History the 427 Mystery, mystery

So here's the deal, the other day I was bench racing with an old friend, we were batting around different engine combos that could be made, different transmission and rear combos you know the drill right? Anyway the GM 427 Mystery motor came up. Its not likely that I will ever have one to play with, but the question arose about the way that GM made 427" with it.

We both knew that GM used the 409 as its basic platform, and I finally decided that it was a punched 409. Well I have since thought about that and it occurs to me that they would have had to really punch a 409 to come up with 427" like around .125 give or take a little bit. And that doesn't set that well with me, logic wise.

So I know that some of you fellas are more versed in some things than I am, and some of you know things that I think I know. So tell me what you know and solve this mystery for me. Did GM bore and stroke a 409 or did they just stroke it or did they actually hog one out that big. hell did they really use a 409 block to start with or did they actually cast a new block.

Give it up fellas and learn me somethin'.

 

The 409 based 427 is called the Z-11. The 427 Mystery motor was a all-new motor design. Did you read the recent write-up about the Mystery motor in Hot Rod magazine??

 

When i was running my altered ('64-'65) I would often end up in the same eliminator bracket as a W motor Impala that was supposed to be 427 CID. The bore spacing must be the same on W motors and big blocks as I believe the cranks can be reworked to interchange. So I will go with a redesign of the 409 casting.

 

Nope they finally stopped sending HotRod to my house.

So what you are saying is that there was a 427" W motor and that the mystery motor was a complete new design?

 

Don't know anything about recent article (haven't gotten car mags in years) but Ray Brock had an article in the May '63 issue - As above the z-ll was 409 based with special heads/intake/exhaust and was stock bore with a 3.65 stroke - The Mark II Mystery Motor was the same bore and stroke but was mostly a Mark IV design (traditional combustion chambers, etc)

 

Benno...
I seem to remember Fred Hawthorne (remember the San Leandro guy with the black '59 'Vette? Fremont drags, thru the '60s, fastest shift around!)
Freddy was talking with a machinist (Vic Hubbard's Speed shop) who said it (427 'Mystery') was a dedicated block, all its own. Freddy said 'No'.
He went on to mention in balancing it, there was quite a bit of Mallory used.
I did NOT get a number on how many 427s were prepped there, just some 'little known facts'.

I did have a 409 at the time, with lots of stuff to get it into the 12s. ('63 Impala, Muncie, 4.56 posi, Jardine headers, General Kinetics 'cheater' stick, 2 'E' series AFBs.
Hours of port matching, the 12s were hard to get to then. Ha!
Bought a blown up '63 330 Dodge, 426 short ram wedge/Torq Flite...fixed it, then had a short trip into the high 11s! Liked it there...

 

Hey Benno,

Plagiarized from here: http://www.348-409.com/z11.html




The 427 was a modified 409 engine. The stroke was increased, special heads, valves and intake manifold were added. Fuel was supplied by 2-4bbl Carter AFB carburetors. A special cowl induction air cleaner was also used as shown below.

This car was all performance and no frills. You wouldn't find a radio or even a front sway bar. Most Z-11's were ordered with the heater delete option and no sound deadner. Light and fast was the idea with this car and to help lighten it, the Z-11 came with an aluminum front nose and other parts. Hood, fenders, front and rear bumper, front and rear bumper brackets and braces, grill brackets, a 2 piece riveted fan shroud, grill filler panel and hood support catch were all made from light weight aluminum making the car about 300 pounds lighter than a similar 409 powered production car.

To stop the car, sintered metallic brakes and special venting screens and air scoops in the backing plates for added cooling were used. All Z-11's came with T-10 4 speeds, a beefed up posi rear and a 4.11:1 gear ratio. (code JA)

Only 57 Z-11 optioned Impala's were produced and only 7 are thought to be in existance today, making them an extremely rare and valuable piece of Chevrolet history.

Although the Z-11 was made for racing, they weren't directly sold to race car drivers. Some ended up on car lots. And although 1963 was the only year for the Z-11, there were about 20 C.O.P.O. 1962 Impala's built mid to late in the year with aluminum front ends and equipped with 409's. These 409's had special features like the Z-11 intake manifold, special camshaft, heads, etc. There were also 18 extra sets of aluminum front ends made for that year and sold to race car drivers.

The base price of a 1963 Impala was $2774.00. Adding the price of the R.P.O. Z-11 option of $1240.00 to that brings the total price just over $4000.00 not including destination charges, taxes, etc.


Edit:
Boy are you guys fast! In the time I pasted the info in 4 responses!!

I just learned something new. Some cool further reading not 427 Z11 but the mystery 427.

http://www.macsmotorcitygarage.com/2015/02/04/inside-the-63-chevy-427-mystery-engine/

 

I vaguely remember some of the articles from the sixties. But I was thinking that the " mystery engine " ,while somewhat different, evolved into the 396, 427, 454 engines we normally think of.

