Hi all - need some tips for this build. Im so far seeing the baby LT1 rods will make up for the reduced 3" stroke - another option is a 6" chevy rod are there ones that would fit the small journal 283?

So technically: small journal forged 283 crank, baby LT1 rods and sbc pistons with available compression heights shd get me in the ball park of an 11:1?

These seem like they would fit the bill - the 6 inch rod from the 5.7 is about as close as the destroke from 3.25 to 3.0 - i can adjust that with pin heights etc if need be

 

Wouldn't that be a 302?...

 

A 4.000 bore and 3.000 stroke in Chevy and Ford world is a 302. It's a 301 in Pontiac world.

In the real world it's a dumb idea and waste of time and money to build a Chevy 302.

Chevy didn't want to build the 302MO & 302DZ. They had to build it because the rules allowed a maximum displacement of 305 cubic inches. Every single 1967 to 1969 Z/28 would have been a way better car with a 1970 LT-1 350.

That said I always thought it would be cool to build a Firebird Formula with a long rod 302 5.0L TPI engine using SLP runners, high flow base, ported plenum, a properly specced roller cam for the engine, and a nice set of aluminum heads with a 5-speed manual transmission, rear axle, and suspension system so you could clutch dump it and power shift like you stole the car and see how it would stack up against a 5.0 Mustang LX 5-speed.

 

'per the math' stock bore 4/2=2. Multiply by itself so back to 4. So 4*3*3.14159= 37.6990. Times 8 for each cylinder= 301.59264. Call it what you want. Pontiac called it 301. Frod and Chevy called it 302. But that's only on a stock bore anyway.

To answer the OP, a small journal sbc is .10 too small rod journals for gen 2 rods. If you find the rods, honestly take the gen 2 crank and use a roller gen1 block. You'll need a domed piston to hit 11:1 unless you have really small chambers.

And are you staying in a 5.0 class? There's no real world advantage at the end of the day. There are plenty of ancient posts on here debunking the rev theories if that's what you're shooting for.

 

Thats kinda where im at- i already ordered a 257/257 cam for it on a 102, solid lifters, beehive LS springs, 11:1 and i have 205 alu heads to go. 5 speed t56, with a tall gear all i wanna do is wind the snot up out of the thing and fry clutch packs.. But now im eyeballing the 454 roller in the driveway for a 427 OR doing the L$ thing-



https://catalog.elginind.com/engine/...-e3287932483a/

 

Well I assumed it would be bored. And isn't it a Chevy motor?...

 

Even a .01 overbore would've made it a 303. And what does make have to do with math?

 

I just don't understand why you're calling a Chevy 302 a "301". It's not important at all. I was just curious.
As for math; 0.5 or more typically rounds up to the next whole number, not down...

 

before chevy made this engine, racers would bore 283 blocks to 4 inch. They called a 301 at the time. While I wouldn't personally call it a 301, this combination does add up to it and has been called it before. You are right, it's unimportant, so unimportant the manufacturers didn't bother to agree on a number to call it.

 

If you already have the foundation and you're vested in it, then there's no turning back. But just so you're aware, a de-stroked 400 (377) will rev just as high as the DZ302, and it uses the 350 stroke, maybe even higher when pushed. There's a lot more to the story why GM needed to design the DZ302, aliceempire nailed it...

GM eventually rounded it off to 302 (301.59). Just like the 350 which is 349.85, they just rounded it off...

- Rob

 

Yeah, Ford did the opposite. In the mid '80s they marketed their 302 (whch should round down to a 301) as a "5 Liter", when in reality is a 4.9 Liter...

 

Hi aliceempire- thanks for asking, i have a 67 im restoring and has the priginal matching block so was hoping to keep the block original to the car- and i wd like to do it for nostalgia-

already have the heads and a bunch of parts lying around - ill be going with a t56 manual or sth similar.

now im bouncing between the LS in the driveway and the roller 454 id build a 427 from it-

 

4.000" bore × 3.000" stroke = 301.5928947 CID

Properly, it rounds to 302. Not sure why it was called "301" back in the day by hot-rodders, but you're exactly right, it was.

Standard rule for rounding is, if the 1st digit to be discarded is less than 5, round down; if greater than 5, round up; if it's 5, round to the even # whether that's up or down. By the rule therefore it rounds to 302. In this case also, depending on how many decimal places the original calculation was carried out to, the result might be 301.6, which would of course definitely round to 302.

AFAIK the Frod 302 is the same dimensions as the Chevy. 4.000" bore × 3.000" stroke.

301.5928947 CID converts to 4.9422220681 L. Definitely rounds to 4.9. Not sure why Frod decided to call it 5.0.

The Chevy 305 is actually 305.19179069 CID. which is 5.001197406 L. So, yeah.

There's LOTS of non-mathematicians included in the human species. How unfortunate. Math is so eeeeeezzzzzzy to begin with, and this sort of thing isn't even math, it's just arithmetic. Grade-school stuff. No excuse for getting it wrong.

 

If this were my situation personally with the block and crank good, I would probably build it with those and find a custom piston or rod. It'd be worth more to me and possibly the next person to keep it in factory condition. Despite the fact that I'd have the overwhelming desire to go roller cam and aluminum heads on it. But that's clearly up to you. At least you're not chasing a myth.

 

I was just curious, guys. Not at all trying to make an actual issue about it...

 

end of the day it's certainly not gospel but people get particular about it. The factories didn't seem to care as much as the enthusiasts. Pontiac alone had a "326" that was actually a 336, the 389 is labeled as 6.5L while measuring a 6.37L and a 350 that is actually 353ci.

 

I have an 11:1 Chevy 302. Do what you want but what you are proposing is a bad idea.
I had to go to great and expensive lengths to make mine streetable.
Just for starters, yours will not idle below 2000 rpm, idle vacuum will be below 5", and 11:1 is not enough compression for your cam.