Is the ”new” cast of 427 zl1 block still avaliable, its on the chevy performance website and in the catalog, but I cant find any place to buy it?

https://www.chevrolet.com/performanc...aluminum-block

its part number 12370850

Thanks

 

Discontinued
oem-parts/gm-block-eng-12370850

 

https://www.karlkustoms.com/product/...num-big-block/

 

Not so nice price....wasnt it below 5000 at summit?

 

Maybe look at the Dart Big M aluminum block?

 

Hmm, what bore size is that?
But GM is GM 😀

 

Why do they gotta discontinue all the neat stuff?!

 

Why anyone would pay 5k for a block that will go 4.280 bore is beyond me......total "legend hype" piece.....what exactly is the point? Because it says GM on it....has a little bowtie cast on it? It isn't even "correct" to make a clone engine really......many changes.
Get a Brodix, Dart, or Donovan and spend the same money for a real block to make real power.

Jebby

 

So you can pay more money for an inferior product just because it is GM?

 

Some of us bought the GM block for the primary reason for having an aluminum block: Less weight on the front end. According to the Brodix, Dart, and Donovan websites, their aluminum blocks weigh 25-50 pounds more than the Chevy block. And "Real Power" is pointless when trying to get around corners quickly, and particularly useless when trying to brake for those corners.

If you're spending your time just going in straight lines, buy the aftermarket pieces. If there's a corner on your track, my preference is the Chevy.

Your money, your choice.

 

Wasnt the GM block cheaper then dart/Brodix?

 

I don't know. My only focus when I built my engine was getting mass out of the car, and all the other block alternatives were 20-50% heavier..

 

Are you limited by displacement rules? I see that the GM block is 26# lighter than the Dart M (110# vs 136#) but with Dart you can go for a 4.6" bore and 4.75" stroke (632 cubic inch) vice 4.3"x4.375" for the GM (508 cubic inch). The extra displacement would more than make up for the 26# weight savings and I can save 25# by going on a diet.

 

Ahhh... but thats a MASSIVE can ov worms to open up. Massive cubes (read: torque) can cause more problems than it cures when trying to out-corner and brake other cars... especially in a car as light as his. Jack his car 100 cubes and he'll need to jack just about everything else to keep the balance... 427 is still a big engine. I'd take the lighter block too.... IF... its solid. I just slogged through a goddamn 18-page treatise on Speedtalk about the perils ov aluminum blocks. I'm still gonna use one, but man... i'm gonna do my homework.

 

they have choices based on need.

https://dartheads.com/big-m-aluminum-blocks/

I just got one of the iron versions and it is real nice. Way better than the GM block it’s replacing.

 

No limit, but what's the sport of running an engine (632 ci) that is 50 to 100% bigger than the other guys on the track?
There's a wide variety of cars on the course during track days, and few things look sillier than rocketing down the straights, only to be passed in the braking zone or in the corners. On a road course you'll typically spend two thirds of your time in the corners or the braking zones, and horsepower does nothing for you there. A lighter car comes out of the corners faster than a heavier car, offsetting some of the horsepower "deficit", and doesn't have to slow down as much as a heavier car when coming into the corners. Lighter cars don't need as big (and heavy) of brakes as a heavier car does, and a modest size/hp engine doesn't need as much fuel capacity (ie: weight) to last the duration of each track session. As a couple sayings go, weight begets weight, and weight is the enemy.

As I mentioned earlier, if you're going in a straight line, big cubes and big horsepower will overcome the inertia of a heavy car. But if there's corners in the mix, that big heavy/heavier engine won't be earning its keep a good share of the time.

 

My GM Aluminum SBC Block sold across the parts counter was made by Schwartz Manufacturing. Wouldn't be surprised if they didn't produce the new ZL-1 Blocks. For what ever its worth my Engine Builder said its the first aftermarket block he didn't need to grind on to get every thing to fit.

 

Spending more to make less power.
Sounds like the story of my life...

 

Schwartz did the machining on the new ZL1 blocks also. (I don't know if Schwarts is involved in the casting or not.)

I don't remember the source (Chevrolet?), but I recall reading that Schwartz was similarly involved in the machining of the original ZL1 blocks way back when.

edit: Ran into an old picture of my block.

 

The ZL1 blocks used to be $5000 ten tears ago. Some of $1500 or so you might have saved buying a Big M block (talking aluminum here), could have been offset by the machine work required on the Big M. I have heard they need a little 'massaging'.
My ZL1 block was perfect out of the crate. My builder was really shocked that he had to do absolutely nothing to it. Schwartz Machine did indeed make them and they are a work of art in my opinion.

True enough it was limited in cubes but after you get up past 600hp/torque you are going to have to re-think the rear end of a C3 as was mentioned earlier. How much power does a 50 year old car really need?
Plus you are shaving 200 lbs off the front end. Fully built the engine weighed about the same as a small block.

It was an easy decision to make, especially if you are building a ZL1 Corvette or Camaro 'Tribute'. Its as close as you can get in that world, short of finding & using a really expensive vintage ZL1 block. Therefore the GM label is more valued than all the cubes a Dart can supply.

I can't disagree that a Dart could be built a little cheaper and made more powerful. But it depends on your overall goal and the vision of what you want to accomplish. Looks like the Dart has a raised camshaft location although the stock deck height would work in a 'vette.

It helps to already have a non-ac '69 427 big block car in your garage before you start.