Also wasn't there a 402 or 403 derivative that was mainly a truck motor?

 

Looks like someone beat me to it...

 

The 402 came from a bunch of bad blocks in the later '60s or earlier '70s, it was a punched 396 or so that is how it was related to me by an aging GM assembly line guy.

@Atwater Mike I do remember that guy. One of my thoughts about the porcine heads was that the W motor had a weird deck angle as well as the top of the cylinder being the combustion chamber. Seems like to add a combustion chamber would drop the compression considerably.

So many questions whirling around in my head right now, not nearly enough keys on my key board. LOL

 

Benno
Long time no talk.
I don't know if the exact answer to your question is here, but this the link to the HRM February article

http://www.hotrod.com/news/world-ex...963-427-mystery-motor-built-by-smokey-yunick/

HTH
Willy_P

 

Yes. There are 2 427 Chevy engines, different designs.

 

So the other 427 was just a big inch W motor, correct? I wonder how many of those are around, I don't think I have ever seen one.

 

Yes, in 1963, and it was referred to as the Z-11 and installed in 63 Impalas with Aluminum body panels for drag racing. A factory drag car.

 

The 402 Rat Motor found its way into some Monte Carlos and Impalas. In the Impala, it was labeled a "400", which means that Chevy had both a BBC and SBC 400 at the same time.

 

Chevrolet built 50 complete Z11 427 W-engines. These were all install in 1963 Impala 2 door Sport Coupes (non-SS cars). They all had aluminum hood, fenders and other parts. I've personally seen 1 up close and it was perfectly restored and awesome!! "Z11" is the RPO.

 

The 402 replaced the 396 for the 1970 model year. I kind of doubt it was done to use up old blocks, since they made the engine for three years.

The hot rod article about the Mystery Motor....I went to SEMA last fall, and made sure to touch that engine. Not many guys have.

 

Years ago, I built a 427 from a 454 block, 396 crank, and TRW L2238f's, that needed a slug of mallory in the front counterwieght.
and another "yes" on the 427 Z-11's.

 

During this time, Chevrolet referred to the BBC 402 as "400 - 4 barrel" and the SBC 400 as "400 - 2 barrel".

 

Some reading
http://hotrodenginetech.com/chevrolet-427-mystery-motor/
http://www.superchevy.com/features/sucp-0703-1963-chevy-biscayne-427/
http://www.hotrod.com/news/world-ex...963-427-mystery-motor-built-by-smokey-yunick/
http://hotrodenginetech.com/mystery-motor-development-engineer-bill-howell-tells-all/
http://www.hotrod.com/how-to/engine/ccrp-0611-chevy-mystery-motor/
http://www.macsmotorcitygarage.com/2015/02/04/inside-the-63-chevy-427-mystery-engine/
http://www.hotrod.com/features/rare-1962-chevy-mystery-motor-mark-ii-revealed/
http://www.superchevy.com/features/sucp-0707-1963-z11-impala/
http://www.factorylightweights.com/museum/9-uncategorised/92-1963-chevrolet-z11.html

 

Yep, I had one of 'em. A 71 Monte Carlo 400 4 BBL

 

Beaner was asking about the Mark II 427 Mystery Motor, not the 402.

 

I am far from a W-motor expert, but I believe the W-motors and the later MkIV BBC share the same bore spacing. There are several stroked 409-based engines that use a 454 type crankshaft, machined to fit the 409 bearing bores and crank snout. Going from memory, but I believe they can get up to around 480 cubes in a W-motor block.

Beaner, your memory is right, the W-motors do have a different angle on the deck, I think 72 degrees instead of the 90 used by most engines. The combustion chamber is in the block, the heads are essentially zero cc's with no chamber.

 

They did share the same bore and stroke but they also shared the same engine paint, too.

 

The 427 Z-11 and the 427 Mystery Motor were two different designed engines that happened to have the same displacement and were manufactured by Chevy at the same time. The Z-11 was the hottest and probably the final design of the W engines. The Mystery Motor was basically a pre production Rat prototype. Z-11 made their mark in drag racing. Mystery Motors were a NASCAR deal.

 

From the info I have the Z33 mystery was the same bore and stroke as the Z11 crank used the same bearings but the block had conventional 90 deg deck and heads very similar to the mark IV.

 

Local guy has a z11 car...Engine got stroked to 484 with a 454 crank..Last I heard he was getting an aluminum reproduction w block from some place down south..All the W engines had angled decks and heads that had no chamber..Ford MEL engine series were like that also, the 430, 462 and bigger ones in trucks into the 500 plus cube.....

 

FYI, a restored Z11 Impala is worth in excess of $250K and rising.

 

We are arguing semantics here. Do Z-11 heads bolt onto the Z-33 block? Of course not.Are the Z-33 and the Mark IV that followed a natural evolution of the Z-11/W motors? Duh!

 

Z11 427: