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4L head flow figures

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Hey people, I thought I would start another thread for the OHC heads I'm starting to work on. I setup a head today for testing, I had to make a new valve opening fixture for the 4L which took a bit of time but I got some base tests done before packing up for the day.

First head to get tested is a stock 94AB and stock intake manifold (BBM)

Head by itself, 1.84in valve, 3 angle seat cut.


50            35.31

100          57.37

150          88.73

200          121.52

250          148.44

300          173.54

350          195.72

400          207.48

450          215.09

500          216.38

550          217.66

600          219.62


Now I remember Dave putting up some results of a head before and they were quite different to these, I checked and recalibrated my bench and these are the results I got twice, maybe earlier heads flow less I don't know.

Anyway I did 2 more tests with the stock manifold on, Test 1 was with the internal butterflies closed so that means running in long runner form.


50           34.93

100         56.54

150         84.14

200         112.15

250         130.87

300         145.16

350         157.23

400         164

450         167.78

500         170.16

550         171.44

600         172.32


Test 2 was with the internal butterflies open so that means running in short runner form


50           36.16

100         56.39

150         86.35

200         114.58

250         135.57

300         154.27

350         169.43

400         177.97

450         182.73

500         187.93

550         189.06

600         189.33


So as you can see the short runner flow is a fair amount better than in long runner, tomorrow I will start some mods to the manifold and test them, it will be aimed more at higher sustained revs like speedway and burnouts so 3000rpm and above. I will post some pics when I take some.

After that I will start to port the head and will post the results, I have a head to do for a burnout car next week, it is a later EL tickford head with beehive springs like the AU so it must be a very late EL head, reasonable cam and a very good driver, I have seen him perform before and he pulls good skids, part of the deal is a big sticker on his car and he enters quite a few events so I have to come up with a sticker design as well, good times :)

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The above head is a brand new casting, supposedly copied from a stock AU head.


In your opinion, what cam specs would make the most out of the above flow figures?

(as incomplete as they are)

I'm in two minds to get it re-flowed, just so the chart gaps can be filled in.

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I suggest removing the throttle butterflies and shaft completely for the burnout head.  Reality is that he will not need them as the car will always be operating in the high rpm zone. 

We did this on the twins EF burnout car and there was a gain there.  Is he running a switch auto on the E series burnout car?  They are a piece of piss to wire up and they get rid of the overspeed issue, which just leaves the rev limiter to get over. 

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Dave I would get it reflowed to see the mid lift figures mate, as for cam if you want to run the stock computer then the crow 22519 is a good street cam, if you can run an after market ECU then you can step up to the 22549 as it has more lift.

The burnout car will be running the 32546 crow cam.

You read my mind Tony LOL I pulled the butterflies and shaft out yesterday and I'm about to go test it to see what the results of just doing that will gain, I was also considering doing that for a street stock speedway car also, whats you opinion on that, again I expect the revs to stay over the 3000rpm in a race also.

Thom yes you are spot on that why it needs the different cam grind, 7mm stems on the valves I believe?

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Great posts Clevo, if any test could show a timeline of engine development, it's this. After seeing some figures from a log head, an iron 2V, alloy cross-flow and now these E-series numbers you can see how over 30 years time, the flow figures have doubled. The DOHC figures are even more impressiveb.


I do get the shits sometimes knowing that my 302C is about on par with a modern V6 for performance, (at double the fuel consumption) but then I do take some salvation in the fact that my engine was designed over 40 years ago. And that it sounds tits.


I know you get it all the time, but keep up the good work. I'm always interested in the latest project you've got going.

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Thanks mate, yeah I'm keen on all this sort of stuff, being a bit of a tight arse I like to see if I can get good results by modifying stock items LOL.

I too hang my head when I flow more modern castings and they make the older stuff piss hahahaha especially when comparing the different engines in the speedway classes, like street stock you have crossflows v ecotec, the ecotec heads and manifold flow around 180cfm stock were the crossflow is 138cfm stock so we have to try and squeeze power out of every little thing. This is why I'm trying to convince the local crossflow racers to swap to Tony's manifold if they want to keep up.

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If it helps at the factory setup for the bbm has the changeover from long runner to short runner at 3800 rpm (when I first put my ute on the dyno the intake was controlled by a jaycar rpm frequency switch I played around with the changeover rpm and dicovered on my car there was no gains fro deviating from the stock changeover point, that combo was an au short motor with an ef xr6 head (94dt casting) ea camshaft and a el bbm)

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Bugger no gains from the throttle plate removal -seems odd given the gains found in removing the screw protrusions on the Holley carb.  Did you fill the throttle shaft with pieces of alloy - perhaps that is causing an issue. 


You can't beat the new manifold for consistent flow and the horsepower and torque gains that everyone that has fitted one has made.  I've made a few mods to mine and I'm taking it to Brisbane with me in December to flow test it on Bertha V2.  Should be interesting. 


Keep up the good work Clevo.  just tell those street stock boys that there is something special about kicking EFI cars arses with the good old x-flow - its why I persist with them. 


