642 HP Budget Iron Head Build - Iron-Headed Rat

[Grumpy]

642 HP Budget Iron Head Build - Iron-Headed Rat
You can make a lot of horsepower with good iron heads, as we prove on this big-block.
Richard Holdener Jun 11, 2014
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Old-timers must look around at the proliferation of affordable and power-producing aluminum cylinder heads and think to themselves, “These young guys have it easy.” Back in the day, aluminum big-block Chevy heads sat on the shelf right next to the supply of hen’s teeth. Yeah, they were that rare—and even more expensive.

It seems like every big-block buildup in the last 20 years has been blessed with aluminum heads. Despite this, we should remember that with the exception of very few, Rat motors came from the factory with iron heads, and those same iron heads won thousands and thousands of races. On the plus side, for the budget conscious, there are still great iron cylinder head castings available from the aftermarket—all the latest technology in port design applied to fancy aftermarket aluminum heads has also been applied to their cast-iron counterparts. A cost analysis of iron versus aluminum made us wonder: Can you build affordable big-block power using iron head castings? To find out, we made a casting call.

Top Searches

• summitracing.com, they’re quite the bargain. You could easily triple that at a machine shop refurbishing and upgrading a set of stock heads. Of course, what the heads flow and what the engine makes are two different things, but starting with enough flow to support the intended power level is mandatory for maximum performance.
  
  To get the displacement we wanted, we secured a 4.25-inch stroker crank and matching 4340 forged steel rods and teamed them with a set of 18cc dome, Probe forged pistons. Sealing the pistons was a set of Total Seal rings. The result was a forged, four-bolt short-block displacing 496 ci. Even at just 1 hp per cubic inch, we were creeping up on 500 hp, but we had more tricks up our sleeve to inch it closer to 600 hp.
  
  Big power and big displacement required adequate cam timing. No RV cam was going to get us the power we needed, so we gave Crane Cams a call to secure a beastie bumpstick. Knowing our goals, Crane supplied a solid-roller cam that included 0.714-inch lift (intake and exhaust), a 254/262-degree duration split, and a 112-degree LSA. Crane also came through with the necessary roller lifters, hardened pushrods (8.6/9.5), and Gold roller rockers. Completing the valvetrain was a double roller timing chain, cam button, and ARP retaining hardware.
  
  The job of feeding the beast was handled by an Edelbrock 454-R (Victor Jr.) intake and 950 Ultra HP Holley carb. MSD supplied the billet distributor and ignition amplifier while spent gases exited through 2.25-inch dyno headers. Additional touches before testing included a Milodon oil pan and windage tray filled with 30W (break-in) oil.
  
  Once assembled, the 496 was installed on the dyno in preparation for a pair of break-in cycles to properly seat the rings and bearings. Though it was equipped with a roller cam, we filled the motor with high-zinc break-in oil and primed the motor with a drill to ensure every surface had plenty of oil before start-up. The iron-headed big-block fired up on the first try, and settled in for a pair of computer-controlled, 15-minute break-in cycles. Once we were satisfied that the rings were seated, we began the time-honored mix of jetting and timing to unearth the maximum power. The initial load in at 3,600 rpm netted 550 lb-ft of torque, but this eventually climbed to a maximum of 591 lb-ft at 5,100 rpm.
  
  What can we say? We overshot our goal of 600 hp, which came and went at just 5,300 rpm, and by more than just a few ponies. The iron-headed 496 exceeded our expectations by reaching a peak of 642 hp at 6,200 rpm. The stroker also excelled in the hunt for grunt, as torque production exceeded 575 lb-ft from 4,200 rpm to 5,800 rpm.
  
  Does this test mean cast-iron BBC heads will replace their aluminum counterparts? Not likely, but if you are looking to build a stout street/strip BBC on a budget, these iron castings from Summit Racing should definitely be considered.
  
  
  
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  1. The bottom end consisted of a four-bolt Mark IV block stuffed with a forged crank and rods.
  
  
  
  4/14
  2. To improve oil control, we installed a Milodon windage tray and pickup along with a Melling HV oil pump.
  
  
  
  5/14
  3. With the Summit iron heads capable of supporting nearly 700 hp, we needed sufficient cam timing to properly motivate the valves. The Crane solid-roller cam offered 0.714 lift, a 254/262-degree duration split, and a 112-degree lobe-separation angle.
  
  
  
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  4. Running a solid roller cam in the early Mark IV block required use of a cam button to eliminate cam walk. Note also the adjustable, double roller timing chain supplied by Crane.
  
  
  
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  5. With an endless supply of alloy heads available for the Rat, we often forget their cast-iron counterparts. These cast-iron, rectangular-port perfor-mance heads from Summit Racing fea-tured 308cc intake ports, a 2.25/1.88-inch stainless valve package, and a multi-angle valve job.
  
  
  
  8/14
  6. The heads were supplied with a spring package designed for a flat-tappet cam of less than 0.660-inch lift, so we upgrade the spring package for our roller cam.
  
  
  
  9/14
  7. Crane Cams came through with solid roller lifters and hardened pushrods for our buildup.
  
  
  
  10/14
  8. Accurate valvetrain geometry was ensured with the installation of 1.73:1 Crane Gold roller rockers.
  
  
  
  11/14
  9. Before running, we filled the Milodon pan with 6 quarts of 30W, high-zinc, break- in oil.
  
  
  
  12/14
  10. Feeding the iron-headed stroker was a Holley 950 Ultra HP and single-plane intake manifold. The induction was designed to optimize power production in the upper half of the available rpm range.
  
  
  
  13/14
  11. Run with dyno headers and pump gas, the iron-headed 496 produced 642 hp at 6,300 rpm and 591 lb-ft of torque at 5,100 rpm.
  
