Engine tuning
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
And not your first time on this subject, but hopefully the last.
Ever heard of the modified saying:
If You Can't Write Something Helpful, Then Don't Comment At All.
Thread Starter
Intermediate
Joined: Jul 2024
Posts: 47
Likes: 11
Sorry for (extremely) late response
I just got a new carburetor with an electric choke, since the old carb had been on there for a very long time and just needed replacing. Its pretty much the same exact carburetor except a little more updated.
Engine seems to stay pretty cool. Even on warmer days the temp stays a little under 220, which is half way of the temp gauge. On cooler days it runs about 200-210 depending on how fast i run it
I also fixed that throttle return spring, and connected the two of them as shown in one of your pictures.
also, i made a mistake saying the entire distributor cap was replaced, it was not. The mechanic i take my car to just did a full tune up by replacing the sparkplugs, and some stuff to do with the distributor. I think he said he replaced a rotor or something like that. My fault.
Engine seems to be doing even better than it used to with this new carb. Throttle response is like butter and really added some pep to it.
I just got a new carburetor with an electric choke, since the old carb had been on there for a very long time and just needed replacing. Its pretty much the same exact carburetor except a little more updated.
Engine seems to stay pretty cool. Even on warmer days the temp stays a little under 220, which is half way of the temp gauge. On cooler days it runs about 200-210 depending on how fast i run it
I also fixed that throttle return spring, and connected the two of them as shown in one of your pictures.
also, i made a mistake saying the entire distributor cap was replaced, it was not. The mechanic i take my car to just did a full tune up by replacing the sparkplugs, and some stuff to do with the distributor. I think he said he replaced a rotor or something like that. My fault.
Engine seems to be doing even better than it used to with this new carb. Throttle response is like butter and really added some pep to it.
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,082
Likes: 4,431
From: Marlton NJ
It must be tuned pretty well if you say it runs strong. A decent distributor timing curve must already be in there. But it still pays to check.
A good running L48 can run pretty strong if it is sort of back-dated to 1970 specs.
I am assuming, because it has headers, that it has real dual exhausts running all the way back. But you should still check. OEM was a single pipe in the middle of the car. A 2-1-2 system.
Easy mods:
Enjoy it!
A good running L48 can run pretty strong if it is sort of back-dated to 1970 specs.
I am assuming, because it has headers, that it has real dual exhausts running all the way back. But you should still check. OEM was a single pipe in the middle of the car. A 2-1-2 system.
Easy mods:
- Definately get rid of the solid fan spacer. Add a fan clutch and gain ~15 HP at higher rpms. Fan will never go over 2800 rpm then. Buy a good Hayden std duty recommended.
- Check if the rear mufflers are the straight thru turbo-style. Also worth 10-15 ponies over std GM ones.
- Air cleaner. A good open element air cleaner with 3" deep filter is worth some HP over the stock snorkel setup. ~8-10HP? But you will need a corvette specific 2" drop base for it to fit.
- Do a compression check. Swap heads to the smaller 57cc chamber Trick Flow to raise compression ratio, and better ports as well. ~30-40HP maybe. Your biggest bang for the buck. Your stock L48 had a low 8.2 CR. This one might have more since it has been worked on. It will run far better if you can get it to 10 or close. A compression reading might tell you. Sticking a borescope down a spark plug hole and identifying the piston top, dished or flat, is the the only way to know for sure with the engine still together. Read the casting number off the head under the valve cover. 75-79 heads were not that great. But they may have been changed to raise the CR.
- A cam is worth far less than the heads, if you keep the cam mild & driveable. But there are a few more HP there to be had.
- All-in you could be at 300-330HP and have a fast car. Better than a stock L82 at that point.
Enjoy it!
