434 stroker

[54Caddy]

i have a stock 400 sbc. Thinking of stroking it out to a 434. Ive read many threads saying its not a good idea with the stock block but have read some that are using a stock block with no problems. Any one on here own a engine machinest shop have some input let me know. thanks

[djracer]

I don't own a machine shop but stock 400 blocks are WEAK! I wouldn't spend big money on a stroker setup and put it in a stock block.

[dbmx66]

if your on a budget get one of the dart SHP blocks, the sbc block can be bored and stroked up to a 455ci.

there cheaper then the normal dart blocks, but still a very reputable brand.

and if you wanted to get a good block, get the little m


from what i hear, world and brodix make good blocks as well.

[Marv D]

I don't own a machine shop, but have built a dozen or more 434's and more 4" bore motors than I can count (both drivers and race motors)

The ONLY blocks I've ever broke are GM production 400 castings.

Just a few random thought about your build..... Take them for whatever weight you wish

First and without moving one inch forward,, have the block mag'd and sonic checked. KNOW that after your done with the machine work your going to have a sound platform, cylinder walls, and a block deck that is going to tolerate what your throwing at it.

+.030 over in a GM production casting is max target,, +.040 ONLY if it just took a fuzz more to powerhone the bore to perfect! Were not talking about a very substantial cylinder wall to begin with. Add 4 decades of rust to the back of the bore, and an era when coreshift and production tolerances went out the door at GM,,, (in favor of production) so bad that you can see the problems with your naked eye. Bore with as much reservation as possible. The stock short rod 400 put a lot of wear on the (looking at the front of the motor) top left of the bore, and bottom right causing it to wear in a "S" pattern. Getting it back round can take BIG cuts at the boreing bar. Don't go there. It's not worth it.


One thing that will help if your determined to use the casting you have,, build a 420 (3.875" stroke rather than 4") I know the little 1/8: stroke difference doesn't seam like much, but when you start grinding away at the bottom of the bores,, 1/16" smaller swing will seem like 10! Plenty of guys making HUGE power numbers with the 420,, it's not the extra 1/8" stroke that makes or breaks the combination, it's the heads!

Weigh the options. Two times I was foolish enough to dump a bunch of cash into a production 400 casting. The first was for a friend,, he convinced me to build him a 406 (lent him a set of AFR heads I wasn't using). It ran fine for a couple of years,, put the car solidly in the high 10's. But when she went, she went big. Cost me $400 to weld, repair, and fix the heads up so they could be sold. NOTHING else in the motor was salvagable.
Fortunately the second time the deck failed and the cylinder pressure was lifting the head,, the head studs lifted the deck and had spiderweb cracks from the bolt hole to the edge of the bore. That's a real common failure when the stock casting is put to the limits (above 500HP) That was a 509 , 2bolt casting I had spent a buttload on adding splayed mains, epoxy filled, align bored, deck trued, stress plate honed,, a BIG WASTE of CASH!!!!

In the end it's your choice. I've built 434's in Motown blocks, in the SHP (which presents it's own challanges) and the Little M. The Motown had some bad internet reputation a few years ago, but this block has been rock solid for almost 8 years of mid 9 second ET's. The Little M is probably a superior piece IMO, but about $300 more than the Motown. The SHP is only available in 350 mains, so your buying a crank that is not mainstream,, adds a bit and takes some of the price advantage away from it over a littel M,, but still a hell of a block.

What's all that saying about your production casting..... Is it worth risking a bunch of money invested in a rotating assembly by using an inferior casting??? If it is to 'you' ... Go for it.

Myself,, I'm done with the production junk. There are too few good cores left to choose from,, you grab what you can get these days! I'd rather spend the $1400 simply for the peace of mind knowing that is one part that 'probably' isn't going to fail and cost me everything in the motor (again). Actually, if you shop around, some shops that stock them have them 'left over' from the economic slump at the 2010 price of $1299,, in fact I just bought a Little M from a machine shop in Tucson for the 2009 price

[bigboybodry]

bump on the sock block info. I have bored one .040 and had water seeping in the cylinders.

[54Caddy]

dj racer and marv d ive read alot of your guys threads. good info on all of them. the thing is i just have this bare 400 block sitting and wanting to do something with it. if i build it, its not going to be a full out racer more of a daily or a weekend cruise. so if i use my stock 400 block is the 406 better? and how big of a stroker engine would you go with too be safe with the stock block or is a stroker in a stock block just a total waste of time, dont really want to buy an aftermarket block.

[Marv D]

Has the block been to the machine shop to be checked yet? That's step one. I went through 3 of them last time I started down this road with a GM production casting before I found one that was OK. (notice I didn't say 'good' LOL)!

[hotrod 80]

If you have to use the block 406 it is . I bought the crank , rods and pistons to build a 385 . Why ? I'll never do it again . Next time ill buy the block and have the cubes .

[54Caddy]

ahaha no it hasnt been to the shop yet just sitting here in my garage. will have to take it down and see what can be done. I just rebuilt the 350 in my truck but its not what i want. Maybe a cam and some aluminum heads will get the job done, what you guys think. Its a stock bore 350 with an rv camshaft 64cc cast vin x heads 194/150 edelbrock 600 cfm carb and an edelbrock rpm intake.

[nxtruck]

You could always stroke the 350 you currently have, making either a 383 or a 396, depending on the crank you use. A 3.75 stroke crank will make a 383 with a .030 overbore and a 3.875 stroke will make 396 inches with the same .030 overbore 350 block. Generally, the 350 blocks are stronger than the 400 blocks and will tolerate the extra power and stress a little better.
If you're not looking for huge power #s with the 400, as long as it checks good at the machine shop ( sonic-test, core shift, etc. ), I would stick with a 406 to minimize any reliability problems. I run a stock-block 434 right now and, while it has been trouble-free so far, I wouldn't build another 434 using a factory block.
Just my opinions...

[54Caddy]

yeah. i also have a 99 suburban engine, its a 350 roller engine. so many ideas but dont know which to choose from.