Pinto Big Power Secrets

[RWD fords rule]

I have been doing some experiments recently and am willing + ready to share some of what I have learned if anyone is interested

This is if you want to gain an advantage over the competition, forget about off the shelf parts everything is custom when you want the best

The main area that creates power in any engine is the head, if you can flow X CFM @28" at 90% of your maximum valve lift you have the potential to make 1.03 x the CFM @28" if the inlet valves can reach and go beyond this lift flow point to create adequate "inlet flow area"

So if your max cam lift is .500" multiply this by 0.9 = 0.450", let us say the flow is 190CFM @28" at this lift point that equals a max power of 195.7bhp if everything else is maxed out including the full inlet system, exhaust, chamber pistons, ring seal, AFR etc which is a realistic power figure when using 48's or 45mm TB's completely unrestricted apart from the head flow itself

The injection head has a far superior inlet port shape having a better higher short turn and also much more room for improvement when squeezing all of the power you can get from a pinto as you will see later in this thread, carb heads can also be made work well but more work is involved and there is less potential working within the casting limits

First of all let us look at the limitations of the inlet ports and where the biggest improvements can be made

Although the injection ports have a higher short turn the port angle is still very low and is close to 83* measured from the valve guide centreline to the port centreline, however this isn't as big of a limitation to flow as one might expect, the real limitation is the distance/vertical height between the inlet valve seat and the port roof + port floor especially

An ideal port would be at least 2" taller creating much needed space between the inlet valve seat and the floor + roof of the port, this in turn creates a straight lead up to the valve throat and seat area so that the airflow can use much more of the valve area instead of the air skipping the short turn and flowing right across the back of the inlet valve but also restricting some of the flow around the long side of the port's turn into the throat area

To sum up the better we can make the short turn flow the more power we can make

What about optimal valve sizes?

Converse to what has been written in may books the exhaust port does not need to flow 80% of the inlet flow to make best power, for a NA Race/Rally engine with over 11 to 1 CR 65% exhaust flow vs inlet is about ideal when using the same cam lobes for inlet & exhaust, with even higher CR over 12.5 to 1 we can successful use as low as 60% exhaust flow vs inlet simply by using longer exhaust duration, opening the exhaust valve a little earlier as with high CR most of the cylinder pressure (what moves the piston and translates into torque & HP) is made in the early stages as the piston moves away from TDC, when the exhaust valve opens with high CR most of the power has already been made so opening the valve a little earlier isn't going to hurt power But what it does do is to change the "optimal inlet to exhaust valve diameter"

A good rule to follow for a 2V per cylinder engine such as the Pitno for optimal valve diameters is to make the inlet valve 50% of the bore diameter and to make the exhaust 40% of the bore diameter, with a 93mm bore that equals a 46.5mm inlet valve and 37.2mm exhaust valve as a good working estimate to follow without running into bore shrouding issues, and this will give a little over 65% exhaust flow vs inlet flow which can be used with an available cam

This is very different than the usual 44.45mm and 38.1mm valve combinations, with NA there is Never any need to use over a 37mm exhaust valve, even a 36.5mm exhaust valve is more than adequate for a high rpm heavy breathing roller cam monster

Is there really any advantage in using a 46.5mm inlet valve over a 44.45mm or 45.7mm inlet valve? - YES

Up to 46.5mm every bit of extra valve area counts as it gives increased inlet flow all the way from 0.050" / 1.27mm valve lift up to maximum lift and up to this valve diameter bore shrouding is not an issue, fitting a 48mm inlet valve might sound like a good option at this point but with a 93mm bore size it will not give any more flow than a 46.5mm valve unless you could move the valve away from the bore

Depending on the port shape used as a good estimate a 46.5mm inlet valve is worth 10 CFM @28" vs the same port with a 44.45mm inlet valve due to the larger throat area, the throat area is the area just under the valve seat and ideally it needs to be make 90% of the valve diameter, so with a 44.45mm inlet the the throat diameter will be 40mm ID and blended into the rest of the port, and with a 46.5mm inlet the throat would be 41.85mm or a 4.63% increase in throat diameter not to mention the increase in Flow Area at All valve lift points which shows up with flowbench testing

