Tall deck blocks aren't rare, at least around here. Look for 'em in 2 ton and bigger trucks, school busses, etc. The easiest way to tell is to check the distance from the top water pump hole to the deck of the block. If it's about 1/2" or so, it's a standard/passenger block. If it's more like 3/4", it's a truck block. They use 2 thermostats as well, makes for a screwey looking t-stat cover. They're ALL 4-bolt blocks.
They're not worth the hassle when you consider you'll be limited on selection of intake manifolds and possible header fitment issues, IMHO. On a drag car with less hood and clearance restrictions, they're fine.

 

[QUOTE=gkull;1562949013]It works out to 525 cubic inches.

The bad is that the engine is undersquare. When you go through all the calculations to determine redline, you discover that the long stroke really starts to become an issue, causing extreme stresses to occur to the pistons at about 5500 RPM. Those same forces will also start causing piston rings to flutter at around the same same.

The good is that the extra stroke will create enormous torque values from off-idle all the way to the redline. I'm already looking at Comp Cams, Crane and Lunati, to find a good cam that'll make the flattest torque curve available, since this won't be a high-winder. Hoping to find something that'll fit the band, but idles like a stocker.

As to the grinding, I don't really know, yet. It LOOKS like it'll just about drop into place. The 427 crank had an easy 1/2" of clearance all around the block, when I examined it before disassembly.

Right now the block is at the shop, and while I have been acquiring parts as quickly as my budget (and wife) will allow, I don't have the lower rotating assembly yet, since the magnaflux on the block is not yet complete.

The ultimate goal is to have this *appear* to be a generic BBC that could be passed off as a 396 or stocker 454, until you hit the gas... It shouldn't be too difficult (except for the intake manifold), since the engine will never see sufficiently high RPMs to require things like a roller-cam, stud-girdle, heads with monster-sized ports, etc. Keeps things simple... and CHEAP.

 

[QUOTE=breathial;1562951091]All those piston speeds and crap are 35 year old BS. That only applies to stock junk metal parts. Drag racing 4.750 stroker motors often spin over 9000 rpm. I was able to run my 4.25 "lower budget" 509 ci BBC at 7600 rpm for two hours at a time in endurance boat racing producing about 1000 hp.

Your lower rpm idea will definately last longer. I've worked on few of these 4.25 stroker 496 and 509's and I really can't see any additional room for a 4.5 stroke. Maybe small rods and bolts with the lower water jackets filled.

 

[QUOTE=gkull;1562951389]Don't hold back, bud... tell me how you FEEL...

As I said, this is my first stroker motor, so I'm learning as I go. Given that, I try to research everything as much as possible, before I lay out the dough, to buy parts that, should they not fit, or simply be beyond the capability of my skills to use, would put a serious hurt on my cash-flow. In short, I study, to see what's been done, to make sure I'm not asking for the impossible.

Since I'm building this engine- and hopefully a few more- to make extra dough to buy another *nice* Corvette, reliability is going to be a huge factor.

I don't want the guy to tear the motor to pieces, because I put a cam in it that would spin it up beyond it's limitations, sacrificing long-term reliability. If the guy who buys this engine wants to shell out additional $5K for a roller valve-train, huge cylinder heads and King Demon carb, then that's his choice. But at least, if they break it, I won't have to eat the cost of pulling the engine, and building it again.

Actually, your point gives me a great level of comfort- my combination will be *over*-engineered, with regard to strength. I find this comforting, because I know the customer will be satisfied, and won't be complaining that I put poor-quality parts in, or that the motor threw a rod, three weeks after I did the install.

JMHO.

 

[QUOTE=breathial;1562951575]
Please enlighten me. What kind of rotating kits or crank is this going to be using?

 

[QUOTE=gkull;1562952384]Since you've already built stroker motors, I doubt I will "enlighten" you...

