81 hp upgrade
05-28-2014, 09:20 AM
#21
Safety Car
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?
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?
this would be my advise if the motor is in good running condition!
05-28-2014, 11:14 AM
#22
Burning Brakes
Lose the computer and all smog stuff.
Cast vortec heads are cheap, plentiful, and easy to put on. Instant 40 HP.
You will want an Edelbrock manifold to match the heads. Holley 600 cfm carb, and the Summit HEI distributor.
Add some headers and you are good to go.
Shop frugal, check swap meets etc, and this is good for up to 100 HP for about 1200.
Cast vortec heads are cheap, plentiful, and easy to put on. Instant 40 HP.
You will want an Edelbrock manifold to match the heads. Holley 600 cfm carb, and the Summit HEI distributor.
Add some headers and you are good to go.
Shop frugal, check swap meets etc, and this is good for up to 100 HP for about 1200.
05-29-2014, 04:29 PM
#24
Safety Car
For that kind of money I would expect better aluminum heads and a better Carb..... I guess geography plays a big part though...
05-29-2014, 04:32 PM
#25
Le Mans Master
This is a Jegs engine
Well the desktop dyno and dyno 2000 programs I'm using must be way off from reality because the little 355 I just built for 1100 puts out close to 400hp and 414# of tq according to them.
For that kind of money I would expect better aluminum heads and a better Carb..... I guess geography plays a big part though...
For that kind of money I would expect better aluminum heads and a better Carb..... I guess geography plays a big part though...
05-29-2014, 04:36 PM
#26
Le Mans Master
Well the desktop dyno and dyno 2000 programs I'm using must be way off from reality because the little 355 I just built for 1100 puts out close to 400hp and 414# of tq according to them.
For that kind of money I would expect better aluminum heads and a better Carb..... I guess geography plays a big part though...
For that kind of money I would expect better aluminum heads and a better Carb..... I guess geography plays a big part though...
05-29-2014, 05:45 PM
#27
Le Mans Master
Member Since: Mar 2008
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There is an age old recipe for souping up a smog era small block chevy. 64cc heads to increase compression. Free up the intake and exhaust (Edelbrock Performer and 1 5/8" headers with 2 1/2" dual exhaust) Install a cam with around 215 degrees of duration at .050" lift. Re-curve distributor (this alone will give you a "seat of the pant" improvement in performance) Install a slightly looser converter. An upgrade to a 700r4 transmission and higher numerical diff ratio will top off the whole package.
Scott
Scott
05-29-2014, 08:24 PM
#28
Instructor
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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.
.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.
05-29-2014, 11:02 PM
#29
Safety Car
And the real question should be how much do you think its worth to me to have accomplished learning to build it myself and make it my own? To have a beeter understanding of how my hobby works and have the power to not be afraid to make any changes or improvements as I see fit?
To me that alone is worth much more than ten times the "labor" of doing something I have enjoyed thoroughly And the knowledge I gained will help me on all my future automotive projects.... Its a win win situation for me the way I see it. And If my ramblings inspire even one other person on this forum to do for themselves and try to learn more about the cars they own and not be intimidated by comments like "its not worth it " and you'll regret it , its cheaper to buy a crate engine already customized for you like everyone else" well then Its worth it just for that.
There's something to be said for someone complementing you on your ride and asking about it and being able to take pride in knowing exacting how it was built and that you made the car a reality by learning to do it yourself instead of just picking and having someone else build and install the same catalog engine that's likely in a half dozen others cars in a particular car show or cruise night.
There are those that want and can learn how to do their own work and my comments are directed towards them.... its not for everyone and those that aren't interested in how things work and just want to drive or show it off that's fine nothing wrong with that but I didnt buy all the comments that tried to steer me away from doing my own work mainly made by those that payed others to do it for them and I am just offering the other point of view from someone who didn't go that route.
Last edited by augiedoggy; 05-30-2014 at 01:20 PM.
05-30-2014, 12:16 PM
#30
Le Mans Master
I agree with you and I always look for deals too. I've built an engine before myself and if I was to do it again ill start with a complete short block next time. Some people don't have the skills, space, or time though to any any part of it
05-30-2014, 01:19 PM
#31
Safety Car
I didnt want to deal with machine work either so I looked and found one that was just rebuilt... I got lucky (sort of) that the guy took it on partial trade at his shop and wanted it gone.along with all sorts of goodies like new chrome alternator mounts and carb spacers and such he threw in free. I wasnt expecting to have to replace all the bearings and crank but for $300.00 it was still worth it for the new speedpro pistons, moly rings and hipo oil filter and such it came with. Plus i know the history since he showed me the 76 gmc it came out of which was mint... the guy just wanted a stroker crate engine as he was older and retired and wanted to drive his truck while he could.
The best part is I dont have to worry about messing up my numbers matching block so it can go with the car or I may rebuild it for future use. its only a 2 bolt but that will be fine for my driving habits. although I think my next build will be a stroker.
Last edited by augiedoggy; 05-30-2014 at 01:21 PM.
05-31-2014, 09:18 AM
#33
Burning Brakes
The stock engine was less than 200hp (when new), most were automatic (eats more hp), then pair it with a rear gear of 2:72 or 2:87, and what you have is a dog. Again, it depends want you want to do with it. It will be fine for parades and cruising around, but if you really want more performance, I would drop in a crate engine. But, to really have a total balanced high performance package, you would probably do work to the whole drive train = engine, trans, rear gear. Then you would probably want to improve handling - then it can get out of hand. 
