AAZ valves, springs, and lifters for performance build.

[Jetmugg]

I've done the searches and read what I can about the different varieties of AAZ cylinder heads, with respect to valve sizes, spring types, and spring shims.  I still don't have a clear picture of all the possibilities of valve, spring, retainers, and lifter combinations.

Right now, I have my AAZ head at the machine shop, getting a rebuild for a "hybrid" 1.6L TD block / 1.5 rotating assembly / 1.9 head setup.  This engine will be used for a land-speed record attempt.  It will not need to turn stratospheric RPM's.  My goal is to run through the timing traps at slightly less than 5,000 rpms, but will probably need to wind it up a little higher before shifting each gear.

This will not be a "time bomb" type of engine setup.  It needs to make pretty good power (over 120hp would be nice), but needs to be able to live for some extended full-throttle runs (the race course is 3 miles, flat out.).  It will have plenty of turbo boost, air-to-water intercooler, a top notch injection pump from "The Man" in Canada, and a big oil cooler.

Anyway, the head as I recieved it was set up for 8mm valve stems, and used the single spring configuration, with steel seats under the springs.

Reading up on the various combinations, I'm trying to figure out a strong, reliable, affordable spring & valve combination.  Here in the US, most shops are not familiar with the AAZ engines. 

I have not yet seen a factory set of valves with 7mm stems for both intake and exhaust valves for this head.  I'm not even sure that an AAZ head ever existed with 7mm valves for both intake and exhaust.

Can anyone guide me to information about whether there are any other factory VW engines that can share valves with the AAZ, or a source for 7mm replacement valves for the AAZ?  I have some 7mm valve guides that came with the head, that have not yet been installed.  Should I keep the "stock" 8mm valve configuration, or try to figure out a combination of parts that will let me use 7mm valve stems if they are available?  Recommendations are welcome.  My machine shop says that the 8mm valves that were with the head are OK to use, but if there are 7mm available, they should allow for better flow and lighter valvetrain.

I have similar questions regarding valve springs.  I think I would feel better knowing that I was running dual springs on this engine, but don't know if it's worth the effort.  I have "heard" that the springs may be interchangeable with 8V gasoline engine springs, but don't have a way to confirm that.  The same goes for the hydraulic lifters - any recommendations for those?

I'm hoping this topic will spark a discussion of the performance options for building an AAZ head.

Thanks in advance.

Steve M.

[R.O.R-2.0]

I've done the searches and read what I can about the different varieties of AAZ cylinder heads, with respect to valve sizes, spring types, and spring shims.  I still don't have a clear picture of all the possibilities of valve, spring, retainers, and lifter combinations.

Right now, I have my AAZ head at the machine shop, getting a rebuild for a "hybrid" 1.6L TD block / 1.5 rotating assembly / 1.9 head setup.  This engine will be used for a land-speed record attempt.  It will not need to turn stratospheric RPM's.  My goal is to run through the timing traps at slightly less than 5,000 rpms, but will probably need to wind it up a little higher before shifting each gear.

This will not be a "time bomb" type of engine setup.  It needs to make pretty good power (over 120hp would be nice), but needs to be able to live for some extended full-throttle runs (the race course is 3 miles, flat out.).  It will have plenty of turbo boost, air-to-water intercooler, a top notch injection pump from "The Man" in Canada, and a big oil cooler.

Anyway, the head as I recieved it was set up for 8mm valve stems, and used the single spring configuration, with steel seats under the springs.

Reading up on the various combinations, I'm trying to figure out a strong, reliable, affordable spring & valve combination.  Here in the US, most shops are not familiar with the AAZ engines. 

I have not yet seen a factory set of valves with 7mm stems for both intake and exhaust valves for this head.  I'm not even sure that an AAZ head ever existed with 7mm valves for both intake and exhaust.

Can anyone guide me to information about whether there are any other factory VW engines that can share valves with the AAZ, or a source for 7mm replacement valves for the AAZ?  I have some 7mm valve guides that came with the head, that have not yet been installed.  Should I keep the "stock" 8mm valve configuration, or try to figure out a combination of parts that will let me use 7mm valve stems if they are available?  Recommendations are welcome.  My machine shop says that the 8mm valves that were with the head are OK to use, but if there are 7mm available, they should allow for better flow and lighter valvetrain.

