Engine rebuild
Thread Starter
Intermediate
Joined: Nov 2004
Posts: 28
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Engine rebuild
I have a 75 L-48. I want to put in a much higher horsepower engine. Can anyone tell me if the 1975 engine block is worth rebuilding into a better powerplant or is a more recent 350 engine block technologically better or all standard 350 blocks equal?
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Any 1st generation 350 block can be built to any level of performance you want. If your current block is the original one, you may want to consider leaving it intact and storing it to retain the originality and building your "play" motor from another core. 350 blocks, cranks and components parts are cheap and easy to find, so you can build a complete engine while keeping your car running during the process.
Team Owner
Joined: Feb 2005
Posts: 32,519
Likes: 1
From: central America
St. Jude Donor '08-'09
nvvetgirl,
I was in your same shoes roughly 4 months ago. Rather then use another block, I decided to use my original block for the build, that way I'd keep it in the car if I ever wanted to sell it. The engine needed a rebuild anyway, and the block was perfectly good, so I figured, why do I need another piece of cast iron sitting in the corner that isn't working.
A couple of things about getting the original block rebuilt...always make sure that the engine pad (passenger side front of the block) has the correct numbers stamped in that match your engine...and make darn sure that the machinists do not deck the block to the point that those stampings are removed...that is your sure bet for authenticity (mostly).
Good luck with your rebuild...look around, you'll get a lot of advice on what you should do.
trw
I was in your same shoes roughly 4 months ago. Rather then use another block, I decided to use my original block for the build, that way I'd keep it in the car if I ever wanted to sell it. The engine needed a rebuild anyway, and the block was perfectly good, so I figured, why do I need another piece of cast iron sitting in the corner that isn't working.
A couple of things about getting the original block rebuilt...always make sure that the engine pad (passenger side front of the block) has the correct numbers stamped in that match your engine...and make darn sure that the machinists do not deck the block to the point that those stampings are removed...that is your sure bet for authenticity (mostly).
Good luck with your rebuild...look around, you'll get a lot of advice on what you should do.
trw
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
The Cast Iron in Chevy blocks untill about 1977-78 is pretty good. The L-48 won't have a "race worthy" 010/020 block like a L-82 Vette but can still be built to 420-450HP levels with good reliability (plenty for a street motor!)
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
About 3 yrs ago I was in the same position. Although my 79 "smog" L82 was a great running engine, it just didn't have the performance you'd like to have in a C3. I believe the 79 L82 as quoted as only having 220HP and I'd believe it. Anyway, I pulled the engine to save just in case someone, sometime wanted the numbers matching engine. I found a nice 350 4bolt block out of a 85 Suburban that had spun the bearings for $50. I tore down the engine to the bare block and had a machinst clean it and magnaflux to check for cracks. The block was OK. Next I got out the Summit, Jeggs and SDPC mags and bought EVERTHING except the block: cam, bearings, rotating assembly, intake, oil pan, oil pump, etc. I had the machinst bore the cylinders to 30over and match the pistons. I did everything else and had to buy all specialty tools to "blue print" the engine. I ended up with about $5,500 in the completed engine but had a great time learning and a few brewsky's along the way. I've now got about 7K miles on the new engine and have had no problems. According to my CR, heads and cam specs, I should have about 350+ HP. I can really feel the difference.
If you're not mechanically inclined, you might want to consider going the GM crate motor route.
If you're not mechanically inclined, you might want to consider going the GM crate motor route.
Le Mans Master
Joined: Mar 2002
Posts: 7,456
Likes: 2
From: Coming home from Luckenbach Texas
Personally, I wouldn't worry about keeping the '75 L48 "numbers matching" block intact. With 165hp stock, it represented a low point in Corvette history. Rebuild that sucker into a monster!!!
Melting Slicks
Joined: Apr 1999
Posts: 2,010
Likes: 3
From: Moon Twp. PA USA
Originally Posted by Solid LT1
The Cast Iron in Chevy blocks untill about 1977-78 is pretty good. The L-48 won't have a "race worthy" 010/020 block like a L-82 Vette but can still be built to 420-450HP levels with good reliability (plenty for a street motor!)
