My current build (head work, etc)

BRN2RUN

Active Member
All of my past specifics is listed in my garage area, so i'll devote this to current and future modifications. I'd recently bought a used set of ported and polished heads off of another member here, to work on. Whoever had worked on these before, had did a pretty good job.....including bowl work. It looks like they had removed light casting from the combustion chambers, and I wanted to do a full job on them.

Bear in mind that i'm not an expert and these are my first heads that i've worked on, but i've spent many hours of research on various things--dry flow versus wet flow, intake versus exhaust bowls, compression, fuel atomization/ maximizing efficiency, air flow patterns, etc. It's time to put it into practice.

The great thing about these is that they were already put on someone's car, so it gives an indication of what could be improved. Having the fuel burn patterns and seeing what residues are left, gives a good idea of where flow design could be improved upon. The stock combustion chambers had built up a little bit of carbon in some of the smaller casting marks in the combustion chambers, which may likely be creating small hot spots and hot ridges that may lead to an increase in detonation.

I cc'd the original chamber, and it was 60 cc. It looks like there was only a light casting finish removed, but it's safe to say that if anything was hogged out, it still measured less than Ford's factory specs. My almost finished chamber measured 62 cc (with spark plug and valves in), and considering that Ford's official specs on their chambers are 61.5 to 64.5 cc's each, it's clear that even from the factory, there's no real strict measurement. I'm wondering that if, because these are even fire engines, if the two opposing banks aren't vastly different in combustion chamber size and costing some power. Also, i'm wondering if some of the cylinders aren't higher in compression than they should be, which may be causing some light detonation and some power as well. Detonation doesn't just ruin engines--it robs the engine of some power.

Analyzing the unburnt fuel residue that is pooled up around the valve seat in the bowl area, as well as on the back of the valve, it's evident that even a rougher finish (what looks to be about 80-100 grit or so), there is some fuel that isn't getting atomized, and isn't even making it into the combustion chamber. Whoever had worked on the heads that i'd bought, had left some rougher casting marks right by the injector, which is a good idea to break up the spray a bit, also because the angle that it's on is shrouded a bit from oncoming air and any air that hits it would experience turbulence pretty much right at the injector. But based on the fuel pattern, this isn't the problem area. The problem is where the air/ fuel mixture slams up against the far side of the bowl, when the far side of the bowl is basically at a 90 degree angle. Air travels at the top of the runners, and it makes sense that the full air wave/ pulse would smash against the back of the wall, along with the fuel. The air is slippery enough to make it through, but i'm thinking that putting some dimples in that area might break up the fuel enough so that it's a finer mist, so that any fuel droplets are much lighter, to make it out the valve.

Here's some rough work after a few hours--the middle chamber still needs some work, but it shows a bit of an evolution. The spark plug boss is almost finished on the left, the middle one needs to be ground down a bit more, and the almost stock right one is quite the hindrance in airflow/ fuel flow. I've still honoured the heart shaped pattern, but i've tweaked it and refined it a bit.

mustangheadswithgasket.JPG


Here's after a bit more work and refinement. It may not be evident from the pictures, but there was an additional layer that was removed and smoothed out around the spark plug bosses and in that general area, to contour it more.

heads650X366.JPG

PIC_0135.JPG

ccingthechambers.JPG


I'd taken the chambers almost out to the gasket (allowing for 1/16" of an inch for gasket expansion), and although these aren't yet polished and finished, these two combustion chambers are almost completely done. I'd grinded down the spark plug boss/ bung area to cut down on flame/ spark shrouding, and smoothed out any sharper edges (especially the one around the outer edges of the combustion chamber, and the angled line right by the quench/ squish area, so that it has more velocity in and out of the chamber. These had cc'd at 62 cc's, so that's well within Ford's factory rating of 61.5-64.5 cc's per chamber. I don't suspect there to be much, if any, compression hit, though the efficiency of these chambers seem like they would be more conducive to a better burn. My estimate is that the intake side will be more or less the same efficiency, but the flame will burn better and the exhaust valve will breathe better as well, considering that i'd de-shrouded it quite a bit.

