Hey Guys,

I'm not necessarily new to the forum, but I've only visited a few times since registering, unfortunately. So, here's a bit of a backstory. I'm the 2nd owner of an '81. Original owner of the Vette was my grandfather, until he passed in 2013. It was his baby, to a fault. An absolute garage queen. From 1990 until 2013 it didn't leave the garage. Honestly, 1990 was the last time it was plated, but doubtful it was out the previous year or two prior, my grandmother says. Anyways, when I received the car, it had 1,600 miles on it. The last time I knew the car had been running, was about 1994 or so... carburetor issue. So, it sat. Bad gas and all.
Now, I'm no mechanic. In 2013, the most extensive maintenance on a vehicle I had done was oil changes and alternators. So, to a local "Corvette" garage it went. Entire fuel system rebuilt and cleaned, from the sending unit to the carb, new master cylinder, new calipers, pads, rotors, shocks, power antenna, fan clutch... blah, blah, blah. $7,000 later. Oh, new wheels and tires. I still have the original. Over the last few years, my love for vehicles has grown exponentially. I wish I would've done the majority of the work myself now. But, it is what it is. All and all, I'm still no master technician, to say the least. As of July of this year, the car had always been stored at my grandfather's estate so I always had an issue driving it much; only 3,500 miles on it. Now, I've got her home and am really starting to get an itch to start upgrading the performance,
It seems, by reading some of the various threads on this site, that there are many extremely knowledgeable and helpful people. This is an absolutely bone stock 350. TH350 Transmission. I'm not attempting to get 500 HP out of it. Somewhere around 350 would be great. I know my first step is the exhaust. I'm currently in the process of saving up some cash to have duels ran and removing the cat. I'm not sure the gain, but I know it's a start. Where to go after that I'm lost.
I'm having an issue finding much information on the L81. I know it was one of the first years they used a few things that can make upgrades a bit more difficult, but I just don't really know where to start. Will removing the smog pump help? I guess, any help you guys could give me on budget friendly performance upgrades on an '81 would be awesome. I'm gonna attempt this in stages. The exhaust being the first thing. After that, I'm looking to put about $3,000 into the engine itself. Suspension's another story. I'll have to post another thread on that one. And the A/C.
Again guys, I appreciate any direction you guys can give me. Thanks.

 

first, if you have a look around (do some searching). you will find HEAPS of threads on 81's!
most common advice, if you don't live in a emissions testing area. loose the smog pump, the cat. true duels, (2 and a half inch). headers, loose the computer controled carb. loose the computer controled distributor.
then, all the normal 350 Chev hotrod stuff comes into play.
better intake. better/biger cam .better heads , ETC. ETC.

 

Remove engine..... drop in a mild 383 crate engine carb to pan.
You will spend a lot of time and money trying to make that engine perform.

 

All-original low-mile 81s are very rare.

Sell it and buy a car you can enjoy modifying, without worrying about tallying miles. Make sure it has a manual transmission, or budget in a conversion.

 

Based on what you wrote above, I don't see you selling your grandfather's car since it is low mileage nor do I see you wanting to pull the the OEM L-81 for a 383 that is not needed or wanted, if you are looking for around 350 Gross HP, Net HP, will require more dramatic changes...A reasonable build of your 350 (no 355 required with a .030 bore with such low mileage), if you went that route, will get you all the gross HP you would want on the street without going 383 (GM BTW never made a 383 nor ever had one in a corvette, just saying...).

I think 4-Vettes advice is spot on. Ditch the computer controlled carb and all the emissions crap/nonsense that was extremely crude back then and frankly, mostly weakly effective emissions, at best.

2.5 inch duals with free flowing mufflers (no LTH headers, not on a mostly stock motor) will get you close to 300 Gross HP (remember your 81 and all factory engines are rated at Net HP starting in 1972, not gross HP). A good set of iron cylinder heads, if you want to save money, not interested in saving weight, and getting most of the HP benefit with stock engine look compared to the best aluminum heads, will dramatically increase power along with a roller or better flat tappet cam from your engine. You can easily hit 350 Gross HP by swapping out the heads and cam and could achieve even 400 Gross HP with relative ease, all form the engine looking very OEM/Stock.

Below my OEM L-82 rebuilt/upgraded to 355 and 425+Gross HP in 2014.....Looks very OEM stock, idles better than the Stock L-82, and makes power like a modern sportcar....

 

Geez... thats a decent time capsule..
i would let fuel injection experts chime in (like if any adjustment with exhaust changes) but
-exhaust remove cat
- add duals...headers? If so air pump etc coming off..
- buy r12 and gauges..see whats in system now..you may get lucky
leave everything else until something needs replacing / fixing.. save old parts to honor your gramps and low mileage car..
It will at least sound like 350 hp
Indiana...welcome to emmisions freedom

 

You might want to think long and hard before you perform extensive modifications to an unmolested original low mileage car. I realize its was your grandfather's and holds a lot of sentimental value for you, but low mileage original Corvettes are highly prized within the collector community, and once you modify it, it's all over. It will never be original again. It's your car - you can do whatever you like with it, but I'd hate for you to modify it without knowing its value, and then decide later that it was a mistake.

