That one (being from 1958) might have the rope rear main seal and if it does, you can not use the rubber seal in it. GM changed the design to a 2 piece rubber seal later in 1958. A friend had one of the early ones. He liked the engine, but it leaked seriously and as I recall you had to pull the engine to replace that rope seal. Might be worth getting the engine number and seeing if you could figure out more about it. Good luck.
I had that engine in my 1958 Impala convertible. It's the largest stock 1958 Chevrolet engine, called the "W", it's the ancestor of the 409 and 396/427/454 etc. A more modern engine will be easier to rebuild and service, but those valve covers!!! No small blocks allowed.
The 348 was intended to be a low RPM, high torque medium duty truck engine- - - -never intended to be installed in passenger cars. Above 5500 RPM, the valves start to float. Then in 1957, the supercharged Ford 312 engines started eating the 283 Chevy's lunch at the drag strips. GM cast a 3-2 BBL intake, stuffed a hot cam into the 348, and shoved it into the 58's to buy a little time while they got the 327 into production. They made good anchors for big boats back then- - - -60-something years hasn't changed that much, if any. The 348's 409's and early 427's with the W valve covers all had an oddball angle between the pistons and the heads- - - - - the "combustion chamber" is actually a part of the cylinder. The only recess in the head is a tiny depression where the valves fit. The heads are notorious for getting heat cracks due to uneven cooling. Jerry
"Freedom's just another word for nothing left to lose" Kris Kristofferson
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. Ernest Hemingway
I know the 348 and 409 were a short run for Chevy. They were not really known for making power, and had a host of issues from the start. Even the great Smokey Yunick said you couldn't make power with those engines. You do have to agree that it's still one of Chevy's best looking engines.
Last edited by TUTS 59; Fri May 21 2021 03:34 PM.
Craig
Come, Bleed or Blister something has got to give!!! 59' Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
The 348 was intended to be a low RPM, high torque medium duty truck engine- - - -never intended to be installed in passenger cars. Above 5500 RPM, the valves start to float. Then in 1957, the supercharged Ford 312 engines started eating the 283 Chevy's lunch at the drag strips. GM cast a 3-2 BBL intake, stuffed a hot cam into the 348, and shoved it into the 58's to buy a little time while they got the 327 into production. They made good anchors for big boats back then- - - -60-something years hasn't changed that much, if any. The 348's 409's and early 427's with the W valve covers all had an oddball angle between the pistons and the heads- - - - - the "combustion chamber" is actually a part of the cylinder. The only recess in the head is a tiny depression where the valves fit. The heads are notorious for getting heat cracks due to uneven cooling. Jerry
In addition to the tripower, Chevrolet offered a Carter AFB single four barrel on an engine they called "Super Turbo-Thrust".
The posers bought the tripower.
The racers bought the four-barrel.
The engines produced more power (regardless of the marketing dept.) and had less heat cracks due to better A/F distribution with the four-barrel than with the tripower.
Jon.
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify If you truly believe "one size fits all" try walking a mile in your spouse's shoes! [image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
