Here's the plan:
Yes I know a 350 is better.
350 4in bore block,
262 crank
I'm not sure on the rods and pistons yet, hopefully I won't have to buy something custom.
If so then I'll find something light, but I'm hoping to find factory stuff.
I've run some of the numbers on this but not the specifics, that's where you guys come in.
Make me proud.................

 

get a nasty valvetrain, and you'll be able to make that thing scream no problem. heh, i see an 8000RPM redline in your future.

 

Custom pistons. No way around it that I can see. Unless you get custom length rods.

And, it's more like 5.2 l (316.3 cid, 5.18 liter) with a .030" overbore assumed. 311.6 cid for 4.000", which is 5.1 liter.

 

I've been kicking this around for awhile, to do it right would mean a custom forged crank, but I don't have the $$ for that. So I'm stuck with a cast one.
How about offset grinding the crank and using small journal rods?
Unfortunately, while I've assembled a lot of engines, I haven't been invovled with the machining stages. I've just gone to someone that I trust and then check their work during assembly.

 

There's only a .1" difference between the journal sizes. You need to take .38" off the stroke.

Cheapest route would probably be a 3.00" stroke. Cranks & pistons are available off-the-shelf for that.

 

It's not going to work out. I'd need a (or feel more comfortable with) a 4bolt block and forged crank, because to get HP out of that, it's gonna have to be wound pretty tight.

 

Take a late model one piece rear main 350, take a 1994-1996 caprice 265 crank and rods. Rebuild the engine with factory 350 type pistons. The 265 rods are exactly 1/2 longer than the stroke change. The 265 rods are 5.94" long versus 5.7. The crank is 3.00" vs. 3.48. That means the rods are .24" longer compensating for 1/2 the stroke which puts the piston at the right place with the standard 350 compression height.

 

That might work, thanks.

 

I've already built the exact motor in my previous post. Put in a LT4 cam (not the hot cam). With a pair of 305 vortec heads on it, it is a screamer. I used a GM intake for their crate motors ($65 shipped to my door on Ebay). That whole motor minus the block was bought on Ebay. I am using a 750 CFM Quadrajet off of a 70s cadillac. Right now it has 2 1/4" outlet rear dump manifolds from a 1992 chevy van on it. I let a buddy borrow it for a few weeks until he could build a 350 for his firebird. Now that he has the 350 he wishes he had my 305(4.020" Bore, 3.000" Stroke) but still a 305. I am putting it into a late 70s to early 80s 2 dr Nova, Omega, or other GM clone. Backed to a six speed and a 3.73:1 rear it will be a fun little ride. I will be looking at 400 hp @ 6,300 and 320 ft/lbs @ 3,800 or so and a red line of near 7,000 rpm. In a 3,000 lbs car it will be the **** burner killer.

 

Spend more; work harder; get less.

Why?

 

400 HP @ 6,300 rpm = 333 TQ @ 6,300 RPM.

I suspect you will find it's TQ below 3,000 rpm weaker yet.

 

Spend more; work harder; get less.

Why?

Because the thought of running a 350 makes me want to puke

 

If you build that, I just hope you're the guy in the other lane next time I'm at the track. Because that way I won't have to worry about who's going faster.

If you're going to do that much work and spend that much money, I'd recommend accomplishing at least some kind of an upgrade, instead of a downgrade, to your parts.

In other words:make the right decision, spend money, work harder, get more.