School me on 4TH Gen F Body cars. LT1 specific please.

So I'm thinking of getting one. Trading the GTI for it. Either a 94 Z28 or a 97 Trans Am. Both auto. 94 has a new trans and opti spark. 97 has been sitting for seven years but is untouched. Both have 100k miles. I've run the carfax on the z28. Not on the trans am. I'm inclined to go to the Z28. Has new tires and has been gone through and seller is interested in swapping. Both cars private party value are very close. I am a SM at a GM dealer and have access to tools parts and expertise on the product. What should I know that I think I know.....but don't. 
 

Thanks!

If the 94 doesn't have the upgrade to the later model (95-97) vented optispark, you'll want to do that.  Spark plug changes are a total pain in the a**.  If you get the Trans Am be sure to check the headlight motors.  They came with a nylon gear from the factory and those wear out, replacement motors are $$$.  A guy named Brent Franker used to sell brass replacement that are a drop in (once you crack the case for the motor) and solve the stripped gear issue.  Parts are cheap, and the iron block LT-1 seems to last forever.  Mine liked to eat trans mounts for some reason.  Urethane fixed it but made the interior rattle, i went back to a factory style rubber mount before I sold it. 15 years ago. I still miss that car, with the torque they make they are silly fast and could actually use more rear tire to put the power down.   Power window motors/regulator are riveted into the door panel, if yours dies and the rivets are still there then the motor most likely hasn't been replaced.  Quick work to drill the rivets out and replace with nyloc nuts and bolts.   I'll add to this if I think of anything else. 

Mine was a 97 Formula LT-1/4L60E hardtop.  No transmission issues to speak of.  Plan on replacing a water pump if it hasn't been done on either.  It's pretty straightforward, but you want to do it before it leaks out of the weep hole on the bottom and trashes the optispark.  If it has a coolant leak, 9/10 time that's the culprit.  Kooks used to have the best aftermarket header/exhaust combo.  Stock should be a single cat for the 94 and dual cats for the 97, it's why the LT-1 got a small horsepower bump before the changover to the LS1 in 98.  The dash pads crack on all of them eventually, and the flip out passenger cupholder on the Trans Am/Formula is prone to breakage.  

To me they feel completely different than a contemporary Mustang, you sit in these cars, not on them.  Having said that, the S197 mustang chassis actually drives much like a 4th gen, i'm guessing because Ford went to the same type of rear suspension for that generation.   I've actually had adults in the back seat of mine for extended periods of time, there's more room back there than it looks.  If it needs a fuel pump you will have to either move some suspension links to drop the tank out of the bottom or cut an access hole in the trunk floor if the PO havent done it already.  Stock rear suspension trailing arms and panhard bar are stamped steel, most of the performance guys go to tubular replacements from the aftermarket.  Brakes are PBR and not bad, but i believe the bigger brakes from the 98-02 cars are a bolt on. 

It looks like that Z28 has later model 17" wheels from a SS.  The Trans Am will have 16" on it.  Corvette wheels from the last 3 generations (C5, 6 & 7) are upgrades i think.  Not sure about C8. 

In reply to 06HHR (Forum Supporter) :

Thank you. I am leaning towards the Z. It has more of the styling I like. I wasnt aware of the headlight issues, but that makes sense.  Owner stated he had a transmission and optispark replaced by himself.  The car looks solid in pics, and vid. I will be seeing the car Sunday and will re-evaluate. Interior stuff is sorta my favorite thing to fix.  I have a flocking kit, maybe a dash repair/flock.  So far as mods go, we will see.  I plan to start a build thread as I have done recently and perhaps a youtube channel (for fun and if I make a couple bucks......even better). 

Thank you for the time it took to type all that. Lots of good info!

Thanks!

Chris

No problem!  Everyone gushes over the LS 4th gens, but the LT1 is a very good engine and optispark issues are kind of overblown.  I did have to replace one when I had mine, but it was due to a leaky water pump.  That Brent Franker guy still has his page up, he's a good resource for 4th gen issues and upgrades; http://www.bfranker.badz28.com/ Some days i'm tempted to find another one. 

Hotchkiss, BMR are two of the aftermarket companies I remember having suspension parts.  SLP sells upgrades and actually did final assembly of the Trans Am/Formula Firehawk models and the early model Camaro SS cars.  So there's still a big aftermarket, not like the Mustang, but these cars don't need as much, they are fast right out of the box. 

