Okay, i have a spare 91AA (EB/ED) head here that i am slowly doing a DIY port/polish job on before i take it in to get all the machining work done on it. At the moment im trying to suss out my options with regards to larger exhaust valves - im renewing all the valves. I plan on keeping the intake valves the same size with this head so i have no problem getting new valves for the intake side. As most of you will know the ex valves on these heads are the 39mm ones so i want to upgrade them to at least XR spec (41mm) problem is, most of the engine parts places i have contacted so far can only supply brand new 39mm ex valves and dont have the 41mm ones available with the 11/32 (8.7mm) stem. However i can get the 41mm ex to suit the EL hybrid and AU head which has the 7mm stem.

What i want to know is, can these EL hybrid/AU valves be used on earlier e-series heads with the normal e-series type valve springs, retainers and collets? I know the hybrid heads have the conical valve springs so is there any other differences in the EL hybrid/AU valves apart from the stem diameter? Are they the same height etc? I know the valve stems are 7mm which would require new matching valve guides. Im hoping they will fit because this would be better for the head as i would be able to get a bit more cross sectional flow through the ports.

If they dont fit though, what other options do i have other than going for custom made stainless ones?

I know that the clevo 2v valves have the same 11/32 (8.7mm) valve stem but apparently from what ive read/heard the ex valves are a bit shorter (dont know by how much) than the ones on the e-series head, which would render them useless im guessing? Would be good if they could work though as i can get them in 42mm diameter. Clevo intake valves on the other hand only have to have the tips machined down to length as they are slightly longer.

Anyways any help on this would be greatly appreciated, that way i can start sorting out what parts i need to get to get this head back together

Cheers,
Nathan.

you will need new collets. and obviously valve guides.
retainers should be fine so long as you get the collets

Ahh cheers tickford_6 appreciate it.

Okay so i'll need new collets to match the valves, matching valve guides and valve stem seals to suit the 7mm stems. Cool, will look into it and see if i can source all these things, so far all ive been able to find is the valves. just waiting on a few places to get back to me then i'll know for sure. The guy who usually does my cylinder head machining can custom make the valves to suit from stainless Ferrea or Manley valve blanks but im thinking that may be costly. I'll have a chat with him sometime this week and see what he can do for me and then sort out my options i think..

Thanks again

I think you'll find your guy would simply place and order manley and they would make them to suit.
Go to the manley or ferrea website and check out what they can do.

KWIKXR Contact your local engine reconditioner. When I did my head they supplied 41mm exhaust valves no problem then I replaced the standard intake valves and they supplied them for under $70. I live in Mandurah W.A. and have a choice of two engine reconditioners, give yours a go they can generally supply what you want and will be cheaper than speed or auto shops.

Thanks for the advice guys

Gave the cylinder head guy a call this morning asking what he could for me with regards to larger exhaust valves. Sounded like he didnt want to give out too much info lol but all he mentioned was maybe sourcing tickford valves from ford or they will see what other valves they can get to suit the head, which im guessing is what tickford_6 pointed out by saying they will place an order with manley/ferrea and get them to make the valves up to suit.

The guy was certain that Ford still stock the tickford valves so i gave Ford a call to get price. In short, Ford NZ needs to be shot. They quoted me $130, EACH!! f**k that

EDIT: Also went to my local parts/speed shop this morning as i had to go pick up some snap straps for my heat wrap. They dont do any oversize exhaust valves to suit other than the std 39mm ones. Can get the std size 47mm intake valves though which will cost me around $60 the set brand new. According to them (going by the dimensions in their parts database), both the intake and exhaust valves from the AU are shorter so im guessing i might run into problems with lifter to valve clearances from this if i put the larger 41mm AU exhaust valves in??

These were the height dimensions according to their database, they dont have any in stock at the moment so we could compare them side by side..

AU intake: 129.3mm
E-series intake: 131.1mm

AU exhaust: 128.1mm
E-series exhaust: 130mm

So at this stage i think i'll just play it safe, take the head into the cylinder head guy, and let him sort out the larger exhaust valves for me and fit them accordingly when the seats are recut.

you should be able to get 1mm lifter shims to sort that out. and you could get 40thou offset collets to fix the valve spring height.

you should also be able to get custom manley valve for less then what ford want.

std 39mm aftermarket valves will be around $10ea from an engine shop...

proper porting and back cutting of the valves should yield flow superior to the a std 41mm tickford setup...

I would only go to clevo valves if I wanted to run stainless valves as new springs, collets, retainers and valves will cost heaps compared to just optimising the 39mm valves....

whats your budget and intension for this project?

Hmm i didnt think of that at all, good point. Ive got an extra 1mm shim in each rocker right now due to the regrind cam im running and have quite a few spares so theres no shortage of those


I hope so lol, $130 for off the shelf tickford valves is ridiculous IMO. Just had a quick skim through both the Ferrea and Manley catalogues, couldnt find any valves the exact same height, but as long as they have the same stem diameter and suitable sized head diameter they could always have the tips turned down a bit and have the grooves machined - even the cylinder head guy should be able to do that. Anyways i'll cross that bridge when i get to it, still have a fair bit of work to do on the head before any of the machining needs to be done but its good to have a little bit of knowledge about what can be done

Thanks again, for your help and suggestions, appreciate it

Last edited by KWIKXR on Wed Nov 04, 2009 10:54 pm, edited 1 time in total.

