.310" X 4.250" = 496 632/4000 606/5500
4.500" X 4.250" = 540 680/3700 622/5500
4.600" X 4.250" = 565 706/3500 626/5500
4.625" X 4.250" = 572 713/3600 627/5500
4.280" X 4.375" = 504 639/4200 606/5700
4.310" X 4.375" = 511 646/4000 610/5500
4.500" X 4.375" = 557 696/3700 622/5500
4.560" X 4.375" = 572 712/3500 623/5400
4.600" X 4.375" = 582 723/3500 623/5300
4.280" X 4.500" = 518 652/4000 609/5500
4.310" X 4.500" = 525 659/3800 611/5500
4.500" X 4.500" = 572 712/3700 620/5300
4.600" X 4.500" = 598 738/3300 625/5000
4.280" X 4.750" = 547 681/3800 610/5500
4.310" X 4.750" = 554 690/3500 611/5500
4.500" X 4.750" = 604 743/3000 620/5200
4.600" X 4.750" = 632 778/2800 623/5000
4.600" X 5.300" = 705 862/2000 611/4500
That's a lot of engine sizes to choose from.
You will notice you can choose either torque or horsepower.
The largest engine will make the most torque,
but for racing where high RPM is important, the biggest bore shortest stroke
combo will make peek BHP at the highest RPM.
In the "real world" a balance can be struck.
The 4.625 X 4.250" = 572 will give a good balance 713/3600 627/5500.
Notice that the bigger bore shorter stroke 572 makes for a better power curve.
The following test show some examples of strokers on a "real" dyno.
Notice how the last few monster engines make both huge torque and horsepower
at a modestly high RPM. This reveals that today engine technology surpasses the parameters
of a computer dyno and do make more horsepower in spite of the addition friction.
While these last dyno test were for race engines, they can be tamed for the street.
Do not ask about the gas mileage.
________________________________________________________________
532CID Dart Big "M" Block. Dart Pro 1 Aluminum Heads
Comp Cams Hydrualic Roller Cam. Edelbrock Super Victor Manifold.
TPC 950 Carburetor. MSD Ignition
___________________________________________________________
540CID 4.500 Bore 4.250" stroke. JE Pistons. Brodix oval-port heads 2.250-inch intake valves and 1.88-inch exhaust valves. Hydraulic-roller camshaft with 230/244 degrees at 0.050-inch lift. Ported Dart single-plane intake and a 750-cfm 3310 Holley carburetor, 2-inch headers.
________________________________________________________
540CID 4.500" Bore 4.250" stroke. JE Pistons. CNC-ported Dart 320cc heads with 2.25 & 1.88-inch valves. 287/300-degree at 0.050-inch roller cam with a 0.782-inch intake and a 0.748-inch exhaust lift. Compression ratio 13.0:1. Dart single-plane intake and an 1150-cfm Holley Dominator. 2-1/4-inch dyno headers.
________________________________________________________
598CID Dart Big "M" Block. 4.600" Bore 4.250" Stroke. Dart Pro 1 Aluminum Heads
Comp Cams Hydrualic Roller Cam. Edelbrock Super Victor Manifold.
TPC 1050 Carburetor. MSD Ignition
_____________________________________________________
632CID Dart Big "M" Block. 4.600" Bore 4.750" Stroke. Schmidt Racing 12° Pro-Filer Aluminum Heads Comp Cams 4 & 7 Firing Order Swap Roller Cam. HRE 2x4 Fabricated Intake Manifold.
Pro-Style 1150 Dominators.
________________________________________________________
705CID Block 4.600" Bore 5.300 Stroke. 11.625 deck height +.400 raised cam. Schmidt Racing 12° Pro-Filer Aluminum Heads Bracket Racing Roller Cam. HRE 2x4 Fabricated Intake Manifold. Pro-Style 1150 Dominators
This guide is intended to help you sort out the more major differences among Big Block Chevrolet engines produced since 1958. Chevrolet has designed and produced several different "big block" engine families. Within each family, there can be evolutionary changes, and special parts designed for competition use which may not be directly interchangeable with the regular production items. I don't intend to cover every possible variation. For practical purposes, all big block Chevrolet engines use a cylinder bore spacing of 4.84 inches although note the one exception below.