  
  
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  Sources
  Crane Cams
  Daytona Beach, FL 32117
  866-388-5120
  http://www.cranecams.com
  Summit Racing
  Akron, OH
  800-230-3030
  SummitRacing.com
  Aeromotive
  Lenexa, KS 66214
  913-647-7300
  http://www.aeromotiveinc.com
  Holley Performance Products
  Bowling Green, KY 42101
  270-781-9741
  http://www.holley.com
  MSD Ignition
  915-857-5200
  www.msdignition.com
  ARP
  800-826-3045
  ARP-BOLTS.COM

I read through that build and the first thing that struck me was that why would anyone spend close to $1800 for a set of 2 those cast iron 308cc BIG BLOCK HEADS ($875 x 2), without carefully comparing the options they had first to verify they were the best option
theres dozens of other options both cast iron and aluminum

aluminum heads can be easily welded to make repairs if damaged
but one factor on a bbc engine is weight, a iron head weights close to 74 lbs , aluminum heads tend to be 20-30 plus lb lighter in weight each, so saving 40 lbs -60 lbs off the front of the car plus another 5-7 lbs for an aluminum water pump and another 20-25 plus lbs with an aluminum intake makes a great deal of difference in total engine weight, easily 80 plus lbs less with an aluminum water pump,intake and heads used vs the similar factory cast iron components, and no less than 100 lbs save if you also swap to headers vs the factory cast iron exhaust manifolds

 

[Grumpy]

I read through that build and the first thing that struck me was that why would anyone spend close to $1800 for a set of 2 those cast iron 308cc BIG BLOCK HEADS ($875 x 2)
theres dozens of other options both cast iron and aluminum
http://www.dragzine.com/tech-stories/engine/ultimate-guide-to-budget-bbc-cylinder-heads-under-2000/

http://garage.grumpysperformance.co...t-intake-on-oval-port-heads.13146/#post-69975

Ultimate Guide to Budget BBC Cylinder Heads Under $2,000



In general terms, big engines make big power! It stands to reason that if you want earth shaking, ground pounding power, you probably want to build a big block engine. Power, however, comes at a price. The old adage of “there’s no replacement for displacement” still holds true, but cubic inches of power doesn’t have to cost you cubic dollars. The high performance aftermarket has seen an influx of big block Chevy cylinder heads, many of which can fit into the tightest of budgets and still bring thundering punishment to the pavement.

When you are putting together the big block puzzle, one of the worse things you can do is buy whatever part is on sale this week. Randomly buying parts because they look good or because they have good street cred may cost you more in the long run. Big Block Chevy cylinder heads are a perfect example of where money spent wisely can pay off with some decent power without spending your kid’s entire college fund. Power does come at a price, but you can make some wise choices that produce the power you are expecting by picking up affordable heads.

With some smart shopping techniques, like knowing what your overall goal is, you can purchase a set of cylinder heads without breaking the bank, and more importantly, without compromising on power. To help answer the question of “What cylinder head do I need for my big block Chevy?”we have assembled a guide that will help you get through the dense jungle growth of BBC cylinder head choices. Follow along as we go for a run through the jungle.

The Key to Finding the Right Cylinder Head

RHS’ Product Manager Kevin Feeney summed up the process of finding the right set of heads for your BBC, “The first step is to determine what you are trying to accomplish with the engine. Are you looking for torque or horsepower, or the best combination of them both? This and the size of the engine are vital to choosing the proper runner sizes, valve sizes and ports for the application.”

With so many variables, and so many choices, it’s easy to go down the wrong path or find a shortcut to less performance. “Too many times guys tend to buy cylinder heads based on high lift flow numbers that are easily achieved with large ports and valves, but do not necessarily provide them with the performance they are looking for,” added Feeney.


Cast Iron being poured into molds at the foundry. (Photo from CFM Corporation)

What this Guide Covers

Our comprehensive guide to budget-friendly big block cylinder heads is strictly limited to fully configured and assembled units that are sold as a set for under $2,000 and are perfect for street use. We limited the spectrum of head choices to engines that are designed to run 91 octane pump gas and are not trailer queens. If you’re building a car that you can’t drive to the track, you’re probably not looking for a budget friendly set of cylinder heads anyway and this guide won’t cover the range of cylinder heads that you are looking for.

Our Criteria for budget friendly:

• A fully configured and assembled set of cylinder heads
• Priced under $2,000
• Street or Street/Strip use
• Designed to run on pump gas
• Must be able to make more power than stock OEM cylinder heads

Take a look at the big picture before rushing out to buy the first set of BBC heads you see.

Factors To Consider

There are several factors to consider when selecting the right set of heads for your big block. Dart Machinery’s Advertising Director, Jack McInnis explained “The size of the engine, rpm range, camshaft, type of fuel, weight and gearing all factor in. Whether the car will be street driven 99% of the time, or if it will be primarily raced and driven on the street only occasionally will make a big difference in the choice as well.” Armed with McInnis’ warning to take a look at the whole picture, we have broken down some of the basic characteristics that you need to consider when selecting a budget big cube head.


Aluminum heads look great and have a lot of good things going for them, but are they right for you?

Aluminum VS. Cast Iron

Cast iron is pretty common to most of us because it has been around the longest. Cast iron is inexpensive when compared to aluminum and is strong and durable. There are hundreds of different cast iron alloys but the kind that is typically used in cylinder heads is a gray cast iron. Gray cast iron is generally about 92-percent iron, 3.4 percent carbon, 2.5 percent silicon and 1.8 percent manganese. Rated at a tensile strength around 25,000 psi and a hardness somewhere near 180 on the Brinnell scale, cast iron heads are heavier than aluminum heads and can weigh as much as 30 percent more.

Aluminum’s main advantage is its light weight. Aluminum also dissipates heat very quickly, which may or may not be an advantage, depending on what you are trying to achieve. To make horsepower, you want some heat to be retained in the combustion chamber without detonation or preignition, which makes aluminum a great choice.

We talked to Billy Briggs of Briggs Performance about aluminum heads. “About the only drawback with aluminum is the simple fact that the aluminum alloy itself only has a life span of so long, but the pros are still huge. Ease of repair, ease of machining, heat dissipation and lighter weight are just a few,” said Briggs.

Aluminum alloys have become much better in recent years and the problems associated with heat warping aluminum heads in the early 1980s have been eliminated. There are some installation procedures that should be adhered to when installing aluminum cylinder heads for trouble free service.

