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.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
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
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln 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 Love your enemies and drive 'em nuts!
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; 05/21/20213:34 PM.
~ Craig 1958 Viking 4400 "The Book of Thor" Read the story in the DITY 1960 Chevrolet C10 "A Family Heirloom" Follow the story in the DITY Gallery '59 Apache 31, 327 V8 (0.030 over), Muncie M20 4 Speed, GM 10 Bolt Rear... long term project (30 years and counting)
If you don't like driving yourTruck, you won't drive yourTruck..| Living life in the SLOW lane
I've got the 348's big cousin in my 61 American LaFrance fire truck- - - - -a 401 GMC V6. It's got the W-shaped valve covers also! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln 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 Love your enemies and drive 'em nuts!
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! The Carburetor Shop
One of the huge mistakes they made was offering the 348 in combination with possibly the worst automatic transmission GM ever produced, the Turbo-Glide. All the transmission techs back then referred to it as the "Terrible-Glide". The thing acted sort of like a governor to keep the engines from getting up to valve float RPM, however! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln 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 Love your enemies and drive 'em nuts!
I have a "warmed over" 348 in my 1957 Napco truck, some reflections: - If you have a prior v8 installation (mine was a 283) the mounts match up - The problem is the clearance between the #7 cylinder and the steering box. Usually some grinding is required. My steering box was worn, so I went to a power steering set-up (1968 Saginaw box) and mounted it outside the frame. Power steering makes the truck a pleasure to drive. - Since I have 3:38 axles and an 3 speed overdrive trans (split for six gear operation) I needed more grunt than the 283. This engine is very strong. - I had 3 deuces, but had some problems, last problem was the gas leaking back onto the manifold after operation and sitting a while. This problem appears that it can be solved with carb spacers; they make total rebuild kits for this setup. There are people who specialize in rebuilding the carbs as a set, but usually expensive. Some people are very satisfied with the 3 carbs, others not as much. It seems if you have the expertise they run great. I went to a 4 bbl carb, which ran great right of the box and actually makes more power. However, the tri-carb setup does look great. - I would recommend going to: http://www.348-409.com/forum/ for expert advice, some of those guys seem to live and breath W engines. Bottom line for me, I wanted a 348 and I didn't care about anyone else's opinion, and that was it. It makes great power and people always seem to like a "different" engine. Good luck, that looks like a good engine at a good price. They are a little more to rebuild, but you can get all the parts needed at "Show Cars" on-line. They are located in New Ulm MN. by the way. don
Built a 348 for my 58 Impala back around 66/67. I was one of the lucky ones as i never had any problems with the 3 duce set up. I raced a lot, lost some, won many back in the day........ ...but oh that faithful night, after some drag racing at the "Draytonville Straight" I got behind on my steering while going to another spot to continue racing. I well past 120, and I still carry many scars to prove it, there wasn't a 12 inch square on that car that wasn't twisted and mangle....including me, but I lived to race another day!...the good ole days? yeah, right. Ohhh, that faithful night!
Last edited by Achipmunk; 06/06/20212:45 PM. Reason: puntuation
A W engine can be made to rev and run IF you have some very deep pockets. Performance Engines in Denton, Texas did many many hours of flow bench work on a friends 409 and eventually got it to dyno 565hp. The exhaust ports/runners had to be DECREASED by 22% and the valve train re-engineered from scratch. Since they were intended as truck engines the bottom end is strong but still ended up with splayed Milidon main caps. Blown one has a complete bottom end girdle and makes 900+ hp. It has a 454 crank and this gives 500ci. Carbed one turns right at 10 flat in the quarter and blown one is in the high 8's. Both in the heavy 62 body. Well over a hundred grand in the two engines.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln 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 Love your enemies and drive 'em nuts!