I have similar questions regarding valve springs.  I think I would feel better knowing that I was running dual springs on this engine, but don't know if it's worth the effort.  I have "heard" that the springs may be interchangeable with 8V gasoline engine springs, but don't have a way to confirm that.  The same goes for the hydraulic lifters - any recommendations for those?

I'm hoping this topic will spark a discussion of the performance options for building an AAZ head.

Thanks in advance.

Steve M.

why do you need the 1.5L bottom end if not for revs?

or is this for that stupid displacement limit?

[Jetmugg]

Displacement limit for the class.

Steve.

[theman53]

IIRC all 8v hydro components should work with the AAZ head minus the cams from gassers. Check it but that is what I believe is accurate from discussion. I do not know if the dual spring will be needed. Your engine and its rev characteristics will be based on what Giles does with the pump. The same 8v single spring gas head will rev well beyond 6,000 rpm, so the head isn't the limiter. The pump will be, have Giles set it to what you need.

The TDI valves, guides, retainers, and seats could be used in your AAZ head. Then you find all the 7mm stuff you want.

I am having my 1.6 head built to the same specs at Air Cooled Engines Plus in Tiffin. If you want something and can't find it he will make it. I have stainless swirl polished valves being made now for it since no one is making them in production.

[rallydiesel]

I believe the tdi valves are a different height than the AAZ ones.

[Thezorn]

My AAZ head used dual valve springs. I havent seen any with single personally.

[Jetmugg]

I have only seen one AAZ head (the one I have), which has the single springs and the lower seats.  Apparently, there are at least 3 configurations with respect to the springs - single springs with lower seats, single springs without lower seats, and dual springs, which I assume use the lower seats.

There don't seem to be major problems with any of the setups, and I haven't been able to find the reasoning behind the changes.  Right now, I think I'll put it back together with the same setup that it had originally (single springs with lower seats).

Steve.

[Thezorn]

Just an FYI if its important. The dual springs in my head have lower seats also.

[R.O.R-2.0]

I believe the tdi valves are a different height than the AAZ ones.

they are different length, 99% sure ive read that somewhere..

[RabbitJockey]

Tdi valves are bit of a different length but they are the same diameters so there's not really a reason to worry about them anyway.  The valve guides and retainers are the same on gassers so long as u get the 3 groove but it's not like ur gonna gain a bunch of hp there haha.  I would just do a ported head with 7mm valve stems with a good turbo and pump you'll set a record for sure

[R.O.R-2.0]

Tdi valves are bit of a different length but they are the same diameters so there's not really a reason to worry about them anyway.  The valve guides and retainers are the same on gassers so long as u get the 3 groove but it's not like ur gonna gain a bunch of hp there haha.  I would just do a ported head with 7mm valve stems with a good turbo and pump you'll set a record for sure

i still think the 1.9 head on the 1.5 rot/assy is going to be too much. (not enough compression to run efficiently)

i would build a 1.6 head also, just for incase you have to swap the head to get it to start good, and make decent power..

for what you are asking the engine to do, i would think that a ported 1.6 head would be BETTER, in terms of efficiently making power.

low compression is NOT good on these IDI engines..

there have been a couple 1.5/1.9 engines built, but none of them actually saw the light of day that i know of, due to starting/running issues..

i believe Sauerkraut built one, but ended up not going that route, because of (LACK OF) compression..

[R.O.R-2.0]

i WANT this engine combo to work out in the worst of ways.. trust me.. but i just dont see it happening.

there are substantial issues that arise when using a 1.9 head on a 1.6, and they are going to be WORSE with LESS displacement..

[RabbitJockey]

im optimistic, its certainly not a set up for a daily driver, but i think the only issue will be starting not not how it runs

[JamesT]

From the sounds of it, once it's fired up and warm, the low compression ratio should be fine. The things only going to be making power on boost, so at a certain point the cr won't make a huge difference to combustion. If it won't start at that low pressure, machine up some glowplug blanks and start it on ether. Either that, or pre-boil the coolant and get the engine to operating temperature before it fires up.

[theman53]

If the TDI valves are a different length have the machinist cut some off and if nessesary cut new groves for the keepers. Or like I said have air cooled engines plus do the dirty work for you.