ya, can you turn a 305 into a 383? i know all it is is the length of the piston arms & a few other things....so can i do it? i've found kits for 500-1000 bucks. And i figure, if i can, why not..

I'd probably also have it bored 30 or 60 over.

Would i have to get new heads? If so.. would aluminum or iron/steel(whatever) be better/more durable/easyier to port & polish.

 

not possible to turn a 305 into a 383 the most with bore and stroking is a 337 I beleive and many will tell you thats not worth it. Prepare fro a flaming

 

lol, k, thx.. that's what i found out after looking thru google searches for awhile, :-).

 

Are the bores on 305 and 350 different? I read 2 differing texts on the matter - the latest one I read said that a 305 had a 3.74" bore and a 350 had a 4.0" bore - is that correct?

 

you are correct on the bore sizes and that without boring them over. Boring over doesnt raise the CI very much it is the length of the stroke is what significantly changes the CI

 

we had a big discussion on a similar topic and the general consensus was that if you had the 305 block bored and sleeved you could take it out to a 4" bore. Not that it is in any pratical nor do i think anyone has done it but it is "possible". Any way just get a bore kit - that would be a 350 block BTW.

 

a 305 and 350 share the same stroke, the bores are different... which is what increases the CI

 

OH DAN you still need to stroke a 350 to increase the CI to 383 hence the stroke is what increases the CI SIGNIFICANTLY.

 

And in the formula : Bore x Bore x Stroke x .7854 x Number of cylinders there are two "Bores" so that's going to make more of a difference than stroke unless, you figure the stroke can be increased more than the bore (I.E. 3.48->3.875 vs 4->4.060)

-Rippin

 

i see i opened a can of worms, :-).

 

what do you have to do to get a 383 out of a 350 you have to stroke it. Boring alone will not get you there. The equation is bore size x stroke distance x the number of cylinders. What is the most CI you can get when you bore a 350 .060 over is only approximately 360 Cu In wow a 10 CI difference now calculate that with a 4.00 stroke and see what ya get.

 

I you bore a 350 out to 4.185 you will get 383ci. The reason you get more cubes from stroking a 350 is that chevy made the blocks for more room to stroke than to bore. This ins't universally true. Some 283s can be bored to 302 and some 396s can be bored to 427. Shrug. On a 350 the max you can bore it to is 360. But put the 350 crank into a 400 blockthat is bored .060 over and boom all bore 383. THe same goes for a 400 crank in a .030 over 350... 383 cubes.

 

Ok, back to the original question...

You will need a 350 block as you know already, and a 3.75" stroke crank. You can either use a 400 crank and cut the mains down or get a crank made specifically for a 383 (probably the cheapest and easiest way to go). I think the cast 383 cranks from Eagle go for about $200. You can use either 5.7" or 5.565" rods (most common, but longer rods can be used as well). With 5.565" rods you can use pistons from a 350, but with 5.7" rods you will need "383" pistons.

I would probably be a good idea to get the block bored .030" to clean it up and get it honed w/ a tq plate. Also I would get the rotating assemly balanced. That's another thing, most 383 cranks are externally balanced so you will need an ext. balance flywheel/flexplate and damper. Internally balanced cranks are availible, but more exspensive. They allow you yo use a neutral balanced damper and flywheel/flexplate.

You don't have to get new heads, but I would reccomend it. A set of preped Vortecs are good for a budget motor, Iron Eagles are also nice, but a bit more. Pro Topline makes good heads that are very good for the price. AFR's are top of the line in my book, but they will cost you...

If you can get aluminum heads they allow you to run more compression and they are easier to port since aluminum is a softer metal than cast iron, but it also makes it easier to mess up. A little chatter from a carbide cutter will wreak havoc on an aluminum head. If using a cutter on aluminum you will need to keep it lubed with light oil to prevent chattering. With aluminum heads you will also need a gasket that does not brinnel (indent) aluminum.

Wow, that was a lot of typing... Hope it helps, anymore ?'s let us know...

 

No.... No its not.

its Bore Diameter (inch) x Bore Diameter (inch) x Stoke (inch) x Number of cylinders x constant (~.7857) = Cubic Inchs

 

Technically, displacement is the difference in the volume of the cylinder with the piston at the bottom of its travel minus the volume with the piston at the top of the cylinder, times the number of cylinders. Since the volume of the cylinder above the piston at TDC is the same at both TDC and BDC, it can be subtracted and hence the equation simplified.

Volume of a cylinder is area of the base time height. Translated, bore radius squared, times pi, times the stroke length. Times # of cyls = total displacement.

This "constant" to which you refer is pi/4 (which is closer to .7854). Hope you can figure out where that came from...

Now, does everyone understand why you can't make a 383 out of a 305 block? And, why you can't make a 383 out of a 350 block bored to 4.185"?

 

(4.185/2)^2*pi*8=382.95702172949812751411719655425
rounded to 383 to make it easier to digest. you're dumb

 

How to turn a 305 into a 383, in 3 easy steps:

• 1. Throw 305 block (3.736" bore) away.
• 2. Acquire 350 block (4.00" bore) and bore it .030", a typical maintenance bore.
• 3. Install a 3.75" stroke (400 stroke) crank, with the right combination of rods and pistons to yield a total rotating assembly height of 9.000".

There, not so hard, is it?

 

and if i bore a 4 cyl 3 inches over, its a 383 too!!


just because you can do the math doesnt mean its somthing that can be done in real life. its when people post stupid crap like what you posted in this thread that other people like anubiscougar get mislead in thinking they can make their 305s into 350s or 383s......

 

what is exactly so hard about putting a 350 crank into a 400 block with a .060 overbore? People do it all the time it is just usally with a .030 overbore. Granted the cracked idea about boring a 305 to 4" and sleeving it was bad advice but i stated so in my post. I also never said that a 350 could be bored to 4.185 (it can just not with a factory block). shrug.

BTW I need to apaligise for the late 2 words of my previous post. I was drunk and they are pretty inlfamitory.

 

Friends don't let friends post drunk...

Next time I'm gonna take away your mouse or something... lol

 

But I LIKE wild turkey. And anyway the mouse thing wouldn't work... I know hot keys

 

whoa... I dont know what ineed to get through this thread, high waters or a flame suit... maybe a little of both.

basic volume measurments...
volume of a cyl = pi*r^2
THEN multiply by the stroke of the crank
now, multiply times the number of cyls...in this case 8...
there is more then one way to skin a cat. both ways will net you the same answer. happy? And yes the 350 and 305 share stroke, but not bore.

 

whats hard about it? well as long as you can find a 400 block that doesnt have too much core shift you can do that bore.. (alot of them cant go out that far.... walls too thin in places)

matter of fact, i had a 400 that was .60 over.... wasnt a performance motor, but we wernt stupid, so we didnt take away cubic inches.


name one fuggin good reason you would want to destroke the 400.

and i mean in the real world, not theory. because i can make a 400SBC spin just as fast as your 3xx SBC... and make more power doing it.

 

and just FYI, the motown block can go out to a 4.200 bore with a .250" wall thickness remaining.
and a 4" stroke, with no clearancing.

 

That's the area of the base. You still need the height (stroke).

 

acutally pi*r^2 is AREA of a circle, not volume.

volume of a cylinder is pi*r^2*h

height is the stroke .

just a little math refresher

 

fixed her

 

Mr. Dude_1, "name one fuggin good reason you would want to destroke the 400.

and i mean in the real world, not theory. because i can make a 400SBC spin just as fast as your 3xx SBC... and make more power doing it."

I work with a guy that has circle track cars and he told me that the most ideal rev engine for power in a SBC would be a 377 which is a 400 downstoked. He has built a couple stroked 42x something or other and he said that they dont rev enough and dont come off the turns fast enough. Thats why he said he would like to build a 377. What you think. Dont bite my head off just what my buddy told me and he knows his stuff.

 

CI formula for a 350:

4.00 x 4.00 x 3.48 x 8

Multiply the CI by 16.38 to get displacement in CCs.

 

I was referring to a 305 and a 350, I suppose you can't read? I know perfectly well that a 400 has a bigger stroke than a 350, as well as my 327 which has an even smaller stroke than a 350.

 

Uh, no it isn't...