Looking for insight on a 348, price for a mild rebuild, parts availability, difficulty in finding machine work, WHAT TO BEWARE of, problems they are known for, TIPS for power etc. GIVE IT TO ME
What I can tell you, is that the '58 motor is kind of an oddball as compared to the 59-61 engines. Also, the truck engine is different than the car ones, so be sure to decode it so you know what you're getting. Also, there are small valve heads and hipo heads, the hipo ones are a must for big horsepower. One more thing. You are more than likely going to hear a bunch of dumbasses saying "that's a truck motor" and that you shouldn't use it. Ask those people what a "truck motor" is. None will be able to give an answer. 348's can give lots of reliable horsepower, they bolt up to any Chevy tranny and they have way more cool factor than a small block.
True truck motors though are still a good engine, and can be built to run well, with most any speed equipment right? Just lower compression from the factory?
The truck engine can be made to run as good as the car motor. I believe they have an extra relief in the block that gives them less compression, but compression can be upped if they're put together right. The '58 engine has a lot of interchangeability differences. Not that there's anything wrong with them, but not all 348 stuff fits onto a '58 motor.
Just remember the combustion chamber is in the cylinder. Unless you buy high comp. pistons you'd have to deck the block to increase compression.
The 58 348 blocks and heads do not have the coolant holes that allow coolant to flow around the spark plug area as the 59 and later W-Motors have. Head gaskets are different for that reason also. Max
As stated, the combustion chamber on a 348/409 is in the block. The deck is NOT at 90-degrees to the piston/bore as other engines are. Imagine a wedge shape sitting on top of a regular engine block. Then set the heads on top of the wedge. In essence, that is how a W-motor is set up. The area with the valves is flat, the combustion chamber is that wedge sitting on top of the bores. On a truck block, that wedge has a big notch cut into it by the exhaust valve. That notch drops compression pretty hard. You can't deck the blocks a significant amount--certainly not enough to equal the amount that notch displaces. However, you can buy higher compression pistons for them. I know Lamar Walden in Doraville, GA sells forged pistons, and others may as well. Lamar just put together a dyno mule 409: Truck block (with 9.5:1CR total), factory hi perf heads, mild hydraulic cam: It made 409hp, just like the original high compression (11.25:1) big cam engines. There are several casting numbers for the heads, but in essence, there are "High horse" (409 and 425-horse, big port heads), and all the rest. Most of the aftermarket intakes you can find (Edelbrock made a multi-2bbl intake, Offy still carries a 2x4 and 6x2 intake) were designed for the smaller port heads. These will bolt to any 348 and low-horse 409. They WILL NOT bolt to a high horse 409 head. The high-horse factory 2x4 intake won't bolt to the low-horse heads either. I'm building a stroker 480-inch 409 with Lamar now, and will drag race it pretty hard. But I wouldn't hesitate to build a tame 409 or 348 for a street rod, and I'd SERIOUSLY think about building either for my '62 Suburban tow rig. Brad
i always thought the 348 "truck" motor was actually 366 cubic inch, with a taller deck height than the car 348. i heard that or read it somewhere, but i don;t remember where. i know very little about 348's & 409's...so maybe this is totally wrong.
Many machine shops cannot bore them due to the deck not being parallel to the bores. I still like the old W motors though.
I am not a Chevy fan, but the W motors I liked and they ran like gang busters when done up right. The W motor and the Ford MEL engines shared the design factor of the comubustion chamber in the block and not the head. Both designs were real torque monsters. And besides, the valve covers on these engines were coll looking. 2 cents worth from a Ford nut.
Be careful with the heads. It's really easy to get into water passages when cleaning them up. I was warned not to put hardened seals in my heads... just a valve job and use good valves. I'd recommend talking to machineshops to see if they have done work on the W motors. DO NOT take the heads to just any shop. Do some digging on the forums at 348-409.com... not just the main page. There are a lot of good answers to any questions you have. The major problem with them right now is the price. Tin for them is outrageous... but anything W is high. If you can score a complete engine with all of the pullys and brackets... that is your best bet. I was quoted $4,000 for a standard bore 409 passenger car block. $4000 for just a block... here is the tech archive link http://www.jalopyjournal.com/forum/showthread.php?t=78281
Truck 348s do not displace 366 the 366 is baised from the 65 and newer Big Block. All true truck engines have the compression decreasing releifs (Alot of blown 348-409's use truck blocks) but the deck is same and still set at 74 degrees. Trucks also use different water pumps, pullies, etc, but they can be converted. High performance 409-425hp (409) heads use a different intake bolt pattern so the 348 tripower unit most are after does not fit as is. You can tell Hi-po heads easily as they have rectangular ports where standard heads have a bolt spaced between them with a notch in each port to clear it. If you are building one of these they are a great engine but you really pay for it if you want performance out of them.
Have a question for you 348-409 gurus. Is the motor mount placement in the '58-'64 chassis exactly the same as for a SBC? Reason I ask is because when you install a BBC in a Chevelle type chassis you need to replace the SBC frame mounts with BBC mounts to maintain the correct bellhousing and transmission location.
