NKB 200cc/64cc ULTRA HIGH FLOW CYLINDER HEADS, STRAIGHT PLUG, FOR SBC CHEVY 327 350, 355, 383 ENGINES. Setup for hydraulic flat tappet cams. 200cc RUNNERS, 64cc COMBUSTION CHAMBERS. Important note. Our eBay user id is: skipwhite, and our eBay store name is whiteperformance1. You may have noticed other sellers using a similar name offering similar products. These other sellers have capitalized on our name as we see it, and many customers searching for us will inadvertently find them, thinking we are one in the same company. There is only one "Skip White." We are the original premier eBay seller under this name since approximately 2003. We have no other eBay names, nor are we associated with any other company regardless of the similarity in the name or location. Our official company name is Skip White Performance. Please see the article in the lower part of this ad for a more detailed explanation. 11 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 flat tappet cams up to .535 lift. For those running hyd. roller cams, see our other listings for these heads with the part number NKB-200-274.
The NKB aluminum heads have 64cc combustion chambers with 200cc runners, 2.02/1.60 stainless valves. These heads are not built by Procomp, and have no association with them in any way. PART NUMBER # NKB-272 Our 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 NKB cylinder heads are that “something
better" coming along. Considering the price is only slightly higher than
our former line of heads, this has to be the best value in a set of cylinder
heads we have ever offered. We now use the NKB heads on all of our 350, 383,
and 406 engines. The performance has been outstanding on every combination we
have tried them on. In the rare event you have issues with our NKB-200
heads, the problem will be addressed. As of today (2/17/16), we have been
selling the NKB heads for around 2.5 years. We have sold approximately 3500
sets, and problems have been near non-existent. We have complete top
end hardware kits available for the NKB-200 heads in our other listings. The
kit has the correct head and intake gaskets, head bolts with special washers,
and stainless intake bolts. The part number is TEK-1003-1206, or for those
that favor the MLS multi layer style head gaskets, part number TEK-5219-1206, or any TEK kit that
has the 1206 part number in it. The first number is the type of head gaskets,
and we offer around 5 different head gaskets that will work with the NKB heads.
The 1206 is the intake gasket part number, and that is mandatory for use with
the sbc NKB heads. 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 NKB 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 angle plug style, and with steam holes. See our other listings for
the part number NKB-200-A-274. A breakdown of the part number. The NKB stands for
"New Kid on the Block"; 200 represents the runner size, 272
designates the use of 100 long valves, and single springs with a damper setup
for hyd. flat tappet cams. You will also see the heads listed with the number
274. The 274 designates the use of 200 long 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 583 rather than 272 or 274. The
heads listed with the letter "A" in the part number are angle plug
design. We also offer these heads with steam holes for GM 400 blocks. These
will have the letters SH (Steam Holes) in the part number. 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 these heads with our Competition Series
PBM valves. Our NKB-200 heads
have been designed especially for us. 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.
Part
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Part
Number
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Intake gaskets
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Felpro # 1206
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Extra thick: Felpro # 1266
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Head gaskets
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Felpro Z-1003-2
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GR-30-PAIR, .030 THICK
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GR-40-PAIR, .040 THICK
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5219-PR, multi-layer
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Exhaust gaskets
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5206 oval port
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Valve cover gaskets
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7483 extra thick
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7484
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Head bolts
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2451-W
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ARP-134-3601
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Head studs
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PCE-279-1001
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Spark plugs. See Important Note.
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Autolite 3923, head range 3
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NGK 4554, heat range 8
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Pushrods (length
needed may vary; check with pushrod checker)
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HB-BULK-7.250-16 recommended for 274
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HB-BULK-7.900-16 recommended for 272
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Important Note For those running an HEI distributor, the plug gap should be approx. .040-.045 Those running an MSD 6AL unit should gap the plugs to approx. .035-.040 These values are very controversial and you may experiment as to what runs best in your engine. Widening the gap too much can put a strain on the ignition components. Be sure your plug wires are completely fastened onto the spark plugs. Flow chart information.
Below is our
flowchart on several different heads. All tests were performed on a Superflo
1020 bench by our expert head builder. We stand behind the accuracy. We have
noticed many other sellers posting what we consider to be false flow numbers on
the heads they are selling. We find this to be nothing short of outright fraud.