You're spot on there gogetta, i can get the exhaust valves aftermarket for $9 something each and intake valves at $8 something each. Plus i know a guy that works there so id get a few bucks off that so its fairly cheap if i go for standard valves and get them back cut as you suggested..

So far i have a budget of up to around the $600~ mark, not that i have that much at the moment lol, but when the usual machining work etc gets done thats about as much as i'll spend on it. The head will need to be skimmed (i plan on taking off at least 20 thou to give a decent comp increase with the AU gasket), have the seats recut, either new guides or get them re-lined, will probably get the guides shortened a bit and tapered while they get done, obviously the larger exhaust valves, etc. The head will also be getting uprated springs (possibly Crow but most likely from Manley as that is what the guy who reground my cam has suggested i use and thats what i can get readily available) and most probably new retainers and collets which will most likely require me to extend my budget a bit further. Im doing the porting myself to keep the costs down and will be getting the head flowtested after ive done the porting just to see how it goes.

This head im working on is basically only a replacement head i can have ready to go on when i change the currently leaking headgasket on the car, only thing is, i want to give it a refresh and the works before it goes on. Its not going to be an all out race spec engine, just a solid street engine with a bit of grunt that will see the odd track/drag day if you get what i mean.. So far its faily mild - mild cam, extractors, full exhaust, intake mods, tickford ecu and fuel reg, cleaned up intake manifold and T/B etc, just the basics for now but i intend on possibly running a bigger cam from the likes of Wade later on down the track with the possibility of a chip if need be. I plan on keeping it NA for the time being and with it being auto i doubt id ever get this thing to see past 150-160rwkw mark , although id like to get it around that figure and pull a low 14 sec pass once the diff gearing and auto are sorted.

Either way the head i am using isnt the most ideal base for porting, seeing as i dont have a lot to work with especially when it comes to shaping the short side radius and the big valve guide bosses but it can be improved upon which is why id like to at least upgrade the exhaust valves from the std 39mm while im doing all this work. Besides id rather do this now before the head goes on so i wont have to take it off again to get anything else done later on. From what i can gather on most of the ford forums, its a must if you are spending a bit of time working on the head.

Once i get prices for custom valves i'll know where i stand but for now all i can hope for is that they are no where near $130 a valve . Will try and get a bit more info over the next few days and see what the other local head places can do for me. If i can get oversize valves at a reasonable price i'll go that way, but hell if all else fails, i may just go with new 39mm ex valves and get them back cut as that might save the old wallet a lot

Cheers.

Have a look at valve blanks in the manley catalog, there should be a blank in there that would suit you needs, should also be one there that could be used to make a 48mm intake valve

Hi all, just a comment. I have always been under the impression that bigger inlet valves were more important than exhaust valves (unless you have forced induction ie turbo or supercharger). Inlet gases alway travel faster if the valves are larger. Exhaust is pushed out by the completion of the combustion process and the piston coming to the top of its travel which is why the exhaust valves in every motor I have worked on are somewhat smaller than the inlet valves. Is there any real benefit in modifying exhaust valves?

why dont you just get a tickford head that has 41mm ex valves, i had mine touched up by head shop for just over 400, was chemical cleaned, crack tested, all 12 guides replaced and valves got a 3 angle cut, head looked brand new when i got it back and went so much harder. I really would not waist my time on a standard falcon head if your chasing power

if you're chasing power, the ports should end up the same shape regardless of what head you start with,
the other point is that just buying a tickford head only guaranties that you have 6 used valves.
Due to wear these may not be suitable for use in performance engine build.

Thats the exact reason why i chose not to go looking for a Tickford head, and of course the price it would cost for one . I picked this 91AA head up in fairly good condition for $35 including a cam, i doubt id ever find a Tickford head in similar condition cheaper than triple the amount i paid for this head - they generally sell at high prices from wreckers just because they are Tickford spec.

Even if i went along and bought a Tickford head though, it will still be needing a fair bit of work and like Tickford_6 said, if the already used valves are pretty worn they would need to be renewed anyway. I pretty much want the head im working on to be in tip top condition before it goes on so almost everything will be renewed.


I have read/heard about how larger exhaust valves give minimal gains (have even been told directly by some local engine re-conditioners that have experienced this with other engines) but there would be a valid reason why the exhaust valves are larger in the Tickford heads over the standard models. The guy who usually does my cylinder head machining work does quite a bit of headwork on i6 falcon heads used in stock car racing so he knows them pretty well. He always goes oversize on the exhaust valves on standard falcon heads as he reckons they dont flow too well on that side. Reckons the intake side flows quite well as it is, just needs a bit of work done on the ports.

I guess the main benefit from going oversize on exhaust valves would be gaining better exhaust flow on the way out. If i can get some larger intake valves maybe 48mm like tickford_6 suggested up above, i may consider it when i get the exhaust valves done.

I found this little article quite interesting. http://www.pumaracing.co.uk/Exvalve.htm. Has a bit of info on larger exhaust valves etc, even has a table which can be used to kind of give you an idea on what size exhaust valves would suit the CC's of the engine. So if an EF/EL engine is roughly 3984cc, divide that by 6 cylinders gives you say 664cc per cylinder - according to their table at the bottom of the page a sensible exhaust valve size for that engine would be between 40mm and 41.5mm