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Discussion Starter #1
Is there any way the L99 can get some love? Since I haven't been able to find an LT1 around my area for cheap, I was thinking some work to the 4.3 would be the way to go. Is a cam swap even possible with this motor or am I going to have to stick with bolt ons like intake, headers, exhaust and tune for now?

I'm not looking for huge power gains, but something that I can have fun with, and still be a manageable daily driver.

I know this is probably a noob question, but I figured at least someone on here would know the limits of tuning this motor.
 

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I would do a stall converter and shift kit, this will let the L99 reach the meat of the torque curve sooner and still be great to reuse with an LT1 later. Then I would get an 8.5" axle and put 3.42-3.73 gears in it. There is some chance the car came with a 8.5" but it is more likely being civi L99 it would have gotten a 7.5" which a stock LT1 would break with traction.
 

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Discussion Starter #4
I've read up on doing the rear end swap, and it definetly sounds like a good mod. Stall, and shift kit is something I've wanted to do as well. But, is there anyone who has done a mild cam in an L99? It seems like the motor has potential, but that GM choked the hell out of it for fuel economy...
 

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A cam swap needs gears, stall headers to really work. Trust me I did a mild cam on an LT1 before I had those things it was a mistake.

The L99 got the same cam as the LT1 which is why it takes a little while for it to get into the powerband. You know how you punch it from a stop and it is slow for a little than maybe say 20mph or so it begins to wake up. Well that wont improve with a cam and is likely to get worse.

I had put a ZZ4 cam in my LT1 before the supporting mods and gained nothing but then as I gave it the supporting mods I saw big gains.

FWIW my car started life as an L99 car, almost 10 years ago that I swapped in the LT1, I did a lot of things wrong along the way but eventually got my act together..

Oh and a cam swap is going to cost a lit more than you think. If you can install a torque converter and shift kit yourself that will be cheaper than a cam so long as you buy something like an Edge 9.5" converter, don't buy any cheaper than that, if you want to spend more I would look at Yank.
 

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People give you good advice, and you keep after a cam swap. Do the other stuff FIRST like was said.
 

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Discussion Starter #7
I totally understand that a cam is going to require full bolt-on's to reach its full potential... I was just curious to see if anyone has done, or has seen a cammed L99.

Headers, exhaust, intake, stall, rear end/gears, shift kit and tune are definetly on my to-do list before I even think about tearing into the motor.
 

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Discussion Starter #8
Also, are there any markings or RPO codes that show the car came with a 7.5" or 8.5" axle? An 8.5" car should have come with posi from the factory, correct?
 

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The 8.5 didn't necessarily come with posi, so without a tag it could be hard to say. All LT1 cars came with the 8.5, however I'm not sure if any L99 cars did or not.
 

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Discussion Starter #10 (Edited)
The only RPO on my car that even remotely relates to the rear end is GW9? Just a quick google search shows that it's a 2.93 gear, but no direct link to what axle came with the car...

And, when I search GW9, it also comes up with the code GU3. But, all my searching seems to fail on that one.
 

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Ok, GW9 can be a few different options. Best bet is to read the code on the axle itself, it will be 2GF, 2GG, 4ZB, or 2LQ. Only the 2LQ is posi, and it would also have the larger 11" drums.
 

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Discussion Starter #12
Is that stamped on the pumpkin, or on one of the axle tubes?
 

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Axle tube, don't remember which side. Your brake drum size will also tell you though, if you have 9 1/2" drums you have a 7 5/8" open diff. If you have 11" drums, you have an 8 1/2". There were two options for that, one for taxis with an open diff, and the other posi with the 2LQ code on it.
 
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