cracked heads on a 426

[akintosyali]

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?

 

[drburke]

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-tech/a-guide-to-mopar-v8-cylinder-head-and-block-casting-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

 

[Captain Ralph]

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?

 

[jim rosenthal]

Should he even use alloy heads if he has an open cooling system? He is in fresh water.

 

[Captain Ralph]

Should he even use alloy heads if he has an open cooling system? He is in fresh water.

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.

 

[akintosyali]

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?

 

[drburke]

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

 

[akintosyali]

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?

 

[jim rosenthal]

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.

 

[akintosyali]

I would think you would want 426 Wedge heads, with 426 Wedge engine block. Esp since the valves are the same size.

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.

 

[Captain Ralph]

Larger valves will not hurt. The chamber size and piston top clearance are the concerns.
I'm not a Mopar guy so I'm not sure; Will the intake manifold fit the different heads?

 

[drburke]

Hi Akin,

In a broad sense, Chrysler made two blocks: the small block "A" block, and the larger "B" block.
The A has the distributor in the back mounted vertically, and the B has it in the front at an angle.

Later the B block (now obsolete) was supplanted with one with longer cylinders, the so-called "Raised B" which is what RB stands for.

It is used in the 383, 400, 413, 426 (Hemi and wedge), and 440 (I know little about the early 330, 350, or 361).

(The early A block similarly evolved into the "LA" is 273, 318, 340, and late generation 360.)

> Akin said:
> 1964-1967, 361/383 B/RB-series big-block, 2.08/1.60 valves, 73.5cc (not a wedge!)

In Chrysler nomenclature, everything *but* the Hemi or early polysphere (Red Ram) is considered a wedge.

I am not at all surprised they used that casting since as far as I know they are fully interchangeable and may just be what was on the assembly line.

The Max Wedge is a pretty special racing engine and *extremely unlikely* to be in your Hatteras.
https://en.wikipedia.org/wiki/Chrysler_B_engine

I used to drive a 426 Hemi with a RB and cross-bolted mains. It may be that the casting you have is two/four bolt (which I think some are) but since the year is right, I think it is original and not a concern.

DAN

 

[drburke]

Hi Akin,

> Why is my casting for a 361/383 block, when the engine is a 426 RB?
Because the 361 and 383 are also RBs which is fine

>Is it possible that the prev owner put something different than the original?
Possible but he would have had to blow up the original engines within the first year to have picked up 1964 castings, so doubtful.

>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?
No, I think what you have is the original and fine.

======
Regarding new head choice, as I said earlier the alloy heads do run cooler which helps avoid predetonation especially on a non-computer-controlled engine. (BTW, I think any cast iron head 383, 400, 413, 440 will work if you go that route, but really the new after-market heads are much better.)
Always possible to have corrosion issues as mentioned; just keep an eye on them. That said, a raw water cooled engine is more likely to be too cold so that benefit may not be realized.

But use good head gaskets to prevent differential expansion/contraction issues.
https://www.cometic.com/applications/automotive/chrysler/rb/426-wedge--426ci70l-v8
(The Cometic MLX use stainless shim layers which would be good for a raw water engine.)
Also, while you are in there, change over to ARP studs for the same reason.
https://arp-bolts.com/kits/arpkit-detail.php?RecordID=459
(Using head studs instead of head bolts improves the clamping load.)

The new aluminum heads seem to have bigger intakes, which is okay for wide open operation but slightly less torque (potentially) depending upon your intake.

The slightly smaller exhausts don't bother me; there have been enormous strides in flow simulation and clearly the alloy engineers have something in mind--I bet they flow significantly better than the original cast items.

The combustion chambers should definitely be the larger ones, which is a significant concern. Your engine will operate in a high-output low speed regime almost all of the time. The older 73 cc heads theoretically deliver better compression and performance in general, but our fuel octane is *much* worst (lower) than when those engines were designed so you are far better off with the 84-85 cc ones for longevity.

DAN

 

[akintosyali]

Hi Akin,
>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?
No, I think what you have is the original and fine.
combustion chambers should definitely be the larger ones, which is a significant concern. Your engine will operate in a high-output low speed regime almost all of the time. The older 73 cc heads theoretically deliver better compression and performance in general, but our fuel octane is *much* worst (lower) than when those engines were designed so you are far better off with the 84-85 cc ones for longevity.
...
DAN

Dan,
So, I looked at heads for 383 vs the 426 blocks, and you are right, the same heads fit both blocks, so the difference is CC, and valve sizes. This is the head that is closest to my current cc:
Edelbrock 5090.
https://www.autozone.com/engine/per...ock-performance-cylinder-head-5090/300702_0_0

It has slightly larger exhaust valves, - do you think it will be ok?
2.14"/1.81 vs 2.08/1.60

Regarding the head gasket, with raw engines running cooler, do I really need the multi layer (5 weeks to produce) or can I use the stainless marine gaskets I already have at hand?

 

[drburke]

Hi Akin,

I think for this application (vs some all-out performance balance thing) the new valve sizes are fine in my opinion.

And sure, use the SS gaskets you already have.

Previous commenters are correct about the raw water engine being cool, so I may be imagining a solution to a problem you don't have

Looks like you are getting close to a solution, but I am no expert so get lots of confirmation checks from the manufacturers.

A little less compression from the 84cc head may be a good idea for low octane pump gas, but see what Edelbrock says...

DAN