I have an L82 automatic in my 78 corvette, 220hp. I know that the engine could essentially get around 300 to 350 horsepower if things were upgraded. I don't know much about engines, but I know that a new cam and some new heads would make a difference. Anyone got any knowledge/ experience/ prices on anything about this?

 

The biggest bang for buck you'll find is in opening up the exhaust (headers, true dual 2.5" exhaust) and getting your carb and distributor dialed in.

Going beyond that, the $$/hp goes up, but it depends on your goals from there. I think an L-82 with a nice exhaust system and a well setup ignition and carb would be making close to 300. Beyond that and you're going to have to start opening stuff up - which is pandora's box, in a way.

 

I think aluminum heads are the biggest bang for the buck when it comes to power. Exhaust doesn't do much except give a nice sound. A cam will work in the upper rpm range but at the cost of low end torque and throttle response.
IMHO

 

use the search function , this is almost a weekly topic.

 

Headers, timing, dual 2.5" exhaust took dropped my 0-60 times from low 8s to low 6s. Actually, timing took it to low 7s from low 8s, and exhaust took it the rest of the way. 2" exhaust dumping into a single 2 1/4" pipe is NOT enough for these cars. Mufflers may not have as big an effect, but headers and pipe ID, definitely.

 

I would open up the cat first.better exhaust next .but I would also think about what gears I have .better heads and cam will be a great improvement but you have to decide what you are going to do with the car and how much you want to spend .

 

o.k. here is what id recommend IF the engine is in good shape.headers dual exhaust a set of aftermarket 64 cc heads, an r.p.m air gap intake and a new carb.a new timing chain and gears. if you are willing to invest in a new roller cam you can do that. but the last thing you really need is to swap out the L-82 cam with better compression it works very nicely. very drivable good response and power pretty much everywhere, the 350/350 was duntovs favorite street engines and it had an virtually identical cam.i added 1.6 roller rockers and people can't believe the way it runs .

 

Hi Guys, I also added 1.6 roller tip rockers on my 75 L82 .
Definite seat of pants improvement.

 

this is exactly what i did on my 78 l82 manual and you don't believe the difference. (If you are alowed take the cat and pump air out too). After that made ,if you want more power get prepared to spend lot of money opening the engine

 

I'm in the process of doing the same thing for my '74 L48 on this thread:
https://www.corvetteforum.com/forums...-my-plans.html

I found the Danger Mouse series of articles from SuperChevy very helpful.

 

The L-82's are held back because of low compression and a weak camshaft. Increase the compression ratio to at least 10 to 1 and install a camshaft with about 230 to 235 degrees duration. Then to really make it haul install a TH700R4 and a set of 3.73's to give you awesome acceleration while maintaining a low cruising rpm.

 

Shorty headers will typically get you 10-15 HP. Long tube headers will get you 20-25 HP. A high flow cat back system will increase either of those by another 5-10 HP. A true dual exhaust system w/o cats will get you a bit more. Exhaust upgrades are your easiest HP gains on a mid 1970s GM product because those factory exhaust systems were TERRIBLE.

After that your next easy upgrades to consider would be something like an Edelbrock Performer intake... that will get you maybe 5-10 HP over the original L82 aluminum intake. Going to 1.6 ratio roller tip rockers will get you another 5-10 HP without changing heads or cam...

But you are right the heads and cam are really where you are going to get the most increases. You need to do both because the L82 heads and cam pretty much maximize each other so doing only one or the other won't buy you nearly as much as upgrading both... What you probably want is a good set of aluminum heads with 64cc chambers, 180cc intake ports and 2.02" intake/1.6" exhaust valves. Combine that with a moderate hydraulic roller cam, retrofit (link bar) roller lifters, roller tip rocker arms and a double roller timing set and you should get 30-50HP increase between the heads and cam setup. The aluminum heads will also drop your weight by 30 lbs or so, which doesn't sound like a lot, but the traditional rule of thumb is every 100 lbs weight savings drops around a tenth of a second off 1/4 mile time which is approximately the same as adding 10 HP.

For the ignition side you will probably want to put in a stronger coil in and maybe upgrade the module in the HEI and some high performance wires.

Anyway, all that together with a good tuning ought to get you close if not into the HP range ballpark you want...

The suggestion of a TH700R4 (or TH200-4R) transmission upgrade along with going to 3.42 or 3.73 rear gears is also excellent... Those mods will really improve your launch and still not kill you on cruising speed.

 

I can CERTAINLY Verify all of the above since I did each in my 74

You will be quite happy

 

at least 10 to 1 compression with iron heads?.... are we talking about a pump gas street engine still?

 

I don't have a dyno test, but i can bet with exhaust, ingition, and 1.6 roller rockers you can reach the target of 300 hp. If you want more, then open the engine (but get your bucks prepared!)

 

Good point... 10:1 with iron heads isn't happening on 93 octane pump gas. With some carb work you could do it on E85 since that is equivalent of around 100 octane... But at least around here there are only a handful of stations which have E85. Aluminum heads will allow more compression without running into detonation issues.

 

AFR 180 64 CC heads, Headers to 2 1/2 dual exhaust, 1.6 rockers, Timing recurve and carb tune will get you close to 400 HP if the bottom end is solid. I would do a timing chain and gears while it is apart. First thing you need to do is compression and leakdown test.

 

So in just 0 to 60 MPH low 8s to low 6s, 2 seconds off. Just a timing change got you a full second in just 60 mph. I'm Elvis back from the dead would you like to hear me sing.


Whats sad is someone will probably believe this laughable nonsense

I'm all for someone putting some headers and better exhaust on there car if they want some more power but lets not go to silly hard sell laughable BS like this to convince someone.

 

It sounds like "pipe dream" and for all of you youngsters who don't know what a "pipe dream" is its what people do when they're smoking an opium pipe................hence a "pipe dream". Its an old 1900's term that was popular until the 1960's and 1970's when stronger drugs hit the streets.

My '82 ran 8 second flat 0-60's and it took a set of 3.73's, 10 to 1 compression, and a cam change to hit the 6 second flat mark. Timing and headers alone won't even come close to dropping 2 full seconds off a 0-60 time.

 

Agree; did cam, aluminum heads, intake manifold and shorty headers and dual exhaust for my 78 TH 350 (shift kit and stall converter). Still have the stock gears, if you're running the same (3.08) you will be disappointed with the low end response. Will probably change to 3.73 and maybe a line loc.

D'oh! Just realized I responded to a year-old post, wonder what the op decided?