Machine shop called. I have cracked head on my 426 Chrysler.
Current heads are cast iron, but most new replacements are aluminum. I am assuming I should stay with aluminum, but is there a strong case for not using aluminum?
It looks like the wedge blocks come in 2 different combustion chamber sizes. 75 cc and 84 cc. Any tips on which chmaber sizes were used on our models?
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Thread: cracked heads on a 426
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09-21-2021 05:32 PM #1Senior Member
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cracked heads on a 426
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09-21-2021 05:54 PM #2Senior Member
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Re: cracked heads on a 426
Hi Akin,
Long time, no speak! Hope you are well.
This is a table of casting numbers with chamber sizes which may help:
https://www.enginelabs.com/engine-te...sting-numbers/
Regarding cast iron vs aluminum, I think the general thinking is that the greater expansion-contraction of the aluminum means that you certainly will invest in good multi-layer head gaskets (MLS).
Aluminum can run a greater advance since the chamber stays cooler due to better conduction.
Cast iron can be repaired at a really good shop; probably there are some in Chicago/Gary. There is an exotic heating and cooling procedure that permits some welding--I have had this done for a different application.
DAN
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Re: cracked heads on a 426
If you have a closed cooling system, I'd go with the 84 cc.
Low octane will run better.
What was the chamber size in the cast iron?
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Re: cracked heads on a 426
Should he even use alloy heads if he has an open cooling system? He is in fresh water.
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Re: cracked heads on a 426
That would be a tough question to answer.
Mixed metals in a real fresh water environment may not have the issues that salt water can induce.
In an uncontrolled cooling system (thermally speaking), it may be better to fix or replace with iron heads still.
As commented on already, There are good cast welders out there.
There is a shop in Jax that did block and head work for me long (LONG) ago on my Chevy blocks. There were some heads that they just could not fix but they would find replacement heads for me and match them up to what I needed.
Pending the budget may be the further force behind these decisions also.
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09-22-2021 11:09 AM #6Senior Member
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Re: cracked heads on a 426
For clarification, these are raw water cooled engines, in fresh water.
I had not heard of Multi Layer head gaskets. Is that a different type of head gasket or simply multiple head gaskets on top of each other?
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09-22-2021 12:07 PM #7Senior Member
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Re: cracked heads on a 426
They are the second thing: multilayer but with several thin steel shims inside.
The idea is they are supposed to be a better seal under head movement...
DAN
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09-25-2021 01:14 PM #8Senior Member
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Re: cracked heads on a 426
The machine shop said that there are multiple cracks, and while they could fix it by pinning, they said that the cost would be extremely high based on the number of the cracks.
The casting number on the heads is 2406516
Thank you for the link to figure out what this means,
1964-1967, 361/383 B/RB-series big-block, 2.08/1.60 valves, 73.5cc, 300L
Question 1:
-Why is my casting for a 361/383 block, when the engine is a 426 RB?
-Is it possible that the prev owner put something different than the original?
-The better fit would be: 2406518 – 1964, 426 B/RB-series big-block, 2.08/1.88 valves, Max Wedge, 86cc. Should I get this instead of what I have there now?
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Re: cracked heads on a 426
I would think you would want 426 Wedge heads, with 426 Wedge engine block. Esp since the valves are the same size, if I read you right.
I think I would try to find a set of good castings and have a machine shop go through them, as opposed to using alloy heads which are new.
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09-26-2021 03:25 PM #10Senior Member
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Re: cracked heads on a 426
That is the issue I have:
the casting on the block is :2406730: So this confirms I have a 1963-65 426 RB Bigblock wedge/Maxwedge block.
The casting on the headers are 2406516. Based on the link from DrBurke, this is for a
1964-1967, 361/383 B/RB-series big-block, 2.08/1.60 valves, 73.5cc (not a wedge!)
Instead, it should have been:
2406518 – 1964, 426 B/RB-series big-block, 2.08/1.88 valves, Max Wedge, 86cc
There are NO cast iron replacement heads. The only thing I can find is replacement aluminum heads.
Replacement options for a 1965 wedge engines are:
Edelbrock E-Street Cylinder Heads for Big Block Chrysler Part Number: 350-5090
Port Volume: 210cc/70cc, 75cc Combustion Chambers, Valve Size: 2.14"/1.81" OR
Edelbrock E-Street Cylinder Heads for Big Block Chrysler Part Number: 350-5093
Port Volume: 210cc/70cc, 84cc Combustion Chambers, Valve Size: 2.14"/1.81"
The first head is closer to the current heads for cc volume. The second one is close to the cc of a wedge, but neither replacement head has the same valve sizes.
I am stumped! Any advice would be highly appreciated.Last edited by akintosyali; 09-26-2021 at 03:36 PM.