On the area around the spark plug leading up to the quench/ squish zone, I think that i'll have a rougher, almost satin finish, around 80-100 grit. From what i've analyzed on other heads (as well as the carbon/ fuel patterns on these heads), that's where the majority of the make or break zone will be in terms of burn/ combustion quality. Fuel swirls across the spark plug area, towards the exhaust side, and fuel should atomize well in the burn as it swirls across a rougher texture. The eased ridge should promote an easier transition over and across and to and from the quench/ squish area, across the stroke/ cycle range. The chamber also goes just a little deeper around the intake and spark plug area, giving a slight advantage in cc area and overall shape.

I don't know what that weird indent was in the middle of the chamber, but I took it out. Does anyone know what this is? My guess (if it's not a casting flaw) is that it may have been for some sort of purposeful turbulence (intentional dimple?), but it was bugging me--most of the really high performance heads that i've seen, have these types of things taken out of them, or the heads never had them in the first place. The slightly roughened finish around that area should speed up flow and velocity (in both out of the intake valve, and into the exhaust valve--there's tons of shrouding around that whole middle area), but atomization should mostly be addressed already in the fuel bowl with dimples by slowing down the fuel just enough, and as the fuel sweeps across the 80-100 grit spark plug area as a failsafe to burn whatever fuel isn't atomized.

Judging on these dye patterns that HotRod Magazine had seen after they tested wet flow on some of their heads (they're not 3.8 heads, but have a similar heart shaped pattern), it's clear that fuel takes an outermost circular pattern, but it's also clear that if you leave the atomization until the combustion chamber, that it's going to have adverse effects--the concentration of blue dye is fuel, and quite a bit even gets up into both of the quench/ squish areas. That gives credence to the theory that the intake bowl work can be make or break, in terms of power.....and that a dry flow bench only tells part of the story. It gives an idea as to how air flows in the combustion chamber. The dimple appears to be effective in its general area, but if fuel isn't getting atomized well before that point, it looks like it's of little use, anyways, because a large portion of fuel is still getting past the spark gap and outside of the flame pattern.

Some guys dimple the combustion chamber, but I think that would be too turbulent and could cost some power and flow in and out of the chamber (though some strategic dimpling may be effective in the intake bowl). Plus, it may lower the compression ratio a fair bit. Other guy have cut lines into the chambers, and there's also Singh Grooves, to which i've never seen anyone try it and notice any difference (again, this would likely drop the compression level). Even on the back of valves, some people have noted that the only thing that they've noticed is that fuel pools up. I think that the more efficient way is to create swirl, to create light 80-100 grit sanding marks in the direction that the air/ fuel flow is headed, across the spark plug boss and towards the exhaust valve.

combustion chamber burn dye pattern.jpg


Here's a combustion chamber with a much better burn, where the blue dye is not concentrated anywhere

combustion chamber burn dye pattern2.jpg


Of course, if anyone has anything to add on theory, or anything else, feel free to contribute.
 

BRN2RUN

Active Member
Analyzing the Thunderbird Super Coupe 3.8 heads, there's many similarities. That casting mark/ dimple around the spark plug is still there, and the basic heart shape is the same, as well. Though there is an additional area around the valves that cause more shrouding, and of course, they are single port instead of split port, and the quench/ squish area around the plug area is not there, and compression ratio is lower for an FI head. These were finished ported and polished heads that someone else had got for their SC:

supercoupeportedandpolishedheads.JPG
 

BRN2RUN

Active Member
Two chambers are done to a mirror finish now. This took a lot of time, and it's easy to see why many chambers are finished with a rougher grit, because it took a lot of sanding steps and buffing, finished off with some metal polish. Not sure if the mirror polish adds much to the efficiency, but as far as reflecting and retaining heat into the chamber to maximize a burn, this seems like it would be better, and one would think that this would help aid some airflow in and out of the chamber, as well.

The machined lip around the valves (not the valve seat) is almost completely gone to remove more shrouding, though there is still a small one left so as to not lose too much lower lift flow. The lip is essential a part of the chamber floor now, eased/ rounded into the transition (especially on the side walls), instead of being an outright recessed/ sunken part of the chamber. The lip between the valves, I could assume would be a problem at high revs, as it becomes an obstacle when the engine is trying to get as much air in and out as possible.

