Hello all,
A friend of mine at work is looking into purchasing a 40th anniversary edition coupe (1993). I own a 2003 Z06 so he came to me to ask about the car. I told him what I knew, but I am sure there are others on this board that know alot more.

Are there any reliability issues to look for in these cars? From what I understand the LT1 was a pretty reliable platform. The car he is looking at is a Six speed, is this the T-56?

He currently owns a '70 mustang with a mountain motor (429, bored and stroked, lots of compression, big cam, dual quads....). He will definately be looking to get some more power out of the C4.

What is the tried and true recipe for reliable, streetable power for an LT1 leaving the bottom end stock? Are the LT4 parts compatible? Do lots of people put a LT4 top end on the LT1s and run a hotcam? What would be involved in doing this? How do the CPUs work on the '92s? Would he have to burn a chip or have it LT1 edited by a tuner?

Sorry For so many questions, thanks in advance for any help.

-Nick

 

1993 C4 LT1's = Good Cars!

Probelms:
1. junk between the radiator and the condensor causing really warm temps when in traffic!
2. Opti-Spark: The dead giveaway that this is on the frits is to put the car in drive with your foot on the brake and just sit there and let it idle for 3-5 min.. (A/C off) if the idle is steady its a good sign (but not a sure sign) the opti is in good condition.. if the idle starts to wander it usually indicates the opti is toast. As a rule of thumb the opti and the water pump should get replaced as a pair since the weep hole on the water pump drops water right on the opti-spark (distributor) which in turn kills them.. none of us know what GM was thinking with this one..
3. weatherstripping on these cars are usually toast at that age.. its expensive to fix... if its in bad condition I would use things as a bargaining chip on the price.. new stripping (just parts) runs around 700 bucks!
4. obviously look at the tires.. like your Z06 they are somewhat pricey.
5. Check all the speakers on the bose stero are working and the CD works.. these are typical failure pieces... Also along those lines make sure the bright light switch works and the windows roll up and down freely in the tracks.


For the mods:

A stroker is a popular option but requires a new bottom end. If he only wants to monk with the top end the LT4 conversion kit with the Hot cam is a very popular option.. This will require a new chip for the ECM (1993 is still OBDI). The good news is because this mod is VERY common places like Ed wright, PCM for less etc..etc.. have this tune down to a science and it can be had for around 200 bucks (mail order).

Feel free to have your friend PM me if he has any other quesitons..

 

Somewhere on this forum is a great checklist for inspecting a C4 before buying. I just can't find it. I'd do a carfax on it. Also put her up on a lift and look for oil leaks. Our LT1s that are still originally built by the factory, usually start to leak from the intake manifold and seals on the timing cover. Check the rear wheel bearing hubs. If the opti is original along with the water pump, most last to the 70K range, the water pump can easily leak (when it is starting to fail) and take out the opti. I went with an electric water pump that can't leak on the opti when it fails. If he expects to have the power of his Muztang, he'll need to do some building. BUT, he'll love the way it can go around the curves. The LT4 top end is a popular upgrade, but some can build stronger motors with less money by working the LT1 heads and installing a cam. When you get to the stroking option, standby for some big bucks. These upgrades should be a package deal that is already proven to work well. Oh, go drive it if you can.

 

Man! Thanks for the help, it amazes me how so many people will take time out of their day to post this information, I think you guys covered most of my questions in two posts. Great forum.

one more question. What all is involved in the LT4 top end package for parts? Is it just heads, or Heads/intake manifold/injectors.... What kind of power would you expect from a hotcam/LT4 conversion?

Is there any advantage to going with an aftermarket head instead of the LT4 pieces? Does AFR make a head for the LT1?

 

Man would I love to have your 64...Fuel Injected?

 

With heads/cam, the most cost efficient thing to do is to have someone port the factory LT1 head and change the cam. Need new lifters, sometimes pushrods and guideplates. Intake does not have to be ported but many companies like to that.

As for reliability, it is like most 350's except for the opti. & gear driven waterpump. I would say if he wants to mod it that the gear driven pump is an issue as I am having trouble with getting quality parts--I would be ok with the stock LT1 set but the chain is no good with the 352 rwhp engine that now revs to 6300 rpm.

 

Here is what comes in the conversion... GM PART # pk12550630
CATEGORY: Accessories & Misc.
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $2,943.28
OUR PRICE: $2,091.16
DESCRIPTION: LT1 to LT4 Conversion Kit
A bolt on LT4 performance upgrade for your LT1. The LT4 conversion kit includes parts needed to change the top end of the LT1 to LT4 specs. Conversion kit includes:
2 Cylinder Heads P/N 12363287

1 Intake Manifold P/N 12550630

1 GM Performance Parts LT4 Hot Cam P/N 24502586

1 1.6:1 Aluminum Roller Rocker Arm kit P/N 12370839

2 Head Gaskets P/N 12551488

2 Intake Gaskets P/N 12367777

1 Front Timing Cover Gasket P/N 10128293

1 Water Pump Seal P/N 10217886

1 Front Crankshaft Seal P/N 10128316

1 Oil Pan Gasket P/N 10108676

2 Valve Cover Gaskets P/N 10108625

2 Exhaust Gaskets P/N 12552470

Also includes: 1 Distributor Seal(1995-1997 cars) P/N 12552428, and 1 Distributor Seal (1992-1994 cars) P/N 10128317, but only one of these is used depending on apllication.

Not included in the kit, but recommended is the "Extreme Duty LT1/LT4" timing chain kit P/N 12370835.

These are the basic components that make up the LT4 engine and performance please note other parts may be required to properly install these parts on your non-LT4 engine.

1993-1994 ignitions are different than 1995-newer LT1's and may require changing to the newer ingnition system.

Please check with a certified installer before performing this conversion.

Additional parts may be required. AFR does make both LT1 and LT4 heads (might take you 6 months toget them) http://www.airflowresearch.com/ If you really want to get wild, AFR makes a 215 raised runner head, but it will require a custom intake. Try stroking it to 396, use those raised runner heads, drop the compression down to about 9 to 1, then slap on a blower. Next, you'll be in line to upgrade all of the drivetrain you break.

 

93 is a great platform. If he can find one in decent condition/low mileage then theres not mcuh to worry about. when i bought my 93 the only thing it really needed was shocks because there was some floating on the highway going on. Optispark? seems to be a not as common as eveyrone thought problem as there are numerous people on this board who have had theirs last over 80k without problems. Mine went 70k. on top of that it an hours job if your mechanically inclined and is fairly cheap.

Other than that for streetable power i suggest staying with the lt1 heads. too many people are brainwashed into thinking the lt1 heads are garbage and go for the lt4. A good head job on lt1 heads will embarass a not so good job on an lt4. As for power a few lt1 c4s doen by my local shoppe had just heads/cam done and they put put out 375-415 rwhp. The ones with the higher output cams naturally have a slightly rougher idle.

 

 

"Man would I love to have your 64...Fuel Injected?"


thanks - no.. the FI '64 had 375hp.. This was the top Carb motor for that year.. basically the FI motor sans the intake.. with a holley carb in its place.


All good adive above! Your friend will love his car!

 

Check out the C4 Tech FAQ at the top of this page.

 

Perhaps the 2nd post in This Thread?