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LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

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Old 07-15-2017, 05:32 PM   #1
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Check out this gem

Hey everyone, new member here.
I recently came across a rough looking 95 z28 on Craigslist for dirt cheap and had too buy it. The owner didnt know much about it, only had it a few weeks.
But said it has a Roller Cam, 2.02 Heads, Flowmaster Catback exaust, and a BBK intake/throttle body, 2002 wheels. So after getting it home and cleaning the inch if PNW moss out of it I've found some other interesting stuff.

The rear Diff cover has been replaced with a summit racing one, so I wonder if the gears or rear end have been as well. Any way too check or identify?

The rear shocks are comp engineering 3 way adj drag shocks and the front are KYB AGK adj '"struts" I believe these are'. Any reviews or opinions on these?

The Transmission is pretty much fried, drags from 1st-2nd and lucky if I get a 3rd. I'm thinking about a 'Monster' 4l60e replacement this winter. Any suggestions?
I plan on doing the swap myself and using it as a weekend street/strip car. We have an 1/8mi open in the summer. I know I'll need software too set shift points so could use suggestions there as well.
I also plan on buying a tuner for the engine to be able too check what has been tuned already with the cam, heads, gears? Etc... is it the same software for both??
Iv always loved Camaros and this is my first one, my dad always had an SS or z28 or Iroc while I was growing up but never modded them, I plan on taking care of it and would love help doing it right.
Any insight is helpful! Thanks guys!

Last edited by LoneZ28; 07-15-2017 at 06:17 PM.
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Old 07-15-2017, 09:42 PM   #2
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The LT1 came with a roller cam from the factory, so saying it has one isn't meaningful. 2.02 would be the diameter of the intake valves in inches. I'm pretty sure that's bigger than stock, but doesn't tell us much about what they are. Could be stock heads with a valve job, or anything else.

To check your rear gears, there are two things you can do. One is easy and approximate; the other is hard but precise.

1. Jack up the rear of the car. Put the trans in neutral. Make a mark on the bttom of the driveshaft and on the sidewall of the tire. Have a friend watch the tire and tell you when it has made exactly one full rotation as you rotate the driveshaft. The number of times you turn the driveshaft is your gear ratio. You can make this more precise by having your friend count any number of tire rotations; the more, the better. Then divide your count of driveshaft rotations by the number of tire rotations. If you turn the driveshaft 37 times and your friend counts ten tire rotations, that's a 3.7:1 ratio, probably 3.73 gears.

2. Open up the rear end and count the teeth on the ring gear (it'll be in the 35-45 ballpark), then on the pinion gear (it'll be in the 8-12 ballpark). Divide the ring gear tooth count by the pinion tooth count and you'll have an exact ratio. For example, 41 ring gear teeth and 11 pinion teeth is 3.73. This is a great opportunity to put in fresh diff fluid. Don't forget the friction modifier!

I'm unfamiliar with those shocks, personally. Hopefully Fred (Injuneer) will drop in; he knows more about LT1s and drag racing than I do, for sure. He'll probably have tuning advice as well -- best I can do is tell you that I'm 90% sure that the LT1 PCM controls both the engine and the transmission.

Monster is a pretty expensive option for your 4L60E. Personally, I'd look into Cahall Performance Transmissions. Frank Cahall was a sponsor here some years ago. He was out of the business for a while for personal reasons, but I just heard recently that he's back in business.

Congrats on your new car! Enjoy it!
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Old 07-15-2017, 09:47 PM   #3
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Two option on the rear gears. 1 - pull the cover and count the teeth on the ring and pinion. # of ring gear teeth divided by # of pinion teeth equals gear ratio. 2 - jack rear end, place jack stands under both sides of axle. Mark driveshaft w/ chalk, mark tire with chalk. Rotate BOTH rear wheels exactly one full turn. Count number of rotations of the driveshaft. Number of driveshaft rotations equals gear ratio. Method 2 is hard to get exact, but should get you close with repeated attempts.

95 4L60E is unique year. Replacement must be made with a 95 4L60E, due to that year being the first year to use pulse width modulated converter lockup. Subsequent years continued w/ PWM, but electrical characteristics of internal components were changed.

4L60E year differences and interchanges.

You might want to look at the website for the author of that page. He builds excellent 4L60E's.

Tuning software like TunerCATS or eeHack will allow tuning of both the engine and the trans. Used to be another software called LT1_Edit, but the author is no longer selling licenses. Good info on this site:

LT1 PCM Tuning - Tips & Tricks for DIY Tuning!

Your photo links are not working.
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Old 07-15-2017, 09:59 PM   #4
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AGX, made by KYB, is an entry level adjustable shock. Serves the purpose. Just not up there with QA1, Afco, Strange, etc.

