GM big block question- what is this?

So, I got a lead on a 454 engine that's just kind of sitting in a garage. The seller knows nothing (bought at an estate sale) and neither do I.  I'm fully intending to do some Google-Fu on it, but you guys can probably answer the question within minutes.

The problem is that I couldn't find a casting on the block, which was laying on its side. I'm guessing the cast mark was on the face down side and well, I wasn't going to risk a hernia trying to move it. It looks like it was put together and never saw an installation: the heads had grade 8 bolts with shiny washers and absolutely no traces of oil. Plenty of spiders, though. 

The markings I could see were:

7.4L

IV Hi-perf

455 (backwards)

The heads it was wearing are 353049

Pictures included. Sorry for the Craigslist quality, it was pitch black in there.
 

The seller also has 2 A11 MR2s, an IROC Z with a Corvette engine in it, a Corvette, and a Porsche 928 that looks like it was driven into the garage and left there. There is a bunch of other stuff, too including the house all this is at, so he's liquidating a lifetime of stuff he's collected. I'm not even going to say how much he wants for the engine, but I'll certainly get a receipt. 

Those are GOOD HEADS

I was looking in the wrong spot for the casting number. Crap.

Any idea what he wants for the 928?

Well, not sure if it is a Pontiac or a Chevy engine at this point, since I was looking in the wrong spot. Patrick says the heads are good, and it has some kind of Weiand intake on it. For the price he said, it sounds like this is worth picking up, even if I don't wind up using it. I have visions of transmissions or differentials just disintegrating into scrap.

I can ask, Cotton. It's dusty, but appears complete and not rusty.

928 bodies are aluminum, they don't normally corrode like steel.  They're also so complex that this might be one of those times where rust repair would be preferable to about anything else on the car.

Doubtful it's a Pontiac. I've never seen those numbers on a Poncho engine.

A picture of the actual engine would solve it right away. They're about as different as can be.

343049 are early 70s big bock Chevy heads so if those are bolted to it, it's a Chevy motor. They won't fit anything else.

Those might be good heads but more than likely they WERE good heads 50 years ago and now they flow pretty poorly compared to 454 Vortec heads that can be gotten in a junkyard.

The backwards numbers are 445 not 455. 

Brett_Murphy said:

I can ask, Cotton. It's dusty, but appears complete and not rusty.

Yeah,  I’m always up for something German and overly complex.  If you don’t mind asking I appreciate it. 

Brett_Murphy said:

Well, not sure if it is a Pontiac or a Chevy engine at this point, since I was looking in the wrong spot. Patrick says the heads are good, and it has some kind of Weiand intake on it. For the price he said, it sounds like this is worth picking up, even if I don't wind up using it. I have visions of transmissions or differentials just disintegrating into scrap.

People run TH350s behind 500+ci drag engines because they have less losses than TH400s and in some cases having three gears is quicker than using a Powerglide.

You be fine.

Even without casting numbers, telling a Chevy from a Pontiac is simple.  Chevys have canted valves, Pontiacs (and Buicks and Oldsmobiles) are inline.  Pontiacs also have the most spitefully bad exhaust port layout ever devised if you want an engine that is easy to work on and/or looks good.  You can tell a Pontiac that never gets driven except for idled off the trailer into its spot at the car show:  The paint isn't burnt off of the heads.

the 049 head is one of the better heads,very similar to the 781 head about 122cc CC.

THE CORRECT BLOCK NUMBER IS ON THE AREA WHERE THE TRANS BOLTS ON  THOSE NUMBERS CAN BE LOOKED UP UNDER MORTEC / GOOGLE .

MOST OF THE TIME HI PERF. MEANS IT IS 4 BOLT BLOCK BUT NOT ALWAYS. IF FROM A CAR IT COULD BE 2 BOLT ,IF FROM A TRUCK LIKELY 4 BOLT. ONLY SOME LATER MK.4 BLOCKS WERE 454 4 BOLT THAT WERE IN TRUCKS MOST TRUCKS GOT TRUCK/TALL DECK 427CI, iDO HAVE A TALL DECK 454 FROM A BOAT/MERCRUSIER THAT IS FOR MY NEXT CHALLENGE CAR. THIS BLOCK ALSO WAS USED IN THE LAST BB454 IN SCHOOL BUSES.

GTXVette said:

the 049 head is one of the better heads,very similar to the 781 head about 122cc CC.

THE CORRECT BLOCK NUMBER IS ON THE AREA WHERE THE TRANS BOLTS ON  THOSE NUMBERS CAN BE LOOKED UP UNDER MORTEC / GOOGLE .

MOST OF THE TIME HI PERF. MEANS IT IS 4 BOLT BLOCK BUT NOT ALWAYS. IF FROM A CAR IT COULD BE 2 BOLT ,IF FROM A TRUCK LIKELY 4 BOLT. ONLY SOME LATER MK.4 BLOCKS WERE 454 4 BOLT THAT WERE IN TRUCKS MOST TRUCKS GOT TRUCK/TALL DECK 427CI, iDO HAVE A TALL DECK 454 FROM A BOAT/MERCRUSIER THAT IS FOR MY NEXT CHALLENGE CAR. THIS BLOCK ALSO WAS USED IN THE LAST BB454 IN SCHOOL BUSES.

