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19_Chevelle_69
06-19-2006, 09:55 PM
Chevy's Big Gamble
The launches of the small-block V8 and the all-new '55 Chevrolets were simply the most important in the division's history. And they were a gamble.

Chevrolet had built its reputation on high value, but the cars were boring. They'd stutter-stepped into the exhilaration business with the 1953 Corvette, but that was a niche item; an experiment that, if it failed, meant little to the division and less to GM's bottom line.

The small-block V8, on the other hand, was going into Chevrolet's bread-and-butter cars and trucks. If buyers embraced it, Chevy would take on Ford in every mainstream market segment. If it failed, the division risked also-ran oblivion.

It soon became known as the "Mouse" motor and this reputation as a light, compact powerhouse soon propelled the V8 into the forefront of a burgeoning hobby of "engine swapping."

Chevy V8's have come with stock displacements of: 262, 265, 283, 302, 305, 307, 327, 350 and 400 cubic inches. Other variations exists within performance and aftermarket circles.

The height of the muscle era saw Small Blocks delivering glorious amounts of power. The fuel crunch of the early seventies saw much of that progress wane as motors were detuned, saddled with ever more complex carburetors, emissions systems and other restrictions. As the Small Block entered the '80s, they reached their peak in anciliary complexity, though the same basic design remained the same, and they still enjoyed a level of reliability and servicability that kept them popular.

As GM struggled to maintain its CAFE ratings, more agressive and intelligent engineering spawned the mainstream advent of throttle body fuel injection, and just at its heels, the tuned port injection systems. Computer controlled fuel, spark and other systems began to take hold and significant power and economy strides were made simultaneously.

Chevrolet V8's built from 1955 through 1992 were of the Generation I designation. Even though these motors were throttle-body and multipoint injected since the mid-eighties, they were still based on the same block design. In 1992, with the introduction of the LT1, Chevrolet entered the Generation II era. These engines featured aluminum heads, reverse flow cooling, and advanced electronic controls. However, these motors were still largely based on the classic design. In 1997, GM released the LS1 in the newly redesigned Corvette. Though inspired by the ubiquitous Small Block, the LS1 essentially featured a whole new design. This motor is of Generation III.

Mongoose
11-26-2006, 01:48 AM
Don that is a very interesting and factual post that will help anyone get a thumb nail history lesson on the small block Chevy engine.

Some don't know the story behind the 302 Z28 engine. When the Mustang came out and was competing and beating everything on the SCCA circuit with the 289 Hipo, the Camaro couldn't compete with the 283 and the 327 was over the 305 cubic inch limit for SCCA.

So some guy at Chevrolet pulled out his slide rule this was BC (before computers) and figured out that if they took the 327 block and installed a 283 crank the result was a short stroking, hi reving engine with a 302 cubic inch displacement. And the Monster was born. The rest as they say is history.

For Camaro enthusiasts, the 67 Camaro has the disticinction of being the first production car to have the 350 C.I. engine to sit between the front wheels. Also, Tonawanda engine production records show there were 121 of the 283's with an "MJ" code (for powerglide transmissions) and 72 were tagged with "MD" code (for 4 speeds) and no one knows if any got out the door installed in Camaros. What a find that would be eh? A factory installed motor that was never available?

Or what about RPO L70? You never heard of it? There was documentation found refering to RPO L70 describing installation of emissions equipment on its triple two-barrel carburation system. It was a variation of the L71 427 "3X2" big block tri power, except the drafting illustrations show it on a small block!

I guess all we can do is wonder what else we don't know about the Chevy small block. BTW thanks to Jason Scott for some of this information.

WINGNUT
11-26-2006, 07:07 AM
Nice post. I have often wondered why GM did that instead of just putting a high output 283 in there..............anybody know?

Mongoose
11-26-2006, 12:35 PM
Thanks for the compliment Wingnut, I think the answer is as simple as "cubic inches".

That is really the only way to increase torque output (to increase cubic inches). I know 6 cubic inches (to Ford's 289) isn't much, but it is the equivilant of boring the 283 over .030 of an inch. And the move to 302 gave Chevy a 13 cubic inch advantage over the Ford 289 and a 19 cubic inch increase over the 283 which is substantial, because they were getting well over 1 hp per cubic inch out of that engine. Chevrolet's 302 was the direct reason Ford designed and built the BOSS 302 Mustang.

Also, by destroking the 327, it will rev higher than an engine with a smaller bore and longer stroke to make the same displacement. Making it more responsive to the throttle. Realize too, that putting the 283 crank in the 327 block was the same thing as boring a 283. The advantage was they already had millions of 327/302 blocks, pistons, rings, wrist pins, etc all scienced out and ready to go. Brilliant eh?

All of the above are my thoughts and do not come from the Chevrolet factory. :D

WINGNUT
11-26-2006, 06:51 PM
Thanks for the info! I had a feeling that was probably the reason why Chevy did it that way (more cubes from a simple mod) but I wanted to hear from someone who knew for sure. Thanks again.

dseale4888
12-02-2006, 01:02 PM
The other awesome part was that most of the parts were highly interchangeable. Heads, cams, rockers etc...
Dave

PaPa Mike
12-26-2006, 05:54 PM
Those GM engineers stole the 302 from the "good ole boys" who used to take a 283 and bore it .125 and called it a "301":p .

Mongoose
12-26-2006, 11:51 PM
PaPaMike, that is what I said. The 283 had a bore of 3.875 and the 327 had a bore of 4.000 inches. You could either bore a 283 block to a 4.000 inch bore, but why do that when the 327 was already bored to 4.000 inches?

It is much simpler to take a 327 block, install the 283 crank with the larger main bearing journals and you are done. It uses the same piston except the 302 had the "pop up" piston, wrist pin, connecting rod, push rods, 1.6 rockers and the fuelie heads. Add the aluminum high rise and the mechanical cam/lifers and you have the Z/28 302.

I don't think the GM engineers needed to "steal" anything. It was just a matter of math. If the "good ole' boys" bored a 283, 1/8th of an inch, they must not have had a 327 laying around or it was before 327's were made.