Early engines were designated as Mark I, (Mk I) Mk II, Mk III, and Mk IV. Later engines continued the numbering system as Generation 5 (Gen 5), Gen 6, Gen 7. There are some conflicting theories as to the reason for the change from "Mark" to "Generation". My first guess: "Gen 5" sounds much more modern, hi-tech, and trendy than "Mk V".
Mark I: The original "Big Block Chevy", also called the "W" engine because of the layout of the valves and therefore the shape of the valve covers, this engine family was installed in vehicles beginning in 1958, as a 348. In 1961, it went to 409 cubic inches, (as immortalized in the Beach Boys song "She's so fine, my 409") and for one year only (1963) a few well-connected racers could buy a car with a 427 cubic inch version called the Z-11. The 427 version was all about performance, and had special parts which were not directly interchangeable with the 348/409. While production of the 427 was severely limited, both the 348 and 409 were offered in passenger cars and light- and medium-duty trucks. The truck blocks were somewhat different from the passenger car blocks, having slightly different water jackets and of course, lower compression achieved by changes in the piston in addition to more machining of the top of the cylinder. A novel feature of this engine is that the top of the cylinders are not machined at a 90 degree angle to the bore centerline. The top of the cylinder block is machined at a 16 degree angle, and the cylinder head has almost no "combustion chamber" cast into it. The combustion chamber is the top wedge-shaped section of the cylinder. Ford also introduced an engine family like that in '58--the Mercury/Edsel/Lincoln "MEL" 383/410/430/462. The "W" engine ended it's automotive production life part way through the 1965 model year, when the 409 Mk I was superseded by the 396 Mk IV engine.
Mark II: This is more of a prototype than a production engine. It is the 1963-only "Mystery Engine" several of which ran the Daytona 500 race, and in fact won the 100-mile qualifier setting a new record. It is largely the result of engineering work by Dick Keinath. Produced mainly as a 427 but with a few 396 and 409 cubic inch versions, all in VERY limited numbers. Even though it was intended as a NASCAR-capable engine, it had 2-bolt main caps. This engine was never installed in a production-line vehicle by GM, it only went to racers. And even though it was available in 1963, it has very little resemblance to the 427 Mark I "W" engine of the same year. The Mark II was a "breakthrough" design using intake and exhaust valves that are tilted in two planes--a canted-valve cylinder head, nicknamed the "Semi-Hemi" or "Porcupine" because it is "almost" a hemi head, and the valve stems stick out of the head casting at seemingly random angles. The engine was the subject of an extensive article in the May, 1963 Hot Rod Magazine. Because of NASCAR politics, Chevrolet was forced to sell two 427 Mark II engines to Ford after the '63 Daytona race, (to "prove" that it was a production engine, and therefore eligible to race in NASCAR events) and so this engine is not only the grandfather of the Mark IV and later big block Chevies, it's also the grandfather of the canted-valve Ford engines: Boss 302, 351 Cleveland and variants, and the 429/460 big block Ford. The bore and stroke of the 427 MK II is not the same as the 427 MK IV.
Mark III: Never released for production. This was rumored to be the result of GM/Chevrolet's proposed buyout of the tooling and rights to the Packard V-8 engine of the mid-to-late '50's. The Packard engine was truly huge, having 5" bore centers. The former president of Packard wound up at Ford after Packard folded, perhaps because of that, Ford was also interested in this engine. Ford wanted to make a V-12 variant from it just as Packard had once envisioned. One way or another, neither GM nor Ford actually went forward with the purchase.
