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Old 08-20-2008, 09:38 AM
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350 bored .080

OK, i know what you guys are prolly gonna think, not possible right. Well i got a junk yard motor (350 SBC) pulled the heads and oil pan cause it was locked up. The guy gave me the whole motor for $25 cuz it was locked up. and i figured all i wanted was the block anyway, so who cares.
Any-who, when i pulled the heads the pistons were 4 relief flat tops with .080 stamped on the top. ALL of the head bolts and main cap bolts said JASPER on them, so i assumed it was a jasper exchange engine.
I put a set of bearings and rings in it, (honed cylinders) checked that they were all "true" and sure enough bore was 4.080. I slapped it back together and the motor ran like a raped ape, with stock heads and cam, and only 1.76 intake valves w/ a 750 double pumper. I'd say the motor was in the 350-400 HP range, just from feeling the power of other motors that have been dyno'ed. motor ran great for 3 years (NEVER got hot) or so, then i decided to put a comp 280 magnum cam in it @ .480/.480 lift. it ran for 20 min After the cam install, i guess the valve springs were to weak for the lift, and at 7600 rpm's it shattered 2 pistons and bent the valves (rookie mistake but i learned). But the block is still good according to my machinist, "nothing that can't be honed out". so i'm gonna used it.

Now to my ????'s, Any one got experience with the SBC 302, my 350 crank is like .020 and .040 ground, and i Don't wanna use it, i wanna do somethin different. I have a 283 crank from a 66 bel-air. I wanna built an rpm monster. I guess i just wanna know how the 302's ran stock and how you guys think it'll run with that same size cam (comp 280 mag), speed pro flat top replacement 4.080 pistons, and a set of the 64cc summit aluminum heads.

Opinions, comments, criticism, suggestions, and experience all welcome.

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Old 08-20-2008, 11:11 AM
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engine

Well...

I'll try to make this easy... Going back wards from a 350 to a 302 would be like having Pam Anderson for a wife and deciding you would rather have that girl from ugly Betty as a wife.


I have about (6) 302 chevys under my belt, not one of them would out perform a like built 350...

If you have no problem running a .080" over block the crank at .020 and .040 should not be an issue for you either... I would run (100 ) .020/.040 under cranks before i would trust 1 .080" over block.

Keith
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Old 08-20-2008, 12:03 PM
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Is the 283 crank a medium journal?
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Old 08-20-2008, 12:17 PM
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Quote:
Originally Posted by k-star
Well...

I'll try to make this easy... Going back wards from a 350 to a 302 would be like having Pam Anderson for a wife and deciding you would rather have that girl from ugly Betty as a wife.


I have about (6) 302 chevys under my belt, not one of them would out perform a like built 350...

If you have no problem running a .080" over block the crank at .020 and .040 should not be an issue for you either... I would run (100 ) .020/.040 under cranks before i would trust 1 .080" over block.

Keith
Very well said,I agree.
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Old 08-20-2008, 12:44 PM
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Who the heck is "Ugly Betty"????????
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Old 08-20-2008, 01:08 PM
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Quote:
Originally Posted by Jmark
Who the heck is "Ugly Betty"????????

Oh yea,,,,you know who Pam Anderson is....L.O.L.

It's some show on abc, I can't spell the girls name and i am not going to try.. My wife used to watch it...


Keith
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Old 08-20-2008, 01:42 PM
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Maybe she's related to this guy?



http://www.imdb.com/video/screenplay...3/]Ugly Betty?

Last edited by Jmark; 08-20-2008 at 01:48 PM.
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Old 08-20-2008, 03:16 PM
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283 crank

I'm pretty sure the journals are 2.45, i'm pretty sure the crank shound just drop right in place. i dont think it's ever been ground either. I don't really know if it's a feasable idea or not, it was just more like a what if scenario. I've got another 283 in a truck of mine, and just downright screams with a 4 speed tranny.
I was just thinking, a bore that big and a stroke that small and tight could produce some incredible rpm's, rpm's = HP in my book. I guess i dont understand why most people think more ci's always = more power. It's simply not true, it's all in how it's built.

