Projects 426 HEMI block guru

The mp is for the max wedge.

 

At first I thought it was Mopar Performance...

 

There was no mopar performance back then.

While the 426 mp was for sure a max wedge thing i wanted to look further into the mp for hemis. I called hemi joel. He has a real deal ro 23 car. I told him about this thread. It sounds like he will providing In-site. He did say there is evidence the mp stamp was used on the ro/wo cars. I Wil let him fill in the rest. I learned something new today.

 

I own an RO23 factory superstock car, and I have spent 15 years researching them. They made 55 Plymouths which were called ro23, and they made 55 Dodges which were called wo23. They both used the same engine. I can tell you that a normal 1967 Street Hemi is stamped CH426, but a RO23 or WO23 is NOT stamped CH426. HC426MP is the correct stamp for an RO23/WO23 block. I can also tell you that the date code on your stamped pad is Jan 23, 1967, which is correct for an RO/WO23 car. I can also tell you that my RO23 block has a casting date of 10-03-66. My block comes from a guy who said he knew the guy who took it out of an RO23 car, just like yours. Do either of us have proof that that really happened? No, but the evidence starts to add up. There are other experts who dispute the validity of the 10-3-66 casting date. But this info is hard to come by, and hard to verify because nobody paid attention back in the day.
But I can also tell you that I have a survivor Hemi 67 GTX convert, whose history is known back to 1972, and it is supposed to have all original engine and stuff. THis story is bolstered by the original, top, paint, interior, etc. The engine is supposed to be stamped CH426. But it says HC426MP. And it has a 10-3-66 casting date. The car has a VERY late build date, July 6th 1967. So it was the very end of the 1967 production run. Did they throw a left over RO23 engine in it? Probably. Did engines occasionally get this unconventional stamp? maybe. Did this car get an engine swap very early in it's life? (Unlikely) SO the point being, that a RO23 engine was stamped HC426 MP, but a block stamped HC426 MP is not a guarantee that it came from a superstock car. YOu need to look at all the available evidence. It sounds like you have found a rare piece of history, that should be returned to a real RO/WO23 car. I'm sure there are owners of these cars that want it badly.

SO here is what I would do if I was you: get the details of the engines history in writing and signed from the previous owner, even pinpoint the car it was in if possible. Send the block to a reputable machine shop and have it cleaned, thoroughly magnafluxed, and the bores and deck height measured. Get all the info in writing, signed by the shop owner. Do not do any machine work, or welding or any corrective work on it. Leave that for the next owner. Then start seeking an owner of a legit RO/WO 23 car and sell it to them.Roll the $ into a more complete Hemi for your project. I think $5000 - $6000 or maybe more would be obtainable if the block checks out good. Excessive boring, decking, or any cracks really kills the value. The original bore was 4.250 and the original deck height was 10.720. Pictured are the dates and stamp from my RO23 car. PM me if you need help. Good luck, Joel

 

And thanks to RacerX for tipping me off to this thread.

 

Wow!...

 

Well damn.... ya know... sometimes I think I know what I’m talking about. Thanks for keeping me from proving to opposite Joel


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in pic 064639 [bottom rear of block casting] is that a roughly 1" crack in the cylinder
lowest in the picture? And what are those hammer-mark looking dents in the pan rail?
Strange place for a crack...

 

Sure does.... Bummer!

 

No, the top row of holes in the head use studs and requires a nut and washer to be torqued from the underside of the lifter valley.

 

Blowing the photo up I'm not sure that's a crack, I guess we'll soon know. Something funky on the pan rail though..

 

That's why I ask He thought he was getting a wedge motor. A wedge motor would have threads.

 

I believe that the "WT" on the #38 post means "water tested".

 

Correct, the wedge blocks are threaded and the Hemi uses through studs on the upper row of holes.

 

Probably due to a blown over threaded hole.... By peening around the hole, shrinks the diameter... And then re tap the threads to size.... I would have used a heli-coil....

 

That's it!! It's junk, I would be glad to come get it and double your money. Oooh Jiiiiiim. LOL

 

I use screw in studs for everything including oil pan mounting.....

 

Street and race hemi blocks used the same casting number. Race hemi blocks were dash 1 or 2 only. Which meant the casting mold was used the first and second time for these...much less core shift. Also race hemi blocks were square around the distributor hole where as street hemi ones were round like all other blocks. HC means high comp as race ones were somewhere around 12-1. MP means Maximum Performance. And WT means it did pass the water test. Gene.

 

Now days we use P.T. for pressure tested.... On aluminum castings anyway.....

 

No doubt its a hemi block. The question is what do you do with it since your original plan was for a wedge motor! Unless that block is cracked or has some other major damage you could probably get an easy $5000 for it and pay for your complete wedge motor.

 

even if it is cracked or wallered out at $50. it's worth sleeving... major internal cracking would be the only thing that would keep me from using it... a Hemi Deuce is pretty much as good as it gets
...now the question is does he have a pair of heads stashed away for another $50.?

 

Amazing about of knowledge all of you guys have. Thanks again for everything. I'l check the top head bolts and check on the possible crack. I don' think its cracked but never know.

 

As said, if you plan on selling it, have it cleaned properly and checked. Even if issues are found, the block is worth money to the guys that want correct vintage parts.
If you plan on building it, do the same then do some heavy research and budgeting. These are not cheap motors to piece together.
The top row of holes are through without threads. The heads have studs that go down through the bosses and have a washer and nut that attach from the valley area.
This pic is from
http://www.hemihaines.com/build-a-late-model-hemi.html
Plenty of other pictures and description of the stamps there

 

Rarely do I hope to see bad ass old parts go to a damn restorer, but this is one of those times. Trade that block for a bad ass ready to run RB big block and don't look back. Someone out there is absolutely drooling for that block.

And IMO, you should give the guy you got the block from a cut, he made you a hell of a deal on a very valuable part.

 

That sounds fair......

 

Gotgas, something like
https://www.racingjunk.com/Big-bloc...e=4&categoryId=5702&offset=30&from=category#1

 

http://board.moparts.org/ubbthreads...495638/cool-hemi-block-found.html#Post2495638