Rule #1.  Don't listen to people who say things like "opticrap" or "optispank."  The optispark is a ridiculously fantastic piece for what it is.  Optical trigger is said to be accurate to 0.05 degrees.  The crank flex will cause more spark change than the trigger will.  Having said that, they are a distributor with a cap and rotor.  The fact that they tend to last well over 100k without needing anything is pretty impressive.  Mine went 130k before the rotor broke.  GM only ever sold the whole unit, not just parts.  Aftermarket like MSD had cap/rotor combinations.

The main thing that kills them is that the water pump weep hole is directly above it.  The pumps do tend to weep... mostly from the Dexcool turning into sand jello.  If it has Dexcool, I suggest a complete double flush and switching to old-school green.

There are a few ponies to be had with a cooler stat, but I don't recommend it.  The reverse-flow cooling means that the 190 degree stat works a bit backwards.  Instead of the engine heating up to 190 and opening the stat, it basically waits until the radiator is 190.  So instead of a normal car that the engine gets to 200 and opens the stat to cool down, the LT1 waits until the radiator coolant is 180-190 and then heats it up from there.  There is absolutely not an overheating issue.  No reason to switch unless you're chasing the last couple ponies.  Basic breakdown.  You can flash the PCM for a a little leaner fuel curve and get +5hp.  You can also bump up the timing a bit and get another +5 but you have to run 91 octane.  You can put in a 160 stat and reflash so the fans come on earlier and get another 5-7 hp.

The aluminum LT1 heads don't flow as well as the LT1 iron.  AL heads flow about 20% better than the old TPI heads.  LT1 iron heads are actually an accident, and they flowed so well that GM copied the ports exactly to make the Vortec heads.  If you don't mind the extra weight, the budget thing to do is swap to iron heads and stab in the LT4 "hot" cam.  Easy 330-340 hp.  Aluminums can also be ported to flow as well as the irons, but not much more before you hit water.

Rotating assembly is straight-up one-piece SBC, so strokers and pistons are dollar-store cheap.  As I'm sure you probably know, the head/deck water passages are different between LT1 and SBC.  There was one Impala SS guy who did the swap... welded the holes in the heads and re-drilled to put old heads on an LT1.  So... um... congratulations, he made an old school SBC for no gain.  Aftermarket LT1 heads are basically the same casting as SBC heads, they are just drilled and ported to match one engine or the other.

Stock intake is compact, and very capable.  It's not a restriction until about 450-500 hp.  Factory exhaust manifolds kinda suck, but if you think changing plugs on an F-body is tough with manifolds, better hire a trained rat to do it with headers.

If you turn up the power, but cautious with super sticky rubber.  My buddy swapped a modded LS/T56 into his 92.  He would have been fine if he didn't put R888s on it.  First time he grabbed second, the 7.5" rear ejected the carrier out of the cover.  Sheared the axle ends right off.  The downside is that there is no bolt-in upgrade.  You can't just find an 8.5 from a [insert car] and bolt it in because of the unique mounting and torque arm.

If you're going to track it, subframe ties are worth their weight in gold.  The ticket is to buy bolt-on ties and weld them on.

I ran an Opti in my 9C1 to 194,000 before a dead 4L60E (big surprise) and terminal rust killed the car. The engine was still running fine on its original Optispark. 

Buy the cleaner one, whichever it is.

Don't be scared if the opti it's not as bad as it's made out to be. My 94 drag car had a non vented option, and most of the stuff hiding it was removed and I regularly pressure washed the engine bay. The vented is a worth wile upgrade while your in there but it's not the end of the world if you don't have one.

Tuning a 94-95 can be done with free software and a cheap cable.

Trans, plan for a rebuild just in case but hope for the best. Throw a shift kit in it, and some John deere hygard, and a big cooler if you are going to run a looser converter.

Tune ups aren't fun. Run good wires because once you do them you won't want to ever again. No parts store wires. I think 7.5 mm is as large as you can get in the stock holders. You can also run them over the valve covers. I routinely had the VCs off for valve adjustments so I ran mine in the stock locations.

Good shocks totally transform the car. Bilsteins for stock height or slightly cut springs and Konis for everything else. Stock shocks are real bad on these. Konis and much stiffer than stock springs made my car ride and handle better, and quoted it down..

Subframe connectors are a must. People talk about the handling and noise benefits of them on stock cars, but good shocks will give you the same things. The real benefit is a stiffer chassis and a much safer car in a collision. I've seen multiple 4th guns hit real hard in the back, and the damage literally stopped at the back of the SFCs

I had a 97 for about 8 years, that I loved and refurbished and modified pretty much the whole car, and I had a 94 drag car that was bolt on and weight reduction, that I sold but still lives at my house.

