First post, what have I got here?
Thread Starter
2nd Gear
Joined: Apr 2026
Posts: 2
Likes: 3
First post, what have I got here?
Finally got a C3 and love it, but it's a bit of a mystery. Being of the year of worst performance across all 'vettes, it should be a bit of a pig, but it goes like a scalded cat.
It's had work done. Electronic ignition and headers are immediately visible. It's got a nice body kit. No lope so I assume no cam.
When I punch it, it downshifts and kinda snaps your head back. Haven't had it wound fully out yet, but I ran out of what road I had before I ran out of motor.
Sure doesn't feel like any 170 horses I ever drove.
Short of taking it to the dyno, how can I figure out what's been done to it?
It's had work done. Electronic ignition and headers are immediately visible. It's got a nice body kit. No lope so I assume no cam.
When I punch it, it downshifts and kinda snaps your head back. Haven't had it wound fully out yet, but I ran out of what road I had before I ran out of motor.
Sure doesn't feel like any 170 horses I ever drove.
Short of taking it to the dyno, how can I figure out what's been done to it?
Popular Reply
Apr 17, 2026, 05:25 PM
Melting Slicks
Joined: Apr 2021
Posts: 2,714
Likes: 2,162
From: Minnesota
Welcome to the forum, but
Race Director
Joined: Nov 2006
Posts: 13,248
Likes: 7,839
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Welcome to the forum.
And I'll guess you have a 75 model.
And yes all the crap you read about the mid 70's cars having no power is just that. Crap.
Most of these cars have been warmed up.
Things you can do. Check the heads, are they original? Pull a valve cover, look for numbers. Cast iron? Aluminium?
Run a compression test. Put a vacuum gauge on it. Vacuum at idle? Check the timing? You certainly don't want to see stock timing specs.
Number 1 thing. Ask the previous owner. Although they have been known to stretch the truth.
And I'll guess you have a 75 model.
And yes all the crap you read about the mid 70's cars having no power is just that. Crap.
Most of these cars have been warmed up.
Things you can do. Check the heads, are they original? Pull a valve cover, look for numbers. Cast iron? Aluminium?
Run a compression test. Put a vacuum gauge on it. Vacuum at idle? Check the timing? You certainly don't want to see stock timing specs.
Number 1 thing. Ask the previous owner. Although they have been known to stretch the truth.
Thread Starter
2nd Gear
Joined: Apr 2026
Posts: 2
Likes: 3
Thanks!
It's a 78, actually.
I will check out all the items you mentioned.
Previous owner is unavailable. I bought it from a couple who got it for their 16 year old grandson. His mom said no. Imagine that!
Pics coming.
I will check out all the items you mentioned.
Previous owner is unavailable. I bought it from a couple who got it for their 16 year old grandson. His mom said no. Imagine that!
Pics coming.
Drifting
Joined: May 2020
Posts: 1,663
Likes: 702
From: Baton Rouge, Louisiana, metro area
Welcome. 78 is a great looking year. Pics please.
A previous owner spiced up my stock 75 with 3.70 gears in the diff from the original 3.08’s. Makes a difference for sure.
Could be a number of things done.
A previous owner spiced up my stock 75 with 3.70 gears in the diff from the original 3.08’s. Makes a difference for sure.
Could be a number of things done.
Melting Slicks
Joined: Sep 2004
Posts: 3,226
Likes: 670
From: Northeast
First of all you need to read up on the specs of a 1978. It is not the lowest of the low. If you have a L82 it started with 220hp, L48 with 185hp. The VIN number will tell you what it left the factory as. It appears the previous owner did some work on it and might have even changed the engine. Find the engine stamp pad, and post a photo. It will have a partial vin and engine date and suffix. Engine came with HEI.
Here is a pdf from GM heritage that will give you lots of information about how it started out as with options. Page 0a-3 shows you where to find the engine stamp pad. If painted use paint remover, nothing harsh.
https://www.gm.com/content/dam/compa...t-Corvette.pdf
Here is a pdf from GM heritage that will give you lots of information about how it started out as with options. Page 0a-3 shows you where to find the engine stamp pad. If painted use paint remover, nothing harsh.
https://www.gm.com/content/dam/compa...t-Corvette.pdf
Race Director
Joined: Mar 2017
Posts: 11,953
Likes: 4,508
From: Virginia
Please post some photos!
A dyno is the correct answer, of course. You can also use a phone app to determine 0-60 and 1/4 mile, then use a calculator to back out the HP with a guess of your car's weight. Grok suggests:
Pure Software Apps (Phone-Only, No Extra Hardware)These turn your phone into a performance meter using its built-in sensors. They're fully stand-alone with the phone.
If you are impressed by your 78's performance, perhaps someone has replaced your torque converter, in addition to a modern tune and exhaust work.
Be sure to get a copy of your car's dealer invoice. Link in my signature. Welcome to the Forum!
A dyno is the correct answer, of course. You can also use a phone app to determine 0-60 and 1/4 mile, then use a calculator to back out the HP with a guess of your car's weight. Grok suggests:
Originally Posted by Grok
Pure Software Apps (Phone-Only, No Extra Hardware)These turn your phone into a performance meter using its built-in sensors. They're fully stand-alone with the phone.
- RaceChrono (Android + iOS): Developed by RaceChrono Oy in Finland (European company). It's a professional-grade lap timer and data logger used in motorsports. It handles acceleration tests (0-60, quarter-mile, custom runs), supports video overlays, and works with phone GPS (better with optional external receivers if you want). Highly accurate for an app; includes track library, sector timing, and analysis tools. Free basic version; Pro unlocks more.
play.google.com +1 - Dragger – Car Acceleration Meter (Android): Developed by MILES Mobility GmbH in Germany. Specifically designed as a phone-based acceleration tool—no extra devices needed. Measures 0-60 mph, 0-100 km/h, quarter-mile, and custom speed ranges with a claimed "unique calculation algorithm" for better accuracy using GPS + sensors. Simple interface, shares results, and compares to manufacturer specs.
play.google.com +1 - FastR – 0-60 Acceleration Test (iOS): Developed by an individual (Erhies Fekarurhobo, with a .com privacy site—not China-based). Hands-free automated 0-60 and quarter-mile timing with millisecond accuracy claims, leaderboards, and car model comparisons. Fully automated launch detection.
apps.apple.com - FastTrack (iOS/Android): A newer 2026 GPS-based performance tracker from a car-enthusiast-focused platform (appears Western/U.S.-oriented based on marketing). Measures 0-60, quarter-mile, etc., using iPhone/Android high-frequency sensors + GPS fusion. Claims accuracy within ~0.05–0.1 seconds of dedicated hardware like Dragy. Includes community/leaderboard features.
fasttrackapp.biz
Be sure to get a copy of your car's dealer invoice. Link in my signature. Welcome to the Forum!
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