3/8" Rocker Studs

AFR Enforcer 200cc/65cc ULTRA HIGH FLOW CYLINDER HEADS

ANGLE PLUG , FOR SBC CHEVY 327,350 & 383 ENGINES.

Setup for hydraulic roller cams.

200cc, (Actual size) RUNNERS, 65cc COMBUSTION CHAMBERS.

ARP studs, 3/8's or 7/16's, (your choice) and AFR 2pc. adjustable guide plates included.

See our other listings for the AFR Enforcer heads for use with hyd. flat tappet cams, solid roller cams, with angle or straight plug design, and non steam hole applications. Be sure when selecting the heads you need for your application. We are offering these heads in a much broader selection than any of the other sellers.

Important note.

These heads will include a full set of genuine ARP rocker studs, and most other sellers we will allow you to chose the stud size, 3/8's or 7/16's. So be sure to let us know what stud size you would like. Adjustable AFR guide plates are also included.

AFR Enforcer 65cc 200cc ALUMINUM HEADS

The AFR Logo's clearly display the true mark of excellence that these heads are known for.

In the flowchart below, the AFR Enforcer heads are superior to the Procomp/Speedmaster heads in flow rates, and also edge out the Dart SHP heads on the intake side. The intake numbers are far more important than the exhaust. The overall average flow numbers on the AFR heads are higher than most any brand of non cnc'd cast aluminum heads on the market of an equal runner size.

Notice the intake ports on the AFR Enforcer heads. They allow for a perfect fit with most intakes on the market. Our engines all include an intake manifold. The picture below is one of our engines in the build process.

The difference in horsepower and torque generated by the AFR Enforcer heads is monumental compared to any of the low cost sbc heads on the market.

Assembled by AFR with premium  metric competition grade valves, Pacaloy dual springs, Viton valve seals

THE BEST FLOWING, BEST QUALITY SBC ALUMINUM HEADS ON THE MARKET FOR THE MONEY.

This sale is for one fully assembled set of heads (2 heads).

The springs in these heads are set up to operate with hydraulic roller cams up to .600 lift. For those running hyd. flat tappet cams, see our other listings for these heads with the part number AFR Enforcer heads with the part number 272 in the title.

The AFR Enforcer aluminum heads have 65cc combustion chambers with 200cc runners, 8mm metric 2.02/1.60 stainless valves.

PART NUMBER # AP-274-AFR

The AFR Enforcer cylinder heads are made from AC4B alloy and tempered to T6 standards. Details about this alloy are in the lower section of this ad.

We certainly know where to draw the line with low end products, and we continue to eliminate parts that we once accepted but that eventually had problems. Sometimes it's not that a particular product has had a problem that leads to its elimination; something better just comes along. The AFR Enforcer cylinder heads are that "something better" coming along. We now use the AFR Enforcer heads on all of our 350, 383, and 406 engines. The performance has been outstanding on every combination we have tried them on.

The 1206 is the intake gasket part number, and that is mandatory for use with the Enforcer heads. Some intake manifolds will sit too low due to their design, and the 1266 extra thick intake gaskets may be required.

Very Important Note.

If you are using an Edelbrock Performer EPS intake then you will need to use a 1205 intake gasket instead of the 1206. This is due to intake flange not covering the top of the 1206 intake gasket properly. The 1205 is slightly small for the AFR Enforcer heads, and may need a very slight amount of trimming to avoid any gasket materiel hanging over into the intake runner. We have been through this procedure in our engine room many times for engines using the Performer EPS intake.

These heads are also available in straight or angle plug style.

A breakdown of the part number.

272 designates the use of standard length valves, and single springs with a damper setup for hyd. flat tappet cams. The 274 designates the use of longer valves with dual springs with a damper, setup for hyd. roller cams. We also have the valve train setup for solid roller cams, and will have the number 919 rather than 272 or 274. The heads listed as angle plug in the part number are angle plug design, and those wanting straight plug heads will notice this term in the part number. We also offer these heads for use on blocks that require steam holes. Be absolutely certain of what you need before buying. Feel free to call us if you need assistance deciding what you need for your build.

See our other listings for our former line of heads heads with our Competition Series PBM valves that are used to create the 68cc combustion chamber.

