the one in my pics is WR2T-6090-bb

ill have a closer look tomorrow as i didnt take the belt cover off, i just looked through the gap and it looked like bc, i could have miss read it...

there is most likely a bunch of difference ones.

just measured the EF tickford head and the EL GLI head that i have. Both of the have identical insert OD and the ID is within 0.20mm.
All that seams to be different is the position of the seat it self.
By that it will be no trouble to fit 41mm exhaust valves (which i have done before) though I would spend the time to open the throat out to suit the valve.

I will be starting to do the port work on my eb xr6 head in the next couple of weeks.Ive got a guy in w.a that has been telling me what to do and not to do he has told me to flaten out the 90" radius and cut the valve guides down by 1/2 an inch and dont increase the size of the intake port and dont match port it to the manifold he also did say not to go any bigger with the valves he has said with these mods i will get up to 245cfm and the thing will rev like crazy he is a head specialist with all the flow benches and what not they have just finished a au speedway motor making 450hp

wagon dad got about 245cfm @28inches with his head. 240-250 is about where the good heads flow.
problem is with out 12:1 comp and methanol they won't make much more then 300hp and still be streetable. To make more you need to cam the crap out of them and they become to grumpy for the street.

They are a very efficient port, for the valve size 250cfm is pretty good flow, hence why people aren't making more. Once you get to that sort of flow you'll need bigger valves to get any significant flow increase, If we can a head to flow up around 280-290cfm, we'll start to see true 200+ rwkw cars.

Yep spot on mate,mines running a aussiespeed manifold and 650d/p holley my comp will be right up there as its not street driven the cam will be a custom one once we get the flow figures.He has also given me the part number for autolight spark plugs wich i cant find at the moment that he has dyno,ed over a 100 sets of plugs and these gained 10hp on the same engine he said he couldnt believe that you could gain that much with just plugs but he has the proof.Woops just found it autolight 0985 i will put pics up as i go with the head.

Yeah 985 is the ones. JMM have been selling them for years with their package deals. nice and cheap too, i can buy them for about $3 each

I got my new toy working today, an old sand blasting cabinet that i have spent some time repairing and drying out the sand.

So here are some photos of the same VCT head i posted before, but these ones are nice and clean and all casting and machining marks are visable.




on the above photo i have marked in green the seat its self the narrowest point of the throat in red and in blue is the bottom of the third angle cut. You could call these seat a 4 angle seat. as there is one cut on the chamber side of the seat, then we have the seat its self we then have 2 more cut on the port side.

The ID of the red part is 32.60mm the ID of the blue line is aprox 34.40mm.
the throat can easily and safely be taken out to 34.40mm and you will see an improvment in flow when this is blended into the port.


On the intake seat you can see the same cuts.

In this case the red line is 40.60mm (there is a step at the transition from seat to port, the port at the same line is 40.38mm)
the blue line is 41.25mm.
The applies here, the throat can be opened and blended. Given the width id the cut i'm talking about, the throat can be opened out to 42.25mm and then blended to the port. This will give the same width as the same cut on the exhaust port.

what is the considered opinions on which is the best head to start with???
how does say an ef xr6 head stack up against el hybrid standard head for porting potential (this is my case)?? or is the eb xr6 (91aa) the best head???

Tickford 6 they are fantastic pictures and detailed information. Much appreciated.

Love this thread, so much information. Thanks to you guys contributing.

Autospeed did an article on porting and compared an EB head to an AU head - i think they said that the AU head had the better potential for porting or something along those lines. Probably because the ports are supposedly smaller in the AU head, you have a better base to start from with regards to shaping and opening up areas of the ports as there would be a little bit more alloy to work with from the get go. With the earlier heads the ports are fairly large already, so there isn't as much alloy to work with, but there is still room for improvement. By the way the 91AA head is just a std EB2-early ED head, not XR spec

The way i see it, it doesn't really matter which head you start with. If heads are going to be ported the port shaping/sizing will end up similar anyway.

The reason the early heads aren't as good for porting is that in some places there is no metal where ideally there should be. They limit you to a less then ideal finished port shape.

so an ef xr6 head and cam p/p (port and polish)would ultimately be no better than a p/p standard au head and mild cam? or turn out roughly equal...without major working, bigger injectors, shave, j3, blah blah that is.. was always under the impression that the ef xr6 was good because of the bigger valves and large ports...more fuel, more flow, and less work needed........plus i've got one sitting in the garage!!! bear in mind i'm not after 2000rwkw! just good solid, responsive driveability and easy tuning...
was hoping for (or should i say: told to expect!) a noticeable improvement with mild p/p and stock cam on ef xr6 head, with good extractors and better air intake... am i fooling myself?