I see mace nor ZZP sell these anymore but I managed to find a disabled page on Mace's site with the info.
They're NLA. They work and they work well. Only real gains over well ported iron heads at higher boost levels
The port angles are heavily revised and the coolant passages re located to both fix known valve seat cracking due to poor heat transfer in middle pockets and allow heavier porting without hitting the coolant galleries.
you can get them made to order for cheap LOL immortality went and checked out a set exactly like these that were for sale here but they are for an old carb buick v6 .them chinese all state they can make any head you wish might be worth a few emails in bad engrish to see what you can get cause thats damn cheap Lol http://www.aliexpress.com/item/Buick-cy ... 17085.html
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
delcowizzid wrote:you can get them made to order for cheap LOL immortality went and checked out a set exactly like these that were for sale here but they are for an old carb buick v6 .them chinese all state they can make any head you wish might be worth a few emails in bad engrish to see what you can get cause thats damn cheap Lol http://www.aliexpress.com/item/Buick-cy ... 17085.html
Sorry, I refuse to use Chinese stuff unless its Taiwan lol.
I get all my engine parts genuine, direct from a GM factory outlet in the states.
I can get brand new genuine heads from there. wonder it thats a better idea than using used heads?
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
I reckon the biggest problem with the heads is the fan settings...... 90 deg thermostat but fans dont come on till over 100 something degrees. so in traffic stopped you sit on 104 ish degrees and then you start driving the moving air cools you down to 92 again then you stop again back up to 104 degrees. thats a recipe for cracked heads IMO
and peak coolant temp in the heads would be hotter than this? Also from reading the workshop manuals the stock 91c thermostat doesn't actually fully open till 104 which is why the fan temps are so high.
I have done a few boiling water tests on 81c thermostats and found all the ones ive tried opened fully by 83c.
From what I read on Mace's postings about the alloy head, there was revised coolant passages around the valve area to remove more heat that causes cracking in the iron heads.
I guess running cooler will prevent reaching the point where this might happen.
But that said, the pre ecotec run the same fan settings and its not a problem as far as I am aware.
there is a fare bit of claims the latter heads were revised to fix this issue anyway. I have not heard of the later (post 00ish) heads cracking. In fact because I have only dealt with 03-04 engines from the ecotec series I had never heard of cracked heads before until it was mentioned on this forum.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
yeah the V6 sprintcar guys do this (although i believe they arn't supposed to ) and they use vn-vr motors.
as far as the ecotecs go, we have actually die grinded a cracked head on the crack area, and there is only about 2mm of meat between the valves before you hit water! i don't know what there is in an earlier head though.
i totally agree that the higher fan temps can't help things!
No matter what the question is, the answer is always more horsepower!
2136 early heads, known to crack? No injector boss or pockets.
4781 revised head 98-99? has boss and injector pocket for L67 and L36 and is drilled for the injectors in L67
8134 ?? No injector pocket . Possibly L26 heads.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
) and they use vn-vr motors.