I was once told by an old guy that all bbc are stamped hi perf except the tall deck medium duty truck blocks, but don’t know if it’s true.

there’s a post on nastyz28 with someone claiming those heads are on par with edelbrock aluminum heads as far as flow goes.  I just know those are one of the good ones.  I don’t know where you’re at but i’d be interested in it if you get it home and then decide it’s too(heavy, old, torquey, expensive) for you to use.  

Trans_Maro said:

Doubtful it's a Pontiac. I've never seen those numbers on a Poncho engine.

A picture of the actual engine would solve it right away. They're about as different as can be.

343049 are early 70s big bock Chevy heads so if those are bolted to it, it's a Chevy motor. They won't fit anything else.

Those might be good heads but more than likely they WERE good heads 50 years ago and now they flow pretty poorly compared to 454 Vortec heads that can be gotten in a junkyard.

The backwards numbers are 445 not 455. 

Thanks, Trans_Maro, that's great information. Being a Japanese Car fan (rotary sub-class) for so long I'm short on traditional American V8 trivia. I'm going out there Sunday to take another look at the engine.

TRUTHFULLY THAT'S A GOOD HEAD FOR AN ENGINE OF THAT SIZE, any thing larger in the intake port will make the engine lazy untill it's at it's maximum rpm, so though old just right . if you had a 500 inch engine you still don't use anything over 320 cc port UNLESS you are lookng at 700 hp and up. aluminim has a lot of advantage but get pricey, the Eddie's are really still fairly small and work well on the street.

I'll be out there tomorrow afternoon to try to get a look at the actual casting numbers. I plan on snapping pictures of the other cars on the property so that I can post them in a thread in case anybody is looking for something he has.

 

You should put that motor in a RX8 and then post a build thread on that RX8 forum.  It'd be GREAT.

No way it would fit in an RX-8. Though a GM LV3 would be right at home in one, and might be better than a V8.

Hi Perf doesn't mean anything really.  GM cast things using mix-n-match cores.  They change the part with the casting number but the nickel content, the Hi Perf, 2 or 4 bolt, etc happen during machining, not casting.  I remember the craze where everyone wanted an 010 SBC because of its high nickel content, until a GM foundry worker spilled the beans.  There are some exceptions, for instance block 10237300 is believed to always be a 4-bolt because it was designed that way as a 502 ci application.

049 heads are very good heads for being old school.  They are oval ports (as opposed to the smaller peanut port or larger rectangle port).  The oval port is a good compromise of flow and velocity and they are about as good as you can do on a BBC without going aftermarket.  Rectangle ports are just huge and aren't really necessary until 500 hp.

The IV means Mark 4 (4th generation 1965-1974).  It could be a 396, 402, 427, or 454, but the 049 heads suggest 71-74 unless they were replaced.  Also, don't be surprised if you pull the other valve cover and discover 781 heads.  They are so close to identical that Chevy sometimes grabbed one or the other for the same assembly.

get some casting numbers and we'll dig deeper

Mark IV bbc went to 1990 in USDM trucks.  

In reply to Patrick :

Oh yeah... I was thinking cars.

Here is the casting number. The picture isn't great, but eyeballing it in person, it seemed to read 14015445



Now that I got the right casting number, it seems to be a 1978 - 1987 short deck block with either two or four bolt mains. No way to tell unless I pull the pan.

The cast number, early heads and brand new looking grade 8 hardware seem to back up that it was a custom build that never got put in anything. I think I'm just going to pick it up. 

Thanks for the help. More comments and feedback are always welcome. I'm going to start another thread on the other things.

Don't stress about 2 or 4 bolt.  You don't need more than 2-bolt unless you're going big power.  There is also something to be said for the fact that 2-bolt mains are cast with more meat in the main webbing, so the order of weak to strong goes: 2-bolt, 4-bolt, and finally a 2-bolt machined for 4-bolt caps.

But, as mentioned before, unless you're going beyond 500 hp, don't worry a second about it.

The 049s have large-ish chambers that don't really promote flame front propagation or quench, but that is pretty true of most BBC heads.  Not quite as bad as a Hemi, but not ideal.  Focus on hot spark with an aggressive timing curve.  You may need domed pistons to get the compression you desire, but try to keep it to a minimum.  Domes kill flame front speed requiring even more ignition.  The short story is, BBCs aren't very detonation tolerant.  Capitalize on the good flowing heads, tune it for what you want knowing that you may need 89 octane sooner than you would expect.

Four bolt will really only be a resale point. I don't want big power, it would be a street/strip kind of build. Hell, I may not even use it. A well developed 350 or LS1 would probably do everything I want for a street driven truck.

I mainly just don't want this thing sitting in a dark shed and having the OPTION of using it is a good option to have for now.

In reply to Curtis :

Aggressive is right.  I remember one of the first street-type BBCs that I had to work with.  Was told to "set max timing at 46 degrees".

What.

"46 degrees, it'll be fine on Sunoco 94, it's only a 12:1 motor."

What.

It was fine.

Meanwhile the Kaase-headed Ford I am working on right now is very happy at 28 degrees.  Much faster burning chamber than 70's-era open chamber smog stuff.  (Same for LS engines)

My 468 I built with 049 heads was at 8.7:1 with a 198/204 cam.  Mechanical was locked at 36 degrees with another 16 from manifold vacuum.  If it was fully hot and I started it when the ambient temps were above 90, it would sometimes kick back a bit....

with 36 initial degrees of timing.

Aggressive is an understatement