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Loweguy5
Loweguy5 GRM+ Memberand Dork
8/24/24 6:12 p.m.

I started another thread on this but my title was so cryptic I'm guessing many folks who know C4s missed it so I'm starting again here, not to mention I just actually got it home.

The specs are as follows:  L98 350 producing a face melting 240hp, 700r4 4 speed automatic.  Base suspension, power sport seats, heated mirrors, glass roof.  2 owners, 0 accidents.  The fellow I bought it from was in his later 70s.  He's owned it since 2008.  65,126 original miles.

I was given proof of lots of maintenance and repairs done at the local Chevy dealer.  Recent fuel injectors, brake rotors and pad all around, and as far as air can tell:  everything works!  The digital gauges work perfectly.  The ac blows freezing cold.

I drove the car and it goes pretty well.  The idle is a bit off which is making me think the timing is off or there is something going on with the distributor.  No smoke, no milkshake in oil and according to the owner who I trust it hasnt overheated.  The tires are at least 15 years old which is a shame as they look new.  The car has been garaged during current ownership so the seals which normally look horrifying on these things are in pretty nice shape.

Oh, and I paid $5500 for it.  While I fully realize these aren't rare and they aren't particularly fast, it does feel "special" (at least to me).

The car needs a good cleaning and the previous owner did really terrible paint touch ups on the nose which I'm hoping to improve upon.  I want to get the idle straightened up, get her some new shoes and get her clean.  Then comes new carpet and upholstery for the drivers seat.

While this is a fully maintained car I know some things will pop up.  My plan is to get to driving it (gently) very locally at first to let it earn my trust and then go a little harder with it.  Maybe next year sees some auto-x activity.

Stampie
Stampie GRM+ Memberand MegaDork
8/24/24 6:27 p.m.

Looks nice.  I really like the 87-91 C4s.

Dusterbd13-michael
Dusterbd13-michael MegaDork
8/24/24 6:31 p.m.

My favorite era of c4, with my second favorite color combo.

 

It's amazing how much porting the intake, throttle body and maf, and bumping the timing improves the car

Run_Away
Run_Away GRM+ Memberand Dork
8/24/24 7:01 p.m.

You know, I've never paid attention to the interior of a C4. Are the wiper controls on the drivers door? Whats with the passenger side glove box area, why does it stick out so far?

Are you keeping the exhaust tips?

 

I like the colour combo, neat car!

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/24/24 7:36 p.m.

In reply to Run_Away :

The exhaust tips stick out WAY too far.  

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/24/24 7:36 p.m.

Quick video of the car running:

 

https://youtu.be/_Mf6HsUEOB0?si=EVH-ViHaTk8RE8Js

Stampie
Stampie GRM+ Memberand MegaDork
8/24/24 7:51 p.m.

In reply to Loweguy5 :

Embedded for the lazy.

 

Piguin
Piguin Reader
8/24/24 8:10 p.m.

She sure does look good.

 

Love the red interior - it really works against the white. Miss the days when not everything was pitch black inside...

Looks like the leather seats are in need of some moisturizing, but it could just be the photos. 

Congratz!

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/24/24 8:17 p.m.

In reply to Piguin :

The drivers seat needs to be recovered for sure.  Passenger seat looks great!

NY Nick
NY Nick GRM+ Memberand SuperDork
8/24/24 8:27 p.m.

Nice car! You will have a blast with it  

I had a 1994 back in 2002 and it was a really fun car  

My father is also in his late 70's and has a similar car, it is really fun for him and I am so glad he has got to have it for the last 6 or 7 years. He bought it from a guy who was almost 80. I hope he gets to enjoy it for a few more years. 
 

 

Iusedtobefast
Iusedtobefast Reader
8/24/24 8:38 p.m.

Nice car! Love the color combo, same as my 91. Hope you enjoy it, it is very cool to drive

Datsun240ZGuy
Datsun240ZGuy MegaDork
8/24/24 8:48 p.m.

Did the bulge in the dash represent safety?

No airbag on that side?  I think it had no value but the illusion of a padded safety bulge?

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/24/24 8:56 p.m.

In reply to Datsun240ZGuy :

You said "bulge" twice huh huh.

I think the Vette guys call that the "bread box".  It looks totally ridiculous.