Of course, flow numbers can vary a few points depending on equipment used and
testing methods, but not by 15-25 points. Notice the low lift flow numbers
produced by our new heads. That is as important as the upper lift numbers, and
it’s why these heads produce so much peak power and torque. We are very
impressed with the flow numbers of our new heads.
In the flowchart above, the NKB-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 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 Procomp heads. We offer four different cam
choices with our 383 and 406 engines, and every combination has shown an
increase of up to 50 horsepower and no less than 40 hp when coupled with the
various combos. We assumed the new heads would generate a considerable increase
in power, but to our surprise, they generated even more power than expected.
We tore down the heads that were on our 383 house engine and
checked the guides as this was an area we are most concerned about, and found
zero wear. The seats were also in perfect condition. We tested the spring
pressure to see how much was lost after a brutal 80 or so dyno passes, and saw
approx. 5 lbs of pressure drop on the nose, and even less on the seat, and
this is to be 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. Update, 1/15/16 The two paragraphs above were written a couple years ago. We have now sold several thousand sets of the NKB heads. To this date we have had no problems of any kind with them.
ONE YEAR WARRANTY, UNLIMITED MILEAGE.
Here is a rundown on the hardware used in these heads and the assembly process.
Melling High Performance springs. Our Melling springs are 1.46 diameter, with an internal damper. Others are using springs that are much smaller in diameter. Smaller diameter springs may be in the correct spring pressure zone, but they usually have a shorter life. Melling springs are made in the UK,(United Kingdom) by a company that is now owned by Melling. Spring failures are near non-existent.
Our PBM valves are high temp stainless steel. PBM/Erson stainless steel race series valves, swirl finished one piece undercut, the same valve we have used for years. Our cost on these valves is nearly double the price of some low cost valves on the market. These are made from high grade non-magnetic stainless. We know for a fact that many head builders use the low cost valves. It is very rare we ever encounter a problem with our valves. We also offer the PBM Competition Series valves in our 68cc heads. Below is a copy of one or more of our invoices from Engine Parts Warehouse showing a recent large order for our PBM valves. We have removed the price and our account number for privacy reasons. This is the best way we can prove to our customers that the valves we use in our cylinder heads are genuine PBM products.
COMP CAMS "POSITIVE STOP" VITON VALVE STEM SEALS. # 529-16
Comp 10 degree machined valve locks. We use only Comp Super 10 degree machined locks. Our head builder noticed the low grade locks on the market fit more loosely than he felt they should, not to mention the possibility that they were made of inferior metal. He envisioned the engine being much more prone to dropping a valve at high rpm. Using these locks, we have yet to have an engine drop a valve due to a valve lock failure.
Comp Cams retainers # 75740-16 and Comp Cams ID locators Part number: 4771-16 Our Comp Cams retainers # 75740-16 and Comp ID locators # VTH-4771-16 are made from 4130 chromoly steel. These retainers have a perfect fit with the Comp valve locks. We have used these on all of our engines for many years, and have had zero failures.
Assembly Procedure We hone all of the bronze valve guides with a ball berry flex hone to establish not only perfect clearance, but also a semi cross hatch finish for oil retention. We finish off with a natural bristle brush. The heads are then placed in our parts washer and cleaned with high pressure hot water, then pressure dried. Before installing the valves, we apply a heavy coat of engine assembly lube to the valve stems. The coating on the valve stems is essential to protect the bronze guides from gaulding on initial startup. Our next step is to set the spring pressure to a predetermined pressure using a spring height checking device, most suitable for street rod use. The springs we are using allow for a near perfect seat to nose ratio. Be warned that some sellers of aftermarket heads may not be checking the installed height when assembling the heads, and may not be setting them up to the correct pressures. We have a full scale machine shop with several very knowledgeable engine builders that know and fully understand how to properly assemble a set of heads. Combine the possibility of poor assembly methods with incorrect or low grade hardware, and it is easy to see how failures can result. We purchase most of our valve train hardware in bulk for our engine program. Below is a copy of one of our invoices from Comp Cams showing several of our rather large purchases of valve train hardware. We have removed the price and our account number for privacy reasons. This is the best way we can prove to our customers that the valve train products we use and sell are genuine Comp Cams products.
