1975 L48 motor upgrades
Thread Starter
Advanced
Joined: Dec 2013
Posts: 97
Likes: 1
1975 L48 motor upgrades
Hi everyone,
I'm a new owner of a 1975 corvette. Just wondering if anyone out there has made any modifications to increase performance/HP without spending to much money?? My vette has matching numbers, t400 auto & mileage is 78k.
thanks
I'm a new owner of a 1975 corvette. Just wondering if anyone out there has made any modifications to increase performance/HP without spending to much money?? My vette has matching numbers, t400 auto & mileage is 78k.
thanks
Racer
Joined: May 2011
Posts: 373
Likes: 6
From: Dover Delaware
Save your $$$
I have a stock 78 L-48.......and it is what it is.......and I enjoy driving it as is!!!!!!
mk's 78
Thread Starter
Advanced
Joined: Dec 2013
Posts: 97
Likes: 1
Hi mk's78. thank you for your input. When I got it, someone changed out the original carb. with a holley light truck carb.?? Don't know why they did that, so off came the holley & on went the rochester quadajet 4-barrel like the original. All of the anti-pollution stuff was removed also, and dual exhaust was installed like the 1974 model year. So, yes your right, I'm just going to enjoy it they way it is.
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
I agree to a point. A 75 model engine with 78K miles is not going to be a great starting point for a high performance engine, but could be fine for a better performing one.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
Thread Starter
Advanced
Joined: Dec 2013
Posts: 97
Likes: 1
Hi Revi,
thank you for your input. I would like to keep the original motor, but if this motor gives me any problems, or blows up, I would probably look into a crate one. It's an ice cream car and don't plan on racing it, just cruising.
thank you for your input. I would like to keep the original motor, but if this motor gives me any problems, or blows up, I would probably look into a crate one. It's an ice cream car and don't plan on racing it, just cruising.
Burning Brakes
Joined: Apr 2010
Posts: 1,018
Likes: 9
From: Winston Ga.
john,
I am in the same boat, 75 l48.
The PO put dual exhaust and stripped the cats. I am not going to sink any money in to it. No headers or anything. I'll throw some lipstick on that pig with a couple of chrome pieces but I am saving for a 383 myself.
its nice to tool around in and look at but if I keep it its going to get a transplant.
If numbers matching is the issue, pull it and wrap it in plastic for the next owner.
I am in the same boat, 75 l48.
The PO put dual exhaust and stripped the cats. I am not going to sink any money in to it. No headers or anything. I'll throw some lipstick on that pig with a couple of chrome pieces but I am saving for a 383 myself.
its nice to tool around in and look at but if I keep it its going to get a transplant.
If numbers matching is the issue, pull it and wrap it in plastic for the next owner.
Last edited by jnealg; Dec 4, 2013 at 10:17 AM.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
I agree to a point. A 75 model engine with 78K miles is not going to be a great starting point for a high performance engine, but could be fine for a better performing one.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Advanced
Joined: Dec 2013
Posts: 97
Likes: 1
I agree to a point. A 75 model engine with 78K miles is not going to be a great starting point for a high performance engine, but could be fine for a better performing one.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
thanks for input. yes looked into intake up grade. Looks like Edelbrock #2101 is a direct replacement without modifling the hood. It also will take my rochester carb. I'll look into Lars. The exhaust is already a dual 2-1/2" back to mufflers, so that is done. Looks like there is room for headers, any suggestions on what to buy?
Thread Starter
Advanced
Joined: Dec 2013
Posts: 97
Likes: 1
john,
I am in the same boat, 75 l48.
The PO put dual exhaust and stripped the cats. I am not going to sink any money in to it. No headers or anything. I'll throw some lipstick on that pig with a couple of chrome pieces but I am saving for a 383 myself.
its nice to tool around in and look at but if I keep it its going to get a transplant.
If numbers matching is the issue, pull it and wrap it in plastic for the next owner.
I am in the same boat, 75 l48.
The PO put dual exhaust and stripped the cats. I am not going to sink any money in to it. No headers or anything. I'll throw some lipstick on that pig with a couple of chrome pieces but I am saving for a 383 myself.
its nice to tool around in and look at but if I keep it its going to get a transplant.
If numbers matching is the issue, pull it and wrap it in plastic for the next owner.
yes in a way your right. This car is in pretty good shape. Since it's the start of winter up here, the cars stored in my garage, I can get into a little upgrade and see if it will do the trick.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Racer
Joined: Oct 2013
Posts: 254
Likes: 3
From: Tampa Bay Florida
I agree to a point. A 75 model engine with 78K miles is not going to be a great starting point for a high performance engine, but could be fine for a better performing one.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
Headers and better exhaust are a good start. Have the distributor recurved (this helps a bunch) per Lars papers. Search the site for Lars information. Use a 180 degree thermostat with your new ignition setup. Switch out your intake manifold for an Edelbrock Performer and use your current carburetor. Anything else gets you inside the engine seriously.
This would give you a noticeable improvement in seat-of-the-pants performance and possibly better gas mileage.
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
After thinking about it, I would probably leave the stock exhaust manifolds on it. You won't be turning enough RPM's to really benefit much from headers unless you simply like the idea of having them plus the car will be quieter inside with the stockers. Personally, I install them IF I plan on additional modifications that needs them as part of a good foundation. True dual exhaust with decent mufflers is good enough for street use. I like Hooker Headers, but to each his own. They seem to fit well and are as durable as any others.
Thread Starter
Advanced
Joined: Dec 2013
Posts: 97
Likes: 1
Hello John485 and welcome to the forum. Good suggestion from Casey. That L48 is an excellent station wagon motor and will easily take close to 400hp. The Edelbrock Performer will save a bunch of pounds over that cast iron boat anchor manifold (if it's stock) and improve fuel distribution to boot. Plus the Edelbrock gives you the option of spread bore or square bore carbs and CFM choices from 390 to around 950, though 650 is a good all around choice for street. Ignition set to 36 degrees total @ 2800 to 3000 rpm, 180 thermostat and you should be good for cruise nights. No EFI and no computers - Whoopee!
I got this vette from a women that parked it in her garage 8 years ago and forgot about it. So, after getting it to my garage, I went through it to see what it needs. I haven't driven it yet, brakes needed to be overhauled and other stuff done to get it in safe running order. Tank drained and fuel pump, carb. replaced. All liquids changed hand turned crank to make sure it wasn't frozen. New battery turned key fired it up. Runs great!! all original stock motor that I can tell, except the carb. and air cleaner. I will look into replacing the intake as some of the vette guy's said to do. Already went with 180 therostat, timing will be next, along with getting the correct air cleaner.
thanks