Hi I just purchased an 81 from a friend of mine and all i can say is... WOW! bad year for performance. The car is in awesome condition but has sat for 11 years in a barn. My only corvette experience was driving a 2001 zo6 which sadly this car is not in the power department. I really want to replace the kittens hiding under the hood with some pony's if you know what i mean .
So far I have done a full stainless exhaust with headers as the current exhaust was toast, new tires, fuel filter and air filter. Getting rid of the cat helped but NOWHERE near enough. I did hastily buy a jet stage 2 performance chip on advice from someone local. Not sure if its a good idea or not after reading up on it a bit, Not to mention i cant for the life of me figure out how to replace the one in the ecm without damaging it. Other than the headers the car is completely original.
As i am pretty knew to wrenching on my cars I'm kind of lost as to what to do to give this beauty some life. Looking for some advice on where to go to get the best bang for my buck.

 

probably a crate motor. you would need to know a bit more about your engine before we could draw you an accurate map. generally , compression, cam and heads are the target areas

 

I take this is a small block- how about adding a supercharger like a vortech, pro charger ect, only way to really wake it up. Unless you do a head cam package. IMO

 

I would go through the suspension and brake system before worrying about more power at this point.

 

As earlier stated we would need to know more about the car, but generally speaking the basic bolt on stuff will do little on a stock engine. For any significant power increases, and to be able to keep the engine in one piece your going to be rebuilding it, or a different one, or a crate motor. You really need better heads, more compression and cam. More cubic inches also helps.

 

With all the above.

 

First off, Congrats on the new ride and welcome to the forum!
Next, I don't really need pics of what you have in order to know what to tell you what to do, I do need to know what you want the car to do.
So lets start there, what do you want this thing to be? Friday night cruiser? AutoX?
As far as the order to do things in is important as stated above, you want it to stop and turn well before making it fast.
I can tell you this: Since all the CCC stuff is still in place and presumably functional it is possible to put in some more ponies with the CCC, distributor and carb in place.
You can change the cam and heads and intake to get to 250 or 300hp and still use the CCC. You already changed the exhaust so it should breathe a little better.
That would be the least expensive route, a crate motor will cost at least 2, maybe 3 times that, but is certainly a viable option.
AFR180 heads, a good bumpier cam and a qualified rebuild on the carb and distributor will do it.
Make sure the O2 sensor is in place as close as possible to the head port on the collector as possible, if its too far away like on long tube headers you have to change it to a heated model.

So..What ya wanna do with it?

 

Thanks for the welcome!

Easy question ... make it a bit quicker 0-80

My intentions with her is to pretty much keep her on a pedestal in the garage, bring her out on warm sunny days to put a smile on and cruise the coast of Lake Michigan. I'm probably expecting to much out of the current heart she's got as my daily driver is a 500hp Impreza. I know its a different animal altogether but I can't help comparing the pickup of the two. As far as the suspension it really feels ...ok...for where it is at the moment although I haven't exactly been aggressive on it to really test it out. Breaks seem to stop fairly decent just running around, but again I've been pretty easy on her so far.
I have thought about maybe swapping out the motor but was hoping for a bit cheaper way to go as my wife already doesn't like the car. I'm leaning toward a cam and heads at this point but not sure at what point I'd be losing out to get it where i want vs swapping it over to a different motor already built. As my knowledge of motors is just enough to get me in trouble, I would probably be having a shop build it up for me and that factors in to cost on it as well.
As for whats currently in it its a stock 350 which only pushed out 190hp that year I believe. I have a bit of a budget to work with but not a lot in terms of what is possible.Whatever I do to her id like to keep under $5-6k in total beyond what is done now. I realize now budget can get eaten up fast after putting $1600 in an exhaust.
I would love to see 350-400 hp in her while still keeping the original look.

 

Exhaust = easy HP

 

I built my 75's motor about 4 years ago.
It puts out 280hp to the rear wheels and gets +20mpg

Is that enough horsepower or do you need more?

Ralph

 

350 - 400hp is not going to happen with the stock parts. If you really want that much hp is not going to happen with the L81 stock engine. The block is a 2 bolt main and that is probably okay unless you go with nitrous, super or turbo charging...then the block will not hold-up long.
The main limiting factor with the L81 are the heads....thin castings and very prone to cracking. So they must be replaced....and then it begins.

Nice set of AFR heads, full roller rockers, hardened pushrods, etc....then retro roller cam and rockers, dual row timing set, flat top pistons, bore and clearance the block for a 383 crank, new crank, good set of rods, all new bearings.......

Might as well just purchase an already built 383 and drop-in there and be done with it, probably cost just a bit more, but quicker in time and a proven setup. Several speedshops I have seen sell a dyno 383 combination that will give you the power.

However, doubt the rear differential will last long with that much power. So plan on doing something with it...which is limited in what can be done...so might have to go to an earlier differential setup to handle the power.

What was your budget?....not enough!....suggest asking Ralphb what he did and be happy with just under 300hp.

Also as stated above....first need to check the brakes and suspension components.

Good luck.

 

i admit the l81 heads aren't the best but, if they haven't cracked in 35 years they probably won't.

 

After 74 they were all small blocks. I would go with improving the heads , exhaust and cam... make the engine breath easier and you will get more out of all your other mods and maybe ditch the factory computer since you already removed the cat. Just hold on to the original stuff.. You can easily find some good deals on Craigslist I built my whole 400hp/413lb tq 355 with Craigslist and eBay parts for about a grand. With your budget It can be done much easier but expect a 20% loss in power due to drive train... In my opinion 300rwhp is not hard to do but it things get expensive when you are looking for 400rwhp and reliability. Like other said there are other things to consider... like torque converter and rear gears which are all set up now for an engine that makes its power in the lower rpm range..., I built my engine around the 3.08 gears and 2000rpm converter my car has... according to the dyno 2000 dyno curve chart My torque comes in really low and I'm already making 175hp at 2,000 rpm and over 300lbs of torque..... most high power small blocks make all their power at 5-6,000 rpm which is really too high for the stock gearing to still be peppy and fun on the street. This is why I chose the smaller voodoo 262 cam with small 64cc heads. I want quick and fun on the street not looking for drag times.

 

Change the rear gears to bring back the off the stoplight launch

 

I would agree with this except the trade off is when your "cruising the lake shore" your rpms will be higher compared to most cars and this along with all the extra gas it will suck might make it less enjoyable at cruising speeds. It will basically feel like the car is stuck in 2nd gear.. To compensate for this most people put in a better transmission with overdrive which gives you the best of both worlds.

 

Truer words have never been spoken.
1900rpm = 70mph
Plus a lower 1st gear

The 700r4 made a tremendous difference.

Ralph

 

I put a Richmond 5 speed in my car. First gear is like having a 4 speed muncie with 4.56s in the rear, 4th gear is like a muncie 4th gear with 3.55s, and 5th is 1:1 with your regular 2.87s out back.

 

the cheapest and very easy to do, put in a bottle of nitrous.or just drop in a crate motor of what ever horse power you can afford.

 

nitrous will tear apart that stock L-81

 

just buy a nice little stroker motor from one of the engine builders on the Forum. Do it once and do it right... you will spend a lot of money doing all of the little things and you will still not be happy. just bite the bullet and go to the front of the line. In the long run it is less expensive and less hassle. I know,, I went down this road. Just buy the stroker and be done!!