1996 LT4 engine question
Melting Slicks
Joined: Oct 2006
Posts: 2,238
Likes: 10
From: College Station TX
Yes, LT4's have the same optispark as an LT1. Chevy changed the design in 95 from the early models. The 95+ have a vent line, as well as a pin to drive the opti off of the cam instead of the splines of the early models.
Race Director
Joined: Oct 2005
Posts: 11,772
Likes: 177
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Melting Slicks
Joined: Feb 2006
Posts: 2,753
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From: backwoods upstate ny
Burning Brakes
Joined: Oct 2001
Posts: 911
Likes: 5
From: TN
Lt4
I am glad GM did improve the opti-spark. My original owner 96 LT4 has about 38K highway miles on it with no problems yet with the opti-spark. Don't know how much mileage one can get from the improved system.
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Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
Great, more LT4's for everyone else. The presence of the Optispark is a terrible reason to not get one. The Opti is a great engineering feat if you just take care of it and don't wash your engine and make sure your water pump is sealed properly to the engine. I can think of much better reasons not to get a C4, namely the fact that the C5's have 40% more torsional stiffness and 40% fewer parts. And the C6 gets it even better. If cost is not an object, get a C6 instead.
Racer
Joined: Jan 2003
Posts: 360
Likes: 0
From: Sumter South Carolina
I know there are horror stories about the opti, but I've done lots of mods, drive the car hard, never wash the engine, and I've got 50,000 miles on the original opti. I agree with the above posts, there are other reasons to look at newer vehicles, but the opti shouln't be a make-or-break reason to not get an LT4 car.
Racer
Joined: Sep 2003
Posts: 275
Likes: 0
From: West Monroe La.
The opti on my 95 was working fine at 83,000 miles. I replaced it when I had to replace my leaking water pump just because I was in there. The water pump had leaked on it for two weeks before I replaced it, and it still worked fine. I have 5500 miles on the new GM opti, and no problems. I would buy another lt1 or lt4 in a second. Not a good reason to rule out one of the best looking corvettes ever made.
By the way, I work for a sheriff's office, and in the mid 90's we used caprice police package cars. We probably had 50 or 60 of them, and I assume they had opti's on them. They came off the line at 125,000 miles, and there were no problems with them either.
By the way, I work for a sheriff's office, and in the mid 90's we used caprice police package cars. We probably had 50 or 60 of them, and I assume they had opti's on them. They came off the line at 125,000 miles, and there were no problems with them either.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
The C5/C6 are fine cars... but don't go beating on them... the entire transaxle has proven to be not all that stout.
The LS7 is having valve train issues...
From my observations, I have heard of more C5/C6 transaxle failures than I can count. The ZF6/D44 has proven to be seriously strong. And the LT4 is dead nuts reliable.
So... trade off a potential optispark issue for a potential drive line failure... hm...
Pro
Joined: Mar 2006
Posts: 674
Likes: 0
From: Mesa AZ
What's the big deal anyway? If the Opti does go bad, they can be had for around $250, and it takes about half a day to replace and is not that hard.
I was concerned with them too, but once I learned about them - I have zero concerns. All mechanical parts can fail, but I don't see the Opti as being more unreliable than any other piece of equipment.
Maybe I am to new/naive to realize the dangers...
I was concerned with them too, but once I learned about them - I have zero concerns. All mechanical parts can fail, but I don't see the Opti as being more unreliable than any other piece of equipment.
Maybe I am to new/naive to realize the dangers...
Drifting
Joined: Aug 2004
Posts: 1,707
Likes: 285
My '96 CE LT4 Z51 with just 14,000 miles on it was spewing what I thought was steering pump fluid all over the underneath of my hood and onto the front cross member. I screwed around with it by sticking in Lucas leak stop to see if it made any difference. Nope , just got worse. I finally took it to the dealership where they told me that the water pump was peeing all over the place (result of a low mileage non-driven car said Mr Mechanic). The mechanic said had it been an earlier model the opti would have been toast. But because of the improved design , viola. Good to go and no damage. Testament to improved GM Engineering 
Trebor
Trebor
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
btw, the lt4 is ridiculously more powerful than the lt1. the 30hp difference must have been a typo!
Drifting
Joined: May 2005
Posts: 1,336
Likes: 12
From: Chicago Executive Airport, formerly known as Palwaukee
No-IL Events Coordinator
St. Jude Donor '12-'13-'14-'15-'16-'17
I have over 94,000 miles on my original LT4 optispark. The water pump was replaced under an extended warranty at about 50,000 miles. I put on an Accel distributor cap & rotor at 90,000 miles. The opti was in perfect condition, except for the rotor screws that had backed out and were sitting in the bottom of the distributor. The engine was still running strong but had a little erratic idle. The design prevents the rotor from coming completely off. There was side-to-side play which accounted for the idle.
I have washed my engine too many times to count! The '96 OEM opti is sealed very well. The Accel cap & rotor comes with two (2) silicone o-ring gaskets that are pretty trick and seal up the unit perfectly.
What everyone is saying about the driveline is no joke. The D44 and the ZF are bulletproof. I also have the dreaded original dual-mass flywheel and clutch assembly in mine!
I have washed my engine too many times to count! The '96 OEM opti is sealed very well. The Accel cap & rotor comes with two (2) silicone o-ring gaskets that are pretty trick and seal up the unit perfectly.
What everyone is saying about the driveline is no joke. The D44 and the ZF are bulletproof. I also have the dreaded original dual-mass flywheel and clutch assembly in mine!