Remember for every 1CFM the head flows @28" at 90% of the max valve lift we are using the engine can make an extra 1.3bhp

However we should not get too greedy searching for extra air flow by making the ports excessively large especially for a low cc (not stroked & bored) engine

Port Velocity Is Important, the std inlet ports are already 38mm in diameter which is much too large for a 42mm inlet valve and ideal 37.8mm throat diameter, even with a 46.5mm inlet valve a 38mm diameter port CSA is about right for best torque and HP, the reason for this is that at mid to high rpm's on the inlet stroke before the valve closes the inlet system if working well can ram in more fresh inlet charge before the valve closes, remember the inlet valve of a race engine does not close until the piston is AFTER BDC, the piston actually travels up the bore 80* on average before valve closure Almost Half Way up the Bore!

If the inlet system has a minimum CSA that is too large the air velocity will be too low and some of the air will be able to escape out of the cylinders, but if the minimum port CSA is optimally sized the intake system will keep ramming in air up until valve closure giving a small supercharged effect from peak torque rpm upwards

On the other hand if the minimum port CSA is too small the peak air flow will be reduced, it will create great low end torque as the inlet system will have more ramming energy at low rpm than a larger port but the high rpm airflow will be restricted if the port is not made large enough it will flow "super sonic" and choke the top end especially at and after peak hp

So as with everything there is a balance between one extreme and another, a good inlet port air speed to aim for is 123CFM @28" per square inch of minimum port CSA = approximately 295 FPS Average port velocity at the minimum CSA

If we had a well developed inlet port flowing 217CFM @28" at maximum valve lift for a race/rally engine we can say that best power will be made if the port is:

( 217 / 123 ) / 3.14159 = 0.56157

Square root of 0.56157 = 0.749

Multiplied by 2 = 1.498" or 38mm


So a port flowing 217CFM @28" at maximum lift should have a minimum port CSA the same as a 38mm round port for an unrestricted top end and good peak torque



Which is more important mid or high lift flow?


Again it is not all about high lift flow, if the port flows big amounts of air at 16mm lift but the cam only lifts 12.5mm and at this lift point the flow is only average then the shape is not going to work well with the cam

Ideally we want to "tune the short turn shape" to match the camshaft, focusing on improving the mid lift flow as much as possible and having good flow at 90% of max lift for decent peak power, but the Average flow numbers added together are much more important than just the peak lift flow

By adjusting the shape of the short turn, lowering it down to get "a better look at the back of the valve" the high lift flow may increase by 3CFM but if the mid lift flow decreases by 7CFM we would then have made made a step in the wrong direction!

Remember the valve reaches peak lift for only an instant, but is reaches mid lift twice in the lift curve



In the next post:

What port shapes work best for the pinto engine and why?

[5tox]

That is one of the best threads i have read in ages, well done for taking the time to share

[caprimentle]

absolutely brilliant. love reading this stuff. still waiting for the day when you build a pinto to the best of your capabilities. I feel the results would be well up the there with the very best.

[madragon199]

excellent write up....already waiting for the next chapter...full of very good information....thanks ...

[sholdowa]

You've just made me late for work. Thanks for this!

[M11rf]

I wasn't expecting a maths lesson when i opened this thread

[Erikmex]

Great info, the tricky bit is porting the head to match the figures though.

[haz87]

Excellent informative post!!

[Miniliteman]

Remember the valve reaches peak lift for only an instant, but is reaches mid lift twice in the lift curve

2nd bit is true but the first part?
The cam lobe shape isn't a triangle but is rounded, so the valve is at (or near) peak lift a relatively longer time than at mid lift.