The area beneath the valve, before the valve seat, is still at a 45 degree angle (important, as air has the most velocity around the valves at a 45 degree angle), but the lip is rounded off to promote airflow. As far as i've researched and learned, that huge factory lip helps with low valve lift flow, but becomes a hindrance in the higher revs. For the most part, what i've concluded is that the factory cuts that lip to create more low end torque (and also as an initial, almost pre-valve seat cut, almost like the concept of where it's a bit like a crude three angle valve job), but the lip may be larger than needed because of the constraints of machining and cost measures. As far as I can tell, the concept of that lip is a bit like knocking a hole in a wall to put a door in.....you know that you need an opening that gets you through the door, but you don't want more of a door than you actually need, otherwise you're knocking out the whole wall, needlessly.

Nobody (from what i've Googled online) can really determine how much of that lip is needed, though.....some have done CFM tests on, but that still doesn't reveal dyno numbers or actual real world results. Considering that (especially after looking at various dyno graphs on V6power.net) some of those builds, I think, should be creating more power than they are (even with a wild cam), i'm taking a different approach to this head design than others may have. SSM seems to leave that lip, as they do with that weird indent/ casting ridge around the spark plug. They may have their reasons for keeping those things, but any turbulence in the chamber is likely costing some power, and with improvements in airflow and chamber design, you may be able to bump the timing and spark advance in the tune to push detonation to a higher threshold and also possibly lean the mix out a slight bit more (with 94 octane). When I datalogged MBT spark and spark advance on my parameters this year on some spirited runs, the Bama tunes were spot on in where they should be. Advancing the timing even 4 degrees had no effect on power......I couldn't hear detonation, but it was no faster in a stopwatch test from a 0-60.

I may lose a little lower end torque (0-2000 rpms?), with improvements in flow over a greater range in the midrange and top end. This should give the effect of a slightly larger valve, but should give the exhaust side much better breathability, especially since there's much less turbulence and casting flaws in these finished chambers

I'm going to try this on a stock cam and see what type of numbers happen. I'm still trying to keep the driveability of the car as a daily driver and don't want to change the power profile too much, just trying to work with what's already there as a sort of super stock project. I'n not entirely sure that a crazier cam has to be always put in (and it's a real hassle to put in on these cars, compared to heads), that if the right adjustments are made to the heads, that you don't need a bigger gun--you just need better aim and a more efficient bullet.

twochambersportedandpolished.JPG
 
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BRN2RUN

Active Member
Another revision after I thought I was done those two! I wasn't happy with the spark plug boss area. That area (considering that it's right by the top of the runner where the air/ fuel is the strongest and with the highest flow/ pressure) was still sitting too high for me. It's shrouding the spark plug. Considering that the aerodynamics of a car with high air pressure applied to it function in certain ways, a hood scoop, for example, doesn't actually force much air in, since the air has more of a downward force effect there (hence cowl heat extraction hoods facing the windshield). Anything with a wedge shape right at the point of high pressure, though (ie: wedge shaped nose/ windshield) will divert more air across it. The leftmost and center chambers have the revised spark plug boss, whereas the rightmost one is slightly ground down (though still following the factory contour).
sparkplugbossarearevised.JPG


Considering that based on the blue dye patterns in a heart shaped combustion area, above, show that there's high volume/ high flow across that area (especially in an inefficient port/ polish design), a flatter, wedge shaped "ramp" going up to the spark plug should force more of the air/ fuel mixture across the spark plug gap. Also, i'd made the spark plug flush with the combustion chamber, to minimize turbulence and also to make the cc's more consistent with each chamber.

In this picture, i'd indexed the spark plug to where i'd like it to be, to face the widest amount of air/ fuel. As you can see, the rightmost chamber, with the same angle and dimensions. This is the only area where I think that a rounded edge could be a bad thing. I go back, again, to the analogy of a wedge shape at the front of a car, to cut air turbulence. The ramp going up to the spark plug is a 30-35 ish degree angle, which should give it decent velocity across the spark plug gap. When we're talking milliseconds in the cycle, this may help a fair bit. The stock angle is more like a 45 degree angle, but if that causes a ramping action, the shrouding right there is likely making it bypass the spark plug gap, altogether, since the air pressure is too strong to make it follow the rounded edge around the spark plug boss.