Chad Golen of Golen Performance, a top notch GM LS engine builder, explained, “Aluminum has more expansion but doesn’t cause a problem with today’s head gaskets and high quality fasteners made by ARP. You just need to be careful bolting up accessories, like intakes and valve covers so you don’t damage the threads.”







Another company that specializes in big block Chevy heads is Livernois Motorsports in Michigan. Mike Schropp, Engine Department Supervisor at Livernois, confirmed that, “While aluminum heads do contract and expand at different rates than the cast iron block they may be bolted to, most modern day gaskets, bolts and heads require little to no maintenance after being installed.”

The key is using good quality gaskets and hardware. “New style gaskets do an excellent job of allowing the two surfaces to scrub on each other and still maintain a seal,” said Schropp. Using the professional guidance from Golen and Schropp, we recommend budget builders to plan on buying good quality gaskets and hardware with an aluminum cylinder head. Schropp also suggested “using an anode rod to try and prevent corrosion of the aluminum surfaces from the dissimilar metals if you are using an aluminum head and a cast iron block.”


Combustion chamber design and volume are important in how the fuel is burnt.

Closed or Open Combustion Chamber?

These terms get thrown around casually without consideration for what they purpose is behind the design of these chambers. In respect to big block Chevy heads, these terms relate to the size of the combustion chamber. An open chamber will have a larger combustion chamber; typically the valves are not shrouded and the engine breathes better. An open chamber can be identified by the dome area of the chamber extending to the diameter of the cylinder bore.

A closed chamber typically has a diameter much smaller than the cylinder bore. The smaller combustion chamber results in the block’s deck surface extending into the combustion chamber area which forces the air/fuel mixture into the smaller combustion chamber when the piston is on the compression stroke.

When the piston nears the cylinder head and the flat area of the piston top and the flat area of the cylinder head get close, the air/fuel mixture is “squished” into the combustion chamber closer to the spark plug. This is where the term “squish area” comes from. The space between the flat area of the piston top and the cylinder head typically run cooler than the rest of the chamber and piston. This lower temperature is where the term “quench area” comes from.


Semi-open combustion chamber heads can flow extremely well and provide the right mix of turbulence and "squish".

While the terms “quench” and “squish” are often used interchangeably by many manufacturers, quench and squish are not the same thing, nor are they produced by the same set of conditions. The Society of Automotive Engineers (SAE) has defined squish as the gases trapped between the piston dome and head that are ejected across the combustion chamber at high speed by the near-collision of the piston dome and head, causing turbulence and mixture homogenization. For our purposes, if the squish area is too close, there is a pumping loss and if the area is too far apart there will be lower squish velocity and less turbulence.

Quench on the other hand, is the ability to lower temperature of the end gases trapped between the piston dome and head by conduction. This prevents a second flame front from igniting the air/fuel mix prematurely. Members of the SAE acknowledge that for motors with 3.5” to 4.5” cylinder bores, a quench distance of 0.035” to 0.040” work well and result in near zero clearance due to thermal expansion, rod stretch and piston rock-over.






Properly designed quench areas have a dramatic effect on combustion quality and allow for higher compression ratios. For our budget friendly cylinder head guide, we can say in general terms, closed chambered heads can have an advantage in fuel efficiency and emissions by achieving a more complete burn, but valve shrouding can become an issue if the chamber is closed too much.

Combustion chamber size plays a significant role in compression (more is less and less is more). The smaller the combustion chamber, measured in cubic centimeters, the higher the compression will be.

Intake Port Shape and Size

It doesn’t take a lot of imagination to understand that a larger port has the potential to flow more than a smaller port. How much flow your engine needs will vary based on how much the engine can use. Port size is a very important issue when it comes to head design. Simply speaking in terms of flow, the smaller the port diameter, the less air potential there is.

Runner volume (length) is also very important. As the runner gets longer, movement in the column of air will increase the flow at lower RPMs and decrease the flow at higher RPMs.


Intake port shape and size are important considerations in reaching your goal.

If you intend on doing a lot of low rpm street driving with a low-lift camshaft, performance will be less than optimal on cylinder heads with huge intake ports. The reverse is also true; high revving, big lift cammed engines with big displacement will not like smaller intake ports.

It’s true that a larger intake runner will allow more air and atomized fuel to flow through, but the larger area will also slow the velocity of the air and fuel flowing through it. Smaller runners speed up the flow, which improves throttle response and torque, but may not deliver the maximum amount of energy that your engine can use. The perfect combination of good flow and velocity is the challenge.

Common thought on port shapes is that oval shaped ports leave fewer opportunities for eddies and irregularities of flow in the corners because there are no corners, however, for budget friendly street heads running on pump gas, you should think of oval and rectangular ports as a function of size, not of shape.

RPMs are a big deal for street cars running on pump gas. Port shape is not as important as the cross sectional diameter and length of the runner matched to the RPMs. It’s highly unlikely that a street car is going to be spinning 7,000 RPM from stoplight to stoplight, thus a huge diameter, big volume oval port runner will probably under perform in the street RPM range.


Runner volume can make or break a daily driver.

Exhaust port shape and runner volume is even less important than the intake side, however, scavenging all the exhaust gasses from the combustion chamber means that you can refill the combustion chamber with more fuel and air. More fuel and air means more power, so there is some consideration in the exhaust runner size and exhaust port shape. Our best advice is to call the manufacturer’s tech lines or talk to your engine builder for guidance on runner size.

Comprehensive Guide to BBC Cylinder Heads by Application

For our guide, we chose to break down the “budget friendly” BBC cylinder heads into categories that include the entry level and work up to the street/strip category and up to the dedicated performance car level. We also include a breakdown on why we think the cylinder heads represented in each category are the best fit for the application. The cylinder heads are not listed in order of preference, simply by the company’s name in alphabetic order. Where applicable, we have included additional information on engine size as big block Chevy’s covered in this article range from engines manufactured from 1965 through 2006.

