My current build (head work, etc)


Active Member
I'd finished one head, completely, and here's the ideas and theories, starting with the intake ports, and ending with the exhaust ports:

In case anyone's wondering, all the little scratches on the surfaces will be milled away.

This is about 60 hours' worth of work. Some of that was learning as I went; some of it was just improving on the previous work that I had thought was good enough at the time.

intake ports/ intake port side:

I'd polished the high rpm runners, since the injectors aren't going through them. The mindset here is that the port/ polish information that exists today is sometimes stuck in the carbed engine design, where everything after the carb needs to be roughened in texture. Seeing as that the high rpm runners in these split port engines never see a drop of fuel until the bowl area because the fuel injector is going through the low rpm runner, common sense would suggest that polishing the high rpm runner would encourage flow at higher rpms and at higher valve lifts, at least until it finds the bottleneck in the system (valve guide area and or the valve, itself).

The low rpm runner was given an extremely bumpy/ indented finish, with a rotary rasp, to encourage fuel atomization, including a roughened texture into and at the bowl area.

All ports were gasket matched, but still retain a bell-like or trumpet like entry where the entry area is a bit larger, but tapers down a bit (ie: the idea behind velocity stacks on an engine). This should keep velocity up, as the basic shape of the inside of the runners was kept, just refined and tweaked with a better entry and better surface.

The low end runner got a revised design, where the runner was given a mirror polish up until the angle that the injector points downward at (45 degree angle at the port floor) and this allowed the port to be mirror polished up about an inch and a half into the runner. After the air hits the back of the valve once it closes, this should help speed up the pressure wave in the low end rpm runner to arrive back at the valve sooner on the reversion wave. It is incorrectly assumed that any air that doesn't get drawn into the combustion chamber on the intake stroke stays actually hits the back of the valve and is sent back towards the throttle body. The sooner it arrives back at the valve, the more effective the "tuned runner" design it has.

Also, the coolant jackets/ ports were deburred to prevent hot spots in the head, and also to aid coolant flow a very small bit.






Below, you can really see the bell-like shape, based on the shadows:


You can clearly see the port bottlenecks in both runners. Some bottleneck is good, it helps to create the great low end torque that these engines produce:


Below, in the low rpm runners (oval shaped), you can see where the polished area blends into the roughened one:


Bevelling/ honing the injector port area (note: the cross-sectional area and circumference wasn't increased, just the edge coming out of the port):


Bowl work:

Both the intake and exhaust bowls are blended into the ports, and air will have an easier transition out of the ports. The short side radiuses were worked and contoured to assist in low valve lift/ high pressure situations. The transition between the split ports was knife edged in order to promote easier crossover between the short side and long side radiuses, as well as to assist air in entering the bowl. The valve guides were ground down in order to improve airflow, and the valve guides were given a teardrop shape coming out of the knife edge middle divider between the ports



Combustion chamber:

I had kept Ford's original heart/ kidney shape, but refined it to take off the sharp edges anywhere. I opened up the chambers a bit more, to the full gasket width of a FelPro head gasket. Some people say not to do this because the gasket could be exposed, causing detonation as well, but the bore of the cylinders in the 3.8 is 96.8mm. In contrast, the FelPro gasket bore is 99mm. The gaskets are meant to have a little wiggle room in their alignment (with bolt holes being slightly misaligned, combustion chamber castings not being absolutely uniform, etc), and if that be the case, there seems to be little sense in not opening the combustion chamber up to the full width of the gasket at 99mm. 2.2mm isn't much, but any very, very small amount of CC's that you do lose in compression efficiency, to me, it's worth it in the tradeoff to maximize the unshrouding of the valves on the edges of the cylinder, and also to remove the ridiculously sharp edge that was left in the casting stage. You'd lose a small amount of compression that most likely wouldn't be noticeable at all.

Think of the logic--the cylinder bores are machined to very specific tolerances, while the area directly above it that it's going into is filled with rough casting marks. Not exactly the recipe for horsepower.

I was reading up online about polished chambers, and why some guys with high end race bikes and Porsches and exotic Euro cars do it, and then wonder why it's not more popular in American muscle culture. As always, i'm always willing to weigh every aspect to every argument. Plus, if something is "good enough", sometimes that gets perpetuated into oblivion......"don't do that, hey, the existing design is good enough". The reality, is that even with a Google search, you get guys saying that mirror polishing the chambers are a "waste of time", yet they don't post any results of the same heads, but with a mirror polished design. You don't see any dyno results, nor do you see any 1/4 mile tests with a mirror polished versus regular polished set of heads. It's pretty difficult to accurately weigh in definitively if that hasn't been tested in that way.

