Just picked up a 9C1 Caprice and was wondering what the specs were on these things. Any idea how long this tank is gonna last? What are some good starter mods (considering it has 140XXX)? This car is going to be driven daily so I can't blow it up or strip it. Thanks guys.

 

Also does anyone know what the bolt pattern and backspacing is, and the widest rims/tires that would fit without tubbin it?

 

some good starter mods would be a total rebuild to a 396 or 409 with a forged bottomend and sub 9:1 compression, then a big *** turbo boosting 15+ psi.

or, you can do like the rest of us and start off with a catback and an intake.

were you really strapped for money or something? Only reason I ask is becuase I know if it were me, I definitely wouldn't buy a car with 140k on the clock to use as a daily driver...

 

"strapped for cash" doesn't quite cover it. Anyway I've heard the cop cars with the iron heads will run forever. I hope so, although the tranny is starting to go out.

 

I remember trying to buy one of those new. That's way back before the SS Impalas made it a cool style. Everybody thought I was nuts, then the SS's hit the market. You most definitely would want to go over the whole car with a comb. Though they are well maintained in a department fleet motorpool, they do see some use. I would check the cooling system, transmission, rear end. They do have aftermarket brake systems for these. I would check out Global West and see about replacing all of the suspension bushings. Those cars are cool. They have their own hoses, alternators, radiators, special speedometers. You can do anything to the engine that you could to third Gen F-bodies and Vettes. Anything for the Impala SS will work for it. I would love to get my hands on a 1969 Dodge Polara police car.

 

Make that fourth gen LT1 F-Bodies and C4 LT1 'Vettes...

 

you can swap a 6speed out of an f-bod into those fairly easily, make it more fun to drive. check out www.bigfastcar.com for swap info. other than headers and a cat back, you could go with a cam/heads/pcm tune as well.

 

Start with getting a hockey puck and some PVC pipe and removing the two resonators (first base and home plate) from the intake. Then "mod" your airbox by basically cutting the bottom out of it....and vwoala!!!!....you have an intake. Then a catback exhaust (because that is the most restrictive part) would be next. After that goto www.pcmforless.com and get him to program your computer. About half of the Impala board has his programming and I will have it soon. You can expact 15-20 RWHP with his 93 octane tuning alone. Go over to www.impalassforum.com and get out what the other guys are doing. We have bolton cars in the 12's......

 

How can you tell the difference between the LT! and the L99? Thanks for the info

 

Well, the other Corvette motor is the L98. The F-Body used some anemic 305s, but also used the L98 in some cases.

As far as body styles, the L98 only appeared int he F-Body in third gen trim. The Corvette was a bit harder to tell. The rear of the L98 Corvettes was inverted, and the rear of the LT1 'Vettes was more bubbly.

As far as the motors, the intake manifolds are a dead giveaway. Just look for the runners sticking out of the L98 manifolds. Other than that, LT1 intake filters are on the right side of the compartment (looking from the front of the car toward the car), and the L98 filters are toward the left.

I've worked on both motors, and they're pretty similar as far as the basics go. Main differences would be the L98's terrible intake design and super-constrictive heads, and the LT1's opti-spark distributor.

Hope this helped, you can find mroe specific years that the L98 and LT1s were in each car by running a search through the internet. There are literally thousands of write-ups on it.

 

The L99 refers to the 4.3L V-8 in the civi and some 9C1. You can't tell by just looking at the motor because from the outside it looks exactly the same with the LT-1 style intake and everything.

For a civilian Caprice, the L99 motor has a lower output alternator, 100 amps compared to the LT1's 140amp alternator. You can see the difference by looking at the alternator cooling fan. The 140amp fan has blades on the inside, like a vented brake rotor. The 100amp alternator has traditional looking fan blades. If the car is any sort of special service Caprice (9C1, 9C6, etc.) then the above does not apply. All special service Caprices got the bigger 140amp alternator.
The 8th digit VIN code for the L99 is W. The L99 was standard on both the civilian and special service Caprice. The LT1 was standard on the Caprice wagon, Impala SS, Roadmaster sedan & wagon, and the Fleetwood.

There is a machined pad on the passenger side deck surface the is not covered by the head. However, it is obscured by the alternator. That's where the codes Darth posted are located. Those codes will give you the year and displacement of the block. If the block has ever been decked, these engraved codes are usually machined off in the process.

There is also a VIN derivative located on the driver's side rear of the block, above the oil filter pad. If the engine is original, then the VIN derivative on the block will match the 3rd, and 10th through 17th digit of the car's VIN.

The L99 used two cats like the LT1, but a Y-pipe connects the driver's side to the passenger side to a single pipe with muffler and resonator.

I have been told that on the L99 block, there is 4.3 in cast raised numbers on the side of the block near the core plugs. I can't remember which side though. Kind of like 360 or 318 being cast into the driver's side of Dodge blocks. No such numbers are found on the LT1 block

I've also been told that the '96 4L60E transmission case on the L99 is two pieces, with the bell housing being bolted to the rest of it. I don't know for sure if the is just for the civilian Caprice or applies to the special service cars as well.

The best VIN locations are

On the dash visible through the windshield
Federal Safety sticker on driver's door
SPID label on upper left hand side of decklid
If any of these VINs do not match each other, I'd start asking some serious questions about the history of the car. Also check the underhood emissions sticker on the radiator support to see if it matches the engine codes on the SPID and the model year of the vehicle.

For LT1 Caprices the SPID should have the QMU or QMV tire codes The LT1 engine requires P235/70R-15 tires. Check tire placard on the driver's door.

The civilian L99 Caprice also has a 2.93 rear end with rear drums, code GW9. The special service L99 Caprice has a 3.23 rear end with discs on a 9C1 or drums on a 9C6, code GU5.

 

Any "free" mods I can do with this car (besides the above mentioned)? Is the bolt pattern the same as the fourth gen camaros/vettes? My car has a sticker under the hood on the radiator support that says 5.7 on it so I'm positive it's a Lt1, and just how this car moves.