IMPORTANT NOTE CONCERNING ROCKER ARM STUDS. If you have been a regular shopper with us, you will have noticed we do offer some knock-off products that are made off-shore. We do also sell many products made in the USA. We have always been very particular as to the quality and workmanship of such products, while considering the cost. We scrutinize our products very carefully and refuse to sell products that simply don't meet our standards. We have now eliminated another of the low cost knock-off products from our line. The low cost imported rocker arm studs have shown numerous problems unlike those in the past. We have looked at several others on the market, and still find many issues with them that are not acceptable. Many of the studs had run-out in the shaft of up to an eighth of an inch. This caused major problems with rocker alignment, and depending where the position was when the stud tightened up, would determine the direction of the rocker misalignment. If the warped stud was facing toward or opposite the valve, then the roller tip would would not be centered to the valve tip. This would then create a loss of lift and cause increased wear on the valve tip. If the warped stud tightened up in a side to side position, then this would allow the rocker tip to be cocked on the valve tip. This would then side load the valve tip with undue pressure, creating a serious wear problem on the side of the valve tip and create excessive wear on the valve guides in the heads. This also side loaded the rocker trunnion and front roller, creating an excessive wear issue in the roller rockers. We also found a difference in the tread pitch and depth compared to the ARP studs. The rocker studs in an engine are under a tremendous upwards pull and improper thread design may cause the studs to pull out of the head. The ARP studs screw into the heads with a very precise fit and feel. After thoroughly comparing the ARP studs and several off shore models, I am convinced that we will never offer the off shore studs again, regardless of the price difference. They were never as bad in the past as what we're seeing now. This run-out was most likely caused by improper heat treating methods. We are aware of only one other rocker arm stud besides ARP on the market of decent quality, and that's from the GM Performance division, and it's fair to say they are most likely supplied to GM by ARP under private label. We have rejected many products that are outright junk and would cause serious issues in your engine only to see other sellers offering those same exact products. It's all about learning where to draw the line. Studs and guide plates are NOT included. Other sellers may include these items but rest assured, they are usually not suitable for these heads. We use nothing but the Dart adjustable guide plates and ARP rocker studs when we build an engine using these heads, as they allow for perfect alignment of your rockers. See our other listings for a full selection of accessories. See our other listings for valve train related items that you may need for your project. The part number for the correct studs and our Dart guide plates to be used with these heads is 38-GP for those running 3/8's size roller rockers, and for those with 7/16's roller rockers the part number is 716-GP These kits are available in our other listings. We are glad to offer many great low cost items, as well as the high end products, but will always give careful consideration to quality, functionality, and overall value. IMPORTANT NOTE, MUST READ! We have noticed several sellers offering these heads with a one size fits all valve springs for dual use on hydraulic flat tappet and hydraulic roller cams. We are sure this is not the proper way to setup the heads. If they have this one size fits all setup somewhere in the middle spring pressure values of what is required for a hyd. flat tappet and a hyd roller cam, then it would be too much for the hydr. flat tappet cam, and create a wear issue. Putting too much pressure on flat tappet cams is a sure way to kill the cam. If these middle of the road springs were used on a hyd. roller cam, then the spring pressure would be too low. Valve float and its damaging effects, along with a loss of performance, are sure to occur. We use the correct spring for your setup and it is never the same on a hyd. flat tappet as it would be on a hyd. roller cam. As mentioned above, the spring requirements between a roller cam and flat tappet cam are dramatically different. Even the odd ball solid flat tappet cam has its own unique setup depending on the lift. The one size fits all hardware claims also to work on these cams. We know of several sellers offering this insane setup to unsuspecting buyers, and it's not the proper way to set up a set of heads. We would not even consider using a spring setup like this, and believe me, the simplicity of it is appealing. 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. We have sold over 5000 pair of these heads over the past four years. List of Standard Alloy Characteristics Alloy +B4: H16 | AC4B | AC4C | AC4CH | AC4D | AC7A | Mechanical properties | Rm (MPa) | 345 | 285 | 260 | 320 | 245 | R0.2 (MPa) | 250 | 225 | 157 | 240 | 105 | A (%) | 1.6 | 7.3 | 16.8 | 4.1 | 5.3 | Temper | T6 | T6 | T6 | T6 | F | Features | High strength, small elongation Castability: good, for general purposes | Castability: good Pressure resistance, corrosion resistance: good | Castability: good Mechanical properties: good | Castability: good Pressure resistance: good | Corrosion resistance: excellent, anode oxidized Castability: not good | Examples of applied parts | Crank cases, cylinder heads, and manifolds | Hydraulic parts, transmission cases, aircraft parts, lighting components, etc. | Wheels, engine parts, hydraulic parts, aircraft parts, etc. | Cylinder heads, crank cases, fuel pump bodies, etc. | Parts for overhead contact lines, parts for ships, business machines, and lighting components for aircraft