Bear in mind that due to spark plug manufacturing, threads aren't always the same. I'd tried a bunch of spark plugs out in these heads, and some of them sit a good 1/16" to about 3/16" higher. This may be another reason why Ford has such a high fudge factor in the chamber volumes (61.5- 64.5). I have to imagine that type of inequality between cylinders is hindering the pumping action of the crankshaft.
 

BRN2RUN

Active Member
No power adder for this as it's a daily driven car in the winter, as well. I'd got my Thunderbird for a FI build. The head design is pretty close on them (heart shape minus split port and lower compression), so that some of the theories that I have for this build, i'll apply to that, to lower the internal psi and then be able to push a larger amount of boost.

What I find odd in most headwork that i've seen, is that the heads are optimized for dry flow. Far too infrequently, I see failure to mention anything regarding combustion chamber effectiveness, including spark plug shrouding/ unshrouding and the guesstimate to get a better burn and more efficiency. Even with headwork, time is the enemy (or lack of funds in lieu of money), so it is nice to have this being a winter project, where there's no timeframe to have to rush to get them back on the car for either transportation issues or money issues.

I'm still no expert, but the interesting--and really neat thing--about porting and polishing for your own design, is that there's an art and a creativity to it. Even if you tweak a couple of angles, it could be the difference between some really good gains. Hopefully there's some theory and ideas that some people can apply to their own build, or at least question things that either I or other builders are doing. The more information that you arm yourself with, the better. All the information that I've collected in the last little while--pro builders on YouTube, and pro tips, in general--has really helped. Different people have different ways of doing things.
 

BRN2RUN

Active Member
Found a really cool writeup online about the maximization of things associated with power:

http://www.eliteenginesystems.com/technical/LinkbtwCombustionandVolumetricEfficiencies1.pdf

I had no idea that both valves are actually open for a fraction of a second. It makes sense, though, to create air velocity through a vacuum to pull air out of the cylinder (would an analogy of one of those beer drinking assist things be appropriate? Where you have a second source of air flowing through the suction area to ease pressure). The removal of the ridge/ machined lip makes even more sense on my own build, it would seem to ease the crossover of air between the valves. The 45 degree angle would be great for getting air in or out of that specific valve, but between the two valves, that is one heckuva mountain to climb. Contrast that with a nice, smooth area to transition over, and one would think that would create a more efficient combustion chamber. There are so many aspects to each portion of the cycles/ strokes.
 
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Markstang

Polishing my banhammer
What I find odd in most headwork that i've seen, is that the heads are optimized for dry flow. Far too infrequently, I see failure to mention anything regarding combustion chamber effectiveness, including spark plug shrouding/ unshrouding and the guesstimate to get a better burn and more efficiency.
This is most likely because most people don't understand how the mixture flows when the piston compresses.
 

BRN2RUN

Active Member
This is most likely because most people don't understand how the mixture flows when the piston compresses.

No doubt. I don't know about anyone else, but part of the reason I'd get any pro to do headwork is to think about the logistics of making power, instead of just stuffing more air through. You hear these horror stories (and see them on dyno graphs.....V6Power.net has a few examples where you see all these internal engine mods, and the people are at like, 180-205 rwhp), and you wonder how many of those smaller details in the heads are still holding back a cammed build.

Longer duration cams and bigger valves might be costing some builds some really good low end. I wish that I could see more dyno graphs of intake and head work, without a cam swap. No matter what the cam seems to be, there's never enough of a gain in lower to midrange horsepower. The graphs on V6Power almost always seem to trade 15-25 hp at the top end of the spectrum (usually after 5250 rpm) for some losses in the low/ midrange, and keep pulling well up to and usually after 6000 rpm. There's some misleading dyno info, because the peak ratings are given, but it's so high in the RPM range. The problem is that these engines aren't supposed to rev that high. I guess that one could just remove the rev limiter, but then you have to wonder about other issues at extended periods of high RPM's (ie: Taurus SHO's--as high RPM cars--became notorious for reliability issues). These engines have much more usable torque through the whole range, so my goal is to get the breathability up through 1500-4500 rpms or so and get the horsepower graph to rise quicker than it otherwise might. One would think that the backpressure in the heads/ system creates that great low end torque, but if the heads breathed better, it will be interesting to see what transpires.