Mark IV: The engine that most people think of as the "big block Chevy". Released partway into the 1965 model year as a 396, superseding the older 409. It is a development of the Mark II and using similar but not identical canted valve (semi-hemi/porcupine) cylinder heads. It was later expanded to 402 (often still labeled as a 396, or even a 400,) a 427, a 454, and a few "special" engines were produced in the late '60's for offshore boat racing as a 482. There was a 366 and a 427 version that each had a .400 taller deck height to accommodate .400 taller pistons using three compression rings instead of the more usual two compression rings. These tall-deck engines were used only in medium-duty trucks (NOT in pickup trucks--think in terms of big farm trucks, garbage trucks, dump trucks, school busses, etc.) The tall-deck blocks all had 4-bolt main caps, forged crankshafts, and the strongest of the 3/8 bolt connecting rods. All-out performance engines used 7/16 bolt connecting rods, along with other changes. This engine family was discontinued in 1990, with the Gen 5 appearing in 1991.
Gen 5: General Motors made substantial revisions to the Mark IV engine, and the result was christened "Gen 5" when it was released for the 1991 model year as a 454. There were 502 cu. in. versions, but never installed in a production vehicle, the 502s were over-the-parts-counter only. Changes to the Gen 5 as compared to the Mk IV included, but are not limited to: rear main seal (and therefore the crankshaft and block) were changed to accept a one-piece seal, oiling passages were moved, the mechanical fuel pump provisions were removed from the block casting, the machined boss for a clutch bracket was eliminated, the cylinder heads lost the ability to adjust the valve lash, and the coolant passages at the top of the cylinder block were revised. The changes to the coolant passage openings meant that installing Mk IV cylinder heads on a Gen 5 block could result in coolant seepage into the lifter valley. Frankly, the changes (except for the one-piece rear main seal) were all easily recognized as cost-cutting measures which also removed some quality and/or utility. All told, the Gen 5 engine was not well regarded by the Chevy enthusiasts because of the changes to the coolant passages and the lack of an adjustable valvetrain. As always, the aftermarket has provided reasonable fixes for the problems. The Gen 5 lasted only until 1995.
Gen 6: GM recognized that it did not make any friends when it designed the Gen 5, and so they chose to revise the coolant passages again when designing the Gen 6, allowing the older heads to be used without coolant seepage problems. The boss for the clutch bracket returned. The non-adjustable valvetrain remained, as did the one-piece rear main seal. Some but not all Gen 6 blocks regained a mechanical fuel pump provision. Production engines installed in pickup trucks got a high-efficiency cylinder head, still canted-valve, but with a modern heart-shaped combustion chamber of about 100cc. The intake port has a "ski jump" cast into it to promote swirling of the intake air flow. All production vehicles with a Gen 6 used a 454 version, but over-the-counter 502s are available. The Gen 6 is sometimes referred to as the "Gen Fix" because it fixed a number of issues that disappointed enthusiasts when the Gen 5 was released. As an added bonus, most if not all Gen 6 engines use hydraulic roller lifters.
Gen 7: A very major revision of the previous engines resulted in the 8.1 liter/ 8100/ 496 cubic inch Gen 7 in 2001. The block gained .400 in deck height so it is the same height as the previous "Tall Deck" truck blocks, wider oil pan rails, and the cylinder heads have symmetrical port layouts instead of the previous 4 long/4 short port layout. Very little interchanges between the 8.1 liter engine and the previous Mark IV/Gen 5/Gen 6 engines. The head bolt pattern and even the firing order of the cylinders has been changed. There are some things that remained true to the previous Mk IV/Gen 5/Gen 6--the bellhousing bolt pattern, the side motor mount bolt pattern, the flywheel bolt pattern, and the exhaust manifold bolt pattern are the same. Note that the bolt holes are threaded for metric fasteners. The 8.1 is internally balanced, so you could install a flywheel/flexplate from a 396/427 Mk IV provided you use the correct bolts to suit the 8.1 crankshaft.