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The results produced by these heads will vary greatly depending on the type of setup you are running. The engine combos we have dynoed are what most people use for cam and intake selection, and the results are listed below. The engines dynoed were many 383's, and several 406 cid engines in the 10:1 to 11.2:1 compression range. All ran on pump gas. Our Stage 2.0 383 engine ad has a selection of four different cams. I have copied this info from that ad. This will give you an idea about the capabilities of these heads with combinations of cam, intake, rockers, and carb. This may also help you select the proper cam for your build. As mentioned, below is just an excerpt from our Stage 2.0 engine ad. We also built and dynoed a 350 engine recently with the new NKB-200 heads for a customer, and will have the actual dyno results in this ad soon. The cams mentioned below are all hyd. roller cams. If you're using a lower lift than those listed below, then it would be fair to say the hp will drop, but not by much, providing your lift and duration are somewhat close to any of the cams mentioned below. This will give you an idea of what kind of power to expect with these heads, and it can certainly help you choose a cam and intake. Please do understand that a cam is not included with the heads. This is just a guide to show what you may expect with a given combination when building a 383 engine using the NKB heads.
Cam Choice #1
Special Grind # 33161
PART NUMBER: 08-000-8-11323
520/540 lift 236/242 duration 110 lobe sep. Comp Cams SBC Xtreme Energy Step Nose Hydraulic Roller Camshafts. This cam choice, coupled with our single plane intake and our -7.5cc forged pistons with 1.5 rockers, will produce right at 503 horsepower at approx. 5,900 RPM. We recommend the dual plane intake for better drivability, and throttle response. The dual plane intake will move the torque down lower in the rpm range. The single plane intake would allow the engine to make its peak advertised horsepower at the peak rpm, but these type intakes move the torque band higher up in the rpm range. Expect a slight loss of top end power with the dual plane intake, but low speed drivability and cruising are greatly improved. If you car is in the lighter weight range and has a decent final gear, (3.55-3.73 or numerically higher), then you may select this build with our flat top pistons and 6 inch rods at no additional cost. The compression range is a bit on the high side, but considering the flat top pistons allow much better combustion, detonation is really not a problem. An octane boost additive would be recommended. The single plane intake is not recommended for use in vehicles weighing over 3,800 lbs unless your vehicle is set up with a somewhat deep final gear, (3.55-3.73 ratio). Our cam timing components were left in the straight up position. Ignition timing was set at 34 degrees total and 93 octane fuel was used. During very hot weather, total timing should be set at 31-32 degrees. A final gear of approx. 3.73 or numerically higher, and a stall of approx. 2,500 would be the bare minimum. Preferably a stall speed of approx. 3,000 to 3,200 would be highly recommended, especially if you have chosen this setup with a single plane intake. Below are our dyno results on one of our 383 engines with this cam choice with a single plane intake and the 1.5 rockers. Results will vary depending on intake and rocker choice. The horse power numbers will usually improve anywhere from 5-10 HP more than what the dyno results show after the rings have fully seated.
Official Dyno report on our 383 engine with this cam choice, a single plane intake with 1.5 rockers, a Brawler carburetor, and an HEI distributor.
If you choose cam choice 1 with the single plane intake combination, it is highly recommended that you upgrade the ignition system to an MSD Pro Billet distributor and CDI unit. You may also want to upgrade the carburetor to the Brawler dual pumper series. The acceleration and overall performance is greatly enhanced with the Brawler mechanical secondary carburetor. These important upgrades are essential for improved tuning, idling and overall performance. If you do decide to use the MSD Pro Billet distributor, we suggest you use the black timing degree bushing to increase the initial timing and possibly the lighter springs to control how soon the mechanical advance comes in. You may even "lock-out" the distributor, depending on your car's overall setup. The CDI unit will make a huge improvement in how the engine runs at idle and low speed cruising, as well as high rpm operation.
Cam choice #2
Special Grind # 33151
PART NUMBER: 08-000-8-11480
510/525 lift 230/238 duration 111 lobe sep. Comp Cams SBC Step Nose Xtreme Energy Hydraulic Roller Camshafts.