05-31-2014, 11:28 AM
#34
Burning Brakes
Member Since: Feb 2011
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The stock engine was less than 200hp (when new), most were automatic (eats more hp), then pair it with a rear gear of 2:72 or 2:87, and what you have is a dog. Again, it depends want you want to do with it. It will be fine for parades and cruising around, but if you really want more performance, I would drop in a crate engine. But, to really have a total balanced high performance package, you would probably do work to the whole drive train = engine, trans, rear gear. Then you would probably want to improve handling - then it can get out of hand.
What does a crate motor do that you can't do your self?
At 90000 miles I pulled off the heads and saw no ridge at the top of the cylinder, none. Thank you Mobil 1.
I honed the cylinder, bought a ring and bearing kit from Summit.
Asked around this forum and picked out a great cam.
Added Summit headers Edelbrock manifold and Carb, and a 700r4 and BAM.
I have a tire squealing 21mpg ride that turns heads and makes me smile.
There are a few thing I may of done differently, like a 406 block instead of the 350, but maybe not.
And like the OP, I did it all my self. Except for the paint. I hate sanding but that is a different story.
Ralph
05-31-2014, 01:18 PM
#35
Safety Car
What is all this crate motor talk?
What does a crate motor do that you can't do your self?
At 90000 miles I pulled off the heads and saw no ridge at the top of the cylinder, none. Thank you Mobil 1.
I honed the cylinder, bought a ring and bearing kit from Summit.
Asked around this forum and picked out a great cam.
Added Summit headers Edelbrock manifold and Carb, and a 700r4 and BAM.
I have a tire squealing 21mpg ride that turns heads and makes me smile.
There are a few thing I may of done differently, like a 406 block instead of the 350, but maybe not.
And like the OP, I did it all my self. Except for the paint. I hate sanding but that is a different story.
Ralph
05-31-2014, 04:31 PM
#36
Le Mans Master
I am speaking for myself but if i had a late C3 and wanted more power i would go for a crate engine instead of trying to upgrade the the original engine
You have to buy a lot of parts to upgrade the engine and that cost and then you have quite some work ahead of you
How much work do you have to do to your original engine to top 350 hp or more?
If you buy a 383 crate engine all of the work is already done
You have to buy a lot of parts to upgrade the engine and that cost and then you have quite some work ahead of you
How much work do you have to do to your original engine to top 350 hp or more?
If you buy a 383 crate engine all of the work is already done
05-31-2014, 06:08 PM
#37
This is really good advice! EVERYBODY focuses on the engine first but as old as these cars are it is good to know they will reliably go where you point them and stop when you need to.
06-01-2014, 04:40 AM
#38
Burning Brakes
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I am speaking for myself but if i had a late C3 and wanted more power i would go for a crate engine instead of trying to upgrade the the original engine
You have to buy a lot of parts to upgrade the engine and that cost and then you have quite some work ahead of you
How much work do you have to do to your original engine to top 350 hp or more?
If you buy a 383 crate engine all of the work is already done
You have to buy a lot of parts to upgrade the engine and that cost and then you have quite some work ahead of you
How much work do you have to do to your original engine to top 350 hp or more?
If you buy a 383 crate engine all of the work is already done
1900 rpm at 70mph is cruising and 21mpg is better than my wife's Toyota Highlander.
Around town I have to be careful not to to squeal the tires, and in the rain well I have to idle around.
For me this is why there is pride in ownership.
If you can't do it your self find some like minded people who enjoy working on cars.
There are a lot of people who would like to work on it simply because it is a Corvette Stingray.
I know every nut and bolt. I picked out every part in the engine and transmission.
I choose the rear bumper and the spoilers and the color.
I choose the wheels and tires and how much air to put in them... 34 pounds.
I choose the mufflers and the pipes, the stainless steel tips and the headers, then I put them on.
I rebuilt the disk brakes. Make sure you get the new design with the lip on the
seals so they won't suck air into the lines if the car sets to long.
You get my point. This is my car, I built it.
When I brought it home my wife was mad because it was so UGLY.
Will a 383 stroker beat me in a race. Yes and so will a thousand others.. so what.
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Click on the picture it's a video.
Hope I didn't get too carried away.....
Last edited by Ralphbf; 06-01-2014 at 05:08 AM.
06-02-2014, 06:29 PM
#39
Le Mans Master
Great that you know every bolt and nut on your car Ralphbf but you can not really think that every Corvette forum member have the skill to build the engine of their cars?
I think most forum members have mechanics to do that kind of work or some friends that are car mechanics to help with the engine, mechanical work like i have
I think most forum members have mechanics to do that kind of work or some friends that are car mechanics to help with the engine, mechanical work like i have
06-02-2014, 11:59 PM
#40
Safety Car
Great that you know every bolt and nut on your car Ralphbf but you can not really think that every Corvette forum member have the skill to build the engine of their cars?
I think most forum members have mechanics to do that kind of work or some friends that are car mechanics to help with the engine, mechanical work like i have
I think most forum members have mechanics to do that kind of work or some friends that are car mechanics to help with the engine, mechanical work like i have
I think most of the guys in this section either want help with what they are working on themselves or are trying to learn more about how their cars work...not that they are all building engines or anything but I bet most here do their own repairs and maintenance
(Or did when they could)
Last edited by augiedoggy; 06-03-2014 at 12:17 AM.