Hey everyone, i just bought a 1985 c4 coupe with automatic transmission with about 150,000 miles on it for $2250. Fairly good deal right?
My main question is do you think i should bother adding mods to this or should i save my money and buy a newer engine when it blows?
From what i read on other threads, most recommend intake and exhaust mods long tube headers, k&n filter etc. would these be worth the money?What direction would you go if you had about $3000 to spend?

 

freshen it up - I know a guy with a early C4 that has put 300,000 miles on his car!!

 

It depends what is more important to you: better performance now, or better resale value later? Well-preserved stock examples will fetch better resale prices. While modifications in general tend to reduce the value of the car, depending on what the mod is. Some bolt-on mods can be reversed and put the car back into stock form if/when you decide to sell.

When the engine blows...? 150,000 miles may seem like a lot, but if it was maintained well, there are probably lots of miles left in that motor. 200-250K miles is not unusual from these small blocks. They are strong and can handle a decent amount of abuse. The manual transmission overdrive (4+3) in the early models *may* be a weak spot, but again maintenance is key.

I am a bit of a purist. That car appears in very good condition, and completely stock (by the picture) so I suggest you enjoy it the way it is, fix any little things (if there are any) before they turn into big things, and keep up on the maintenance. These cars are great driver's cars even in stock trim. The handling is especially good. You will have a lot of fun and also get a decent return if you keep it stock.

For $3000 I would just fix or replace anything that needed it. Exhaust still good? Shock absorbers? Tires? Any fluid leaks? Strange noises may indicate that parts are worn out. For performance mods, anything to get more air in/out of the engine... ported heads, exhaust headers, cam, etc. You won't need an injector upgrade unless you are doing serious modifications.

EDIT: you may find a supercharger kit for $3000 or a bit more.

 

Nice find. You can go through $3k real fast on these cars. New interior seat covers, new seat foam and front & back carpet will set you back $1k.

 

woah i had no idea these engines could last so long. i do tend to drive it harshly from time to time.
thanks for the feedback ill try not to get too ahead of myself. so far the only noticeable issue is the low idle. my mechanic suspects the fuel injectors but i hear intake manifold issues are common

 

Beautiful car.. I have the same vehicle, it's just not that nice.

Working towards it. I love the early C4's.

Others will disagree, and they race and shoot for real HP on the track. But for the street, I like the vortec head swap and a cam. It makes a lot of torque. It's not crazy expensive.

For a 30 year old street car, I think it is a great compromise.

 

If it were me and it is unmolested, I would leave it unmolested and just take care of the issues all 30+ year old cars have.

I have an unmolested '84 that just rolled over 36k miles. There was a time in my life when I would have been interested in making it a 'zoom zoom go fast car'.

These days I'm content to simply drive it, maintain it and enjoy it.

If more horsepower were important to me I would take the easy route and buy a newer model.

 

Congratulations!

Looks good.

I would suggest driving it a little while first and getting to know the car and what needs repair/improvements before doing mods.



Look at SDparts.com for the heads (several options) and a conversion lower manifold to use the TPI intake tubes with the vortec heads. That conversion alone is claimed to bump it up to about 300 hp. Add a cam and it is more.

Also look at headers. The stock manifolds are very restrictive.


They are nice in original condition and a fun car to drive. However don't consider it to be more collectible/valuable in original shape and save it for that reason. Yours already has a lot of miles, but even with low miles there is no market for these cars. When I sold my '85 it only had about 30k miles and was near perfect, but with no market, I wound up selling it pretty cheap.

Good luck with your new car. Enjoy it!

 

Certainly not fooling myself as to the value of the car and the demand for C4's. I only paid $4300 for it back in the spring.

Also have no intentions of selling it, but have learned after years of modifying cars that when the time comes, it is easier to sell an unmolested car. Though they made a ton of them, unmolested C4's are getting harder to come by.

 

Lets get something straight first. The car is a moneypit. You won't be able to tell me otherwise. Whatever you put into it, you can't assume you will get out of it even money. That said, if you plan to keep it and you want to mod it, lets start with the basics. Especially if you drive it occasionally in winter like I do, I would put a good 304 SS exhaust. Supposedly Corsa will not have the noise like my Borla.