The reality is that nobody has the money or time (or insanity) to dyno or performance test a bunch of slightly similar heads but with different design characteristics. Logic, then, needs to be a better arbiter of what may lead one down the road to better results. A polished aluminum surface should help to keep heat within the cylinders, assisting in the compression/ power/ exhaust strokes. A hotter combustion chamber will heat up the compressed mix, leading to a quicker ignition of the air/ fuel mix in the power stroke, and a hotter exhaust stroke. Hotter exhaust creates more power, which is one reason why ceramic coated headers work better (keeping heat in, and also reducing underhood temps).

On the exhaust stroke side, common sense would seem to indicate that if removing rough casting would be ideal with a 100-150 grit finish, that a 400+ grit polished finish would be even more efficient. People put aluminum foil to reflect the sun out on summer days and keep heat where it already's the same concept here, of why people put the shiny side outward. Aluminum can be a great reflector of heat, so it should be used to its utmost advantage. Cast iron, I can't comment's possible that in cast iron engines of the old days, that there very well may have not been any advantage to doing it.

Also consider this: performance places sell reflective foil tape to keep engine temps down. I wrapped my fuel lines in reflective foil, and it kept the fuel temperatures down by 25-35 degrees on my datalogs.

Another advantage to polishing up the chambers, is that it should help to fight carbon buildup--win, win win all around by polishing the chambers up, if one is a purveyor of common sense.

The spark plug bosses were ground down, to reduce drag and resistance in the chamber, and also to deshroud the spark plug.


The weird casting indent in the middle of the chamber, as well as the massive ridge between the two valves, is gone. I had noticed that the valves had a a funnel shape coming out of the valve seats. This would likely help low lift flow, but would undoubtedly affect higher lift flow negatively. I suspect that a small bit of low end torque would be traded for a bit more midrange and upper rpm power and breathability. Sharper edges create more low lift pressure, but they create turbulence at higher rpms and higher valve lifts.

The funnel isn't entirely gone; you can see in the lower middle part in the picture above, the exhaust valve, in particular, has a bell like shape, especially around the edges of the cylinder. be continued (it is late at night here, and this has already taken me longer than expected.....:)
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6 Shooter

Well-Known Member
Wow. What great explanations and photos. Quite interesting. And quite time consuming. Most will not go there, but the winners surely will.

For contrasting purposes only, the photo shows one of my highly ported heads prior to ceramic coating. Be my guest and compare the two heads. Looks like mine could receive more work for better performance. Lighting not too good, and carbon does not help the view either.

Head ceramic coated.
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Active Member

The picture of your heads before the ceramic coating is an awesome addition. I love seeing those types of things. Earlier on in this thread, the pooling up of fuel in the intake on the heads when I'd got them had given me some crucial knowledge of where a roughened texture is needed. The guy's porting job before me (a decent job), it looks like the finish that he gave the bowl was about a 100-150 grit, but with a flapper wheel. A flapper wheel at that grit is still going to be too fine to atomize anything, I believe.

The carbon in your heads before the ceramic coating goes to show that (what looks like in your case) a 100-150 grit polish job is not good enough for a combustion chamber, at least to prevent carbon buildup. On the quench areas of your ceramic coated heads, I'm wondering if it wouldn't slow down the process of the compression/ squish aspect, since the metal is a smooth surface (ie: the same milled surface as the heads, at the factory). Obviously, a ceramic coating would help keep heat in, but i'm wondering if the surface of it may add some resistance during the power/ exhaust stroke. I'm steadfast in a high mirror polish in aluminum head chambers, because of the inherent reflective properties of bake a potato with the shiny surface inwards, some insulation has aluminum foil on it for housing, to keep heat in, etc. It seems to be a common sense rationale.

6 Shooter

Well-Known Member
Went looking for a photo of a piston top or head after tear down due to bearing failure. In my mind, can recall looking at the parts after ceramic coating and several thousand miles and NOT seeing the black carbon buildup in one location or another. Just recall a more even brown burn pattern across the heads and piston tops.

However, was able to find a close up photo of a single cylinder combustion chamber, post ceramic coating to show in more detail the porting completed. The intake side was more rough, the exhaust more smooth.


Active Member
Here's the second official part of the finished head:

I want to keep the excellent low end torque in these engines, and i'm using stock valves (and most likely the stock cam!), as this is my daily driver and I want it to be a 0-60 car, rather than a 1/4 mile car, moreso. High lift/ duration cams seem to only radically affect the car past 4500-5000 rpms. I'm going to dyno the car before and after, and then see what happens. I may still cam it, but if I could still make the bulk of the power that a H/C/I car would make, i'd be satisfied with that. With the 4.10's and other mods that I have in the car, it's a pretty good 0-60 car already.

Coolant jacket attention:

Any of the sharp edges around the coolant jackets will create hot spots, so I had deburred and had bevelled the edges. It also may serve to flow a small bit more of coolant, as well.