Datsun240ZGuy
Datsun240ZGuy MegaDork
8/24/24 9:14 p.m.

In reply to Loweguy5 :

Of course you can get a delete panel. 
 

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/24/24 11:29 p.m.

In reply to Datsun240ZGuy :

I'll take a look at that thank you.  I didn't know that such a thing existed!  I'll no doubt seek out more plasticky bits as the interior is filled with them, some of whom have seen better days.

I can't make the car new but I think some thoughtfully replaced parts will really freshen it up.

daytonaer
daytonaer HalfDork
8/25/24 1:15 p.m.

After setting base timing reset the tps and iac circuit : TPS and TPS..

 

I found more useful pcm modification info from third gen forums than the vette forums but it has been decades since I played with a tpi vette.

 

Lots of little easily reversed “mods” that add up to wake this motor up.

 

I would be willing to bet the brakes have a nice glaze on them and will feel weak/wooden. After you get new tires beat on the brakes and I bet they will come back to life, there is a lot of braking capability that never gets used with gentle driving.

 

and have fun, it’s a nice car!

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/25/24 3:27 p.m.

In reply to daytonaer :

Wow that is super helpful I thank you.  Good point on the forums.  Seems like many of the Corvette folks farm out most of the work and want to talk about dash plaques.  

Great point on the brakes too.  They are less than 2000 miles old and I know they MUST be better than they feel currently.

I'm trying to be patient and remember that the journey is what keeps me interested sometimes more than the result.

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/25/24 7:18 p.m.

Today was a busy day but I achieved 3 Corvette related things:  I gave it a good bath (didn't have time for interior but I'll do that this week), I removed the tail pipe tips which stuck out at least 3" too far, and I took it for a quick ride.

It cleaned up nicely and I was pleased to note little in the way of water leaks (my wife rinsed with our pressure washer so it got a pretty good blast).

I only drove it a very short distance as it's not registered yet (I have an appointment on Friday but it is already insured).  It isn't fast and stalled once when coming to a stop, but I grinned ear to ear at the both how fabulous and ridiculous it is.  It's peak 80's GM but in a cool way.

I'm really focused on not overspending on the car.  I'm going to deal with issues as they come and will try to avoid getting over the top on anything.  A couple of shots:

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/31/24 7:43 a.m.

Yesterday marked a big milestone for the Corvette:  I got it registered.  I learned that in CT any car over 20 years old can be registered as "classic" which caps my property tax assessed value at $500!  Using my towns mill rate, the Corvette will stand me a whopping $13.75 in annual property taxes.  Win!

I also spent some more time with the car, and really closely examined the tires.  One of the four has severe dry rot in between the tread blocks, rending me unable to drive the car any significant distance without fear of failure.

In what i feel was a very mature move, I ordered the literally cheapest tires I could find in the right size that were made by a manufacturer I've heard of.  Courtesy of Tire Rack, I ordered a set of Nitto Motivo tires with mobile installation.  These tires receve mid-pack reviews, but at the clearance price of $112 each for a Z rated 275/40/17 tire they fit the bill.  

My normal nature on a project like this is to run out and order new wheels and tires but I really want to keep the investment down while enjoying the car.  I have found that used C4 wheels are incredibly cheap, so I'm watching for another set that I can buy and use for some decent track tires when I want to do a track day or autocross it.

So far the issues I've found are:  parasitic draw requiring use of a cutoff located on the battery.  I haven't chased this yet but will in the near future.  Next, it has a cold-start issue where it takes several attempts to get it fired and it sort of stumbles to life.  Once warmed up it runs great.  I'm curious if the start up issue is because of disconnecting the battery and therefore disorienting the ECU?  Another issue is a very noisy radio, who displays a loud buzzing that rises and falls with rpms.  I've seen this many times, and my first guess is a poor ground.  

I'll get my multimeter and start pulling fuses one by one to find the source of the draw, hoping it's something easy that can be replaced or repaired.  

The final issue is that it's leaking transmission fluid.  I 100% expected leaks as I know this is a byproduct of cars that are rarely driven.  I want to address it sooner rather than later.

The car has a bunch of cosmetic issues primarily in the interior that aren't worth getting into right now but I'll pick away at them as time permits.

