noob from Colorado - Impala Tech
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post #1 of 5 (permalink) Old 09-20-2016, 12:17 AM Thread Starter
Join Date: Sep 2016
Posts: 21
noob from Colorado

Hi All,
New old guy from Colorado. Don't have an Impala but may in the future. Have a Chevelle with an IE impala 396/425 engine and wanted to learn more about the engine and maybe if the car it came in still exists. Sort of a long shot but just wanted to say hey.
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post #2 of 5 (permalink) Old 09-20-2016, 08:05 AM
Join Date: Jan 2006
Posts: 12,488
Welcome to the Team Boyd!

The IE engine application code is for a 1965 396 Special High Performance engine rated at 425 horsepower (same engine the next year was rated at 375 horse at a lower RPM to keep the insurance industry happy and the 425 horse was what they rated the HiPerf 427 engine). It was placed in front of a four speed manual Muncie or a Borg-Warner three speed transmission in an Impala or Biscayne.

Has 11.0:1 pop up pistons closed chambered heads with 2.19" intake valves sitting in a 90 cc closed chamber combustion chamber head with 320 cc rectangular intake ports. This motor was developed in 1961 to race the high bank oval at Daytona. It will run for twelve hours straight at wide open throttle without breaking anything.

What it won't do is run worth a darn on the street, it is a high RPM motor that doesn't begin to "wake up below 4200 RPM. A 396 is too small to install in anything other than a museum piece. The closed chambered heads and the small bore obstruct the free flow of air which is why Chevrolet opened the bore size up the following year and introduced open chambered heads in 1969. It was also designed to be a high compression engine and as such it really looses power compared to the same size (400 cube) small block that weighs 230 pounds less than the inefficient big block.

A SBC makes 1.5 horsepower per cube without breaking the bank. Same effort (quality and quantity of parts) in a big block costs you twice as much and only gets you one horse per cube. As such anything under 427 cubic inch displacement and you are ahead of the game with a small block. You have to have go to a 454 to even break even on power with a small block and even then you are still handicapped by the extra 230 pounds of cast iron over the nose. This why today a pump gas BBC starts at 540 cubes with aluminum heads, intake, and water pump; it can approach within 60 pounds of an all cast iron SBC in weight.

Sell the 396 to a museum curator and buy a Dart Big M block, a 4.375 inch stroke SCAT or Eagle rotating assembly for a 4.6 inch bore and build a 582 to run on pump gas to get enough torque to break a 12 bolt axle or to accelerate a semi as fast as a Chevelle with a 275 horse 327 under the hood. Painted orange with some aluminum Broidix RR-2 or AFR 357 heads it even looks the same as your 396 at a car show only pumping out 753 horsepower and 678 foot pounds of torque at 3,400 RPM.

Big Dave
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post #3 of 5 (permalink) Old 09-20-2016, 09:24 AM Thread Starter
Join Date: Sep 2016
Posts: 21
Wow, Big Dave. That's some interesting information. Sure seems that engine runs well in my Chevelle. It has the Crane energizer 282h, so that wakes it up somewhat, but is an older build. I know that it isn't up to date with what's available today, but in the interim, money being a factor, I guess it will have to suffice. It's not quite a boat anchor yet. heh heh.
But the info you put up is interesting and a plan for the future. My how things have changed since the 60's, eh?
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post #4 of 5 (permalink) Old 09-20-2016, 11:09 AM
Join Date: Jan 2006
Posts: 12,488
Tell me about it! I've been playing with cars since the fifties. Got an engineering degree in the sixties (slide rule and CRC books filled with math tables of logs and trig functions) and worked in industry in medium and heavy manufacturing. Got into management and learned WHY things where as they were as opposed to how they could be if engineers ran things.

Of course you need only look at the Macintosh computer to realize that business decisions are best left up to marketers and accountants instead of engineers if you want to make money for the company. The Mac was the best computer around, but you couldn't give them away compared to the MS-DOS based systems that people loved to hate.

Big Dave
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post #5 of 5 (permalink) Old 09-20-2016, 03:01 PM Thread Starter
Join Date: Sep 2016
Posts: 21
I grew up in Illinois and the farm kids had the 65 chevelles with the l79 in em. They used to just block off the 2 lane blacktop on Sundays and have at it. There was no traffic back then. They always impressed me way back then. I remember the 65 vette having more hp that cubic inches with that 396/425. They were pretty quick in their day.
Fast fwd after a brief stint on submarines and a career in masonry and of course we all want to relive the dream. The chevelle is a 66 and the IE block is mated up to an M22 with a 12 bolt 3:73. I take it out on Sundays and do my old man thing and imagine myself being 18 all over again. She's definitely a time machine. I suppose the day may come to upgrade but for the time being, it runs out pretty good. Interesting facts you talked about earlier. Seems like the 962 block and 208 heads bring a pretty good buck on ebay. A guy could upgrade with very little money spent, but then the rest of the drive train would need an upgrade too. Guess I'll just have to be un American and live with in my means for now.
Boyd the brick, in Colorado
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