This cam choice is the perfect all around setup for those wanting a decent bottom and mid range while still generating excellent power at the top. Horsepower rating would drop off by approximately 25 with this cam when using the single plane intake and 1.6 rockers. This setup will generate its peak power at approx. 5600 RPM and this can vary depending on rocker and intake choice. Vacuum is increased with this cam compared to cam choice 1. If your car is in the medium weight range or up to approx. 4,000 lbs, and you want slightly better streetability, then this is a very good cam choice. You still want to keep the final gear ratio at 3.55 or numerically higher. You may choose 1.5 or 1.6 rockers with this cam, but we recommend the 1.5 rockers if you would like to further improve low end response. A stall converter in the 2500 rpm or higher range would be suitable for this setup. This cam should be paired up with the dual plane Crosswind intake for better drivability. The single plane Hurricane can be used, but the dual plane will have much better bottom end and mid range response. You can also expect a longer valve train life with this cam compared to the larger cam choice. This cam will also have a lopey idle, but not as radical as the larger cam above.
Official Dyno report on our 383 engine with this cam choice, a single plane intake with 1.6 rockers and a Brawler 750 carb.
Cam choice #3
PART NUMBER: 08-000-8-13436
498/502 lift 220/226 duration 111 lobe sep. Comp Cams SBC Step Nose Xtreme Energy Hydraulic Roller Camshafts. This cam choice has a lower lift and duration than the others offered above, and is highly recommended for use in heavy cars or full size sport trucks. The low end response and mid-range power with this cam is very good. Horsepower rating would be approx. between 405-420 depending on intake and rocker choice. The rule of thumb for cam size: the smaller the cam in a given application, the better will be the low end response. One more benefit to the smaller cam is the reduced requirements for lower gearing and higher RPM stall converters. A final gear ratio of 3.30 would be acceptable with this cam. This would be the only cam choice for running an overdrive transmission such as the 700R4 cruising at around 2000 RPM in overdrive. A stock stall converter may be used with this cam, but for improved acceleration, a 2000-2250 stall is recommended, especially in heavy vehicles with a tall final gear. If you are running an overdrive transmission, then choose this cam with the 1.5 ratio rockers, and the Edelbrock EPS intake. Valve train life is greatly extended with this cam as compared to the others, and drivability is at its best. Low and mid throttle response is very strong. This cam choice will also produce the greatest amount of vacuum at idle compared to those listed above. You may run power brakes with this cam. This cam is best paired up with our Edelbrock EPS intake. This particular intake is offered at no extra cost. The EPS intake actually has amazing off idle power compared to any of the larger runner dual plane intakes. This intake is the most practical intake to select when you use this cam. Fuel mileage would be at its best with this cam and the EPS intake. We also run a lower compression piston with this combination, making the engine less prone to detonation. Official dyno results with this cam, 1.5 rockers, dual plane EPS intake, SL-600 carburetor, NKB heads, and an HEI distributor. Notice the rpm range where we started this dyno run with this cam. We are unable to start a run at this low of an rpm with any of the larger cams used in a 383 engine. The torque numbers this cam produces in the off idle range would be far greater with this cam and intake combo than with any of the larger cam selections.