To who ever it was that said they'd use the 20-40 crank before an 80 over block. I was just wunderin if that is from personal experience or from a guy who knows a guy, who knows a guy, whos brother said it was a bad idea. I'm not trying to be smart about it, but it always seems like any time you hear someone talk about a motor being bored 80 over, thier like "wow, i'll be surprized if it doesn't run hot, or blow whole if the cylinder wall malfunction is some way." when it comes down to it, how many of us have actually done it or seen it done. I have, with a 1973 3970010 GM 4 bolt block, and it was one off the strongest motors i've ever seen in action. theory isn't always fact, but hey, until i pulled the heads off that motor you would have never convinced me to bore one that much either. I'm a little more open minded after seeing it work, and work well.
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Old 08-20-2008, 04:08 PM
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More Cubes is more power, want proof? why do top fuel dragsters run such massive engines? If high revvers make more power why don`t anyone go out there with a 20,000 RPM 2 cycle engine and blow the field away?
Why is it so easy to take a 305 chevy engine and blow the doors off ricer imports that can rev to 10,000?
The old saying stands true, you can`t beat cubic inches.
There were no medium journal (2.45) sized 283 cranks, the 283 was discountinued in 1967 and the medium journal wasn`t released until the next year and the only crank in a medium journal with a 3 inch stroke was a 302.
Go ahead and get spacer bearings and build your high revver, you`ll find your always against the weakest link in the engine, when you beef that area the next weakest link on the chain will break.
Much as I hate to say so, I don`t buy a stock 350 with 1.76 intake valves ever made close to 300 horsepower just because it was bored .080 over and had 750 carb on it. But thats just my opinion.

Last edited by DoubleVision; 08-20-2008 at 08:35 PM.
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Old 08-21-2008, 05:32 AM
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Quote:
Originally Posted by eatonde
I'm pretty sure the journals are 2.45, i'm pretty sure the crank shound just drop right in place. i dont think it's ever been ground either. I don't really know if it's a feasable idea or not, it was just more like a what if scenario. I've got another 283 in a truck of mine, and just downright screams with a 4 speed tranny.
I was just thinking, a bore that big and a stroke that small and tight could produce some incredible rpm's, rpm's = HP in my book. I guess i dont understand why most people think more ci's always = more power. It's simply not true, it's all in how it's built.

To who ever it was that said they'd use the 20-40 crank before an 80 over block. I was just wunderin if that is from personal experience or from a guy who knows a guy, who knows a guy, whos brother said it was a bad idea. I'm not trying to be smart about it, but it always seems like any time you hear someone talk about a motor being bored 80 over, thier like "wow, i'll be surprized if it doesn't run hot, or blow whole if the cylinder wall malfunction is some way." when it comes down to it, how many of us have actually done it or seen it done. I have, with a 1973 3970010 GM 4 bolt block, and it was one off the strongest motors i've ever seen in action. theory isn't always fact, but hey, until i pulled the heads off that motor you would have never convinced me to bore one that much either. I'm a little more open minded after seeing it work, and work well.

Sounds like you have it all worked out....I wonder why you would ask the questions if you allready have the answers???

I'll offer this challage to you, we both built Like engines, yours a 302 and mine a 350. I'll give you $1000 if you make even 1 more hp then me at any rpm...


Keith
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Old 08-21-2008, 06:24 AM
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my apologies

sorry guys, i wasn't trying to sound like i have all the answers. I know i don't know it all or i wouldn't be here askin questions. I really didn't mean to come off that way.
basically what i was gettign at with the rpm/hp thing is with the 327 v.s. the 350. I'm still kinda a young buck in this engine building game, but i believe my dad, my grandfather, and chevrolet advertising. They always told my that the 327 was a HOT little motor and would out run a lot of the 350's on race night, even some of the breather emblems chevy put out say 327/350hp, or was it 340hp i cant remember, just like the little pic you've got up double vision.
So i'm assuming that if chevy put that breather decal on a specific car with a 327 in it that it's gonna be somewhere in that nieborhood atleast, and also according to you double vision i won't quote this, but you said that you don't believe a stock 350 with 176 valves in it made anywhere close to 300 hp, or something along those lines. So your saying the 327/300hp turbofire pic you got up means a 327 is out performing a 350. so less ci's getting more hp, thats kinda contradicting what you said somewhere in the first 2 sentences. Like i said it depends on how its build. you build them like for like, yea your more power from more cubes, but you also CAN build a 350 that will beat a 568 big block, i've got an episode of pinks recorded where a 68' camaro w/ a twin turbo charged 350 was making close to 700hp and beat a blown alcohol 568 in an 80' camaro, by like 8 car lenghts.
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Old 08-21-2008, 07:40 AM
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You need to stop believing everything "the old guys" tell you and since when is a "sticker" proof of anything?