After receiving many recommendations from our engine builders, we came up with the best quality, best flowing heads on the market relative to cost. The only way you're going to get a set of heads that flow as well or better will be to spend at least double the cost or more. We have installed these heads on all of our 383 and most of our 406 engines for the past 2.5 years. Many of these engines were dynoed on our Superflo dyno. The engines had every possible combination of cam, intake and carb. The results have been amazing. These heads are excellent in design and quality. Our choice of hardware and precision assembly also contribute to the performance and reliability of the heads.

These heads can be used with outer perimeter or center bolt valve covers.

Recommended accessories for these heads.

Please see our other listings.

Important Note

In the flowchart above, the AFR-200s are superior to the Procomp heads in flow numbers, and also edge out the Dart SHP heads on the intake side. The intake numbers are far more important than the exhaust. The overall average flow numbers on the AFR/NKB-200 heads are higher than most any brand of non cnc'd cast aluminum heads on the market. We guarantee the flow numbers to be accurate, as well as the horsepower numbers produced by them.

Most importantly, all three of these heads were tested by the same person, on the same machine, (Superflo bench 1020) using the same testing method, on the same day. These numbers show the true difference between each brand, and that's what counts.

The difference in horsepower and torque generated by these new heads is monumental compared to the 210cc Procomp heads. We offer several different cam choices with our 383, 406 and 421 engines, and every combination has shown an increase of up to 50 horsepower and no less than 40 hp over the Procomp 210cc heads. We assumed the new heads would generate a considerable increase in power, but to our surprise, they generated more power than expected.

Many of the dyno passes were run to 6500 rpm as the large cam needed 6300-6400 rpm to make peak power, and you must run past this to determine the fall off point. The super sized cam (choice 1) was run on the heads towards the end. Considering the size of this cam, it was very impressive to see zero issues with the heads or hardware. We made a good 25 passes with the big cam trying out different carb sizes, jetting, intake manifolds, timing setting, and adding the Super Sucker plate last.

ONE YEAR WARRANTY, UNLIMITED MILEAGE.

H ere is a rundown on the hardware used in these heads and the assembly process.

Brandname: Air Flow Research

Part Number: 1006x2-Pair

Description:

They come fully assembled with the identical components found in our higher end CNC ported cylinder heads; such as ARP rockers studs, PAC Racing springs, viton valve seals, AFR adjustable guide plates, machined bead valve locks (not stamped), hardened spring cups our one piece 8mm 21 4N Stainless Steel valves. They are available in straight or angle plug and bare without any parts for the DIY. Sold as a single piece, 2 are required per engine.

Specification:

• Material: A356 Aluminum, see more details on alloy below.
• Intake Port Volume: 200cc true actual runner size.
• Intake Port Dimension: 2.080" H x 1.270" x 5/16 Radius
• Intake Port Location: Stock
• Exhaust Port Volume: 76cc
• Exhaust Port Dimension: 1.380" H x 1.420" W
• Exhaust Port Location: Stock
• Combustion Chamber Size: 64cc
• Valve Cover Bolt Pattern: Perimeter Bolt
• Valve Angle: 23°
• Valve Spring Pocket Diameter: 1.580" O.D
• Max Valve Spring Pocket Machining: 1.600" O.D
• Deck Thickness: .450"
• Minimum Bore Diameter: 4.000"
• Flat Mill: .006" per cc 56cc Maximum
• Spark Plug Dimensions: 14mm x .750" w/Gasket Seat

ALLOY INFORMATION.

Our cylinder heads are made from AC4B alloy and tempered to T6 standards. You may have heard the alloys 355 and 356 being used on many heads. The alloy used on our heads is similar but slightly different. The AC4B alloy is commonly used by automakers in Europe and Japan. Take notice of the Rm value. This value indicates the tensile strength of an alloy. As you can see, it's higher than all the other common alloys in this chart. It's no surprise as to why we have never experienced a failure of any kind with these heads. Zero failures in the casting, zero failures in the seats and guides.

PART # 180345-10 This is a hyd. roller cam for use with OE roller blocks.

PART # 110345-10 This is a retro hyd. roller cam for use with non roller blocks.

Valve lift with 1.5 Rockers: Intake .565/Exhaust .580

Duration @.050": Intake .245/Exhaust .253
Lobe sep. angle: 110º
Recommended springs #: 274, See our other listings.