[RWD fords rule]

Miniliteman I agree with what you are saying and am very familiar with cam profile shapes having mapped around 15 normal and roller cams for this engine

The explanation of the importance of mid lift flow was just a simple explanation but valid, I am sure you understand why I said to use the CFM at 90% of valve lift for the HP predictions, at 90% of the peak lift there is good "Area Under the Lift Curve" the valve only reaches peak lift for about 3 or 4 crankshaft degrees at most out of its + or - 300* but it "Hangs" at and over 90% lift for much longer

I made a custom spreadsheet that graphs the cam profile in 0.050" lift increments on the Y axis vs crankshaft angle on the X axis but swapped valve lift for CFM @28", then you get better idea of "Flow Area" with each head and cam combination

Mid lift flow is very important as well as high lift flow, just like an engines power curve, the peak figures matter but the engine only reaches that specific rpm point for an instant, it is the "Average torque and HP" than actually accelerates the car

High lift flow is very important I agree, but mid lift flow is almost as important, creating the best flow from as low lift as possible makes more power every time

Remember the piston rising on the later half of the later half of the inlet stroke, the more mid and low lift flow there is the better the cylinder cam be filled at mid & high rpm's, the port CSA has to be good and also the intake + exhaust lengths, it all makes more power when working well

[RWD fords rule]

Cheers guys, since there is interest I will share more

Some of this is bound to "go against the grain" of std tuning methods or "well known theory" but that is what happens when you are aiming for more performance than the rest

This is about optimising your race/rally engine for best HP And Torque based on proven measured results, I don't have a dyno for back to back measuring every little thing there is to test but I do have a flowbench and a decent amount of experience with these engines

If you put these tuning methods into an engine they will produce results

Optimal port shapes to follow

[Erikmex]

Great input Jason, i have a spare head that im looking to do next year as a project, plan on making a DIY flow bench also, your one of the few engine builders ive came accross that doesnt hold back info, i see alot of engines these days still with the cam numbers ground off, bit pointless as cams for Pintos are common knowledge, the only reason i reckon builders do this is that they claim to use their own secret grinds when in fact they use off the shelf cams.

[Graham]

the only reason i reckon builders do this is that they claim to use their own secret grinds when in fact they use off the shelf cams.

yep seen thats one a few times, the truth is there are only so many different profiles you can have on a lobe, and even tweeking a grind with slight lift or timing changes doesnt really make for a totally new cam.

[escortinadriver]

Looking forward to the rest of this.

How far away is the new cam package?

Shaun

[RWD fords rule]

What shape ports flow the most air and make the best power/torque?

The std pinto carb head has an inlet port shape that could hardly be any worse in terms of flow as there is no short turn radius just a sharp edge and around a 70* angle between port and valve guide centreline, however the biggest flow restriction is the low height of the floor of the port especially approaching the valve seat, the injection port is superior over carb as it has a slightly raised port floor which increases flow past the valve but the port floor is still much too low for maximum airflow from mid to high valve lift, at low lift the valve seat shape is more important along with the valve diameter itself, a larger inlet will flow more air not only at high lift but also at low and mid lift, it is only when very large valve sizes are used that valve shrouding would restrict low lift flow simply due to the cylinder bore size and proximity to the valve seat, a 46.5mm inlet will certainly flow a lot more air than a 44.45mm valve at all valve lifts even with a near std bore size

The 38mm diameter injection inlet port itself is already too large for the 42mm valve size which reduces torque especially at low rpm and also throttle response is reduced, it is only when the port can flow enough air that the 38mm diameter can begin to work well, but in order to do this the short turn has to be raised as much as possible which involves either using port filler such as Belzona 1111 or similar, roughing the floor of the port really well with a sharp carbide to key the material in place, or boring the floor of the port out and pressing in an aluminium stuffer and shaping the port to the required shape

To maximum raise the port floor at the short turn the port has to be made significantly wider at this point and also to raise the port roof as much as possible, what you end up with is a short turn that is 44 to 45mm wide and 30 to 32mm tall, the minimum CSA is sized to match the port flow you are getting, if the port flows 217CFM @28” then an area the same as a 38mm round port will make very good torque and hp

Here is a full downdraft port shape I have been developing which flows better than anything I have been testing thus far, this is still using a 44.45mm inlet valve but a 46.5mm inlet would flow at least 10CFM more bringing the flow @.550” lift up to at least 225CFM @28” and good port velocity

Notice the pictures vs an injection port shape with the same valve size!


































