Barn-Find 409 Engine Rebuild - Unearthing A Legend, Part 1

We Take a Mysterious, Barn-Fresh 409 and Turn it Into a Performer.

Tommy Lee Byrd May 7, 2014 0 Comment(s)
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Follow along in this installment, as we reuse the original rotating assembly to preserve the history of a drag racer who is no longer with us. Despite some advice to have the block bored (regardless of the condition of the cylinders), we kept the original bore and will utilize the original 11:1 forged pistons. We know the heavy original pistons are not ideal for today's high-performance applications, but the fact that all of these parts were usable gave us enough reason to give up some horsepower.

Next month, we will finish the bottom end and update the barn-find 409 with Edelbrock aluminum cylinder heads and a Comp Cams hydraulic roller setup. Then, we'll end the three-part build with dual quads and a Pertronix ignition, which will be put to the test on the dyno. For now, follow along with the unearthing process and check out some of the features that make W-motors so unusual (and fun).

409 Engine Rotating 2/26

1 After removing the 348 oil pan, we were pleased to see the cleanliness of the rotating assembly, considering the lengthy dry spell. High-performance 409s had a windage tray, but the extra-long main studs were cut off to provide clearance for the 348 oil pan, which did not have enough room for the tray.

409 Engine 3/26

2 Light surface rust in the cylinders is usually a bad sign. We were optimistic and soaked the cylinders with oil before trying to spin the engine. Here, you can see the peculiar combustion chamber configuration, which is housed inside the cylinder instead of the head.

409 Engine Casting 4/26

3 The casting number 3830814 means this is a block from 1963. All 409 engines from '63 used this block, including the Z-11 engine, which was actually 427 ci. The stamping numbers and suffix code on the front of the block generally determine the engine's configuration and horsepower rating.

409 Engine Stamping 5/26

4 The stamping pad on the front of the block should have given us an answer to this engine's original home, but it had no visible numbers or letters. That means this block was more than likely an over-the-counter piece from Chevrolet.

409 Engine Disassemble Rotating 6/26

5 After spinning the engine over, we disassembled the rotating assembly to check for damage. Each and every component was in surprisingly good shape, including the crankshaft.

409 Engine Crankshaft Casting 7/26

6 A closer look at the crankshaft casting numbers shows another odd modification to this engine's bottom end. For some reason, most of the casting number has been removed, leaving only the "72" on the end of the 3788072. This is a 1961 crankshaft.

409 Engine Clean Crankshaft 8/26

7 We used emery cloth and sandpaper to clean the crankshaft's journals. We then used sandpaper to clean up the counterweights. The forged crankshaft checked out fine, so it will be reused.

409 Engine Clean 9/26

8 The block was sent to Riverside Machine Shop to be cleaned and checked for cracks and distortion in the cylinders. It was determined that the cylinders did not need to be bored, so they were simply honed in preparation for the rebuild. Riverside also installed the new cam bearings and freeze plugs.

409 Engine Lifter Valley 10/26

9 Years of neglect can cause major rust issues if the engine isn't stored properly. After we got the block back from Riverside Machine Shop, it looked like a brand-new casting. The lifter valley cleaned up nicely, and Riverside also ran a hone through the lifter bores.

409 Engine Cylinders 11/26

10 One of the most unique aspects of 348 and 409 engines is the angle of the deck in relation to the angle of the cylinders. This wedge acts as the combustion chamber, meaning the cylinder heads are essentially flat on the mating surface.

409 Engine 12/26

11 Before we got too carried away with assembling the 409, we masked off the important stuff and laid down some classic Chevy Orange paint. High-temp engine enamel paint covers well and offers a glossy finish.

409 Engine Ready For 13/26

12 The flawless block is now ready for assembly. Before we can start installing the rotating assembly, we must take a few steps to help this engine survive some serious abuse.


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