Yeah I could build a BA and do bugger all to it - fit cams and headers and an aftermarket computer and make the same, if not more power - but where is the fun in that.  Last meeting a BA with all this in it could not catch Jason with the carton of beer motor in his XF running on petrol with a 350 Holley - and I mean 350 holley - no 500 base plate - nothing.  Now that is something.  He came third behind a big dollar metho corty - and a massive dollar VZ commy.  Not a bad effort. 


Long live the x-flow!!!!!!

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I was thinking the same thing Tony about the butterflies, I pulled the whole lot out including the shaft and plugged the hole to the outside of the manifold. The top is the restriction because without it on the runner will pull 203cfm, with the top on it drops to 188cfm and nothing you do to the bottom section makes a difference, the best thing to do in my opinion would be to make a fabricated top for it with a large plenum.

Did a quick port today, I will post up the results later but she goes 240+cfm now with the stock valve, here are a couple of pics.




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flow results, again I have been able to keep the port stable and I made the valve guide shorter so I could test higher in the lift range, I could get a test up to 725 thou of lift. This port hasn't got a lot of work in it, just some reshaping around the short turn and in the bowl and valve guide, the entry and cross section is the same as stock just cleaned up.


                stock                    modified 1


50            35.31                    35.97

100          57.37                    63.46

150          88.73                    95.84         

200          121.52                  129.15

250          148.44                  158.21

300          173.54                  178.1

350          195.72                  192.09

400          207.48                  207.29

450          215.09                  223.06

500          216.38                  233.09

550          217.66                  238.26

600          219.62                  242.39

650                                       245.04

700                                       246.68

725                                       248.35



So the port flows alright but she has a bit of a stall between 300 and 400 lift for some reason then she recovers well and charges off in a big way, the only downside of that stall is that most OHC camshafts don't lift much higher than 450 and that when this port recovers so the gain is good in the low lift but only a 8cfm gain at 450 thou of lift, obviously a big camshaft would work well with the port as is but I will work out how to stop that stall for smaller cams.

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Ok never ported a head myself but looking down the bowl, it seems to be the smallest around the circumference between the short turn and valve guide. Also the throat on the short-turn side looks like it needs a bit of meat off. Being a hemi-style head, it may take a different approach to a wedge style in that the direction you want to bias the flow may be different (ie away from the cylinder wall and into the chamber). I've got a feeling that hemis can be tricky.


Again i'm not an expert and you can tell me to get stuffed. Sometimes you just might need an outsider's eye to see it. Even the missus might be able to help!

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Oh a BIG cam you say...thats what I like to hear too.Always said that about xflow's,they need to be lied too to get em to work as well.Too big a cam is just enough in my books...then build around it.But the issue with OHC engines is the rocker gear is the weak link even when using custom billet units.

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Gerg the last thing I would do is tell you to get stuffed LOL I like to hear peoples opinions and I think you have some valid points, the shot from the port face just looks like it narrows a lot because the camera lens was close to the port face, I agree about the bowl, I will open that up a bit when I get to this port again and see how that goes, I appreciate your input mate.

Sly I don't really know a heap about the OHC engines so I didn't understand why I couldn't find a cam with big lift, now I know cheers mate. I will work out how to improve that mid lift it will just take a little time on the bench and slowly removing material and retesting, it's on the sideline for now because I got some clevo gear today that I'm keen to test :)

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Info from the old Autospeed article - Awakening the Aussie Ford Six -



Cylinder Head

As a generalisation, the flow capacity of the Ford cylinder head gradually improved with each model. The exceptions to this are the ED (which appears to use the same head as the EBII) and the AU (which use relatively small ports).

Jim says the EA head should be avoided - "there are weaknesses in the casting, design faults and flow problems." The EB was slightly improved and the EBII was better again.



The EF/EL head uses nice large ports and runners and improved combustion chamber design. Be aware, however, some ELs were released with hybrid engines using an AU-spec small-port head.

By far, the best head is that fitted to the EF/early EL. "The EF head makes good power in standard form and, when you decide to go further, they’re easier to port," says Jim.



Valve sizes went unchanged except the EF XR6 and AU received 2mm larger exhaust valves. Inlet valve size cannot be increased due to space limitations. Regardless, Jim says there’s no gain in fitting bigger valves unless the engine is already modified in a big way.





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Id be interested to see the difference between they inlet port that you  have worked to achieve those figures and a stock EF XR6 inlet port as they have been throated out a fair bit at the factory, removing the guide and dressing the turns without it in the way.   Also Id also like to see what happens when you open up the lower half of the BBM by cutting the 12 D shaped runners into 6 large oval ports and then building a upper to accomodate as much flow as it has without a lid.

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Just for my curiousity... if you have a unmodified BBM can you test one port with the long runner hole blanked off and just the short runner open with the butterfly in place?  And then shut the butterfly and tell how mu cfm this flows shut?  Ideally it would be 0cfm but if its like 30-40cfm then thats probably cool too as long as they are all equal.... Get where im going with this one??  its been an idea ive had for a while but i dont have any test subject to prove it on yet.

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I did cut the section between the 2 ports out in the BBM and it made a 3cfm difference with the top off, a custom open top plenum would be the way to go.

I want try and test as many different stock heads as I can get my hands on.


i'm wanting to do something like this with a triple carby set up on top its only ideas in my head atm but i'm hoping it works

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