I was thinking about other things--i'm not sure if hogging out the exhaust ports is a great idea. I think that SSM gasket matches them, and while I agree with gasket matching on the intake side in the heads (and in the intakes, simply because of the mismatched potato/ oval type shapes), I'm thinking that opening up the exhaust ports too wide could really hurt these engines. What I think i'll do is round the edges off--like the bell of a trumpet or horn--while still smaller than the actual gasket. That should improve flow, but not reduce velocity very much (a small step here should help prevent reversion).
 

dstaff

Active Member
If you're sticking with a factory cam, I would be looking into valve and seat forms that favor low to mid-lift flow.
 

BRN2RUN

Active Member
If you're sticking with a factory cam, I would be looking into valve and seat forms that favor low to mid-lift flow.

Would you recommend a three angle valve job?

I assume that I will lose some low lift flow here, in a tradeoff for some higher lift flow. How much yet, I don't know.
 

dstaff

Active Member
I would do 4-5 angles if it were mine... 15-30-45-60-75 is tough to beat unless you have access to a flow bench and several cutter profiles to try on a spare head. I would also make sure there is a .060" wide, 30 degree back-cut on the intake valves. My experience has shown that the back-cut can be worth 7-15 CFM up to about .350" lift on most 2-valve wedge chamber heads.
 

dstaff

Active Member
On the exhaust seats, I would use a cutter that has a radius to transition from the seat to the bowl of the port.
 

BRN2RUN

Active Member
That makes a lot of sense, as the air would transition better. I've read that on a street engine, though, that some have reported eventual problems with valves sealing on 3 (or more) angle valve jobs, as there is less material on each particular part of the seat and that it's easier to wear down. Mine is still going to be a daily driver, so would you recommend it?

Would polishing the valve yield some airflow gains in lieu of a backcut? I would think not as much, but what type of gains have you seen in CFM by polishing the backs of the valves?

I was going to do a non-cam change just to see the changes in the heads and dyno just those changes, but I think that i'll just do the cam swap with it, anyways. What type of duration and lobe separation would you recommend for the changes that I'm doing? I don't want anything with too much duration, because I don't want to lose tons of low end torque.
 

dstaff

Active Member
As long as the surface isn't insanely rough, you'll likely see no gain from just polishing the valves, but the back-cut on the intakes will definitely show a measurable increase in flow up to approx. .300" lift. If the 45 degree seat is kept around .040"-.060" wide on the intake and .060"-.080" wide on the exhaust, you should not have any issues with reliability. Valve float and heat is what damages valve seats. The other angles shouldn't be wearing down because the valve doesn't contact them. Many OEM engines come from the factory with 2-3 angle seats. Make sure your guide clearances aren't on the loose side because that will wear out a valve job quicker if they are too loose.
 

BRN2RUN

Active Member
I'd taken off the springs/ valves, and this was what was inside:

portedandpolishedbowlasIgotitwithfuelresidue.JPG


A pretty good job of whoever had ported/ polished it before me. And the bonus is that you can tell where the fuel is pooling up and needs a rougher finish in that particular area to atomize a bit better. It looks like a 120-150 grit finish or so, and it's too fine to break up the particles that pool right before the valve. There's actually quite a lot of unburnt fuel (brown residue) on the whole valve seats, even though we can see that the fuel is a fine mist for the most part in the rest of the bowl. My assumption here is that after the intake valve closes, with the lack of vacuum in that cylinder to pull the air/ fuel through at the top of the runner, it's pooling up around the whole valve seat. One would have to wonder how long the valve would seat for, before there's too much gunk on the seat. I may just hit this area with a rough rotary rasp finish, which almost leaves a divoted finish.

