Hi All,

Just looking for feedback as a multiple C3 owner I am thinking of selling one of my C3's (1978 4 speed car) to buy a C4. Please feel free to check or comment on my logic, as I know very little about C4's.

Reason for wanting to make the switch:

1. Since I own C3 corvettes (1969 original engine trans 427 car (last years winner of Modified C3 content and a L48 1978 4 speed car), I don't have a car capable of traveling long distances at interstate speeds. I am not interested right now in the expense of adding a 5 or 6 speed trans to my 1978. The 1969 is untouchable and not to be messed with. It has 3.08 rear gears so it can cruise hwy, but that car is not seeing rain etc.
2. I would like a corvette that I can pop in and drive 300 miles with on the hwy.
3. I would also like to track a corvette occasionally and the 1969 is again off the table as it is retired from racing and I don't want to chance beating it up.
4. From what I understand C4's are MUCH better out of the box for Autocross and track days, compared to a C3
5. I believe the 4+# trans ran up until 1988, and should be avoided if the car is going to see any performance driving
6. I believe the 1992 and up motors have more horsepower, but come with some possible issues with OptiSpark
7. I believe the previous to 1992 tuned port motors used a more conventional distributor

That is what I believe so far, so feel free to weigh in. Again the goal is a car that is superior to my l48 4 speed C3 in hwy driving at sustained speeds (70-75 mph) as well as a good base to put some good tires and coil overs on and track the car.

Let the feedback fly and thank you in advance.

 

1. Understandable.
2. A good C4 makes a great road-trip car.
3. Also understandable.
4. The C4 is a vastly superior car to all that came before it, by all measures other than simplicity (if you value that), and styling (subjective).
5. The 4+3 ran through the '88 model year. I personally wouldn't want the 4+3, although I'm sure there are a few owners who see nothing wrong with them. The ZF six-speed that replaced it in 1989 is superior in every conceivable way.
6. The '92 - '96 LT1 (and '96 LT4) engines are indeed stronger than the earlier L98, and are in fact, great performers. The Optispark works extremely well until it doesn't. The challenge these days is getting reliable replacements -- the biggest problem seeming to be the shitty quality of the Brand X optical sensors that are used in some of the replacement units. The original Mitsubishi-built sensors were quite reliable. The Opti was substantially redesigned, with those second-generation units appearing in the '95 & '96 LT1 and LT4 C4s. Retro-fitting the second-gen unit to an earlier engine is not an easy bolt-on proposition, and I wouldn't bother to attempt it (different camshaft, timing cover, etc). But, adding the active venting (uses manifold vacuum) to the earlier units is easily done, and pretty much eliminates two of the chief culprits of failure in the high-voltage section, which are build-up of corrosive ozone and moisture. Don't fear the Opti. It's no reason to avoid an LT1 or LT4 C4 car.
7. Correct.

Happy hunting. Pop in with any questions that might arise.

Live well,

SJW

 

I agree, get any 92+ 6 speed and you will be happy.

I have a 93 6 speed and feel comfortable and confident to drive it anywhere/any distance. 80MPH at 30 mpg no problem too!

89 6 speed if you are ok with less performance but want old style dash and body… 90-91 same deal just newer dash/styling

You didn’t mention budget which is a factor

 

agree with all above, and im one of those who really loves the 4+3 and tracked a 4+3 car for a while before selling it to buy a zr-1.

cheers and look fwd to future posts.

 

The opti really isn't a big deal breaker. I replaced the timing chain on my 92 LT1 and the opti has to be removed to get to the timing chain cover. As far as pulling a distributor, which is what the opti basically is, and reinstalling it this is one of the easier ones to work with. The shaft that drives the opti can only be installed in one way. The computer does all the timing. I have pulled distributors on old SBCs, Pontiacs, Fords and even 89 L98s. It is always a bit of a challenge to get the teeth engaged right. You got to pull and reset the distributor a couple of times. Not the opti. One way only and done. So, I don't fear the opti. Replacements have a bad name, but with local autoparts stores offering lifetime warranties its not too bad.
As for the LT1s themselves I think they are great for what they are. More HP than an older SBC, less than a LS. Parts are still affordable and easy to come by. I myself prefer the older C4 body style of 84-90 (I prefer the 89 rims). I ended up getting a 92 just based on the superior LT1 and the 6 speed.

 

based on your mentioning auto cross my choice would be 96 LT4. I love my LT5 but the width is not as suited to tight tracks. LT4 appears to be fairly easy/reasonable$$ to get close to stock C6 Z06 hp , should you choose to modify

 

Buy a 96 LT4. Be aware that there is a one year issue with the HVAC unique to the '96's (LT1's or LT4's). Otherwise, the '96's are pretty much refined.

As far as a cruising machine, the auto cars are pretty nice for highway/long distance driving.

 

The L98 cars run pretty good. I sometimes drag my 86 at the track here in Indy.I was surprised what it would do and what it would outrun,,, stock. I am 3 thenths from hiting the 13 second runs. Better tires and it will. The c4 corbettes are NOT the stepchild to anything out there.

 

Interesting! So the 92-94 Opti Spark is different from the 95-96 OS. That is good to know. TY!

 

For budget I am thinking the $7,000 to $11,000 range. Does that sound reasonable?

 

Yes. Shop carefully, and you'd be surprised what's available in that price range. Buy a good one, and you'll likely wonder why you didn't get one sooner than you did.

Live well,

SJW

 

Thank you!

 

 

Biggest reliability difference is the venting, and which you can add to the 92-93… I wouldn’t let that deter you. Seats are better pre 94 especially for racing IMO (better and tighter bolsters)

 

I've never seen a C4 owner as happy as the ones with the 6-speed LT1s! The only happier ones are the lucky ones that snagged a 6 speed LT4 (96 MY only)

You're really going to enjoy the C4. If you plan on keeping it stock, the only thing to really add is some sound proofing if you want less road noise. I don't mind it but its probably bc I don't cruise long distances. I will start this year though! An early bienvenido amigo

 

THANK YOU SO MUCH. I am really excited! My 1969 C3 is a forever car, but I am also REALLY looking forward to having a "Cool" car to jump in and drive for long drives. I have a Hyundai which is my Snow and "errands" car.

I am also going to AutoCross and Track the car. All things my 1978 C3 L48 cannot currently cannot do.

 

I bought a '92 with the Z07 brake/suspension package in May. My wife and I flew up and drove it 1500 miles home. It was a blast through the PA and WV mountains. It was also very comfortable. Since you plan to track it, if you can find one, the Z07 package adds the J55 big brakes, Dana 44 w/3.45:1 posi, big sway bars, six speed manual, sport seats, high rate springs, 9.5 inch rims at all four corners.

 

I understand that the 95-96 also come with the J55 brakes stock?

 

I understand that the 95-96 also come with the J55 brakes stock?

I don't know if that's true. I'm sure someone will answer.

 

That is correct.

Live well,

SJW