After learning what shapes work best I believe the most practical way to get big flow from a pinto head is to start with an injection head, raise the port roof around 6 or 7mm, widen the port to 44 to 45mm at the short turn but also wide the port all the way out the the manifold face leaving it 43 to 44mm wide, this way the short turn can be maximum raised all the way out to the manifold face without breaking into the water jacket

I have experimented with welding the port roof, this is still an option to consider as the weld bonded to the casting very well but it is a lot of work boring ports, welding and boring again, using a lower port angle is more practical, full DD like this is completely one off custom but with the right port shape, port filler or an alloy port floor + 46.5mm inlets 225CFM @.550" lift is certainly possible and 230bhp with a roller cam is just about within reach with everything working super well without costing the earth and 220bhp with a flat pad cam from 2.0 to 2.1

The better the head flows the more power the engine will make, especially with correctly sized ports for the application and to suit the cam lift you will be using

Bigger is not always better but in terms of valve size the inlet valves need to be at least 50% of the bore diameter to not restrict top end power

[RWD fords rule]

When I started the full DD port shape I initially made it a 38mm ID round port all the way down to the valve guide making it as tall as possible and around 59* angle to the head gasket face, the shape looked good vs most other port shapes but I knew the short turn was still nowhere near optimum and the flow was not that impressive, it was flowing more than the injection port above (the injection port above flows 200CFM@28" on a 44.45mm valve which was the best I managed without a flowbench!) but I knew there was still a Big gain to be had from optimising the short turn, which resulted in the shape above, the port floor is almost flat and wide around the short turn to maximise flow and the port entry is 38mm ID

A further development of this is to make the port D shaped all the way out to the manifold face

Something I can say for sure is that a round downdraft port shape is Not the optimum port shape for this engine, a downdraft D shape port is best by a long shot and an injection head especially with a lower port angle can be made to flow more air than a downdraft head with round ports

It is All about the short turn! downdraft is certainly the best shape there is no question there but maximum raising the short turn is where the biggest gains will be had

[RWD fords rule]

Here is a welded chamber, as you can see the welding wire sticks really well to the material and the mig welding produces very little heat, the mig wire is Royal 44-30 from Crown Alloys in the US, easily the best way to weld cast iron

[madragon199]

Very.very good thankyou...what product did you use for the port moulds.....would like to take a mould of mine and get a better look at actual shape..

Thank mark

[madragon199]

Hi jason.....when we tested my dd head we ended up with a filled short turn..but also found that tulip shaped vales seemed to perform better...have you tested with both? flat /wasted and tulip valves....be interesting to see....cheers mark

[RWD fords rule]

It is made by "Polycraft" as sold on ebay, it is shore A27 hardness and is absolutely perfect for making port moulds, just spray a little WD40 on he port or chamber before pouring in and it will be a little easier to remove after, although it is also pretty easy to remove with it, the shrinkage is very low not even noticeable which is great, sure there is a cheaper alternative but it has to be silicone and shore A 20 to 30 for best results

About the valve shapes I have done some testing but the difference was not that great between the shapes I tired, imho even with a full DD port the roof of the port vs the valve seat means the port still wants to flow a lot of air across the valve but I will be doing more testing and fine tuning one I have built my 6 motor orifice flowbench, then I can measure anything from tiny changes to huge ones

What kind of CFM @28" were you able to get out of the round DD ports?

[RWD fords rule]

Pic of a full mould:

[5tox]

Can you do a write up on the duratec next

[caprimentle]

great write up any chance of getting some pictures of the head? Silicone is good for seeing the shape you need but sometimes it's easier to see the real thing just to know things are going in the right direction for when we get bored in the shed and get the die grinder out lol.