Get a decent cat and replace the headers with TPIS headers. Yes, they cost a little more but it is so easy to change plugs. After which, I would get a decent intake and while you are at it, toss your injectors where they belong. In the trash can. Get a reman set that will be more ethanol tolerant. After this, dyno tune. Don't waste money on a Hyperjunk or off shelf chip. I also don't like those tunes that are based off what you say was changed unless they do datalogging and retune and retune till it is spot on.

Your next thing to go is the transmission. The stock 700R4 has never worked well for me till it was rebuilt to better specs.

 

Hi

Nice ride

The engine wont blow, the 85 had TRW forged pistons standard and are very reliable.
I ran my 85 engine for 8 years with 8 psi boost, at 170,000 miles I replaced it due to oil leaks and wanting a 383 engine.

Yes go for long tube headers, adjustable fuel pressure regulator set to 45-55 psi. Great for more mid range top end performance, I put headman HTC coated headers on my 85 they keep the engine bay and floor cool.

20 years ago when I first got my stock standard 85 she did 14.4 sec quarters, went back a week later after fitting long tube headers cold air intake and fuel pressure from the lazy 32 psi to 50 psi. New tune up and got her down to 13.2 in the quarter mile, the TPI engines love headers.

Have since gone to 383 engine and blower, now back to naturally aspirated so I can use my a/c in summer.

Don't wrap the headers it will make them wear out very quickly due to the heat, The HTC coating is inside and out so protects the metal from melting.

Well how good is that transmission? Is the fluid bright red has it been replaced? A performance trans build will cost almost as much as the car did.......

Perhaps fit nitrous oxide, an extra 100 hp will make her really fly.

 

Vortec heads and eldebrock manifold will set you back 1,300 bucks. a SET OF HEADERS, another couple of hundred.Vortecs are also cast iron. I been looking for a set of Alum Vortecs for mine. You have a nice car, you might want to leave it stock except for the exhaust.

 

Who knows or cares what the next guy wants?
Make it your own . Whos to say the next guy wont want something with a fresh motor with more power? I sure would



Dont buy into the ncrs its just doesnt apply to the C4. Maybe decades down the road....it will have to all be redone by then anyway. It means nothing really over the long term. Guys that have had thier cars 40 yrs....sure they have some worth...bet they have more in them than that though. Total waste imo.

Some like em stock some dont theres a butt for every seat

Have fun with it

 

If you never plan to sell it, you are right.

I wouldn't. I don't know you nor do I know who built the motor. I know what I built or had commissioned.

 

How would that work? You increase the fuel and it dumps more fuel. The O2 sees it being rich and it cuts the pulse width. Wouldn't you end up back at square 1?

 

Just enjoy it and save money for the engine you want if you mod this one it will kill it fast.

 

From where I stand , after getting 80k on a brand new car with an L98 , I'm going to say he is on borrowed time .

 

I really like the trw pistons and cast iron heads on the 85(mine is 85). I fixed many of the leaks and replaced the power steering system and brake system. But I broke a few things also so be careful. Some thing to do for idle before bying newinjectors is try a minimum idle adjust. You will find the 10 step process here somewhere. A mechanic will be quessing at everything in my opinion these days. Check all vacume hoses and clean connectors. I found that really helps. I bought mine for 1600 and now have about 6k into it but I just bought 4 triple 8s last week (toyo proxie r888) good luck with the 85. I am not really thinking about a new engine(165000) it goes great and no smoke or anything over here anyways.

 

No, following the FSM is usually right but in this case, it is guessing. It assumes the injectors are not partially clogged which they usually are, it assumes ethanol hasn't screwed up the coils, it assumes there are no air leaks, it assumes the IAC isn't full of gunk, etc, etc. In short, that method ASSUMEs too much. Setting minimum idle via scanner will help check for leaks. I'll bet his IAC can be cleaned as can the injectors.

 

Freshen up whatever needs it and just enjoy what you have.