Budget Big Block Chevy Cylinder Heads For Entry Level Street

Looking for an entry level set of heads for street use goes beyond price. Given that GM factory production heads commonly had runner volumes of 230 to 270 cc. Larger volume runners were used in GM’s performance versions. Aftermarket cylinder heads have improved airflow but must be matched to the camshaft, intake and exhaust systems for the optimal results. The heads listed below are good choices for an application that is intended to be higher performing than stock and still used on the street for daily driving.

Smaller ports and runners will keep the mixture of air/fuel at a higher velocity making driving from stop light to stop light and idle quality a lot more steady. With too large of a runner volume, a basic stock type engine will lug at low RPMs until it gets to cruising speed. Entry level heads are designed for engine where there are not too many high performance upgrades already installed and the engine will be running on mid to high octane pump gas. Optimal runner volume for these conditions is somewhere in the range of 270 cc to 290 cc.

Dart 308cc Big Block Chevy Heads, Rectangular Port


Dart 308 cast iron cylinder head.

Perfect for: Entry Level Street or Street/Strip where front end weight is not an issue.
Material: Cast Iron Alloy
Cost: $1,700 per set
Intake Runner: 308cc
Combustion Chamber: Heart Shaped, 121 cc

• Additional Specs:
  • Part Number: 15100111
  • Intake Port Shape: Rectangular
  • Intake Runner Volume: 308cc
  • Exhaust Runner Volume: 129 cc
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.250″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.660″
  • Springs Per Valve: Single
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV(1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Edelbrock E Street 290 aluminum cylinder head.

Edelbrock E Street 290 (#50459)

Perfect for: Entry Level Street or Street/Strip
Material: Aluminum
Cost: $1,725 per set
Intake Runner: 290 cc
Combustion Chamber: Proprietary Semi Open Style, 110 cc

• Additional Specs:
  • Part Number: 50459
  • Intake Port Shape: Oval
  • Intake Runner Volume: 290 cc
  • Exhaust Runner Volume: 110 cc
  • Exhaust Port Shape: D-Port
  • Intake Valve Diameter: 2.190″
  • Intake Valve Angle: 26°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 26°
  • Maximum Valve Lift: 0.700″
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1965-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV(1963), 427 ci Mark IV(1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995)

Patriot Performance Freedom Series 2211 aluminum cylinder head.

Patriot Performance Freedom Series (#2211)

Perfect for: Entry Level Street or Street/Strip
Material: Aluminum
Cost: $1,400 per set
Intake Runner: 320 cc
Combustion Chamber: Proprietary, 119 cc

• Additional Specs:
  • Part Number 2211
  • Intake Port Shape: Rectangular
  • Intake Runner Volume: 320 cc
  • Exhaust Runner Volume: 125 cc
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.250″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.600″
  • Springs Per Valve: hydraulic roller springs
  • Retainer Locks: 7°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Priced around $1,400 per set
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Summit Racing cast iron cylinder head.

Summit Racing Cast Iron (#SUM-152125)

Perfect for: Entry Level Street or Street/Strip
Material: Cast Iron
Cost: $1,500 per setIntake Runner: 308cc
Combustion Chamber: Heart shaped 119 cc

• Additional Specs:
  • Part Number: SUM-152125
  • Intake Port Shape: Rectangular
  • Intake Runner Volume: 308cc
  • Exhaust Runner Volume: 129 cc
  • Exhaust Port Shape: Square
  • Intake Valve Diameter: 2.250″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.660″
  • Springs Per Valve: Single
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1965-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995)

Trick Flow Specialties PowerOval 280 aluminum cylinder heads.

Trick Flow Specialties PowerOval 280

Perfect for: Entry Level Street or Street/Strip
Material: Aluminum
Cost: $1,850 per set
Intake Runner: 280 cc
Combustion Chamber: Open Chamber 113 cc

• Additional Specs:
  • Part Number: TFS-41300001 / TFS-41300002
  • Intake Port Shape: Oval
  • Exhaust Runner Volume: 137 cc
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.190″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.700″
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

World Products Merlin Oval Port Iron Heads

Perfect for: Entry Level Street or Street/Strip
Material: Cast Iron
Cost: $1,675 per set
Intake Runner: 269 cc
Combustion Chamber: Open Chamber 119 cc


World Products Merlin Oval Port Iron Heads.

• Additional Specs:
  • Part Number: 030040-1 (Hydraulic Flat Tappet)/ 030040-2 (Solid Flat Tappet and Hydraulic Roller)
  • Intake Port Shape: Oval
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.300″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.600″
  • Springs Per Valve: 030040-1: Single. 030040-2: Dual
  • Retainer Locks: 7°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Street Performance & Muscle Car

Typically a bigger valve, port size and runner volume are desired in higher performance applications, however, knowing that this guide is for budget friendly, pump gas, street cruisers, we were looking for runner volumes in the range of 290 cc to 320 cc. On the smaller cubic inch big blocks, it’s probably still wise to stay down in the 290 cc to 305 cc range for drivability.

454 cubic inch big blocks are considered small by today’s standards where 502 ci and 572 ci engines are becoming more common. Obviously, a 454 ci engine will not have the same airflow demands as a 572 ci engine. The cylinder heads listed below still have good drivability in stop-and-go driving situations and low speed response while giving improved performance at the top end.

Dart 345 cast iron cylinder heads

Perfect for: Street Performance
Material: Cast Iron
Cost: $1,800 per set
Intake Runner: 345 cc
Combustion Chamber: Heart Shaped 121 cc


Dart 345 cast iron cylinder head.

• Additional Specs:
  • Part Number: 15200132
  • Intake Port Shape: Rectangular
  • Exhaust Runner Volume: 129 cc
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.300″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.660″
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV(1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Edelbrock Performer 454-O aluminum cylinder head.