[RWD fords rule]

Will post some pics tomorrow, good idea about the Duratec, way easier to get big power from any 16V engine, the Duratec is certainly the "pinto" for the next generation, with the std 2.0 valve sizes I imagine 260 to 270bhp is possible!

[madragon199]

Hi jason ..thanks for the info will see if i can order some off e bay....

The only actual figures i have was when tom measured the first prototype for me....its measured at 25" of water?

standard valve and stnd seat...179cfm at 0.550 standard round dd port

short side turn port floor raised standard valve stnd seat 185cfm at 0.550....

since the testing. my flow box only tells me if its better or worse.....but better was of course 46mm valves...port floor raised ..and the pinch point just before the short side turn....the tulip shaped valves made a very small difference on the best flowing port,,,....but on a 90% finished raised floor they helped......

i tested the difference of flow with a bit of cotton fed on the port floor when in suction....with the tulip shaped valve it was always uniform (ie you could mark the valve and it would exit at the same point and follow the radius line)...with a flat valve it was not uniform....(it would exit on the same side but different each time and did not always follow the radius)

As you suggested i will get my bench calibrated....when i get a moment....

Mark

[RWD fords rule]

Something I have been recently using is a velocity probe, super useful for knowing where to remove material from or where to add it in, a good basic version is to use a straight length soft copper brake line, form a tight 180* bend ideally bent round a mandrel, file the edge to make it bullet shaped and then connect the other end to a silicon tube and up to a manometer, you will be able to get the same pressure level you are drawing so if you are getting 20 or 30" vacuum on the vertical manometer at a high velocity point the velocity will read up to the same level but in pressure rather than vacuum, you might even be able to read higher pressure than the vacuum level

It is very useful as you learn where the air actually flows best and fastest which can be counter intuitive at times, a lot of air actually flows along the short turn, it is like the air wants to travel along the straightest path from the roof of the port at the entry down to the short turn and then exiting the port on the long turn next to the spark plug

Something else to consider is that fuel has a higher density than air, the air can turn a lot more easily than fuel droplets which will tend to flow along the roof and long side of the port, developing a really good flowing port at a low port angle does not necessarily mean the fuel is flowing where you want it, where as a DD port can deliver a better more easily burned mixture to the cylinders, which is a hidden benefit to DD even if the flow is the same

About calibration, an easy thing you can do with a lathe is to make some orifice plates to test against, 2.5 to 3mm steel plate works well, a disc shape is the easiest around 6" in diameter, then drill and bore the hole out to the size you need, machine a 45* chamfer on the trailing edge so that you are left with a sharp edge, use a hone to knock off the burr if there is any and leave a nice sharp edge, flow test the plate with the sharp edge facing upwards and the 45* tapering downwards, with the plate sealed against the bench it will flow 91.1CFM per square inch, if testing a 45mm ID orifice your floating scale reads say 25" then you know if an inlet port flow the same test pressure rating you know it flows 224.6CFM @28"

A good thing to note is also the sound of the port, the quieter the port the better indicating less turbulence, the DD port above flows a lot quieter than anything else I have tested, only at quite low lift does the seat shape begin to make noise, at low lifts the seat and valve act like a venturi making the air move quicker through it

I have tried using string in the air path and other shapes but velocity probing would be my preference tbh as you get a nice clear reading of where the port is flowing best

[MemphisTwin]

Jason, by my calculations your dd port flows 134.5cfm at 10" and your injection port flows 119.5cfm at 10". I needed to convert it into a figure that my poor old head understands! Dave Walker claims 122cfm at 10" (as seen in Retroford magazine) and CNC Heads claim 125cfm at 10" for their modified carb heads.

Interesting....

[madragon199]

Thank you jason...i fully understand how much time and effort all the testing takes,,,really glad your sharing....mark

[RWD fords rule]

Jason, by my calculations your dd port flows 134.5cfm at 10" and your injection port flows 119.5cfm at 10". I needed to convert it into a figure that my poor old head understands! Dave Walker claims 122cfm at 10" (as seen in Retroford magazine) and CNC Heads claim 125cfm at 10" for their modified carb heads.

