409 rotating assembly - Impala Tech
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post #1 of 16 (permalink) Old 10-22-2013, 10:15 AM Thread Starter
 
 
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409 rotating assembly

Hello,

I'm new here. I usually hang out at Team Chevelle, although I own a 68 Camaro BBC convertible.

I have a friend who has a 63 SS Impala with a 327/300 hp that has 409 fever.

He found a good block for $500. I've been reading about the available stroker kits and it seems everything is forged and intended for racing use; cost is about $2400 for a rotating assembly.

I've read a 454 crank will fit with minor machining. This would give a displacement of 472 cu in.

Has anyone heard of someone selling a cast crank rotating assembly at a reasonable cost (about $1500) ?

This engine will never see rpm's above 5400. It's intended to be a torquey street motor.

Thanks.
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post #2 of 16 (permalink) Old 10-22-2013, 12:58 PM
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Quote:
Originally Posted by nashville beth View Post
Hello,

This would give a displacement of 472 cu in.


Thanks.
I think you mean 427. of displacement.

There aren't many good options for a 409 crank, but my advice would be to have him use the stock crank if he isn't trying to spend a ton of money. The other option, as you pointed out, is pretty spendy.

-Nick

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post #3 of 16 (permalink) Old 10-22-2013, 03:46 PM
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A 4.333" bore (assumes 0.030" overbore is practical with the 409 block he found), and a 4.000" inch stroke out of a 454 turned down to fit in a 409 block; yields 471.9 cubic inches of displacement.

The difference between a cast crank and a forged crank is the in how they eventually die. When a cast crank fails the two or more pieces break the block into two or more pieces as it breaks apart. When a forged crank fails it will bend instead of break. The bent crank will wipe the bearings and if not caught quickly ruin the block as well; but even then, you can reuse the rest of the parts. A broken block can also take out the heads which are generally expensive and increases the cost of a failure.

A cast crank isn't any stronger physically than a forged crank. If you are doing destructive testing in a hydraulic press the cast part can withstand any forces that you will find generated at any instant in the motors life. Cast iron can creep and will exhibit micro fractures (easily detected if you magnaflux the crank every season when you rebuild the motor). This is due to the constant dynamic bending that the crankshaft undergoes when the engine is running. It deflects both up and down as well as rotational twisting. A forged crank due to the metallurgy (alloys used) as well as the forging process keep the forged crank from failing as fast as the more brittle cast crank.

Big Dave
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post #4 of 16 (permalink) Old 10-22-2013, 04:40 PM
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My mistake... 471 is correct. Wow, that is a lot of cubes!

-Nick

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Classic Nation car pictures.

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6.2L LSX with 4L80E, 3.73 Gears, Disc Brakes, Air Ride
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post #5 of 16 (permalink) Old 10-23-2013, 05:11 PM Thread Starter
 
 
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Quote:
Originally Posted by Big Dave View Post
A 4.333" bore (assumes 0.030" overbore is practical with the 409 block he found), and a 4.000" inch stroke out of a 454 turned down to fit in a 409 block; yields 471.9 cubic inches of displacement.

The difference between a cast crank and a forged crank is the in how they eventually die. When a cast crank fails the two or more pieces break the block into two or more pieces as it breaks apart. When a forged crank fails it will bend instead of break. The bent crank will wipe the bearings and if not caught quickly ruin the block as well; but even then, you can reuse the rest of the parts. A broken block can also take out the heads which are generally expensive and increases the cost of a failure.

A cast crank isn't any stronger physically than a forged crank. If you are doing destructive testing in a hydraulic press the cast part can withstand any forces that you will find generated at any instant in the motors life. Cast iron can creep and will exhibit micro fractures (easily detected if you magnaflux the crank every season when you rebuild the motor). This is due to the constant dynamic bending that the crankshaft undergoes when the engine is running. It deflects both up and down as well as rotational twisting. A forged crank due to the metallurgy (alloys used) as well as the forging process keep the forged crank from failing as fast as the more brittle cast crank.

Big Dave
Hey Big Dave,

Do you know of any companies or machine shops that can do this with a 454 crank ?

I've also read that the stock BBC rods can be used ; I guess the piston pin location might take a custom piston ?

