Funnily enough the chamber on the A series is reversed compared to the VW
The inlet charge comes in from the spark plug side of the heads for the VW
while the A series is towards the sparkplug which creates nasty turbulence.
I always wondered what a pre-chamber would do to the combustion chamber of
a speedway head that had been shaved for ethanol in order to bring the
compression down and not have the spark plug protuding into the chamber.
https://www.ebay.com/itm/Spark-Plug-No ... orman-42009-/311811788035

https://drivetribe.imgix.net/cEu0Npy5T ... press&fit=crop&crop=faces

http://i66.photobucket.com/albums/h25 ... 20EL%20Heads/IMG_2184.jpg

It looks good d I read the article he had to cut the valves down a lot so you have to run caps to which I had to on my last head, if you run a heavy valve spring it tens to start flaring the stem because you cut the hardness off. this time I brought the biggest a/series racing valves I could get so I didn't have those problems that I had before. it a shame someone didn't make a billet head for our motors

Those kiwis are pretty resourceful especially when you
compare how little population & $$ they have vs Australia.
Im pretty sure they were ca20e or z20 valves both 42mm stock
as the bottom of my ca20 valves had the same nissan insignia
and measured 42mm in diameter as do some Z inlet valves.

http://datsun1200.com/modules/myalbum/photo.php?lid=20264



42mm in could be the ticket as you dont need anything but
standard valves for exhausts for turbo.
Yet A14force could have benefitted with 40mm inlets and
34mm ex as supercharging needs a bit more ex flow.

These are the CB vw heads that can make 180+ HP for 1.7L engines
https://www.cbperformance.com/product-p/1409.htm
You will notice how nicely shaped the chambers are to suit
the massive bores avail to VW engines while the Kiwi head
above is like a squashed up version but pays attention to
make sure that big 42mm valve stay more central in the
cylinder chamber to keep the charge away from the cylinder
walls with no notching on top of deck required which is
what you want to maximise a deep compact tornado effect
centered in the cylinder away from walls a very clever design.

only running 32ex 38in all kameari gear after speed,i tried to get valves made in the US they weren't interested it wasn't a chev/ford. like to know how he fitted 42 in they must be hitting what hp was he getting

LOL 28lbs so you are the Yokozuna of the turbo A series guys!

What valve sizes are you running on this monster?
An A series supercharge freak in kiwi land ran 42mm inlets!

it was the head that cracked, 78 mm bore and has a slight crack between 3/4 which was xray and ok.i run 28lb boost which doesn't help ca18 rods and ARP bolts all the way through the motor. I'am trying to bring the boost down for the same hp 270wheel I'll see what I get first with this new set up.

The 90s as far as I know when the pulsar head became more available
Rob that did the BAT (B series to A series twin cam) got the idea
from speedway guys who also ran mazda heads on A series blocks.
In the country out of the box thinking occurs more than in the big smoke.

Shane whats the build you have? I only suffered 1 and 2 cylinder cracking
from going 79mm then 79.25mm on an A15 never had issues with back cylinders.

yeah I,am talking about 360/740hp-410/900hp very fussy engine builder my block has been freshen up with some new ideas from a different engine builder, etc, blue printed and now he,s building a new head ,the last one got to hot an cracked on the dino to lean on back two cylinders now putting in EGT in the exhaust to get all cylinders the right tune . I've always had trouble on the back two.

Were they using DOHC / ET heads in mid 80s ?? Why did some run Alcohol ??

A-series are well known in sprint car
often many have converted A series to use
OHC and DOHC heads, in fact they are still
used by junior sprint series