AC 426 cast molds??

Here is a question for the ole' Allis historians...

what do you need to change  to make it better there seem to be plenty of blocks out there for reasonable money  I have 5 or 6  that I would sell for cheap  Gary Roidt

Mark Gettinger is or was casting 426 heads that flowed big numbers. To steve m ive broke alot of blocks but never had 1 break near the cam but then we dont make alot of boost around 100 max usualy been up to 120 before but that wasnt planned lol

a couple nights agoe I stopped by the neighbors shop, the winter project is a couple new chargers, useing 2 of the existing chargers  and new plumbing.  Putting tie bars on the cyl head to the girdle to keep it togather enough to keep the sheet metal on if things let go.  It's still an IH block at smaller displacement, he'd like a Hyper block but the cost is high, cheap though if the IH lets go.  

Edited by wi50 - 26 Dec 2010 at 11:35pm

I don't think the Hyper blocks, heads, etc should have been allowed either, but it is what it is, it singles out a certain brand.  Same as the fight with alky, diesel.  Now region 3 will have a seperate heavy diesel ss class, my neighbor was fired up and plans on traveling to more this summer.  I hope to get time to help with the tractor and traveling some, but summer spare time is not abundent to me.

We have a Mark Gettinger head on our superfarm now.  Problem is that you need to take a OEM head and get the water journals filled with hardblock.  Over time, the  cast from the head and the hardblock doesnt expand and contract the same with heat and therefore start to leak air. 

Technically speaking cast iron parts are made from molds but the molds are destroyed getting the part out. Those molds are of treated sand, formed around patterns which are the pieces that are reused. Internal cavities are formed from cores usually made of sand glued together with supports to fit the mold. The basic pattern includes extensions for the core supports in the sand mold. Cores are also destroyed getting separated from the casting. Cores are created in "core boxes" which are molds to shape the core. Core boxes need to go along with patterns for a particular part and are reused.

The pattern has to include accommodation of metal contraction, often 5 to 10% in all dimensions. You can't take a metal part and use it as the pattern to make a replica, because the replica will be smaller due to that shrinkage. You can only use the metal part to make a wooden or plastic pattern (metal patterns can be used for high production parts, but wood is the traditional material) that is enlarged to account for the shrink.

The casting foundary and the pattern maker have to work together because shrink is not always uniform and can depend on where the sprues are attached for pouring and details of the part shape. Any wood worker can make a pattern when given the basic rules of casting, but the part that results may not be exactly what somebody expected.

With today's CNC mills, it probably is more cost effective to carve very snall quantities of engine parts from solid chunks of metal, but they are obviously not the original factory cast parts becuase the machined surface will never match a sand cast surface.

Gerald J.

Mark D,  do you have a stock ported head from mark ?or do you have a aftermarket look alike that mark was haveing casted?  I know he had some casted and they were alot of money  and flowed close to what my indy head did.

Yea mark has a head that he had casted it was big money. But me and him discused it and the flow numbers were pretty big and with the super farm turbo being small we didnt think it was gonna help alot cause the turbo cant really flow enuf air for the head/

lol  Im not nameing names but I will say you hit the nail on the head. And its funnay that his father in law More or less owns NTPA. or should I say owns WPI which owns NTPA