THE CAMS LISTED WILL COVER MOST NEEDS FOR ANY STREET ROD OR SPORT TRUCK. An excerpt from our engine ad about our new dyno. As of 9/15/2013 we completed installation of our brand new Super Flow 902S dyno. In the past, we outsourced our dyno work. We were unable to do the research and development we truly wanted, and this prompted us to make the $105,000 investment. It's been one of the best investments we have ever made. Every aspect of our engines can now be monitored, calibrated, and tuned. Best of all, we can now see what combos generate the best power, with consideration to drivability. Update, as of 3/1/16 we have installed our second new Superflo dyno. After the new dyno was setup, Superflo sent out two factory techs to calibrate it, and install the software. We made a comparison between the two dynos with one of our engines, and found them to be within one horsepower of each other. Head bolt washer recommendation. The 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. See our other listings for
many of the items needed to complete your engine build. The correct part number
for the head bolts to be used with these heads is 2451-W or ARP-134-3601. If you
purchase the top end kit we offer for these heads, the 2451-W head bolts are
included. Guide plate recommendation. We strongly
recommend the use of the Dart guide plates with these heads, or with any
aluminum heads for that matter. These guide plates will allow
better rocker tip alignment due to the fact the rocker stud holes in them
are oval shaped. We use them on every set of heads we install on our engines,
including the Dart Platinum Pro-1's. The rocker tip may end up offset to one
side more than is acceptable, and the Dart guide plates allow a decent amount
of correction. The variances in stud position to valve guide alignment vary on
all brands of heads. The rockers could also contribute to this issue, as the
trunnion or rocker body could have variance. By having proper rocker tip
alignment, you are distributing the pressure on the valve tip evenly. This not
only reduces uneven valve tip wear, but also prevents undue stress on the valve
guides in the heads. 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 NKB heads will be 7.900 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 7.900 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. 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. If you have ever removed the valve covers on an engine while it is running you would notice that the oil sprays up out of the back side of the rockers and goes in all directions. The most important reason that oil is brought up into the top of the engine is for lubrication and just as importantly, to cool the valve train components. The oil temp does have a great cooling effect, as its temp is only around 215 deg. and the heat that is transferring up into the valves and springs is far greater than this. If oil were not flushed onto these parts, lack of lubrication would be just one problem. Valve guides and stems that are heated up to high temps, and also lack the proper lubrication may experience excessive wear. We suspect that these parts may be stressed due to the oil not being redirected back onto them, and stud girdles would positively protect these parts to a great degree. We now use them on every engine we build regardless of the degree of cam and spring pressure. Those running cams that are above 460 lift should use stud girdles, since this is about the level that stud flex may come in, especially when running the smaller 3/8's rocker studs. Excessive valve guide wear along with other valve train components can be very expensive to repair.
NKB-200 64CC 200CC RUNNER
SIZE STRAIGHT PLUG FOR SBC CHEVY ENGINES Intake Valve
Dia: 2.02" Intake Port volume:
200cc Intake Port Dim: 2.2”
x 1.2” Int Port Location: Stock Intake
Gasket: 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 has worked very
well with the Felpro 1206 intake gaskets. Head Gasket:
Felpro#
1003 or our line of GR-30 and GR-40 heads gaskets. Must use head gaskets that
are suitable for use with aluminum heads. Exh Valve
Dia.: 1.600” Exh Port volume: 70cc Exhaust Port Dim: 1.356” x 1.420” w Exh Port Location: Stock
location & bolt pattern Exhaust Gasket:
Depends on
what type exhaust you're using. Best to try and match up the gasket to your
header or manifold Flow, Intake:
See chart above. Flow, Exhaust:
See chart
above. Head Bolts:
We strongly recommend ARP # 134-3601 head bolts. Must use
extended reach with head bolt washers or head studs. Head
Studs: PC-2451-Studs (12pt)
or ARP brand. Manifold:
Most any. Our line of intakes fit very well on the NKB heads. Milling: Min.
Down to 58.5cc or 64.5 = .060” See info in this listing for details on
this. Pistons: Most
23°aftermarket pistons. Push Rod length:
When running
a hyd. flat tappet cam use 7.900 length. See our other listings for these. Push rod Guide Plate:
We strongly recommend Dart flat guide plates.
See our other listings for many accessories. Retainers/Locks:
Chromoly Steel
Retainers, with 10° Comp brand machined locks are used on all of our
heads. Spark Plug:
Straight, .750” reach, gasket, Autolite 3923 or
NGK 4554 for one step lower heat range than the Autolite. Spring
Pockets: 1.550”
OD (.030” deeper max) Springs:
1.46 large size outer diameter with internal damper. Valve
Length: 5.015” (+.100”)
for hydraulic flat tappet cams. Valve Stem
Dia: .3415” - 11/32” Valve
Train: STD SBC 3/8”
or 7/16” stud mount Valve
Guides: ½”
OD Int = Mag-bronze Exh =
Phos-bronze (.002” press) Valve Guide
length: 1.950” Valve Guide
clearance: .0014” - .002” (with
our .3415 dia. valve stem) Valve Guide
Spacing: 1.890” moved
.030” from stock Valve
Seats: Hardened
Ductile Iron, .006” press Valve Seat
dim.
Standard Valve Seat
angles: Int
= 32° - 45° - 60° - 70° Exh
= 37° - 45° -
radius Stud
Girdle: Use
any standard girdle. Our Gold Series Stud Girdles work very well on these heads. Torque: Head
Bolts = 65 ft/lb Rocker
Studs = 55 ft/lb Manifold
= 30 ft/lb Block
Use: Any SBC Iron
or Aluminum
Weight:
59-61 lbs fully assembled
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