If I could use a stock 454 crank and stock thumb rods, the cost of the rotating assembly would be far less (hopefully).

If I can't find anyone who can do this, the $2400 price tag for a forged rotating assembly is what we'll have to put up with.
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post #6 of 16 (permalink) Old 10-23-2013, 06:14 PM
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To build a 472 you use a 30 over 409 block or larger, if you can not find one to clean up to that figure. You take a 454 crank that has a minor journal blemish that won't clean up at 20 under (your machine shop should have one or two stacked against the wall as they always turn up) and turn it down to standard 409 journal size on the mains (and hopefully no more than 10 under on the rods). This is combined with standard length stock big block rods, or some longer aftermarket rods (a lot of 472 pistons use long rods), and a set of new pistons from Mahl, JE, or Diamond to make your short block. Top it off with a set of Edelbrock aluminum 409 heads painted Chevy orange and you have the basis for a great rat rod motor or one for your Impala.

I just wish I knew that a BBC crank fit inside a 409 block back in the mid sixties when I had both motors in my garage. I might still be running W motors today instead of 4.600 bore BBC motors as I do now. I think the older W motor had a lot more charisma, if not the raw potential of the Mark IV BBC.

Just keep in mind if you use a truck block (there are a lot more 409 blocks surviving as truck blocks than as car blocks) to increase the static compression to compensate for those big chunks missing out of the top of the bore on a truck block that are not machined into a car block.

Big Dave
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post #7 of 16 (permalink) Old 10-24-2013, 03:05 PM Thread Starter
 
 
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Great info Dave !

I'll check with those piston manufacturers about what I'll need.

Here are the specs on the block :

Block# 3830814
Year used: 1963
Model: Passenger car
Engine: 409
Horsepower: 340,400,425
Bore: 4.3125
Stroke: 3.50
Main Journal: 2.50
Rod Journal: 2.20
Notes: This block was used for all 409 applications in 1963. This block has the "X" on the front. This block was also used for the Z-11 427 engine.
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post #8 of 16 (permalink) Old 10-24-2013, 04:26 PM
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Chevy cast the X in the front of all 409 blocks after the confusion that was caused by car owners in the first year the 409 came out. Since no one wants last years model or to have the little engine; owners ran down to their local Chevy dealership and for $48 in American green backs you could buy a new 409 oil pan and dip stick tube so that they could bolt it onto their 348 motor. Before the X the only way to tell a 348 from a 409 without decoding the block casting numbers was by which side of the block the dip stick tube was on.

I bought at least 348 motors where I had paid for a 409 because of the dip-stick being on the wrong side before I learned to decode the casting numbers or look for the big X (which 348 passing as a 409 owners swore was only used on the rare ZL-1 427 mystery motor). I went through a lot of 409's trannys and rear ends (as well as drive shafts universals and clutch discs) due to my driving style. "Drive it like you stole it!"

Big Dave
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post #9 of 16 (permalink) Old 10-24-2013, 09:24 PM Thread Starter
 
 
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Quote:
Originally Posted by Big Dave View Post
Chevy cast the X in the front of all 409 blocks after the confusion that was caused by car owners in the first year the 409 came out. Since no one wants last years model or to have the little engine; owners ran down to their local Chevy dealership and for $48 in American green backs you could buy a new 409 oil pan and dip stick tube so that they could bolt it onto their 348 motor. Before the X the only way to tell a 348 from a 409 without decoding the block casting numbers was by which side of the block the dip stick tube was on.

I bought at least 348 motors where I had paid for a 409 because of the dip-stick being on the wrong side before I learned to decode the casting numbers or look for the big X (which 348 passing as a 409 owners swore was only used on the rare ZL-1 427 mystery motor). I went through a lot of 409's trannys and rear ends (as well as drive shafts universals and clutch discs) due to my driving style. "Drive it like you stole it!"

Big Dave
Damn Dave,

I need to bring my recording equipment to your house and we'll record a documentary about the legendary 409. Awesome information !

I'm just a half-assed- MK IV expert to a friend who has dreamed for a long time about putting a killer 409 in his pristine 63 Impala.

I know a lot about MK IV BBC's and I have to admit it's a lot of fun learning about the legendary 409.

Now I need to find out exactly what to do to a stock 454 crank to make it fit in a 409 block.