Below are our dyno results on one of our engines with a set of our AFR/ NKB heads using this cam and a single plane intake. The horse power numbers will usually improve anywhere from 5-10 more than what the dyno results show after the rings have fully seated.

Official Dyno report on our 406 engine with this cam, flat top pistons, and a single plane intake.

Official Dyno report on our 383 engine with this cam and a single plane intake.

Cam choice # 1 and a single plane intake.

PART # 180265-10 This is a hyd. roller cam for use in OE roller blocks.

PART # 110265-10  This is a retro hyd. roller cam for use in non-roller blocks.

Valve lift with 1.5 Rockers: Intake .530/Exhaust .545

Duration @.050": Intake .233/Exhaust .241
Lobe sep. angle: 110º
Recommended springs #: 274, See our other listings.

Official Dyno report on our 406 and 383 engines with the cam mentioned above. The 406 engine had a dual plane intake, yet still achieved over 500 hp with the NKB heads.

Cam choice #2 and a dual plane intake.

This cam and a single plane intake.

PART # 180245-10 This is a roller cam for use in OE roller blocks.

PART # 110245-10 This is a retro style roller cam for use in non-roller blocks.

Valve lift with 1.5 Rockers: Intake .500/Exhaust .510

Duration @.050": Intake .225/Exhaust .231
Lobe sep. angle: 110º

Official Dyno report on our 383 engine with our AFR/NKB heads and a single plane intake. Considering the low lift and duration of this cam, the hp numbers are excellent.

This cam and a single plane intake.

Check out the results on the dyno reports below using the AFR/NKB heads with one of our new Comp custom ground street rod cams. All of our engines now use the Comp custom ground cams. This cam has a somewhat low lift and duration, and produced amazing hp and torque numbers when using the AFR/NKB heads.

SBC Comp Cam OE HYD. ROLLER 520/540 Lift 236/242 Duration

110 Lobe Sep.

This cam has a step nose for use in oe roller blocks.

Reduced base circle cam. (1.050)

Official Dyno report with this cam, AFR/NKB

AFR/NKB heads, a dual plane intake, a 770 cfm Brawler carb, and an MSD distributor.

This engine made 533 hp, and an amazing 549 lb. feet of torque at 4100 rpm. This engine had a dual plane intake on it. The single plane intake would have brought the hp numbers up to around 555.

SBC Comp Cam OE HYD. ROLLER 520/540 Lift 236/242 Duration

110 Lobe Sep.

This cam has a step nose for use in oe roller blocks.

Reduced base circle cam. (1.050)

See dyno results below.

Special Grind # 33161

PART NUMBER: 08-000-8-11323

520/540 lift

236/242 duration

110 lobe sep.

Listed below is our 2.0 383 pump gas engine making 508 horse power at 5900 rpm. You would be hard pressed to find a cam of this lift and duration to produce these hp and torque numbers in a 383. We find this size cam to be the perfect all around size to give good drivability yet make outstanding performance numbers. Very little strain on the valve train components with a cam of this size. This engine had our AFR/NKB heads on it, and the regular Speedmaster single plane intake.

The 421 listed below made 526 horse power with this cam and had a set of our low cost 200cc AFR/

NKB heads on it with the 1.5 rockers. Very impressive considering the low cost heads, and size of this cam. Notice the torque numbers in produced. A fairly flat line from 4100 up to 5500 rpm.

Listed below are a few important solutions to preventing valve train issues while having maximum performance and longevity in your engine when running medium to large lift cams.

The solution to running a hyd. roller cam of decent size in an engine and avoiding valve float is an easy fix, thanks to the Howards Max Effort lifters and our Comp lightweight springs. The cost is only slightly more than the regular Howards street tie bar lifters, and they are undoubtedly the most stable hyd. roller lifters on the market without going to all out racing hydraulic roller lifters. The Max Efforts are also very quiet. Not sure what rpm range they can remain stable at, but we have pushed many of our sbc engines up to the 6,650 rpm range in order to establish the fall off point of a particular build.

We now use these lifters with many of our cam choices. We have tried the Morel tie bar hyd. roller lifters on cams in the 550 and higher lift range in the past and found them highly unstable at around 5800 rpm. Well before audible valve float was evident, the horse power numbers were falling sharply due to valve float. Any cam that's approaching the 550 lift or higher range should not use the Morel street/strip lifters. The Max Efforts were very stable well into the 6500 rpm range and higher. The cam in this ad is below the 550 lift range but close enough to the limit that we recommend the Max Effort lifters .