After the two heads are done, I may go into the coolant jackets a bit more with a smaller diamond coated grinding bit to grind down a bit more casting flash. Of note, some of these jackets are actually blocked off with the head gasket, so it's unsure as to the real benefits, if any, but i'm a bit OCD.....might as well do 'em anyways. :naughty: At any rate, I'm going to get some calcium/ rust solution to remove whatever of the rust and corrosion that exists in these.


Exhaust ports:

I'd went a bit further with these than any 3.8 Ford heads that I've seen online, as I have ground the valve guide down more, and have smoothed/ blended the transition from the exhaust bowl area down the long side radius so that it has a slightly longer path, but a less strenuous one, overall, which should help breathing at higher rpm's and upper mids, and hopefully some mids, as well. The long side radius is for higher valve lift, where pressure/ backpressure goes down.

One line of reasoning against grinding the valve guides down this much (maybe about 1/16th of an inch below the natural port roof) is that at higher valve lifts, there is less support for the valve. As I am not doing a cam in this build (unless the power numbers are that underwhelming with this head work and my upper/ lower intake manifold work), it should be fine, because there's plenty of valve guide left. Even if I were to do the cam, unless it was an extreme type of cam, it should still be good.

When I was grinding away material and tapering the valve guide teardrop shape into the port roof, an odd thing happened--there seemed to be a slight inclination/ curve/ angle to the right side (actually the left side, since I had the heads upside down and always use gravity when grinding away material). I can't say that this would necessarily add power, but it just kind of ended up that way and if there is a parallel to artwork in just letting the pen/ pencil flow (i'm an artist, as well), you just kind of have to feel it.



Below, you can see that a sharp step was left, compared to the gasket, so that exhaust reversion/ backflow would be minimized. This is where a trumpet/ bell/ velocity stack shape would be a don't want exhaust gases being sucked back into the engine. These are FelPro gaskets.


With the exhaust bowls, they were given the same mirror finish that I'd given everything else, which should help flow and also help fight carbon build up. The seat transition area was blended into the bowl, and you can see the attention that the short side radius/ low valve lift flow area had received.......there is no sharp step or casting ridge here anymore.



Shot of the head without valves:


Valves/ valve lapping:

I'm using the stock valves, although with some modifications. The design from Ford is pretty good on these--the deep concave design keeps them light, and the natural angle of the backside of the valves is 20 degrees on the intake and 30 degrees on the exhaust. I'm not a valve expert, but from what i've perused online, the backside of some valves in other engines have a real flat angle......if a 30 degree backcut on the backside of the valves is good, then the 30 degree angle on the back of the exhaust valve should already be pretty good in terms of flow, from the factory.

The biggest problem with the valves is that there's a non/ machined, cast texture on the backside of them, and this, in particular, slows down fuel flow enough and attracts it to the backside of the valve, as can be seen in the photos. The brown residue on the intake valve (left side valve) and a blend of carbon and unburnt fuel can be observed on the exhaust valve (right side valve). There's a ridge on the exhaust valve that is pretty extreme, and this can be seen in the material that exists between it and the valve seat face (the silver part).

This ridge also attracts gunk buildup and further slows down airflow. The ridge on the intake valve is next to non-existent, so the exhaust valve would benefit more from it, whereas the intake valve is pretty good in stock form, other than needing a swirl polished finish on the back to speed up airflow and discourage fuel pooling up.

Seeing as that this ridge on the exhaust valve is a part of the 45 degree valve seat face, it wouldn't likely be hurting lower lift valve flow, but at higher valve lifts when the air loses pressure, negotiating that turn--especially on the long side radius port roof, would slow down airflow quite a bit, as there is a sharp edge for it to have to turn.

Also, the seat faces are quite pitted. I'm not sure how many miles are on these valves/ heads, but there's a few. They're definetely in need of a refresh. But all of the material removed from the valves should lighten them a tad, and seeing as that I'll be running the stock cam, I'll be using the stock springs and only revving to 5500 rpm. That should keep the valvetrain light and making some great power within the stock powerband.

The valves in stock form:


Lapped valves to find out where the seats contact, so that I can determine how much of the ridge to grind down:


Lapping the valves, with some valve grinding compound and a lapping suction tool. Of note, make sure the surfaces between the suction cup and valve are clean, so that the tool doesn't lose grip. Many people really have issues with the lapping tool always frustratingly losing suction, but I used some Windex to clean the surfaces and it worked well. I felt like a caveman making fire.