Yes Chevy made some powerful 327's but that was 40 years ago. That was back when the compressions were high, the cams were solid lifter, and everyone had a 4 speed and skinny tires.

Things are much different today. With the availability of aftermarket parts and the low octane of fuel, big cubes wins hands down. Rpm does not equal Horsepower it may equal wheelspeed but not HP.

There is a rapid shift in technology and thinking in motors and if you don't get ON the bus you are going to get your doors blown off by a guy IN a bus.


Roller cams are replacing solid lifters, compressions are lower, vortec heads are better than camelbacks, and flat tops are replacing domes just about everywhere you look. The cam grinds are much more advanced and the components you can purchase "over the counter" are 10 times better than back then.

A 327 will live longer at higher RPM but replace the rods on your average 350 and you can spin it the same.
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Old 08-21-2008, 08:05 AM
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engine

Lets see if we can give you some things to think about…

Don’t base your knowledge about engines on one episode of pinks. The guy with the twin turbo 350…That might have been a 434. Sometime people are not exactly honest on those shows… Remember it’s for entertainment.

I have been building engines for over 25 years, one thing I have learned time and time again is that very few people actually have the knowledge that they speak of.. A few years back a customer came in with a 440 Mopar that wouldn’t fall out of a tree. It was built by a local Mopar hero that builds tons of engines. The customer was told it was a 10.0:1 compression engine, because that’s what the catalog listed the pistons at. When I did all the checking the REAL compression was 8.8:1… After I “fixed” the engine, the car picked up .7 et.

A smaller engine can make more Hp then a bigger engine no doubt, but If all things are equal the bigger engine will make more HP every time, up to the point where the cylinder heads can no longer feed it.

The .080” over block in a passenger car or light duty truck will probably last 100,000 miles. In a performance application it’s a total different story. When they cast blocks there is a thing that is called core shift. It’s what makes one side of the cylinder .200” thick and the other side .120”. When you start over boring a block you can see why the cylinders get thin. Now your block may have had no core shift and the cylinders are the same thickness all around. But that would be 1 out of every 1000 or 10,000 that is like that. With out sonic checking the block you can never know for sure. I will not take that chance with my personal or my customer engines.

Now if you have a thin wall and you detonate the engine at all it “WILL” crack the cylinder. I know because I have done it on .060” over engines. If you keep the engine from detonating then you have a much better chance of it living. Are you willing to take that chance??? It’s up to you.

On to the crank, Back when I first started building engines, me nor my friends had any money, I did a lot of things to engines that I would never do now. One thing I did,(because we were poor) was run standard bore blocks, stock cast pistons, stock rods with stock bolts, and any crank I could get no matter how far it was ground under. That was in the day when everybody would run 4.88/5.13 gears and spin the snot out of your engine. I never broke one crank or had any bearing issues because the crank was under .040 on the mains or rods…Matter of fact the only thing we ever broke were the stock cast pistons. They would break the skirt, twist the piston in the bore and send the rod through the wall…Total carnage, and it was cool!!!

Today in my mild 350 builds I still use crank kits that can be .040 under with zero issues.

Keith
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Old 08-21-2008, 09:58 AM
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crank

thanks k-star, i'll prolly go ahead and use the crank that i have then. I'm prolly just gonna end up throwin this motor in a dialy driver anyway. It was all just a "what if" scenario. I've never seen one of those old 302's or even heard people talks much about them, so i just wundered what it'd be like.
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Old 08-21-2008, 10:53 AM
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302

What’s really funny, Right now I have a 302 engine in my 79 Malibu wagon. I built the engine using a factory roller block. It has a ZZ4 hyd roller cam, and the ZZ4 aluminum heads on it.. That thing is the slowest engine that I have ever built... I originally built it because I was trying for some MPG not out and out HP. The engine has only been in for about 8 weeks. I all ready have another block machined to replace it. I am going to use the same heads, intake, carb, etc on the new engine. The new engine is a 383. Same compression and a bit more cam. I will bet the farm it’s going to run circles around the 302. It would even if I used the ZZ4cam in it.

BTW the gas mileage isn’t all that great…
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