looking at an lt4 corvette
Thread Starter
Racer
Joined: Feb 2009
Posts: 261
Likes: 1
From: Riverside CA
looking at an lt4 corvette
looking at an lt4 corvette. for you guys that have one what do I do about the opti? that is the one thing that deters me. also can it be converted? mods ect. how do they run against c5's ect. bring me up to speed please. thanks..
Le Mans Master
Joined: Aug 2015
Posts: 6,103
Likes: 1,985
From: St. Charles MO
Don't let the opti scare you away. Those don't fail nearly as often as people think - a lot of problems that are blamed on the opti aren't actually caused by it. If you ever do have to replace it, the labor isn't as terrible as many people make it out to be, and there are at least three good options for replacements. The only potential "gotcha" with a 96 C4 is that it's the first year of OBD2, which may mean more stringent emissions inspection requirements where you live. It also means that in order to tune it or turn of self-diagnostics (if you make significant mods) you need more expensive software than for earlier cars (Jet DST). Not a big deal, especially if you plan to keep it stock.
Le Mans Master
Joined: Aug 2015
Posts: 6,103
Likes: 1,985
From: St. Charles MO
Le Mans Master
Joined: May 2005
Posts: 7,354
Likes: 2,279
From: Central Maryland
LT4 has the much improved, second-generation Opti, with active venting, revised bearing, etc. These tend to be much more durable than the first-gen units. As others have already advised, don't fear it.
And, yes, the LT4 can run with the big dogs. If you haven't driven one yet, it'll surprise you when you do.
Live well,
SJW
And, yes, the LT4 can run with the big dogs. If you haven't driven one yet, it'll surprise you when you do.
Live well,
SJW
Supporting Vendor
Joined: Oct 2004
Posts: 761
Likes: 68
LT4 has the much improved, second-generation Opti, with active venting, revised bearing, etc. These tend to be much more durable than the first-gen units. As others have already advised, don't fear it.
And, yes, the LT4 can run with the big dogs. If you haven't driven one yet, it'll surprise you when you do.
Live well,
SJW
And, yes, the LT4 can run with the big dogs. If you haven't driven one yet, it'll surprise you when you do.
Live well,
SJW
Race Director
Joined: Sep 2001
Posts: 14,676
Likes: 751
From: NEwhere Ohio
The optispark had gotten a bad rap due to geniuses thinking a cheap chinese replacement unit is the same as a NOS OEM optispark.
they replace their optispark with a piece of chinese garbage for whatever reason and then falsely believe all optisparks are garbage when it doesnt work.
some people were sold cars with faulty chinese optisparks by PO’s who couldnt get the car to run right so they sold it.
the conversions dont even eliminate the optispark entirely . They still require it.
they replace their optispark with a piece of chinese garbage for whatever reason and then falsely believe all optisparks are garbage when it doesnt work.
some people were sold cars with faulty chinese optisparks by PO’s who couldnt get the car to run right so they sold it.
the conversions dont even eliminate the optispark entirely . They still require it.
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
Racer
Joined: Jul 2007
Posts: 383
Likes: 21
From: Tulsa, OK
I've owned an LT1 and currently an LT4 and never had opti trouble with either. The thing to look for specific to 96 models is the AC tends to have an issue switching from defrost to forward vent due to a rubber material used on the vacuum control that weakens and thus affects pressure. So basically your AC only blows out defrost. The box us underneath the dash to pull out and fix.
https://www.corvetteforum.com/forums/c4-tech-performance/1514042-96-hvac-vent-control-problem.html
https://www.corvetteforum.com/forums/c4-tech-performance/1514042-96-hvac-vent-control-problem.html
Last edited by Jitsu; Oct 20, 2019 at 02:38 PM.
Instructor
Joined: Oct 2019
Posts: 171
Likes: 51
From: USA
I really appreciate this post, thanks. Noticed the A/C vent buttons on my '96 GS didn't seem to respond to inputs--also air didn't feel all that cold. Took her to a dealer, they checked the system, found no leaks, recharged. Cold air comes in now, but it seems to simply respond to the "auto" setting as supposed to specific vent selections.
This makes sense now.
This makes sense now.
Le Mans Master
Joined: Aug 2015
Posts: 6,103
Likes: 1,985
From: St. Charles MO
The thing to look for specific to 96 models is the AC tends to have an issue switching from defrost to forward vent due to a rubber material used on the vacuum control that weakens and thus affects pressure. So basically your AC only blows out defrost. The box us underneath the dash to pull out and fix.
https://www.corvetteforum.com/forums/c4-tech-performance/1514042-96-hvac-vent-control-problem.html
https://www.corvetteforum.com/forums/c4-tech-performance/1514042-96-hvac-vent-control-problem.html
Racer
Joined: Jul 2007
Posts: 383
Likes: 21
From: Tulsa, OK
To add detail here, I think that only applies to 96s with the automatic HVAC controls, right? If you get a really bare-bones-optioned 96 with the manual HVAC controls, like I have, I don't think this is a problem. But someone please correct me if I'm wrong about that!
Mine has the automatic HVAC and the issue is present but it has never really been an issue for me since I typically have the top down.
Its a minor issue that should not dissuade a buyer from purchasing an otherwise good condition 96.
Last edited by Jitsu; Oct 21, 2019 at 08:49 PM.
Burning Brakes
Joined: Jan 2019
Posts: 1,225
Likes: 682
From: Park City, TN
2024 C6 of the Year Finalist - Unmodified
2023 C6 of the Year Finalist - Unmodified
2022 C4 of the Year Finalist - Unmodified
2021 C4 of the Year - Unmodified Finalist
2020 C4 of the Year Finalist - Unmodified
2019 C4 of Year Finalist (stock)
Noticed the A/C vent buttons on my '96 GS didn't seem to respond to inputs--also air didn't feel all that cold. Took her to a dealer, they checked the system, found no leaks, recharged. Cold air comes in now, but it seems to simply respond to the "auto" setting as supposed to specific vent selections.
My 96 (C68) all of the buttons would work almost all of the time when I first start it. After driving a while several buttons would not work (select). Yet, the air was diverted where it should be for the buttons that did work.
If this is the case what I just did is take out the controller, take it apart and clean the buttons and electronic actuators with "Electronic Parts Cleaner" spray and reset the board.
All of the buttons now work, but I have not had time to drive it so my testing is only preliminary.
If this doesn't work, I'll send it to Bryan Thompson (batee.com) to have rebuilt.
BTW, I liked BAT's video on taking it apart.
Racer
Joined: Jun 2019
Posts: 276
Likes: 69
From: Florida
Lt4
I bought mine in July and love the car. I am still in the process of doing the baseline maintenance. It is a great car to cruise with the top down. My AC has the problem as the air takes about 5 minutes to come out the right vents, but I am going to fix that next. I have changed all the fluids and cleaned up the interior a bit and she is looking good.