Head bolt washer recommendation.

The AFR/NKB-200 heads require the use of special head bolt washers, and extended reach head bolts. Using stock length head bolts will not allow the use of the special washers required, as the OE bolts have a limited amount of thread on them. Not using the special head bolts and washers may cause serious damage to the cylinder heads.

Felpro# 1206 fits perfectly with most intakes. Should your intake drop too low, then the 1266 gasket will correct this problem. Our line of intakes have worked very well with the Felpro 1206 intake gaskets.

Pushrod recommendation.

We recommend not using stock GM pushrods with these heads. The spring pressures on aftermarket heads are somewhat higher than on OE heads. Combine this with the larger lift and duration cams often used, and stock pushrods may flex or permanently bend. The stock pushrods are usually made from a mild 1810 steel that has been heat treated. Under high rpm they will usually flex and cause a loss of lift resulting in a power loss. The engine will usually run erratically when pushrods are flexing. The Spintron valve train dyno proves that inadequate pushrods will flex to a great degree as engine rpm increases.

Some GM pushrods have a welded ball on them, and they stand a greater chance of breaking off with the use of larger than stock cams, and increased spring pressure. We offer pushrods made from 4310 chromoly with an .080 wall thickness. They are superior to any stock pushrod. Our prices on them are the best you will find.

The size that you will most likely need with the AFR/NKB heads will be 7.250. This size has worked well for us when using the Comp high energy or Scorpion brand rockers. There are many low cost pushrods on the market in the $29-$39 range. These low cost pushrods are totally unsuitable for use with these heads for the many reasons mentioned above, and they are not guide plate compatible. They usually have a wall thickness of only .065. These pushrods will cause problems when used on a high performance setup. There are many factors that can determine pushrod length requirements. The 7.250 length is the most applicable. Should you purchase a set of pushrods from us and find that the length is not suitable, you may return them, and we will send out the size you request. It is strongly recommended that you use a pushrod checking device to determine the exact size pushrod needed.

Stud Girdle recommendation.

If you are running full roller rockers, we recommend tall valve covers, and this can cause the oil that is pumped up into the top of the heads to not be deflected back down onto the valve springs, valve tips and roller rockers. The lack of oil on these parts can lead to not only a lack of lubrication but also to a lack of cooling on these parts. Heat transfers up the valve stem from the combustion chamber. This heat is very high in temp, and may cause serious damage to the valve guides, springs and roller rockers.

The cure for this would be to install a low cost set of stud girdles. Stud girdles increase stability to the rockers' studs, eliminating flex that is may be present to some degree when running cams several sizes over stock, not to mention increased spring pressures over stock. Stud flex robs your engine of power and smooth operation in the upper rpm ranges. As mentioned above, another very important aspect of using stud girdles is that they deflect oil directly back onto the valve springs, valve tips and roller rockers. On a stock engine this is not an issue due to the fact that stock valve covers are very close to the top of the rocker arms.

We have thoroughly tested these heads on our Superflo 902s Dyno. The results have been amazing with each and every cam combo possible.

Most sellers do no testing whatsoever on the cylinder heads they sell. We do more than just flow testing before we market a new style cylinder head.

They performed faultlessly. Cam, carb, and ignition tuning led to so much testing, and we also took the opportunity to make sure the new heads would not have any reliability issues whatsoever. Our head builder noted the excellent style of cutting on the seats in these heads. He also told us that our line of intake manifolds mounted very well on the heads, and the heads mounted perfectly onto the block. One of the worst mistakes you can make in building an engine is to mismatch parts. We know about combinations and how they work. Take a test drive in a car with over 500 hp vs. a 300 hp or less and you will then see what you're missing. The exhaust sound under load is very pleasing. These heads will generate the power you need without spending a fortune. We are very pleased with everything about these heads. When price shopping, consider the quality of hardware.

Our Stage 2, 2.2, 3.0 engines are all now built using these heads. Read the full story on how these heads performed on our 383 Super Stroker pump gas engine. See our Stage 2.0 engine listing and the Stage 3.0.