Eagle 4340 H-beam rods, 6.7"
JE pistons, 1.27" C.H., flat-top w/3cc valve relief
4340 4.5" Eagle crankshaft

Not going with a "kit," per se, since I can buy the parts independantly for a lot cheaper, from various suppliers, have them all balanced together, and still have less $$$ tied up in the deal.

The only real concern I have (at the moment) is whether the rods will clear the cam. But the bottom end of this block is absurdly roomy, so I doubt I've have a lot of grinding to do, to clearance things.

 

[QUOTE=breathial;1562957324]The reason I was asking is because I have not heard of anything bigger than 4.25 in a stock block. So I went out to all kinds of sites and every 4.5 I came across was for the larger Merlin & dart blocks. I'm going to go down to the shop Sat. and look at this 496. I know that the piston skirts were barely clearing the crank throws. But I will look again.

Maybe they have come up with a smaller throw crank

 

Are you saying that the merlin and dart blocks aren't built around the same size of the stock 10.2 deck blocks?? It would seem odd to me that they would build it differently..

 

BTW, if someone in the Memphis area is looking for a tall BB, I've got a couple I don't need...

 

It is not the deck you have to worry about. It is the bottom of the block. Aftermarket blocks are made physically larger to accomodate stroker cranks. They don't use stock pans. I built a race motor years ago using a stock block. The big aluminum rods hit on both the lower inner cylinder bore and the outer pan casting. It was a PITA to clearance it. Now you just buy a Merlin block and you don't have to worry even building a 585 ci monster

 

I am find this thread very interesting as I have never built a stroker BB. I have built stock block 454's and love BB's. This infromation on the tall block appealk to my posibie idea of installing a BB in my '80.

I was considering an LS and just cant come away from the BB idea.

Thanks and keep the info flowing

 

A 496 is absolutely no problem with a 454 block.
Scat sells assemblies pretty cheap and they're pretty good.

If you want something bigger I'd avoid the hassles of the tall block
and get a 502 or get a Dart block to build a 540.

 

[QUOTE=gkull;1562962311]I did some asking around, talked to a guy who builds these. He told me that the 454 tall-deck block has bigger rod-clearance notches in the bottom of the cylinder walls than the 427, but that the only thing really necessary is to increase the size of the notches to clear the longer rods.

I imagine this will be even more important, when using the 6.7" rods. I'm doing this, of course, to give a slightly better rod/stroke ratio. With 6.535 rods, the ratio works out to 1.45, with 6.7, it's 1.49. IMO, it doesn't make a great deal of difference, but since the cost is pretty much the same, regardless of which rod size I use, better to go with the longer rods.

I know the 496 is the common combination, but since I'm sitting on a tall-deck, my attitude was, "why NOT?"

As to the question of Dart or Merlin blocks, well...... That's fine, for somebody who's gonna' spin an engine up high (like yourself, for example), but I'm taking this approach with a simple mission: to build the biggest, strongest engine possible, with a cash outlay of ~$3000. NOT an easy thing to do, and I think it's gonna' be more like $3500 by the time all is said and done. This budget limit is imposed by

1. My wife. When you have a stay-at-home mom who is also a skilled accountant, your spending choices are seriously compromised.
2. My often-bloated ego. I think it's cool, taking on the challenge of building a real-world, completely streetable, mild-mannered big-block, that will get it ON when you want. But to do this, without breaking the bank (and getting noticed by "she who MUST be obeyed? )??? Now THAT is a challenge!



An example of weighing choices: a tall-deck Merlin intake manifold is $315 +s/h. If I choose a standard-deck intake, I can pick one up cheaply via Ebay. But then I have to include the cost of spacers, extra gaskets, and an adjustable-collar distributor. I'll go with the Merlin intake (sorry, I'd said on a previous post that I'd use Dart), because the total cost of the new intake is much lower than a used one, plus spacers and adjustable distributor.

 

An excellent way to lighten your rod/piston weight too.