Help to ID very Strange 426 Wedge Block

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GTX JOHN

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I found this fresh 426 Standard Bore block in my late
friends Shop (Tri City Perf) along with a bunch of regular
426 blocks. Greg (RIP) was a top Max wedge engine builder
and racer for decades.

It has provisions for 4 bolt mains but does not have them.

It has a lot of support ribbing that I have never seen on any
block in 60 years. I have seen a lot including Marine/Industrial/Race
blocks but nothing quite like this!

It is very heavy compared to my other blocks and very beefy!!

Perhaps aftermarket or a factory race block?

I appreciate any help as I have a Giant shop full of his stuff
to identify and sort out! It is rather overwhelming for me
and I am not a novice on Mopar race stuff.

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Something I'd read from way back when... During the early days of restrictor plates on super speedways in the early seventies (sometime after the introduction of the Boss 429) it's said that some plate designs worked better with wedge heads, others worked better with Hemi heads. I'm guessing we're looking at a hens teeth early seventies NASCAR wedge block, with the ability of being set up for cross bolt caps. What's stamped on the ID pan at the front of the valley?
 
If 426 isn't stamped on the id pad I would be thinking it's a overbored 413, that looks to be a later production block.
That particular style block can almost always be bored out to a 4.320 & very easily bored to 4.250
 
It’d be nearly unbreakable with some main caps machined from forged billet aluminum to accommodate the cross bolts. Better yet… it also looks like it’d make really good use of the BCR girdle system with a little extra machine work on the three center bosses and adding cross bolting provisions to the center caps.
 
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Also, Chrysler did make an "industrial" big block engine block. It is casting number 2658836. These are sometimes referred to as "cold weather" blocks, such as on page 19 of Chuck Senator's "Big Block Mopar Performance" book from HP Books. The casting number on these can be hard to find, especially if the block is covered in rust and grime. It is across the top rear of the block, where the oil pressure sending unit would screw into. One part of the number (2658) is on one side, and the other part of the number (836) is on the other side.

For most applications, this block was used for their "Heavy duty truck or industrial 413" engine. This is the setup with the huge (5 bolt) water pump and housing and very large cylinder heads. These engines were used in lots of motorhomes, large (semi) type trucks and other industrial applications such as generators, pumps, etc. The water jacket cores (or what could be considered the "outer walls" of the cylinders) from these blocks were essentially those from a 440 engine. 413 bore size is about 140 thousands smaller than a 440, making these blocks essentially an "underbored" 440 from the factory. This results in the cylinder walls usually being over .400" thick on these engines. This means that these blocks can be bored out to a 440 size, and used as a 440. Once this is done, it results in standard thickness cylinder walls of .250" (quarter inch) thick, which is Chrysler's standard specification for cylinder wall thickness.

Although the vast majority of these seem to have been made into 413's we have seen some of these made into 426's from the factory (often in boats for marine applications) and VERY rare examples where Chrysler themselves assembled and stamped these as a regular 440 at Trenton. This may have been due to a shortage of standard 440 blocks, or the need to use up "old" inventory, or some other similar "keep the line running" type of reason.

Unfortunately, the internal main webbing and main cap setup on these is identical to a standard 440, not any thicker. This was a missed opportunity. Imagine if Chrysler would have increased the main webbing thickness on these, similar to how they did on the early "230" casting 400 block, and maybe even gone with the cross bolt main capped Hemi type setup. We would have had "somewhat" plentiful 1000 horsepower capable factory "440" blocks available.

Interestingly, some early examples of these actually do have the "cross bolt" bosses cast into them, indicating that they were thinking of doing this, but never went ahead with it. Or they may have been cast only to use in the super stock programs. But these early examples are extremely rare. It is likely only one or maybe a few early production runs ended up with the cross bolt bosses. We've had hundreds of these blocks (most all out of motorhome applications from the late 60's/Early 70's), and none have ever had the cross bolt bosses.

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GTX JOHN said:
I found this fresh 426 Standard Bore block in my late
friends Shop (Tri City Perf) along with a bunch of regular
426 blocks. Greg (RIP) was a top Max wedge engine builder
and racer for decades.

It has provisions for 4 bolt mains but does not have them.

It has a lot of support ribbing that I have never seen on any
block in 60 years. I have seen a lot including Marine/Industrial/Race
blocks but nothing quite like this!

It is very heavy compared to my other blocks and very beefy!!

Perhaps aftermarket or a factory race block?

I appreciate any help as I have a Giant shop full of his stuff
to identify and sort out! It is rather overwhelming for me
and I am not a novice on Mopar race stuff.

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Is there anything stamped on the vin pad? There is also mention in the Mopar Performance racing manual of a PN-3690030 block that was cast for Grand National use after the Hemi was dropped. The only problem to identifying this block is to find someone alive with a memory and a working knowledge of it. Also notice the reinforcing on the lifter bores. I acquired 1 of these blocks this summer and still have no definitive answer.

Randy
 
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