One thing I wanted to do was knife edge the divider between the split ports in the intake, and also to grind down the valve guide and valve guide hump, with more of a 30 degree angle "ramp" on the low end torque (left) side runner. I'd done a bit of an oval shape with the valve guide, to promote velocity, but taper it so that it's not as hard of an angle and not as much of a restriction. The other bowl (middle chamber) has a knife edge between the runners that i'd done, but you can see on the almost finished chamber on the right, that the middle area in the bowl has some contours that are a bit sharper so as to give more of a "ramp" effect. Normally, I stay away from harder shapes and lines, but a bit of sharpness in this area may help to guide the air through, as the rounded shapes of the runners to facilitate the room for the split ports, involve some snaking/ harder turns in the runners that don't exist, for example, in the lower intake and in the runners of the upper intake. A sharper "ramp" is the best compromise, I feel, between having the necessary evil of the valve in the intake bowl, and where the air pulse/ wavelength smashes up against the intake bowl (ie: where we see the brown fuel residue).

This doesn't come out in the lack of 3 dimensionality in the pic, the valve guide area sits a bit lower in the bowl, giving the runners in the head a bit more volume and the air/ fuel mixture a bit more length, but that's mostly just due to removing some of the restriction of the valve guide area. I'd gave it quite a teardrop shape, and this should be the best design (and is what many pro head porters do to minimize air restriction around the valve guide boss area).

The valve guide boss area is inset a bit, because i'm wondering if the forward motion of the intake valve as it slides out of the valve guide may not have a bit more velocity in whatever air it pushes. I don't think that the air in the intake runner should go into that inset, because it's travelling at such a velocity that one would think that it would bounce off the valve stem, anyways or just the outer edge (ie: if you ride a bike off of a ramp, it doesn't curl back under the ramp, it continues in a forward motion). I didn't take the valve guide out......but there's almost no trace of it in the bowl. It is blended in so as to have no harder lines, and the other frame of mind with the inset valve guide boss, is that the air that is coming up on the sides of the valve stem, aren't tapering in to hit the valve stem directly, that the air is following more of a path towards the spark plug (instead of off the valve guide boss and hitting the valve stem).

It's more of an issue in the low end runner, seeing as that the fuel is always directed down the low end torque runner......if the fuel is slowed up at the valve guide boss area, at high RPM's and high engine speeds, the high end/ high RPM runner is always directing air in, but we don't know at what rate the fuel is going down the low end torque runner to meet up with the high RPM air. A much better design from Ford, one would think, would have the fuel injector somehow at a junction point where the air path would dictate where the fuel is going. The IMRC's attempted to maybe correct this a bit, but the hindrance of the IMRC's to a certain extent in the high RPM runner--even when open (and some people remove them for that reason)--sets the design back, and we're still left with the fuel always going down the low torque runner.

bowlwork.JPG


Here's (a very dirty) set of stock split port heads for reference. The split port divider and area around the valve guide boss is pretty inefficient:

split port heads stock bowls.jpg
 

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BRN2RUN

Active Member
I'd finished a full cylinder/ intake/ exhaust. The exhaust port is polished to a mirror finish with 400 grit, then polished with metal polish and then buffed, and i'd done the same with the high RPM runner. Since the low end torque runner always has the fuel running through it, i'd gave it a 60 grit finish to help with atomization, but I figure that the high RPM runner being polished will help with some upper end power to breathe a bit better.

I'd taken a rough rotary rasp to the bowl area right after the valve guide to help with atomization, as well, as it has some fine ridges that the fuel should hit and may slow up the air just enough for it to mix with the fuel a bit better.

intakeandexhaustportsdone.JPG
exhaustportandpolish.JPG
 

6 Shooter

Well-Known Member
Your write-ups and photos are very interesting and informative. Very helpful. Is there any way you can show photos with arrows to define some of the terms you are using? I understand "Bowl", "intake runners", valve guides, etc, but many of the terms you used in the first few posts are in need of arrows to point out which part of the heads you are describing.

Great work with the porting. Think I understand your discussion of atomization. The air has to mix well with the fuel mist entering to get complete burns which gives the best pop in the cylinder which translates to mpg and power. Happened to look at a set of Dart (I think) heads the other day and looked at the detail inside the intake side. Noticed hundreds of tiny horizontal lines cut into the aluminum on the intake side which would obviously create some turbulence or tumbling/bouncing of the air/fuel mix that rushes past. Is it that this air bouncing past the tiny ridges creates some turbulence which forces a better mix of air and fuel coming into the cylinder?

Then, on the exhaust side, am I correct in believing that this area should have a very smooth finish to not create turbulence which would help evacuate the gases without any (or very little) turbulence?
 
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