 

I personally would change the exhaust and see how it goes...save everything that comes off the car....so it can be put back on.....later if need be

 

Im all for modding too but removing things from the engine wont make it any faster
A car in that condition/miles should be left alone or sold..you can get enough to find one thats probably already what you really want
Thats a low compression smog motor youll need to spend too much. Then when its sell time youll find regardless of the miles it aint worth much.

 

I definitely didn't want to do an entire engine swap, though I do understand why someone would suggest that. Even boring over is something that I was hoping to avoid. I understand why someone would suggest it per my request. My goal was to attempt to get a good chunk of performance with reversible upgrades. Though this car will never be sold, at least while I'm alive, I want to keep permanent mods/upgrades/replacements at bay unless absolutely necessary due to something not being able to be rebuilt. All of the parts that I've currently pulled have been kept, waiting for rebuild, if not rebuilt already. Even the exhaust/cat that'll I'll be removing will be kept and properly stored.

When it boils down to it, this car is going to be shown probably more than it'll be driven. I just wanted to get a bit more out of it. I figured if changing the exhaust, possibly the intake, heads. I don't know. At least the removal of the smog pump was reversible if that robbed power. I'm kind of testing the waters to gain a bit of information. I absolutely appreciate all of your guys' responses. Thank you.

 

I'm not certain what an 81 ia actually worth. and or if the OP would even ever consider selling. I've had my 77 for over 30 years and no plans of selling. original engine,trans and diff. original interior except for the radio. but I do have replacement pistons, heads, intake manifold, EFI, true duel chambered exhaust, etc etc.
it's my car and I wanted to enjoy it. and NOT sell it. yet for some reason I'm happy to know it's a numbers matching original block.
The difference is I am a mechanic, so changing pistons, heads and cam amongst a long list of other things was no problem for me. it's a hobby. if you have to pay someone else, maybe dropping in a crate engine would make sense. then oil up and store the original engine. just in case.

 

My .02 is ditch the cat. Back in 81 they were very restrictive. But don't cut it off unbolt it if that's possible and save it. In fact I would do that with the whole exhaust system. The only thing I wonder about is the stock carb able to adjust to the new free flowing exhaust?
It's a tuff call on keeping it all original but it's not much fun getting beat by a Camry at a red light. I think if the mods are done right and all original parts are saved the only thing that will hurt the cars value are the miles that you will put on it while you enjoy the car.
Side note with any car that has so low miles and sat for so long I would replace ALL fluids. Check brakes for leaks. Being the paranoid kind of guy that I am I would pull the plugs and "scope" the cylinders to see if there is any rust. I assume the tires will be replaced.
Good luck with your project.

 

I think if you were to have Lars on this forum find you a non computer qjet carb and rebuild and tune it and get a non computer distributor that had been recurved you would be surprised at the added power. Also a rear gear change to a 3.42 or 3.73 would really wake your 81 up!!

 

You've honored your grandfather by restoring the car while keeping it stock. The capstone of that journey could be to get it NCRS judged.

The typical Lars tune and exhaust advice really works. It worked tremendously on my wife's 79 auto. Unfortunately, you can't do that on an 81 unless you replace a lot more parts. And then it will never be original again, the way your grandfather kept it.

Its your car, and I hope you enjoy it. But consider that you may be able to trade that car for one that to can mod, drive, and enjoy. Then you get what you want, a collector gets what they want, and your grandfather's car is preserved.

 

I know you have said you don't want to do an engine swap that that is realistically the best option if you want to get decent performance. Ideally you will want to replace the cam, heads, carb and distributor. and even then you still only have a 2 bolt main block when you want a 4 bolt main.
Changing the exhaust as you have suggested will get you a good start.
The biggest gain from removing the A.I.R pump is the weight saving. Converting to a manual trans will get you a far bigger power increase at the wheels.
You can change the heads without needing to worry about the ECU and some cams are also compatible.

 

I can say this about all of this. on my 77. back when it was box stock, (and less limited by computers than a 81) A 4 cylinder Ford Pinto could blow me away off the line. Totally embarrassing! one of the first things I did was replace the stock 2 into 1into Cat into 2 exhaust. true duels, 2 and a half inch chambered exhaust, NO CATS! ....seat of the pants , 100 H.P. HUGE difference!

 

It does kinda make you wonder when you have a car that is that intact but the 81' is a one year wonder. If everything works though, remove all of the computer controlled pieces as stated above and sell them to someone that wants them.....as the stuff is hard to find, especially a good 4ME carb.
I personally do not believe modifying an 81' would do anything to the value of the car. Frankly, a large amount of the components under the hood on this year are stop gap measures that are pretty terrible and why anyone would want to keep all of that stuff is beyond me unless the stock 190 horsepower is fine for them. Headers, intake and duals are pretty much all you can do to this model year without tripping up the Atari era computer.
Installing long tube headers requires smog pump removal and gets it out of the way. As stated , removing all of the computer pieces opens the door to all small block performance mods.

Jebby

 

That is a very nice original 81. Sell it and modify another.