NKB 200cc/68cc ULTRA HIGH FLOW CYLINDER HEADS WITH PBM COMPETITION VALVES STRAIGHT PLUG, FOR SBC CHEVY 327 350, 355 383, 400, 406 ENGINES.
Setup for hydraulic flat tappet cams.
200cc RUNNERS, 68cc COMBUSTION CHAMBERS.
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.
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 cams up to .535 lift. For those running hyd. flat tappet cams, see our other listings.
The NKB aluminum heads have 68cc 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-PBM
These heads will accommodate conventional style carburated intakes as well as Vortec (96-up 5.7) style intakes. The heads will not work with pre-Vortec, (87-95) tbi intakes.
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.
These NKB heads have 68cc combustion chambers. The valves in these heads have been upgraded to our Premium PBM race grade valves.
These are custom built NKB-200 aluminum heads with 200cc runners, and 68cc combustion chambers, 2.02/1.60 PBM stainless competition valves, 1.46 diameter dual roller springs. These heads are not built by Procomp, and have no association with them in any way.
The main reason to use a 68cc combustion chamber over a 64cc size is to reduce static compression. For those building a 383 engine setup with flat top pistons for street rod use, this is the perfect combination. The 68cc heads, coupled with the flat top pistons in a 383, will produce right at 10.44:1 compression ratio, assuming your pistons are around .005 in the hole.
If your pistons are at an optimal zero deck ht., then compression ratio would be 10.56:1. with the 68cc heads. These numbers are ideal and reasonably safe for any pump gas 383 street rod. If you were to use the 64cc heads with the same flat top pistons, (.005 in the hole) your compression ratio would be 10.91:1, and if at zero deck ht., 11.05:1. Those numbers are on the high side, and depending on other factors, could put you in the danger zone for detonation.
If you're calculating your piston to deck ht. at numbers beyond .010 or more, then your overall compression would be lower, but this not the way to build the engine with pistons sitting so low in the block, as the quench/squish zone is very poor to say the least. You should have your block at zero deck ht, (pistons set flush with the deck of the block). There are few if any 383 street rod builds that require compression in the 11:1 zone, especially if you're running a pair of heads that have 200cc runners and a cam under 580 lift.
Recommended accessories for these heads.
Please see our other listings.
· Felpro # 1206
· Extra thick: Felpro # 1266
· Felpro Z-1003-2
· GR-30-PAIR, .030 THICK
· GR-40-PAIR, .040 THICK
· 5219-PR, multi-layer
· 5206 oval port
Valve cover gaskets
· 7483 extra thick
Spark plugs. See Important Note.
· Autolite 3923, head range 3
· NGK 4554, heat range 8
Pushrods (length needed may vary; check with pushrod checker)
· HB-BULK-7.250-16 recommended for 274
· HB-BULK-7.900-16 recommended for 272
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.
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.
The Felpro 1206 is the intake gasket part number is the most common used with these heads Some intake manifolds will set too low due to their design, and the 1266 extra thick intake gaskets may be required. You may also be able to use the Felpro 1205 intake gasket depending on the style of intake used.
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.
Please note: Due to a high volume of sales at this time, these heads may take up to 2-3 business days to complete and ship. Please let us know if you are under a time constraint with this order, and we will do our best to accommodate your request.
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.
Heads with PBM at the end of the part number have our premium race quality valves in them, and are only available in the 68cc combustion chamber size. Any of the NKB adds without the letters, "PBM" in the part number will have 64cc combustion chambers. Any of the NKB heads we offer can be setup with PBM valves, but do understand that these valves are what make the 64cc heads into a 68cc chamber size. The PBM competition valves have a concaved face that is much more prominent than regular valves. This increases the combustion chambers size.
See our other listings for these heads with 64cc combustion chambers.
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.
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.
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 valves are high temp stainless steel.
PBM/Erson stainless steel 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.
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.
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.