Do it they are great fun cars, I much prefer the T56 cars for street cars.

I have to say, Trans Am > Camaro. 

Curtis73 (Forum Supporter) said:

If you turn up the power, but cautious with super sticky rubber.  My buddy swapped a modded LS/T56 into his 92.  He would have been fine if he didn't put R888s on it.  First time he grabbed second, the 7.5" rear ejected the carrier out of the cover.  Sheared the axle ends right off.  The downside is that there is no bolt-in upgrade.  You can't just find an 8.5 from a [insert car] and bolt it in because of the unique mounting and torque arm.

This is a weird truism that I've heard for years and years. The tiny 10 bolt is a weak link. I will never doubt that it is but I've been abusing the E36 M3 out of mine for almost two decades, which itself was a junkyard upgrade of unknown miles/condition. Big fan of rolling burnouts and not drag launches, though. Obviously that's one anecdote in a sea of contrary stories.

In reply to iansane :

I've broken my share of 7.5s.  That LS story above happened when I was in the car.  I busted one in a turned-up Olds 403 in a G-body Cutlass.  It lasted forever on 235mm all season rubber.  275mm summer rubber caused it to not be happy.  Accelerating on to an on-ramp I heard the clunk and the rear started making noise. My only guess is that I hit a bump allowing a split-second spin-up before reconnecting with the pavement.  When I took the cover off, it looked fine, but when I pulled the axle the whole carrier fell out along with one of the bearing caps... still bolted to the chunk of the bearing boss which had liberated itself from the rest of the casting.

Stock rubber or one step up it will last forever regardless of how much torque you give it.  As long as your traction is limited by the tires/suspension you choose, you'll never break it.  It's big weakness is shock loads.  The bearing journal bosses are too thin.  They'll take a lot of torque, but not jolts.  Its like hitting it with a hammer which shatters the casting.

I'm a big fan of being able to put the torque I make to the ground and not into smoke, which is one of the reasons I don't own an F-body anymore.  There are plenty of expensive aftermarket axle options, but in all honesty I'm not a big fan of F-bodies.  They have serious potential, but in stock form they are wet-noodles with a couple weak spots that aren't cheap or easy to overcome.  Spirited daily driver and ocassional track day car... fantastic.  Serious performance though takes some serious work.

In reply to Curtis73 (Forum Supporter) :

I definitely understand the wet noodle comparo. I choose the worst of the worst in that regard. A thirdgen convertible. Pretty much the least stiff version ever offered. Then obviously had to add an LS, boost and 305 R888's. But I can't handle spending the kind of coin to make a decent diff last in that and still have a stick axle. IRS would be my preference. So, rolling burnouts, 2nd/3rd/4th gear powershifts are all it's good for now. (Although, that provides a hell of a smile...)

In reply to iansane :

Hell yes.

Traction kills the 10 bolt. Commonly when accelerating hard the axle tubes actually accelerate farther than the rest of the car, pulling the axles out of the carrier slightly and tearing everything up.

They are still a small rear so sometimes they just explode in marvelous ways.

I broke a handful on street tires behind a stick, one was heelhop which will kill anything and 2 were just traction in 1st.

They make a studded cover with braces that run the the axles. I've seen 1.5 60fts on these and they survive. I've also seen 2.0 60 fts on stock ones that result in carnage. Ymmv.

If you don't want to put a different rear in. 3.42s and an ultimate 10 bolt kit is about as good as it gets. It may be on borrowed time on slicks and a really grippy drag radial will probably still kill it behind a stick. Autos are easier on them.

If you've got a couple grand to fix it and not worry, they make drop ins in whatever flavor you'd like. 12 bolt, 9 inch, s60, and 8.8

I would not trust having access to knowledge just because you're at a dealership, unless you work with a lot of old farts.  Those have been out of warranty for almost two decades now, probably not many people still working remember them, and if they do they have had a couple decades of other things to push the memories out.

Plugs are not bad, but plug wires suuuuck.  Plug wires suck with the engine on an engine stand.  They are routed behind the accessories brackets, on retention clips, and go up from underneath like a 60s Corvette.

In reply to Pete. (l33t FS) :

You're right, i did MSD 8.5 wires and plugs at the same time.  MSD says the wires will fit the loom (and retention clips),  found out that's bullE36M3.  