Most parts not hard to find 348/409 will share some parts with BBC, I have used BBC rear main seal, and some BBC gaskets on my 348. great engine runs strong no problems
Here's my list for our 58 Chevy... over the years it's gone thru some changes over the past 25 yeas: 283, 348 w/ trips, 348 w/2x4's, now 409 w/2x4's. Last rebuild we used BBF valves & cut down length. Runs very well... Also... went thru some transmissions too: Powerglide, Turboglide, & now Turbo 350. 348 Chevy Bore - 4.125" Stroke - 3.25" Rod Size - 6.135" Firing Order - 1-8-4-3-6-5-7-2 Weight - 645 Pounds Forged Crank - Round flywheel bolt flange Crank mains - 2.4977" Pushrod Length - Ex. 9.140" IN. 8.772" Pushrod Diameter - 5/16" Dipstick - Driver Side (Passenger Side on trucks) Ignition Timing - 4 degrees before top dead center Spark Plugs - AC44(Standard) AC45(Hot) AC43(Cold) Spark Plug Gap - .035" Rocker Arm Ratio - 1.75:1 Internally Balanced 409: Bore - 4.312" Stroke - 3.5" Rod Size - 6.0" Firing Order - 1-8-4-3-6-5-7-2 Weight - 645 Pounds Forged Crank - Bell Shaped Flywheel bolt flange Crank Mains - 2.4977" Pushrod Length - EX. 9.140" IN. 8.772" Fuel Pump Pushrod Lengh - 5.75" Dipstick - Passenger Side Spark Plugs - AC43N (standard) AC44N(Hot) AC42n(Cold) Spark Plug Gap - .035" Rocker Arm Ratio - 1.75:1 Interchangable Parts: Part Small Block / Big Block Points Yes Yes Condensor Yes Yes Distributor Cap Yes Yes Rotor Yes Yes Vaccuum Advance Yes Yes Distributor Gear Yes Yes Rear Main Seal No Yes Timing Cover Seal Yes No 340HP 409 Valve Springs Yes No Connecting rod bearings No Yes Oil Pump Shaft No Yes Oil Pump Yes No Oil Filter Cartridge Yes Yes Oil Filter Canister Yes Yes Fuel Pump Yes No Fuel Pump Mounting Plate Yes No Fuel Pump Pushrod Yes Yes Water pump bearing Yes No Water Pump Seal Yes No Water Pump Impeller Yes N
Yes and no... the BBC shaft has been used, but Melling has a specific part number for the W blocks now. "The SB drive shaft is 5.960" long, the 348/409 shaft is 6.480" long and the BB is 6.720" long. Melling claims the BB will fit in BUT is actually 1/4" (.240") longer than the required shaft and MAY cause other issues down the road. Downward pressure on the oil pump gears for one. It would also become more of an issue where any head/intake milling was involved, thereby lowering the distributor housing."
Nope, as the newer 59 up blocks and heads have a little extra casting that sticks out and allows for the coolant passages. Nothing wrong with the 58 heads as long as you use them on a 58 block and vice versa. Max
Hey Frank, I swapped the 283 for a 348 in my 59 El Camino and it bolted right up with no problems what so ever. A very easy swap. Max
I had a guy do the machining on my 348 back in the early 80s. Worked at Paul Auto Parts in Lansing at the time. Well, Just took my heads to a shop in Potterville and wouldn't ya know it. Same guy owns it. Dave Parker. He was the only one in the area that had a torque plate for the 348 and 409 engines. Bet he still has it too. If your interested in any moore information PM me and I'll get you in touch with them.
I'll throw this up and it may help out a few others. Engine Machine Service 115 W. Lansing Rd. Potterville, MI 517-645-9000 Something I did for the ring compressor situation. I bored a piece of black pipe out to just under my bore size by .002 or .003". On one side it is square to the bore (up) On the other side it has a 17 degree angle milled on it that will mate up to the deck on the block. Now you can use a standard ring compressor when you assemble the block. Just though a few might like that fix.
I know this is an older thread, but my machine shop guys, simply drill, and tap the water passage holes on the late model heads, epoxy them, then clean them up a skosh, they go right on the 58 block..no issues whatsoever..works great
In late 1970, while looking for a 'winter car' I spied a black '58 Impala in the 'back row' of the local Chevy dealer; A disinterested salesman said it seemed to run OK, a retired dentist had traded it, to get rid of it, on a new Caprice and they were asking $125.00 for it...A lift of the hood showed it was not the assumed 283, somebody had stolen the tri power air cleaner, I bought it for $100.00...It was the 280 horse tri power version, was well equipped with power everything, Turboglide, semi functioning AC, etc....I drove it til the headlights were falling out of the fenders per rust. An old mechanic in my hometown had gone to GM's school on multi carb stuff in the 50's and went over the thing via complete tuneup/carb service....Ran like a top...Finally junked the body [sob] sold the motor to my brother who installed it in a '62 Impala and promptly scattered it at Sunset Dragway in Mercer, Pa...
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