Edelbrock Performer 454-O

Perfect for: Street Performance
Material: Aluminum
Cost: $1,900 per set
Intake Runner: 290 cc
Combustion Chamber: Proprietary Semi Open Style 110 cc

• Additional Specs:
  • Part Number: 60479
  • Intake Port Shape: Oval
  • Exhaust Runner Volume: 110 cc
  • Exhaust Port Shape: Square
  • Intake Valve Diameter: 2.190″
  • Intake Valve Angle: 26°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 26°
  • Maximum Valve Lift: 0.700″
  • Springs Per Valve: Single
  • Retainer Locks: 7°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Patriot Performance Freedom Series 2214 aluminum cylinder heads.

Patriot Performance Freedom Series (#2214)

Perfect for: Street Performance
Material: Aluminum
Cost: $1,600 per set
Intake Runner: 320 cc
Combustion Chamber: Proprietary 119 cc

• Additional Specs:
  • Part Number: 2214
  • Intake Port Shape: Rectangular
  • Exhaust Runner Volume: 125 cc
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.250″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.700″
  • Springs Per Valve: dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

RHS Pro Action 320 cc Hydraulic Roller

Perfect for: Street Performance
Material: Cast Iron
Cost: $1,575 per set
Intake Runner: 320 cc
Combustion Chamber: Proprietary Modified 119 cc

notice picture is in error a SBC
RHS Pro Action 320 Hydraulic Roller cast iron cylinder head.

• Additional Specs:
  • Part Number: 11301-02
  • Intake Port Shape: Rectangular
  • Exhaust Runner Volume: 135 cc
  • Exhaust Port Shape: Rectangular
  • Intake Valve Diameter: 2.250″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.600″
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1965-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV(1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

World Products Merlin Rectangular Port Iron Heads.

World Products Merlin Rectangular Port Iron Heads

Perfect for: Street Performance
Material: Cast Iron
Cost: $1,675
Intake Runner: 320 cc
Combustion Chamber: Open Chamber 119 cc

• Additional Specs:
  • Part Number: 030620-2 (Solid Flat Tappet & Hydraulic Roller)/ 030620-3 (Solid Roller)
  • Intake Port Shape: Rectangular
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.300″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 030620-2: 0.650″ / 030620-3: 0.700″
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Wild Street and Dedicated Performance

For an application where performance is desired over streetability comfort. The heads listed below are for larger cubic inch big blocks where the airflow demands are greater or highway driving where the engine does not have to lumber through the gears to get to cruising speed often. Once you get to cruising speed however, these heads should provide all the flow you need or want.

Cylinder heads in the dedicated performance category will do well with intake and exhaust upgrades that maximize the flow characteristics. Large port openings and runner volumes along with larger valves and valve train set up for higher lift are the standards of a wild street or dedicated performance head.


Edelbrock High Compression 454-O aluminum cylinder head.

Edelbrock High Compression 454-O (#60499) 50 state legal

Perfect for: Wild Street Performance or Dedicated Performance
Material: Aluminum
Cost: $1,900 per set
Intake Runner: 290 cc
Combustion Chamber: Proprietary Semi Open Style 100 cc

• Additional Specs:
  • Part Number: 60499
  • Intake Port Shape: Oval
  • Exhaust Runner Volume: 110 cc
  • Exhaust Port Shape: Square
  • Intake Valve Diameter: 2.190″
  • Intake Valve Angle: 26°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 26°
  • Maximum Valve Lift: 0.700″
  • Springs Per Valve: Single
  • Retainer Locks: 7°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Trick Flow Specialties PowerPort 320 aluminum cylinder heads.

Trick Flow Specialties PowerPort 320

Perfect for: Wild Street Performance or Dedicated Performance
Material: Aluminum
Cost: $1,950 per set
Intake Runner: 320 cc
Combustion Chamber: Open Chamber 122 cc

• Additional Specs:
  • Part Number: TFS-41400001 or TFS-41400002
  • Intake Port Shape: Rectangular
  • Exhaust Runner Volume: 137 cc
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.250″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.700″
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

Patriot Performance Freedom Series (#2216)




Patriot Performance Freedom Series 2216 aluminum cylinder heads.

Perfect for: Wild Street Performance or Dedicated Performance
Material: Aluminum
Cost: $1,900 per set
Intake Runner: 320 cc
Combustion Chamber: Proprietary 119 cc

• Additional Specs:
  • Part Number: 2216
  • Intake Port Shape: Rectangular
  • Exhaust Runner Volume: 125 cc
  • Exhaust Port Shape: Round
  • Intake Valve Diameter: 2.300″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.800″
  • Springs Per Valve: Triple
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1966-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV (1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

RHS Pro Action 320 cc Solid Roller



notice picture is in error a SBC
RHS Pro Action 320 cc Solid Roller cast iron cylinder head.

Perfect for: Wild Street Performance or Dedicated Performance
Material: Aluminum
Cost: $1,780 per set
Intake Runner: 320 cc
Combustion Chamber: Proprietary 119 cc

• Additional Specs:
  • Part Number: 11301-03
  • Intake Port Shape: Rectangular
  • Exhaust Runner Volume: 135 cc
  • Exhaust Port Shape: Rectangular
  • Intake Valve Diameter: 2.250″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.750″
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1965-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV(1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

RHS Pro Action 360 cc Solid Roller cast iron cylinder head.

RHS Pro Action 360 cc

Perfect for: Wild Street Performance or Dedicated Performance
Material: Cast Iron
Cost: $1,780 per set
Intake Runner: 360 cc
Combustion Chamber: Proprietary 119 cc

• Additional Specs:
  • Part Number: 11302-02 (Hydraulic Roller)or 11302-03 (Solid Roller)
  • Intake Port Shape: Rectangular
  • Exhaust Runner Volume: 135 cc
  • Exhaust Port Shape: Rectangular
  • Intake Valve Diameter: 2.300″
  • Intake Valve Angle: 24°
  • Exhaust Valve Diameter: 1.880″
  • Exhaust Valve Angle: 15°
  • Maximum Valve Lift: 0.600″ (11302-02) / 0.750″ (11302-03)
  • Springs Per Valve: Dual
  • Retainer Locks: 10°
  • Valve Train: Standard BBC 7/16” Stud Mount
  • Guideplates: Hardened Steel, 3/8″ Pushrod size
  • Application: 396 ci Mark IV (1965-1970), 402 ci Mark IV (1970-1972), 427 ci Mark IV(1966-1969), 454 ci Mark IV (1970-1990), 454 ci Gen V (1991-1995), 454 ci Gen VI (1996-2000)

The Final Word

It’s been said that the terms “budget” and “big block” don’t go together and qualify as an oxymoron when used together. However, the cylinder heads listed in our guide above are well within the range of what can be considered budget friendly. Nan Gelhard of Summit Racing Equipment emphasized that point by saying; “When you talk about dollars per horsepower you can see how it changes as you go from street to strip.”