Minor point. The front setup on the 4th Gen F-Body uses a "coil-over" shock, part of the unequal A-arm suspension, no strut.
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Old 07-15-2017, 10:48 PM   #5
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That is all great info. Thank you!
I'll pop off that rear cover, take a look and swap some fluids.
Thanks for the web links, I'll be saving those. And I've seen that software talked about on here before, looks good. Ill look at Cahall Transmissions as well.
Ill have too find a part number on the heads and take look at the valves, do some research and then maybe see if i can make a determination on the cam shaft with out removing it.
I'v ran Eibach and liked it so I might do that with a nice shock combo.
Do you happen too know of any 'weak spots' on the LT1 or F-body platform i might need too look into and possibly replace or repair? Or any recommended upgrades for longevity?
Please excuse all the questions, just trying too learn a whole new car, and coming from a '77 Caprice the differences are astounding 😂
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Old 07-15-2017, 11:08 PM   #6
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Weak points:
As miles rack up, the body loses rigidity. The fix is a pair of subframe connectors. If your car has already gone soft, this will make a night-and-day difference. If it hasn't, it's a cheap guarantee that it will stay rock solid forever. I have three-point bolt-ins from UMI. For drag use, two-point are fine.

Window motors. When yours die (first sign is when they'll go down but not back up, and then ten minutes later they'll go up fine), get new ACDelco motors and install AutoTrix.net's hotwire kit.

The rear end is relatively weak. If you reach 400hp at the wheels and go to the drag strip with a sticky tire, you're on borrowed time. Your mileage may vary; some people have bomroken them at stock power, and others have had years of trouble-free racing at migh higher power levels. A full replacement with a beefier unit is the way to go. There are a handful of companies that make bolt-in-ready 12-bolt, Dana 60, and 9" rears, generally about $2500. If you are a decent fabricator, you can do it for much cheaper with junkyard parts.

If the hinge on your center console lid isn't broken already, be careful with it.
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Old 07-16-2017, 08:51 AM   #7
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For springs and shocks, this is a good source of quality options:

Strano Performance Parts - Parts Catalog

He would know what springs are compatible with your AGX shocks.

The LT1 (known as the Gen 2 SBC) engine has two features the are signignificant performance advantages, but also turned out to be major problems.

First is the "reverse flow" cooling system that sends coolant to the heads first, rather than the bottom of the block. That, along with the aluminum heads, allows the engine to run additional ignition advance, and breathe denser air. But the cooling system must be kept free of air. The Corvette version used a self-bleeding system, with a pressurized reservoir to keep the air out. But the F-Body system lacks that feature. It provides two bleeder screws to eliminate the air. As a result the system must be filled and bled very carefully, or the engine is going to overheat. Hot enough and it will lose a head gasket.

Second feature is the Optispark distubutor, mounted on the front of the engine, directly under the water pump weep holes (ooopps). The distributor incorporates an optical cam position sensor which sends the info to the PCM that it requires to time the ignition and time the sequential fuel injection. Benefit is an extremely precise timing signal that reduces spark scatter, allowing more aggressive ignition timing, and more precise fuel delivery. More power with less emissions. Problems - the distributor is expensive, hard to access, is prone to getting wet, there is potential for oil to enter the case via the drive mechanism, and the optical module replacements currently available, particularly Chinese rip-offs are not reliable. I think there's someone on here who still his his original at 300,000 miles. But others saw them fail in less than 100,000 miles. The early years (1993-94) are the worst, called "unvented". GM eventually realized the ozone generated by the high voltage discharge was corroding the internals badly. They added a vent system in the 1995 models (F-Body) that eliminated that problem, and seemed to make them less susceptible to moisture problem. Strongly advise against washing the front of the engine. Need to take extreme care not to spill coolant on the distributor while working on the cooling system

Another common problem is an oil leak at the rear of the engine where the rear edge of the intake manifold sits on the top of the block (china wall). There is no gasket, just a bead of RTV to seal it, and oil leaks when the RTV fails. Properly resealed, the problem can be eliminated.

Good source of info on your car - Shoebox is the Wikipedia of the LT1, and used his 95 for many photos and how-to's:

4th Gen LT1 F-Body Tech Aids

Good article describing the difference between the Gen 1 and Gen 2 (LT1) Chevy small blocks, plus year-to-year variations:
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Last edited by Injuneer; 07-16-2017 at 09:12 AM.
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Old 07-16-2017, 09:13 AM   #8
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Replacing faulty link to article:

Rebuilding the Chevrolet LT1 Engine - Engine Builder Magazine

Another quirk, unique to the 1995 - the PCM is OBD-1, identical to the one used in 1994, but the ALDL connector is an OBD-2 style 16-pin. Shops see the 16-pin connector, use their OBD-2 scanner, and get "will not connect". Simply need the correct OBD-1 cable w/ 16-pin connector, or a 12-pin to 16-pin adapter, or jumper wires for a 12-pin connector, as shown in a Shoebox article.

Last edited by Injuneer; 07-16-2017 at 09:21 AM.
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