Cylinder head work.Machine work
Its important to realize and understand that a great cylinder head begins with great machine work. For this very reason we have made a huge investment in modern machinery. We do our Head work using the latest in CNC technology, Sunnen machinery as well as Peterson machinery. Even with 25 years and counting of race winning engine building experience, if the machine work is not right, the engine will not run right. Its because of detailed machine work that our heads require no break in time. When you receive a head from us, its ready to go.
All cylinder head work requires for you the customer to supply the head (core) for us to work on. In many case we have cores available for exchange or for sale. If we do a core exchange the head must be the same kind of head. The heads must also be in good condition. (bent valves are ok, but don't give us a core with cracks or a blown up chamber.)The cylinder head prices do not include the core. Heads do not come with cams, intake manifold, exhaust manifold, distributor or valve cover. Now that I have that out of the way, lets talk head work.
Valve job.
Hi performance basic pro valve job Stage 1; Head is taken apart and inspected, head is cleaned, resurfaced, valves re-faced, new valve stem seals, multi angle valve job in Sunnen VGS machine and assembled. 4cyl: $350.00
Hi performance pro valve job Stage 2; Head is taken apart and inspected, head is cleaned, resurfaced, new stainless steel valves, new competition dual valve springs, titanium retainers, new valve stem seals, multi angle valve job in Sunnen VGS machine and assembled. 4cyl:
DOHC $750.00, SOHC $700.00.
K20 HIGH PERFORMANCE VALVE JOB AND CHAMBER WORK
The K20 heads flow pretty good right out of box. We have seen on average appx 270cfm through the intake ports and 475'' lift and at 28'' of water. With this new valve job and dozens of hours on the flow bench we have come up with an increase of appx 15 cfm with out any port work. 285cfm with stock ports and with out manifold. With one of our custom intake manifolds we are seen close to 320 cfm with stock ports. We are currently writing up the programs and finalizing the port designs and shapes for the K series and are expecting flow figures with intake manifold to be in the 340cfm+ range.. The K20 High performance valve job and chamber work cost $800.00. This price includes stainless steel valves, dual springs and Ti retainers. To view an animation click on the image.
Note: Often times when your in the middle of building your turbo charged or NOS assisted engine and you find you have exceeded your budget and find yourself short on money, you need to consider a few things. #1 Reliability; Change the valve springs and retainers. #2 Valves; Replacing the stock valves with a good set of stainless steel valves will go a long way in preserving your engines performance. #3 Valve job; This is perhaps the most important part of the head work. A valve job can be responsible for as much as 40% of a heads performance simply by changing the angles and unshrowding of the valves. With certain seat cutters and and valve angles, we can increase the overall performance in a stock head. So in conclusion, if money is tight and and porting the head is not an option at the time of building your engine then consider a high performance pro valve job, JGE style.
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To see a Video of a Professional valve job being performed, click here. 
Years and years of flow bench work. 
Notes: Valve jobs do not include valves, guides or welding. Those parts or services are available at an extra cost. If your building a short block or installing a set of hi performance camshafts and springs then you really should consider a valve job. In my opinion the valve valve springs are one of the most important parts of an engine. They will help keep your engine alive, especially if its turbo charged or supercharged.
Head work.
I will try and keep this simple. To many times we engine builders make things to complicated and hard to understand. As a rule of thumb when we port a head, we will build it to flow the most it can with out killing our velocity. (air speed) The trick here is simple. Here is an example. Stock B16A intake port flows appx 235 cfm@28'' . This is at 450'' lift and at that lift the velocity is appx 92-93% of the port. If we increase the flow to say 285cfm@28'' and maintain the 92-93% velocity of the port, then obviously the head will make more Hp. It would be impossible not to make power. On the other hand, if we increase the flow to 285cfm@28'' but loose velocity and it drops down to say 70-75%, then this head in all likely hood will loose power over stock or not make any power difference at all. At best it will loose throttle response and make the same top end power. ( We see this allot and we usually can't fix them.) From our experience it takes appx 2.5cfm in a Honda engine to make 1 Hp. Now there are certain instances where port volume is necessary and so sacrificing velocity is ok, but you really need to know what your doing. Some examples would be full drag race only set ups, when using methanol fuels, big Hp turbo applications or full NOS set ups. Now in saying this keep in mind that these are our opinions and should be taken as that. Opinion. We will build your head for the best possible performance to meet your needs. 70% of all the head work we do is done by CNC or conventional machines.
Redline series heads: Head is taken apart and inspected, head is cleaned, fully ported and polished to optimize flow while keeping the stock valves and maintaining velocity , Hi performance valve springs and titanium retainers are installed, the head is resurfaced, stock valves are polished and re-machined , new valve stem seals, multi angle valve job in Sunnen VGS machine and assembled. Our most popular normally aspirated street head. (Not recommended for NOS or big Hp turbo because of heat.)
B series V tec heads $1255.00, Average intake flows 285cfm and exhaust flows 235cfm.
B series non v tec heads $1155.00
D series v tec heads $970.00, Average intake flows 185 cfm and exhaust flows 150cfm.
F series heads $970.00, Depends on the year of the head, min flow increase is 25%
H 22A heads $1255.00, Average flows 290cfm and exhaust 250cfm
H23 heads $1155.00
K series heads 1355.00. 305 cfm and exhaust 250cfm
Pro Series heads: Head is taken apart and inspected, head is cleaned, fully ported and polished to optimize flow while maintaining velocity. The port work is maximized for the size of valve we use. See note below. The heads also come with Hi performance valve springs and Titanium retainers, the head is resurfaced, We install stainless steel valves, new valve stem seals, multi angle valve job in Sunnen VGS machine, unshrowded to bore size and assembled. Most of the head heads we sell are our Pro Series heads. These heads are simply the best there is. These are definatly what we recomend for turbocharged or NOS use.
B series V tec heads $1400.00, Average flow with 34mm intake valves 312cfm, and with 28.5mm exhaust valves 245cfm
B series non v tec heads $1280.00
D series V tec heads $1130.00, With 1mm oversize valves intakes average flow is 215cfm and exhaust 185cfm
F series heads $1130.00, Depends on the year of the head. Min flow increase is 25%
H22A series heads $1400.00, Average intake flows 318cfm and exhaust flows 260cfm
H23A heads $1280.00
K series heads $1570.00. Average intake flows 326cfm and exhaust 265 cfm
Note: We will have complete flow charts up soon along with actual video of flow bench testing. Keep checking back.
We often hear that we have really good prices. The reason is simple. We don't sublet any of the head work out and manufacture most of our own parts. In those cases where we don't manufacture the parts like valves for example, we buy in large quantities directly from the manufactures to be able to provide the best possible product for the best price. Through clever buying and more efficient machine work, we have been able to maintain our prices for a few years.
Notes and miscellaneous ramblings: The Redline series and Pro series heads basically perform the same when both heads use the same stock size valves. When we go to an oversize valve in the Pro Series head, then it will perform better. The reason for this improvement is simply because it allows us to do more extensive bowl porting and get a real clean / reshaped valve job. A mistake we see and hear about often, is people installing oversize valves in thier heads and loosing flow and power. The reason for this simple. They install oversize valves with out doing the matching bowl and valve seat machine work. This is such a common mistake. Common sense will tell tell you that if you install an oversize valve in a stock size bowl, you have just shrouded the bowl. Big mistake. If done right, big valve + large bowl + Pro valve job = more power. In a twin cam hemi style head you have to be careful when going oversize on the valves as to not run them into each other when using cams with excessive overlap. Check this when assembling your engine as well as piston to valve clearance. If you don't know or are unsure about how to do this, leave it for a professional engine builder or leave the valves stock. We can weld chambers for increased compression ratios or to increase the quench area of the head for an additional cost.
Frequently asked questions Prices E mail
Some animation may take a few seconds to load, so be patient.
Here is an animation of a recently completed B20A5 Pro Series Prelude head. 
Here is an animation of a recently completed NSX top end. 
Here is an animation of some Misc pics with some CNC ported JG heads 
Here is an animation of a B18C race head 
Here is an animation of a ZC JGE Pro Series head build 
Here is an animation of a B16A head 
Here is an animation of a GSR head 
Here is an animation of an H23 head 
Here is an animation of an H22A full race head 
Here is an animation of a D16A6 square chamber race head 
Here is an animation of our valve train products 
More pics down below. Click on the number to view the images. For more info, take a look at intake manifolds.
B18C, 1 2 3 4 5 6 7 8 9 10 11 12 13
B18A, B18B, B20B, 1 2 3 4 5 6 7 8 9 10 11 12 13
D15B, D16A6, 1 2 3 4 5 6 7 8 9 10
D16Z6, D16Y7, D16Y8, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
F22, F23, 1 2 3 4 5 6 7 8 9 10 11
H22A, H22A4, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
H23 1 2 3 4 5 6 7 8 9 10 11 12 13 14
While the majority of heads we work on are Honda and Acura 4 cylinder heads, we have a lot of experience with many other types of heads. We build Datsun / Nissan, Toyota and Mitsubishi heads as well. Below are some samples of some our work. As we get time we will add more and more pics.
Mitsubishi 4G63 exhaust ports.
Mitsubishi 4G63 with JG valve train.
NSX intake manifold match ports.
NSX fully ported intake manifold.
JG has over 25 years of research and development experience working with mixture motion. I started out with a Superflow 110-120 flow bench and quickly reached its limitations. talking with Harold over at Superflow back in 1996, he quickly affirmed what I suspected as a result I made a large investment and purchased the industry standard Superflow 600 FC computer controlled flow bench. This is the primary tool I use for testing and developing heads, intake manifolds, exhaust manifolds, spacers, mufflers, cat converters, and the all important intake to exhaust flow ratio. I have the ability to measure swirl, velocity and CFM simultaneously (not possible with our old Superflow 110-12). With the Superflow 600 there is no need for conversion charts, calculators or a notepad and pencil. The computer does it all. For seat and guide work we use primarily Sunnen machines including the industry standard VGS20. This is the same machine found in the majority of Winston cup and NHRA teams. This machine cuts a 3 to 5 angle valve job simultaneously ensuring that all valve seats and depths are the same cylinder to cylinder. What does all this mean to you.
It means "quality tools + quality workmanship + 20 years of research and development = quality product"
We use state of the art machinery to get the job done right the first time and its ''all in house''.
This has lead to numerous championships, victories and successes in:
NHRA SPORT COMPACT CAR , NOPI, NDRA, BATTLE OF THE IMPORTS, SCCA, IRL, WILLOW SPRINGS SPORTSMAN DIV., AUSTRAILIAN TOURING CAR, ASIA FFA, SCORE BAJA 1000, BEST IN THE DESERT SERIES, NASCAR, BONNEVILLE SALT FLATS, RUSSIAN ICE RACING SERIES, HONDA CUP, NASA, and many more.
Beware of people selling ''FAKE'' JG heads.
Imitation is the greatest form of flattery. imitated, but never duplicated. With this I will send out a warning for customers to beware. There are some companies and individuals out there that are trying pass off fake junk heads as JG heads to make a sale. If a good deal comes along its best to e mail us pictures of the head so we can give you an idea if it is the real deal.