Whether you have a stock big block that you salvaged from the wrecking yard and are looking for some modern technology heads to bolt on, or if you want to beef up your daily driver to take it to the drag strip occasionally, we’ve got you covered in one of the budget friendly categories listed above.

Billy Mitchell Jr. from World Products encourages enthusiasts to call the tech lines or work with your engine builder. “It’s important to marry the runner size and port shape to the cubic inch size of the engine,” says Mitchell. Chad Bowling of Patriot Performance also recommended working with your engine builder on the engine internals like camshaft before picking a set of assembled heads, “Most aftermarket head manufacturers offer cylinder heads in a variety of spring packages from hydraulic flat tappet to solid roller,” Bowling states. The final word is that it is OK to use this guide as you would any other guide, as a means of gathering information to talk with your engine builder about the best method of achieving your goals.

SOME ROLLER ROCKERS CAN AND DO BIND ON ROCKER STUDS, or rocker adjustment nuts, youll need to check carefully

some roller rocker too retainer combo clearance issues cause problems easily solved with beehive springs and smaller retainer diameters

BEEHIVE SPRINGS GIVE A GOOD DEAL MORE ROCKER TO RETAINER CLEARANCE







SOURCES
Dart Machinery
Phone: 248-362-1188
Edelbrock
Phone: 310-781-2222
Patriot Performance
Phone: 888-462-8276
RHS
Phone: 877-776-4323
Summit Racing
Phone: 330-630-0240
Trick Flow Specialties
Phone: 330-630-1555
World Products
Phone: 631-981-1918



http://www.jegs.com/p/World-Product...-III-Cast-Iron-Cylinder-Heads/746696/10002/-1

http://www.jegs.com/p/Dart/Dart-Big-Block-Chevy-Pro-1-Aluminum-Cylinder-Heads/744672/10002/-1

https://www.profilerperformance.com/174-bbc-24-degree-heads.html

http://www.jegs.com/p/ProMaxx-Perfo...hevy-Aluminum-Cylinder-Heads/2789044/10002/-1

https://www.summitracing.com/parts/pmx-2211

https://www.summitracing.com/parts/tfs-41410001-m22

https://www.summitracing.com/parts/tfs-4141t003-m22

https://www.summitracing.com/parts/edl-61559

https://www.summitracing.com/parts/rhs-11011

https://www.summitracing.com/parts/pfh-174-32-02

https://www.summitracing.com/parts/edl-60555

 

[Grumpy]

I always thought they basically lied or cheated on this build article, not so much on the physical build or parts list but on the price your most likely to find in real life
finding a 496 short block at a great price is just not all that easy

Big-Block Chevy Engine Build – 707 HP For $6,720
Written by Jeff Smith on January 21, 2007

VIEW ALL 16 PHOTOS
With A Swap-Meet Block And AFR Heads, We Made Some Serious HP, You Can Too

‘Face it: Bigger is better. Since it’s a jungle out there, where the meek get eaten for lunch, if you wanna be Tarzan, you’d better swing a bigger club. The days of a 396 or even a 454 as king of the jungle are long gone. When we stumbled upon this used 496ci Rat motor for a righteous price, we snapped it up thinking we could build an affordable big-inch Rat. The problem comes from using the terms “affordable” and “Rat motor” in the same sentence. Nevertheless, that’s the challenge we decided to take on. We think Tarzan would approve.

We knew that bitchin’ cylinder heads, a good cam, and a healthy carb and intake would be where we would have to spend our money, and that’s exactly what we did. There are dozens (if not hundreds) of ways to build a strong, normally aspirated big-block Chevy, so this opened up a ton of options. And since we made over 700 hp on the first try, this is not the last time you will see this motor.


The Beginning
It was a typical Sunday at the swap meet. There, among the cheap rags and rusty Buick valve covers, was a lump of black-painted iron. It didn’t look like much, really. Taped to its side was a hand-scrawled sign that proclaimed this particular round mound of poundage as a 496ci Rat motor (4.310 bore, 4.250 stroke). The owner couldn’t remember who made the crank (“Scat . . . maybe,” he said), and he wasn’t sure if it was even a four-bolt main block. Despite his vague description, he looked honest. Even its history was dubious: “When we pulled it, it wasn’t running right.” But the price was right at $800, so we took a chance and loaded the lump in the back of our GMC pickup.

A quick autopsy revealed the deck was anything but square, but at least the cam wasn’t flat. We found a 1-inch length of broken pushrod lodged in the oil-pump pickup, and most of the bearings were hideously scored. It looked like our Rat had been assembled on the floor of a rodeo ring with all that bulls%*# and dirt in the motor.

We took our orphan Rat to the wizard machinists at Jim Grubbs Motorsports, where we discovered the four-bolt main block needed deck work and an align-hone to correct the oversized main-bearing-housing issues. JGM also resized the stock connecting rods that had previously been fitted with ARP rod bolts. At least the 0.060-over Speed-Pro hypereutectic pistons were in good shape. But we also discovered the valve pockets would have to be machined to clear the 2.250-inch valves used in the AFR heads we planned to run. A good portion of our budget was invested in JGM’s quality machine work, but that also meant we now had control over all the clearances in the short-block, creating a solid foundation from which to build some power

Games Pushrods Play
The engine assembly went fairly routinely until it came time to set up the valvetrain. First, we had to adapt a 0.125-inch-thick aluminum plate to the inside of our stock timing-chain cover to get the proper 0.005-0.008 inch of camshaft endplay using a Comp Cams cam button. Then we ran into a snag with the pushrods.