Specifications:
(sorry if this table loses it's formatting: I don't know how to fix it. It looks "ok" at full screen width on my computer)
Engine family Displacement Bore Stroke Rod length
MK I 348 4.125 3.25 6.135
MK I 409 4.31 3.5 6.135
MK I 427 4.31 3.65 6.01
MK II 427 4.31 3.65 6.01
MK IV 366 3.938 3.76 6.135 (Only offered as a medium duty truck engine)
MK IV 396 4.094 3.76 6.135
MK IV 402 4.125 3.76 6.135
MK IV 427 4.250 3.76 6.135 (Offered in passenger car and medium duty truck versions)
MK IV/Gen 5/6 454 4.250 4.0 6.135
MK IV 482 4.250 4.25 6.405 (very rare, made only for offshore boat races. Used tall-deck block)
Gen 5/6 502 4.466 4.0 6.135 (Over the parts-counter only; not installed in production vehicles)
Gen 7 496/8.1 4.25 4.37
Specials: GM has sold many special-purpose engines, partial engines, blocks, cylinder heads, etc., "over the parts counter" that were never installed in production line vehicles. It is very difficult to track all the various items--suffice to say that heavy-duty "Bowtie" blocks and cylinder heads in various configurations--Mark IV, Gen 5, etc, have been produced. Oldsmobile used the Big Block Chevy as a baseline when designing the first of the Drag Race Competition Engines (DRCE) so that the early DRCE engines have an Olds Rocket emblem cast into the block, but it's Chevy parts that fit inside. There are special high performance blocks and heads, in either iron or aluminum, produced by GM and by aftermarket suppliers to suit almost any racing need.
Coolant Routing Mk IV/Gen 5/Gen 6
There are two different ways that coolant can be routed through the engine: series flow and parallel flow. Both ways work just fine. There may be a slight preference for parallel flow, but it is not a big deal. Series flow has the water exiting the water pump, flowing through the block to the rear, it then transfers through the head gasket and into the cylinder head through two large passages on each cylinder bank at the rear of the block. The coolant then travels from the rear of the head, forward to the front of the head, into the intake manifold water passage and out past the thermostat and thermostat housing. The water cools the block first, then it cools the head. The coldest water (coming out of the water pump) is directly below the hottest water (having already picked up the heat of the block and the head) as the hot water transfers into the intake manifold. By contrast, parallel flow has the water exiting from the water pump into the block, where a portion "geysers" up into the head between the first and second cylinder, another portion "geysers" up to the head between the second and third cylinders, another portion geysers up to the head between the third and fourth cylinder, and the remainder transfers to the head at the rear of the block. The coolant temperature inside the engine is more even that way. The differences in coolant routing is having (or not having) the three additional coolant transfer holes in each block deck, and three matching holes in the head gasket. The heads have passages for either system, and are not different based on coolant flow.
Be aware that gaskets that DO have the three extra holes between the cylinders often have restricted coolant flow at the rear--instead of having two large coolant transfer holes at the rear, there is only one, and it's the smaller of the two holes that remains. This is important because if you use a parallel flow head gasket on a series flow block, you can have massive overheating and there's NOTHING that will cure the problem except to replace the head gaskets with ones that don't restrict flow at the rear of the block, or to drill the block decks to allow the coolant to flow into the head between the cylinders. Here's why they can overheat: A series-flow block doesn't have the openings between the cylinders, no coolant can flow up to the head there. The gasket may only have the single, smaller opening at the rear, so the amount of water that gets through that opening is greatly reduced from what the block designers intended. The result is that the coolant flow through the engine is only a fraction of what is needed.
Most, but NOT all Mk IV engines are Series Flow. ALL Gen 5 and Gen 6 engines are Parallel Flow. A series flow block can be converted to parallel flow by drilling 3 holes in each deck surface, and then use parallel flow head gaskets. You can use the parallel flow gaskets as templates for locating the additional holes. It's really easy: Put the parallel flow gaskets on the block, mark the location and size of the three extra holes. Remove the gasket. Grab a 1/2" drill and a drill bit of the correct size, and pop the extra holes in the block. There is NO modification needed on the head castings. Some blocks have one of the holes already, but it needs to be ground oblong to properly match the gasket. Again, very easy with a hand held die grinder and rotary file.
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