Is there an article that exists that instructs how to do this ?

I did find this Car Craft article : http://www.carcraft.com/techarticles..._chevy_engine/

Last edited by nashville beth; 10-25-2013 at 10:48 AM.
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post #10 of 16 (permalink) Old 10-25-2013, 05:00 PM
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Sure there are. Check PRIMEDIA which is now called Source InterLink Media (the magazines publishing company has changed hands a few times since Petersen owned the empire of car mags back in the eighties). There you can read at least five that I found in a Google search without going more than two pages deep.

Basically you turn the mains bearing journal down to the smaller 409 standard bearing size but leave the rods journals alone as you will be using BBC rods (that are bigger and stronger than 409 rods even though they share the same length as a BBC rod). You could turn the BBC crank down on the rod journals as well to use the smaller diameter 409 bearing size to reduce friction (and thereby pick up more horsepower). SBC journals are frequently turned down to use Honda rod bearings because the smaller journal size has less surface area, and therefore less parasitic drag for longer high RPM operation making horsepower while racing.

Big Dave
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post #11 of 16 (permalink) Old 10-26-2013, 12:47 AM
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Quote:
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(which 348 passing as a 409 owners swore was only used on the rare ZL-1 427 mystery motor).

Big Dave
Just to clarify, the 427 Mystery Motor had no designation such as ZL-1 or anything, it was just a Mk II engine and did not resemble a 348/409 in any way whatsoever.
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post #12 of 16 (permalink) Old 10-26-2013, 10:49 AM
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That is because they bolted on a set of hand made Mark IV style heads on what had previously been a flat head 409. Totally different look I agree.

But they where so rare that few had seen them when I was buying replacement cores to build back in 1964-66. lots of urban legends and misinformation existed even before the internet. Everyone back then thought it was just some Voodoo that the engineers had performed on a W headed 409 to make it run better (more so that the extra power associated with just adding to the stroke).

You wouldn't believe the early stories I heard associated with the 396 and the 427 engines. There was more speculation than actual first hand information.

Big Dave
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post #13 of 16 (permalink) Old 10-26-2013, 08:24 PM
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Are you saying the Mystery Motor short block is just a 409 short block?
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post #14 of 16 (permalink) Old 10-26-2013, 09:50 PM
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Are you saying the Mystery Motor short block is just a 409 short block?

That I don't know off the top of my head. I suspect it was originally.

I have a 20 plus page write up on the original 427 with photos, as well as photos of a surviving factory original Mark II Mystery Motor that was originally given to Smokey Yunick, before it passed into the hands of Floyd Garrett (I saw it on a motor stand in a reconstructed portion of Smokey Yunick's "Best Damn Garage In Town", that Floyd had recreated in one corner of his museum).

A quick look at the block will identify the design as the Mark IV used a different water pump and a different deck height as well as a different angle to the V that forms the block (90° for the 396 vs. 74° for the 409). I would have to dredge up the gasser book that chapter was found in as I really can not remember off the top of my head.

Big dave
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post #15 of 16 (permalink) Old 10-27-2013, 01:27 AM
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Ok, keep us posted because I'm saying they have nothing in common at all but I welcome correction if I'm wrong.
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post #16 of 16 (permalink) Old 04-29-2014, 09:10 PM
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A few years ago, I wanted a 409 for a '56 straight axle gasser that I was putting together. I found a few all of which were very pricey for me. So, I bought a '61 348 and took it to my machine shop. I made a stroker motor out of it. Did the necessary machining; bored .030 over, 454 crank and 396 bb rods. Custom pistons made by Ross. 9.5:1 cr. Edelbrock aluminum heads, single carb. intake and 750 cfm carb. Isky hydraulic cam. The cubes are now 434. TH-400 trans.-2500 stall speed converter-with a factory 3.70 posi. Installed the motor which runs very well. Haven't had a chance to really try it yet because I'm struggling with the steering geometry. It feels pretty potent but I've kept it at low speeds. Have had to a few local shows and it draws a lot of attention. A lot of questions about this "W" engine. Not many have seen them before. I just love the looks and uniqueness about it. It was costly to do, but I have no regrets. I haven't given up on a 409 either. I'm hoping some day to have one and drop it in my '64 SS, Carmine.
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