Overall I'm super pleased with the car as the major mechnical pain points on old C4s seem to have been dealt with on this car already or are in good working order.  I continue to think she is a good canvas upon which to start, with the end goal of doing little more than returning her to closer to her original glory with a little glory.

So far, tires, install, taxes and registration included, I'm just over $6500 invested.  My working budget for her is $8000 in the short term so I feel like I'm on track for now.  Stay tuned.

GCrites
GCrites Dork
8/31/24 5:23 p.m.
daytonaer said:

After setting base timing reset the tps and iac circuit : TPS and TPS..

 

I found more useful pcm modification info from third gen forums than the vette forums but it has been decades since I played with a tpi vette.

 

So the '89 Corvette .bin files have a lot more settings than the F-Body ones. Corvette spark tables are more aggressive out of the box than F-Body ones due to the Corvette's aluminum heads. You can A/B the files in TunerPro and see. Nonetheless most info you will read about 3rd Gen computers regarding engine performance carries over directly. I am running an '89 manual Corvette tune as a base for my '87 T-56 swapped IROC. '89 is the only year of Corvette with both MAF and an available 6-speed.

Loweguy5
Loweguy5 GRM+ Memberand Dork
8/31/24 7:13 p.m.

In reply to GCrites :

^That info tells me I am way out of my depths with regard to tuning the car.  I see that I can download TunerPro to my laptop but I'll admit to having zero knowledge at how to tune the car after that. 

Since it's a base car with zero mods beyond an axle-back I'm assuming the original tune should be about right.  I'm wondering whether all of the disconnecting and connecting of the battery keeps forcing the ECU to relearn its settings each time it's driven, hence the tough starting and inability to idle initially.   Once it's warmed up it runs fine and will restart and idle perfectly with a flick of the key.   

It's not beyond the realm of reason that it simply needs tuneup parts too as it's only traveled 5000 miles in 15 years and was last tuned up more than 10 years ago.   By virtue of our area there is a lot of humidity here and it may be that the cap and rotor are corroded enough to impact how it runs.

I'm going to work on identifying the parasitic draw and am ordering a trickle charger in order to stop disconnecting the battery.  I'll install new tune up parts and will also check the base timing once that's done.   A new fuel filter likely wouldnt hurt either.  I'll travel down the path of tuning once all of that has happened.

I really appreciate all of the input as I know nothing of 80s GM vehicles and haven't owned anything GM in probably 20+ years.  I remain really pleased about the car overall as it is proving to be just as it appeared to be when I bought it.

GCrites
GCrites Dork
8/31/24 8:53 p.m.

Ya, definitely don't go into the computer until all the tune-up stuff is done and the car runs perfectly. I had to tune because of my aftermarket cam and various bolt-ons/free stuff/intake porting. Even the T-56 swap didn't require a tune but it helped a little for decel/cruise. The biggest thing that a tune can do for a bone stock car is lowering the fan on/off temps to pick up a few ponies from a cooler running engine but even that should be matched with a cooler thermostat. Again since the Corvette spark maps are more aggressive anyway there's less to pick up that way as compared to an F-Body. But most of those extra Corvette-specific settings I mentioned aren't worth messing with from a horsepower standpoint so don't be intimidated by them. F-Body people just ignore them and the F-Body computer does too.

daytonaer
daytonaer HalfDork
8/31/24 11:57 p.m.

I burned a new pcm chip to disable the vats as it left me stranded a few times. 

 

I fiddled with the lean burn modes and played around a bit, it’s been a while...

 

do learn up up on the vats and have a plan if it starts acting up. 

 

the gm “multech” injectors have a reputation of failing: I put in a set of Bosch injectors only to find out my problem was bad spark plugs (the wrong ones were installed).

 

I would start with the basics : fix the battery draw, do a tune up and ensure everything is operating properly first. Good luck finding your draw. I often miss my 89.

 

Loweguy5
Loweguy5 GRM+ Memberand Dork
9/1/24 7:46 a.m.

In reply to daytonaer :

Funny you bring up the VATS, it's on my list.  I'm reading everything I can on that and on TPI engines.  Thank you so much for the pointers.

John Welsh
John Welsh Mod Squad
9/1/24 9:28 a.m.

One of those Lithium jump batteries might be a nice thing to keep on-hand (and even in the car) so you have a back up option if the battery draw or failure to disconnect becomes an issue both at home and away.  

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