In reply to 06HHR (Forum Supporter) :

Sweet. It looks to be plenty fast enough as is. I think I'll restomod it. Fix what's broken and restore what I can. Maybe upgrades that are functional. Idk. Thanks again!

I recently acquired a 96 SS for a steal.  For what I paid and expected, I have nothing bad to say about the car.  I am working on suspension mods and upgrades right now.  I have a build thread if you are to look for it.  I'm about to do the front end (Koni's), Detroit speed fender support brackets, lube sway bar bushings (PO clearly didn't understand this), and upgrade to C6 Corvette brakes in the front. 

Yes the 98-02 front brakes a direct bolt on and a good upgrade.  C5 or C6 brakes are a pretty easy upgrade too. 

The LT1 makes silly amounts of torque at almost any rpm.  It makes the car a hoot to drive and it feels really American.  My power upgrades will be good headers, a 24x conversion to an LS computer and coil on plug, and ported factory heads and a custom cam.  Anything more than that will be too much complexity and a reliability hit IMO.  I'm going for more  power and reliability.  This will happen after I verify I have the suspension the way I want it.  I also need to get SFCs because I want the car to last if nothing else. 

And based on the two photos you provided, the Camaro appears to be cared for and loved.  The Poncho was neglected. 

I was honestly looking for an LS SS or WS6 car or a LT1 or LS Firehawk when I found my 96SS.  It was on CL, super close, and I got an awesome deal on it.  It was listed for a good price but was having cooling issues.  The PO feared blown head gaskets.  It was simple to fix after all, so I really made out.  You can read the build thread if you care. 

I will warn you though, there is nothing about a V8 F body that speaks GTI. 

I have a base '97 z28 I am building for a track toy-weekend car. Got it with 54,xxx miles on it 2 1/2 yrs ago. Helped a friend maintain his '97 SS track car for 14 yrs. Stock oiling not good for tracking with slicks of super soft tires. Went through 3 factory replacement motors in 1 1/2 yrs before getting a built motor and RR oil pan and accessories.   Doing suspension and safety first and then worry about adding power. I did the plugs and wires and remembered why I said I would never own one of these cars, but here I am. I giggle every time I drive it. it's a fun car.

Pretty much planning the same engine upgrades as AnthonyGS

http://shbox.com/ 

Is another great source of F-body info. Wiring diagrams and exploded views with clickable descriptions. How to's and other great information.

Hawks Performance builds a drop-in 8.8 rear w/your choice of everything inside. Not cheap but the way I am leaning after seeing all the rebuilds my friend went through with his SS.

In reply to JBruin :

I believe Hawks is just having the guy out of Oklahoma who fabs them build them and then selling them whole. I think his shop is TNT performance, he does the fab work for you and you build it. Last time I looked the ready to run rears from Hawk were just as expensive as a 12 bolt or s60 from one the big names. If you want to go cheaper Id go straight to TNT and have him build you the housing then fill it with your guts, or if you want to go easy, through a Moser 12 bolt in for track stuff or drag racing for an auto or just put a 9" for drag racing a manual

In reply to Opti :

I bought a few parts through Hawks so how I know of their offering. It's about $3600 or so for the rearend through them. I have to research more though. I have a manual and it will spend most of it's track days at NCM. I live 5 minutes away. The plan is a 383 LT1 and solid rear end. 

Is the Camaro a sport package car? You can tell because the gearing is a little shorter (3.42 I think), they have the dual rectangular exit exhausts that I like so much, and the shifter is different. They also got (or at least mine had) a limited slip that somehow still worked great by the time I got it. I don't remember exactly what it was but might have been a PRND321 instead of PRND21 or something like that.

I had a 1994 black over black cloth Z28, 4L60e, sport package, with T tops. Great car, but yes plugs and wires were a pain. I mostly just dailied it, which it was a ton of fun for. For some reason I never felt a strong urge to modify that car. The stock sport exhaust sounded great, and the LT1 makes enough torque with the shorter gearing for the automatic to be fine in that relatively light car. The seating position is something that you either hate or that you think makes it feel like a special car, vs. a mustang that has a much more 'normal sedan' kind of seating position. That transmission can work quite well with some tuning of the shift tables; the stock maps aren't great. they seem to be for emissions or something, because my gas mileage even got better after retuning. Never touched the engine calibration.

Of the two you posted, the Camaro looks better mainly because it looks like someone cared. That Firebird looks pretty neglected.

My old one: