how big can you bore and stroke a 305...and a 350??? thanks

 

Usually about .060 over bore on either one is the limit. It depends on the block, though.

The stroke can be increased up to 3.75" with relative ease, or to 3.875 or 4" with some difficulty, again depending on the block.

 

ya .060" is the limit but if you go that big, make sure your walls are thick enough, when they are cast there could be inperfections which makes the walls different thicknesses in different places. i forget how you check but its done with some sophisticated tools like x-rays or something.

 

what i meant was what the biggest displacement in cubic inches...sorry for the confusion!

 

Well, do the math.

Bore squared, divided by 4, times pi, times stroke, times number of cylinders.

Stock 305 bore is 3.736". Stock 350 bore is 4.000". Stock stroke for each is 3.48". Pi is approximately 3.14159 (close enough for these calculations).

 

what i was gettin at was is the 383 the largest you can make a 350?????????

 

We're trying to teach you to fish rather than hand you a fish.

A 383 is a 4.030" bore by 3.75" stroke. If you can go to 4.060" and 3.875" stroke, then you can go bigger than 383, right?

 

im sorry..i didnt know how long you could stroke a 350! this has got my hopes up..and i have no idea what it would cost to get it bored?..ideas???
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somethin like a 401 that would be??? i hope my math is correct and does eagle or anybody sell a crank rod and piston set for that...with the long stroke and big bore??....thanks for all the help..

 

383 is with a 3.75" stroke.
As Apeiron mentioned, you can get a 3.85" or 4" stroke. I'm not sure if they will fit in a stock block though, might need an aftermarket block.

 

i think 400 is as big as you wanna go before your block becomes too weak. too bad you dont have an AMC engine, you can go to like 502 with their small block, its a special cast designed for bigger crank clearance and for better cylinder wall cooling.

 

They'll fit, but you'd be doing a whole lot of grinding and clearance work on the block. You'd almost certainly be into the water jackets, so the block should be filled first. Then you'd also need expen$ive pistons for those unusual combinations.

The 383 is popular because it was a worthwhile and cheap originally, using cast-off parts from 400s. Then because it was relatively easy to do as well the aftermarket started supporting it with parts, which made it even cheaper and easier and more popular.

Building a 350 block to a displacement larger than a 383 isn't easy or popular, and therefore isn't cheap either. Building a 305 block to a larger displacement isn't even worthwhile to begin with, so it's not likely that it'll ever become especially cheap to do.

 

so you're basically recommending a 383??

 

It depends at least partly on budget, and partly on what shape the existing parts are in when you rebuild. If you're doing a 350 and you already need a new crank and pistons, then there's no real difference in cost to buy the parts for a 383 instead. If your existing crank and pistons are in good shape and reusable, then if you're on a budget you might as well just rebuild it as a 350. Going any bigger than 383 just opens you up to a lot of headache$ that might not be worth the trouble to you.

Stroking a 305 block doesn't make any sense though, since the difference in cost between parts for a 335 (unpopular and therefore more expensive) and parts for a 383 (popular and cheaper than dirt) is usually about equal to the cost of the bare 350 core you'd need to build the 383, so for the same money you might as well build the larger engine.

 

a 305 can go to a 335.. for the 350, the best way to build would be a 383.. not too much work, not too expensive and just enough cubes to make a torque monster.. or an even better idea would just be to get a 400 block.. stroke that to a 434 and you have yourself a winner..

 

If you're gonna go 350 -> 383, step up to the fully balanced
aftermarket crankshafts. Futzing with the stock 400 externally
balanced crankshaft, harm. balancer & flywheel/flexplate is a
royal PITA.

 

If one was to go to all the work of machining, balancing, honing, porting, grinding, fabricating, ie: putting any time into a 350 to make it a 383, why not just get a 400 and work from there? I'm sure it couldn't possibly too difficult to put a 400 in one of our cars.

 

i've got a 350..thats what i got to work with

 

a 400 has the same external dimensionals as any other SBC.. it just has bigger bores and more water holes and such.. swapping a 305 to a 400 would be like replacing the motor.. same thing, no tricks.. ok i'm done here

 

then why do i not hear about swapping beefed up 400's into our cars more or as often as having 383's and such

 

Because for every one 400 block made there were probably a thousand 350s.

 

They're less common to find.
Go to the junkyard and browse the chevy V8 aisle.
You'll see loads of low perf 305s, GOBS AND GOBS of 350's, and if you're really luck, one 400. But I doubt that.

If someone has a 400 block, they'd use it, but if they have a 350, you can get a stroker crank quite easily, and get more cubes out of it.

 

Personally, I built a 395 cu.in. stroker out of a 350 block,,, .030 over bore with a 3.875" stroke. Use the formula above, and you should calculate 395.xx.

In a practical sense, only over bore by .040", and the max stroke without serious issues with the oil pan rail is 3.875". This would yeild a 397.4 cu.in. motor out of a 350.

A 305 could maybe reach 349 cubes, again 40 over with 3.875" stroke.

 

Doc, thanks for replying, I always wondered about the larger strokers.

What issues did you have? Small base circle cam? Grinding rods? Oil pan rail mods?
Were the pistons much more $$? How much did you pay for them, if you don't mind answering? Did you get flat tops?

Thanks

 

The bottom of the cylinder bores need to be ground (touched up) to clear the rods, and the oil pan rails need to be notched for the bolt area of the rods. The cam is a standard base circle, whatever that is, with 1.6 rockers 224/230 at 0.530"/0.536" valve lift. For any stoker motor, you buy rods that are designed for strokers, so really most aftermarket rods are all designed for strokers. You do not grind on rods, maybe just a touch on the edge of the bolts.
Some details: ZZ4 block part# 10105123,,, Callies Dragon Slayer crank 3.875",,, Eagle H-beam rods CRS5850B3D forged 5.85", 650 grams,,, SRP pistons # 148988 14cc dish, comp hgt=1.213",,, oil pan Moroso # 20182 6 quarts.

 

Keep in mind:

More bore is always better then more stroke. If you could get a 383 with alot more bore then stroke, its always better for a few reasons:

1. Less piston travel, Less friction, less power loss
2. Smaller balancer weights, easier to balance, less clearance issues
3. using the oem specified stroke means you will not be having any problems.

I know this doesnt answer your question about how big you can go, but dont be mistaken, i was once in your place, thinking "theres no replacement for displacement" wanting the biggest engine, but thats not the way to go. Take your time, plan things out. A bored engine will come out with more HP, while a stroked motor will come out with more TQ. I had always wanted a 383, but with more planning, and thought put into what i really want, where i want my power band, what induction system ill be using etc, i will probably go wtih a 355 (4.030 bore x 3.48 stroke), then i can use either the stock crankor a nice forget set up.

Oh, and to answer your question of the biggest you can go, its 396 before you start to have issues with weakening the block. Even then you will want to do some serious upgrading, and make sure you have a 4 bolt block.

Hope this helps.

Sheldon

 

I know this isn't what you quite had in mind, but i read a tech article in a hotrod magazine that used all aftermarket parts (including the block) and managed to create a 454 SMALL block. this engine was a beast, but not very streetable. So, some of these other guys may be correct in there displacement #'s with 'stock' blocks, but technically, you can get an aftermarket block up to 454ci. now wouldn't that be something to show off....

 

sweet

 

Hey guys new guy here 1st post! Just wondering did anyone come up with a total cost to bore a 350 to a 383, with new pisons and crank? I know costs will vairy but some where around? Im looking into getting a iroc 5.7 and im trying to get any information before I start my project.

 

Welcome to the club!

Remember, you're "stroking" to a 383, not "boring" to a 383. Don't wanna sound like a NOOB there! (alright alright, technically you're doing both, otherwise you'd have a 377...)

Total cost to go 383? Assuming a machined 350 (bored .030" over, or the virgin bore is good or whatever)

Basic cast iron "383" crank - $189 (same price as a 350 crank)
383 pistons - $240 (total WAG there. same as 350 pistons usually)

misc:
balancing (if desired) ~$300
flywheel/flexplate for external balance $?

Everything else is EXACTLY the same on a 350 as 383, bearings, rods, bla bla. The only relevant changes are listed. So, as Apeiron says

 

And if you DO find a 400 block, the chances of it not already being bored over or having other issues reduce that by another factor of 10. In all honesty, it's been a long time since I've seen one of those in a bone yard.

The vehicles that originally used them (70s trucks, vans & full sized cars) aren't common anymore; long gone and crushed. Any found today are usually on their "second time around" transplanted in some other vehicle.

 

Remind me not to let you see what I've got in my garage.

 

Thanks! Serious I better get my facts straight! Awesome thanks for all the help! Im trying to learn everything before I go out and actually do it so I can make as little mistakes as possible.

My plan is to buy a 5.7 "stroke" it out to a 383. I plan on putting nitrous on the car so I want to build it up to take like a 150 shot. So I need to research brands of pistons, cams, and a crank. Redo the heads. Get some headers. AFter I do all of that drop it back in, gut the interior and put a roll cage in etc.

Another question, after I stroke it out would it be easier to go to a carb set up? Or keep the fuel injection? I feel like a total noob!

 

The general rule is it's cheaper to go faster with a carb. Also easier to tune.


Injection is more expensive for the upgrades, requires more tools to tune, and generally you get less max power, but a nicer curve with better mileage and driveability. All up to you.

 

Ok so then I will probably go with a carb set up for more power with less tuning. What year do you guys recomend? I was thinking 87 up? The 5.7 comes with a 5 speed right?

 

oh, you don't even own a 3rd gen yet?

You can't get a 5.7L with a 5 speed factory. You've got gobs to learn here before you pick a car. If you're thinking about picking a year - head on over to the FAQ board. If you're doing up a 383 with a standard, you can pick any year, you'll be putting a ton of new parts in anyway (engine and trans). Pick based on your favorite styling most likely.

 

I thought so. Ok well now my plan is to buy a manual iroc 305 swap it with a built 383. The trannys should match up right?

 

The transmission will bolt up to the engine, but it might not live long.

 

one of my friends dad will bore my 350 for me 60 over for $90 for the whole engine! sweeeeeeet

 

That sounds like an appropriate price for boring. Don't forget that there are other costs besides just the machine work, though.