The stock-length pushrods we thought would work fell far short, and we were puzzling until we did what some car crafters don’t do-we read the directions. That’s when we discovered these AFR heads come with 0.250-inch-longer intake valves and 0.100-inch-longer exhaust valves. This dictated custom-length pushrods to make the rocker-arm geometry work with the longer valves.

We used a pair of Comp Cams adjustable pushrods to determine the proper lengths. We started by adding 0.250 inch to the stock length of the intake pushrod and 0.100 inch to the length of the exhaust pushrod. Remember that Rat motors use different lengths for the intake and exhaust pushrods.

The technique is very simple: Establish a pushrod length that will place the roller tip of the rocker arm on the inboard third of the valve tip. This can be done by marking the top of a valve with a felt-tip pen and turning the engine so the lifter for that valve is on the base circle of the lobe. Install the rocker arm over the adjustable pushrod and wiggle the rocker to make a witness mark on the valve tip. Adjust the pushrod length until the witness mark is on the inboard third of the valve tip. This allows the rocker tip room to travel across the top of the valve tip without running off the edge. A too-long pushrod will place the pushrod too far outboard at the beginning of its travel. A too-short pushrod runs the risk of running off the inboard edge of the valve tip. We ended up with intake pushrods that were 8.500 inches long and exhaust pushrods that were a long 9.400.

Next, we discovered the proper intake pushrod length placed the inside radius of the rocker arm very close to the retainer. If we lengthened the pushrod, it only made the placement of the rocker tip on the valve-stem tip less desirable by moving it outboard, which we didn’t want. The solution came from Westech’s Steve Brul, who suggested running valve-lash caps on the intakes. This increased our clearance between the rocker arm and the retainer and also increased the contact area between the rocker-arm roller tip and the valve stem.

On The Dyno
After we had carefully assembled the Rat and double-checked all our clearances, we loaded up the rotund rodent and bolted it up to Westech’s SuperFlow dyno. To finalize the combination, dyno guru Steve Brul suggested a set of 211/44-inch Hedman dyno headers that connected to a pair of massive 4-inch exhaust pipes and a pair of Hedman 4-inch mufflers. To tell the whole story, Westech uses an electric water pump just to make testing simpler. But this means there are a couple of free horsepower here by not driving a mechanical water pump.

As for ignition, our budget was so bent, stapled, and mutilated there was only enough money left for a basic, used HEI and PerTronix 8mm budget plug wires, so that’s what we went with, along with a set of cold-heat-range Bosch plugs to light the fire. As you can see from the test, this was more than enough to get the job done.

Brul always makes the very first pull on the engine after the oil and water temps are up to normal, and then it’s a quick yank at a mid-rpm point to see if the timing at 36 degrees and the stock jetting are where they should be. The first pull showed us 599 hp at 5,500 rpm. That’s when we knew this was going to be a good day.

By experimenting with timing finalized at 34 degrees and jetting with two sizes out of the primary and secondary, our fat Rat leaned out to the tune of 685 hp. After a short skull session, we decided on a tighter lash on the intake lobes to increase the effective duration. This kicked the power up to the curve you see in Test 1 at 701 hp at 6,400 and 603 lb-ft of torque at 5,400.

Brul then suggested a simple little plastic 1-inch spacer under the carburetor because we were seeing as much as 2 inches of manifold vacuum at peak power, which indicated (as we expected) that the carb was a little too small for this power level. The spacer took the power to an amazing 707 hp at 6,400 rpm. Finally, we even tried a 14-inch-diameter K&N air cleaner that pushed the peak horsepower up to 708. We liked the 707 number so well, we decided to stick with that. Not bad for a cast-crank, pump-gas 496

Dyno Flog
Test 1 was run with two steps leaner jets than stock in the Demon 850 carburetor with timing set at 34 degrees total. We also tightened the lash on the intake valves from 0.016 inch to 0.012 inch to increase the intake duration.

Test 2 used all the conditions of Test 1 along with a simple 1-inch-tall, plastic, open-plenum spacer under the carburetor to improve the top-end power. In a final test (not shown here), we added a 14-inch, K&N, 3-inch-tall, air-cleaner assembly and peak power climbed to 708 hp. Also note the brake-specific fuel consumption (BSFC) numbers that dip into the 0.390s below peak torque. These are excellent numbers indicating very efficient use of the fuel. BSFC is expressed as pounds of fuel used per horsepower-hour (lb/hp-hr). Generally, any number under 0.500 is considered good; sub-0.400 is excellent.

RPM
TEST 1
TEST 2
TQ HP TQ HP BSFC
3,000 514 294 518 296 0.463
3,200 528 322 527 321 0.442
3,400 544 352 549 355 0.422
3,600 547 375 552 378 0.414
3,800 545 395 550 398 0.412
4,000 552 421 554 422 0.407
4,200 564 451 562 450 0.395
4,400 576 482 574 481 0.387
4,600 586 513 585 512 0.389
4,800 590 539 591 540 0.393
5,000 593 565 596 567 0.403
5,200 600 594 603 597 0.409
5,400 603 621 603 620 0.419
5,600 601 640 602 642 0.422
5,800 598 660 601 664 0.415
6,000 595 680 599 684 0.418
6,200 588 695 593 700 0.432
6,400 575 701 580 707 0.449
6,600 557 700 561 705 0.446
Avg. 572 527 575 529 0.417
Power/ci 1.21 1.41 1.21 1.42


CAM SPECS
CAM
DURATION
(ADV.)
DURATION
(AT 0.050)


LIFT LOBE SEP.
Comp Xtreme 292, (Intake) 292 254 0.660 110
Mech. roller, (Exhaust) 298 260 0.666
AirFlow
Before we assembled the engine, we flow-tested the as-cast AFR 305cc heads on JGM’s SuperFlow 600 flow bench at 28 inches of test depression using a 4.280-inch bore diameter. We also used a handformed clay radius for the intake entry, and no flow tube was used on the exhaust. We also tested both the “good” and “bad” intake ports to give you both flow curves. The good intake ports aimed the intake flow toward the center of the cylinder while the bad intake ports aim the intake flow toward the cylinder wall. This is the main reason for the differences in flow.