Also, make sure that you clean off all of the grinding compound--it's very abrasive and if it gets into the valve guides and the rest of the heads, it could cause issues down the road. I've seen some really big warnings about this, but I have to stress that there's no need to be paranoid....just be careful when you pop the valves back in the seat, because it can squirt the compound out below into the bowls, and don't use excessive valve compound. I used just enough, basically, to cover the valve face, with maybe 1/16" to 1/8" or so thick on the compound. Just think of how when you're low on toothpaste and are rolling up the tube and there's a minute bit of toothpaste, but you know how you're surprised that you still can clean your teeth? Similar concept--a little goes a long way. Don't apply it like it's the start of a fresh new tube of toothpaste.


Finished valves--valve stems blended into the backsides of the valves and tuliped. Note that the slightly browned color on the valve stems further up on the exhaust stem must be some discoloration from oil in the guides or discoloration from the heat inherent in the exhaust port side.....the surface is otherwise smooth, and I didn't want to grind it down in case of wearing the guide surfaces out:


Valve comparison (please note that the finished exhaust valve on the right--the darkened spots on it is just a weird reflection/ lighting thing)


Here's the finished valve seats in the heads:


Sometimes I think another addiction may be cheaper. :) In this addiction to horsepower, however, here is how you CC the chambers--using a syringe, filled with water. One mL = one CC. In this case, the nice thing is that the chambers take about 2 syringes' worth of volume, as Ford's official data lists the 3.8 heads (any year) as 61.5-64.5. In this head, my chambers were all equal, in this range.


I had bought it from the grocery store--I like the description, it's a "flavor injector", ha ha:


Chamber is ready for CC-ing with a cd case, and little grease to surround the perimeter to keep water in. I had CC-d the chambers earlier on in this thread, but that was with a rougher finish on the combustion chamber and I had wanted to make sure, at that point, that I didn't remove too much material and drop the compression too much. Make sure that you drill a few air relief holes in addition to the main one that you'll be injecting water first attempts involved a frustrating process of having an air pocket/ bubble in it, and then water would get forced out the sides of the seal.


The heads will be milled a bit, to bump the compression up to compensate for the slight amount of compression that would be lost from removing material from the combustion chamber.

The finished head, assembled:

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6 Shooter

Well-Known Member
Wow. What valuable information.

One thought about lapping the valves. I visit a head shop frequently In my area. Can wander around in the shop and observe the work going on. Those guys do a bunch of high quality work and numbers of heads per day. When those guys do the valve grinding or lapping, then use a Sharpie and mark the valve to the valve seat it was lapped to. On the above head, there would be 6 valves. Those guys number them 1 through 6, same with the holes. Thus, the same valve always goes back into the same hole. Since the guys work on some very high HP motors and heads, they check the valves for length as well and often trim/grind the tips to get them all the same length which will help get the same lift from one valve to the next. Another think routinely performed is to re-surface the head to where several thousands of an inch are removed to ensure a complete flat surface with no bows, warps, or dips are left. One other step I observe all the time is measuring the consistency of the springs from one to another. They have a little tool/machine that compresses the spring which also has a gauge to measure distance, and another gauge to measure pressure. Think the best and smoothest running motors have very balanced and consistent parts from one hole to the next.


Active Member
Not too bad for someone's first head, I think! It's fun.....aggravating fun, but still fun. All the work and all the small details, while you're doing it, the cool thing is that everything is going to add to the power and efficiency. I'm obviously thrilled to talk about what I've done , but I also wanted to create some sort of comprehensive thread where the information was put out there so that people can take on the task, themselves, but also discuss some things. Again, your pictures of your heads with the carbon deposits really helps. I suspected that the elevated ridge between the two valves was going to be an impediment, and it looks like it's impeding combustion efficiency, as the carbon deposits reveal where the fuel isn't being properly burnt.

If I can do it, anyone can do it. The information is out there, and you just need the time, patience and an understanding of some basic concepts of airflow. That being said, what is really odd, to me, is that the combustion chamber--more often than not--seems to be forgotten or neglected in the 4 stroke cycle. A dry flow bench will tell you what you're getting for the intake and exhaust flow, but it doesn't tell you the efficiency of the burn on the power and exhaust stroke in the actual engine when it's firing.

In the lower left part of the chamber pic that you posted here, it revealed what I suspected as well--that the spark plug boss area is preventing a proper burn of the fuel. When the fuel comes out of the intake valve, it comes out in that lower left part of the cylinder, and swirls toward the exhaust valve. Some swirl/ tumble is needed, but if there's a big hill/ impediment/ resistance in front of it, perhaps air will have an easier time going past that, but the fuel weighs more than the air. The ramp shape that I gave the spark plug bosses should help unshroud the spark plug and help fuel travel moreso in that clockwise motion towards the exhaust valve and should help force/ ram air into and past the spark plug. A fair bit of material around the boss can be removed without any significant penalty in cc's in the chamber.
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