Interesting....

Yes if you want to find the theoretical flow at a different vacuum level you find the square root of the difference in inches of water and then multiply this by the CFM at the old rating, for example 10/28 = .3571 square root = .5976

So if you have a flow rating at 28" multiply it by .598 to get the flow rating at 10"

With a full on DD port with 46.5mm inlet around 235CFM @28" is about the limit or 140.5CFM @10"

For a non DD port but raised 6 or 7mm and widened to 44 or 45mm with the floor maximum raised the max flow would be around 225CFM @28" or 134.5CFM @10"

There is no way to get that kind of flow out of a metal removed only port imho and at least a 46mm valve is needed, also imho to get that kind of flow the port can no longer have a round shape, the floor needs raising a lot which means the port has to be made much wider to compensate

I will be able to give more exact CFM figures later this year when I have the new bench finished, will be way better than a superflow 110 that is for sure, I am not convinced testing at just 10" water is a good idea tbh, most US tuners test at 28" and higher, the reason for this is that if you are searching for small improvements the higher the vacuum level the higher the accuracy level making a small change much more noticeable than testing at lower test pressures, also there is the fact that air flow will want to separate from the short turn at mid to high valve lift due to the air speed increasing, if you test at 28" the air might want to separate from the short turn and flow straight onward at say .300" lift, but if you test at 10" the air is moving a lot slower and is less likely to separate from the short turn until higher valve lifts

Testing at 10" can make a port look like it is flowing better than it really is in an engine, many tuners only use 10" and claim no difference vs 25" or 28" but US tuners think very differently to this and even like to test above 50" for the final port developments along with wet flow testing, not saying this is essential but I would prefer to flow test an inlet port at 25" or more than testing at 10"

Imagine the pistons drawing in fresh charge at 6000rpm+, the time available to fill the cylinders is incredibly short, the suction level will far exceed 10"

A bit off topic but I do believe there are a few advantages to testing at higher vacuum levels/air flow ratings when testing certain items like inlet and ports exhaust ports where flow separation is very likely especially with a relatively low port angle

[ncoll1]

what make and model flowbench do you have at the moment ?


ncoll

[RWD fords rule]

Self built testing back to back against orifice plates, new bench will be full electronic 6 motor, I like minimalist designs to minimise any chance of air leaks

What CFM @28" have you managed to get from a pinto head Ncoll?

[ncoll1]

I am now retired, I have a superflow 110 and a superflow SF260, but if I get chance later in the year I will do some more development as its 20 years since I did any development on a pinto. By the way yes the SF 260 will flow up to 28" test pressure. As I have only previously tested them at 10" 20 years ago, I was getting 121 cfm.

ncoll

[RWD fords rule]

Here is the current port shape, the roof has been bored out to 38mm at 59 degrees, then the roof has been welded in with a special mig wire which worked out better than expected, at first it was a round port all the way down to the valve guide, since then the port has been widened to 44mm and the short turn significantly raised to maximise mid and high lift flow while keeping the CSA small rather than creating a huge lazy flowing port just for a few extra CFM

This is with a 44.45mm inlet, the shape is not 100% optimised but a lot has been learned from it and I believe a port with a lower downdraft angle can be made to flow more air than this when using a larger inlet valve, an ideal shape would be full DD like this with a 46.5mm inlet made a little wider again and the short turn optimised to perfection for the best flow possible without casting a new head altogether


Pics of the port development

It is quite hard to get good pics inside the port after the floor was filled in which is why I posted the pics of the port mould

[RWD fords rule]

I am now retired, I have a superflow 110 and a superflow SF260, but if I get chance later in the year I will do some more development as its 20 years since I did any development on a pinto. By the way yes the SF 260 will flow up to 28" test pressure. As I have only previously tested them at 10" 20 years ago, I was getting 121 cfm.

ncoll

That is quite a good flow rating for a metal removed only port and I am sure you would get more flow with a larger inlet + injection port, it takes a lot of skill to get the carb heads to flow really well that is for sure

SF260 certainly has more flow capability, I wonder if they have an extra motor or lager motors to get the extra 100CFM@10" vs the SF110

My bench will be more like SF450 with max flow around 450 to 500CFM @28" which should be plenty

[RWD fords rule]

As you can see the weld took well to the cast iron, I didn't even pre heat it!