We tested the AFR 305 heads on a slightly smaller bore size (4.280 inches) compared with our 4.310-inch-bore-diameter 496 Rat. Many published big-block flow tests use the much larger 4.500-inch bore size. This simple 0.220-inch bore-diameter increase is worth a few cfm in both intake and exhaust flow. So when comparing Rat head-flow numbers, pay close attention to the flow bench’s test bore diameter. For example, AFR publishes a 367-cfm flow number at 0.600-inch lift when measured on a 4.600-inch bore, while our number, measured on a 4.280-inch bore, is 347 cfm. Keep in mind that max cam lift is calculated without the lash. This means our actual intake valve lift was really closer to 0.645 inch (0.660 – 0.012 = 0.648 inch), including assuming a few thousandths for valvetrain deflection.

By the numbers
AFR 305cc, as-cast, rectangle-port heads2.25/1.88-inch valvesCNC-machined combustion chamberCFM

LIFT INTAKE
GOOD CFM
INTAKE
BAD EXHAUST
0.100 72 68 57
0.200 155 152 116
0.300 225 224 173
0.400 280 274 211
0.500 321 303 243
0.600 347 323 254
0.700 347 319 262
More Power
Here’s what our dyno test reinforced from what we already knew about our 496-inch Rat. The big deal is clearly the induction system. We’ve seen plenty of 500-plus cubic inch Rats run to know that a 1,050-cfm carb would be beneficial. Our budget also forced us to use a stock pan-so there’s a few horsepower in a good oil pan and tray assembly. It would also be nice to run thinner piston rings and forged pistons and maybe a point more compression. With all these ideas, it’s possible with the parts and more tuning we could make 730 hp. If you think that’s worthwhile, let us know and we’ll put the whip to our phat Rat.

DESCRIPTION PN SOURCE PRICE
Used 489 short-block — Swap meet $800.00
Comp roller, XR292R 11-773-8 Summit Racing 245.88
Comp, roller lifters, 819-16 Summit Racing 304.95
Comp, roller rockers 1320-16 Summit Racing 286.95
Comp, timing set 7110 Summit Racing 105.99
Comp, pushrods, exhaust 7755-1 Compcamstore 12.41 x 8
Comp, pushrods, Intake 7932-1 Compcamstore 12.64 x 8
Comp, lash caps 621-16 Summit Racing 34.75
Comp, cam button 205 Summit Racing 8.39
Comp, 1-inch open spacer VH311 Summit Racing 20.69
Tapered ring compressor 104310 Powerhouse 29.00
Pro crank turning socket 103055 Powerhouse 29.95
AFR 305cc, as-cast 3050-1 buyAFR.com 2,045.95
F-M ring, bearing, gasket set 205613M-311 Summit Racing 182.39
F-M cam bearings 1404M Summit Racing 22.95
F-M oil pump 224-4154 Summit Racing 27.95
F-M oil-pump pickup 224-43620 Summit Racing 10.39
F-M oil-pump shaft 224-6154A Summit Racing 7.99
ARP head bolts 135-3703 Summit Racing 93.39
ARP intake bolts 135-2001 Summit Racing 17.95
Pioneer brass freeze plugs 830002 Summit Racing 13.95
Edelbrock Victor Jr. 2902 Summit Racing 217.88
Demon 850-cfm carb 5563010GC Jeg’s 549.99
Distributor, HEI used Swap meet 25.00
Plug wires, PerTronix 8mm 8042VW Summit Racing 31.69
Spark plugs, Bosch FR8DP Summit Racing 31.92
ACDelco water pump 252608 Rock Auto 37.79
ACDelco starter 3361870 Rock Auto 50.79
Thermostat 13187 Rock Auto 5.73
TD valve covers 9235 Summit Racing 47.50
TD breathers 4870 Summit Racing 6.78 x 2
TD thermostat housing 9229 Summit Racing 9.95
TD crank pulley, aluminum 8876 Summit Racing 38.88
TD water-pump pulley 8874 Summit Racing 44.88
Block paint, VHT SP-123 Summit Racing 7.88
Hedman headers, 131/44-inch 68197 Summit Racing 231.69
Fel-Pro header gaskets 1412 Summit Racing 16.95
Subtotal $5,851.94
Machine Work
Grind crank 135.00
Resize rods 124.00
Align-hone mains 164.00
Deck block with fixture 150.00
Fly-cut pistons 160.00
Torque-plate-hone 135.00
Subtotal $868.00
GRAND TOTAL $6,719.94


Sources
Air Flow Research (AFR)28611 W. Industry DriveValencia, CA 91355877-892-8844http://www.airflowresearch.com/
COMP Cams3406 Democrat RoadMemphis, Tennessee 38118(800) 999-0853http://www.compcams.com/
Federal-Mogul26555 Northwestern Hwy.Southfield, MI 48034248-354-7700http://www.federal-mogul.com
Hedman Hedders12438 Putnam StreetWhittier, CA 90602562-921-0404http://www.hedman.com
Jim Grubbs Motorsports28130 Avenue Crocker # 331Valencia, CA 91355661-257-0101
Powerhouse Products3402 Democrat Rd.Memphis, TN 38118800-872-7223http://www.powerhouseproducts.com
Rock Auto6418 Normandy Lane Suite 100Madison, WI 53719http://www.rockauto.com/
Trans-Dapt Performance Products12438 Putnam StreetWhittier, CA 90602562-921-0404http://www.tdperformance.com

 

[Grumpy]

http://www.superchevy.com/how-to/project-cars/sucp-0608-chevy-mark-v-big-block-engine-build-up/

http://www.superchevy.com/how-to/engines-drivetrain/0903chp-540-chevy-big-block-engine-build/

http://www.felpro.com/technical/tecblogs/head-gasket-coolant-holes.html