An ton of time to make ports like this tbh, I am keen to see what we can manage with a lower port angle and more fine tuning, I think this is probably the best compromise

[ncoll1]

the SF260 is quoted as flowing 200 cfm @ 28" test pressure, earlier this evening I tested a PTS orifice plate 300cfm @ 28" test pressure and it showed 294.7 cfm which I was quite happy with, I would sooner be below than higher than 300 cfm.

ncoll

[MemphisTwin]

As you can see the weld took well to the cast iron, I didn't even pre heat it!

An ton of time to make ports like this tbh, I am keen to see what we can manage with a lower port angle and more fine tuning, I think this is probably the best compromise

You didn't preheat it?!!

That is very interesting Jason. Perhaps my 1700 dd head is not lost after all! If I can weld the chambers without preheating (thus damaging the epoxy) I can certainly get the CR up to a decent level.

[para144]

Very good thread!

I thought you might be interested in seeing these. I had the opportunity to photograph a 'Dave Brooks Engines' pinto head recently.
This particular head went back to Brooks for an upgrade, before the cam & cam tower upgrade it was making 200bhp (199.7) on a 2 litre Brooks bottom end. Brooks pintos are a popular choice in rallying.

Its a raised port head..

You can see the extra material in the combustion chambers here


You can just make out the old manifold stud holes from before the mounting studs were raised. Also the extra material in the bottom of the inlet. This is secured with a bolt from the outside & one from inside the water jacket.




The steel cam towers I am told locate the cam in a 'better position' as well as adding strength




Before upgrade the cam was cross drilled, it now uses a Brooks spray bar & splash sheild (squirts oil directly on the pad)


Cam is a Newman 4.75

From the Brooks web site:
"The inlet port on an injection cylinder head is a lot higher than the standard cylinder head because of the shape required to site the injectors on a road car, so we clean out the bottom of the port with a die grinder to allow an alloy stuffer, designed in house, to blend in and locate without thin edges. The cylinder head is then drilled and tapped to accommodate two 1/4 U.N.C. Allen bolts to hold each stuffer.

We then locate the cylinder head to a jig and the valve guide holes and valve seats are machined at precise angles and locations.

The cylinder head is now jigged and the inlet port is drilled and bored in its new position and angle.

The inlet manifold stud holes are now filled in and re-drilled and tapped to 0.2" further up the cylinder head. This enables the standard two litre inlet manifold gasket and manifold shape to fit the modified parts.

The combustion chambers are polished, balanced and blended into the new valve seats. The exhaust ports are gas flowed out to relieve restriction around the valve guide area and the top front area of the port at the head face. This process alone takes 24 man hours and is all done personally by Andrew Brooks, Dave's son who has 25 years experience of all the machinery and process's involved in our business

One 6x1 mm Thread is drilled and tapped on the exhaust side of each cam pillar to locate a splash shield for use with a cross drilled camshaft.

The cylinder head is finished off with bronze valve guides,1.75"in & 1.5"ex in forged stainless steel valves with single collet grooves, allso bronze cam bearings. There is a choice of valve springs depending on cam choice"

[haadee]

Absolutely loving this thread!
Super write up and info, any chance of zetec info? :P
Keep it up!

[escortinadriver]

Here is a pic of my first welded chamber i did some years back when doing my downdraft head.

I used Eutectic Xuper 2233N Arc rods that I got for a steal as they were left over from a large marine welding job.

Never used any preheating, but wrapped to cool slowly.

First proof of concept with 47mm Valve.



Shaun