What are the big differences between a L48 and the L82 Vettes? I know the HP difference, but is there any difference with the engine block itself or is it just a cam and carb?
Is there any other differences between L48 cars and L82 cars?

Please fogive my "stupid" questions. I am just trying to be as knowledgeable as possible prior to purchasing my first and hopefully last vette. My plan is to buy a C3 in the next year or so. Since I was born in the early 70s, my favorite vettes are from when I was a kid. I am not concerned about a "perfectly stock" car. I plan on making it mine forever anyway; after all, after you own a vette what else would you want?

tom

 

The crank was forged among other things. I'm not a mechanic so i'll let one of them fill you in on the rest.

 

Other differences are the interior trim level. Leather seats, upgraded carpet, deluxe door panels and I think power windows

 

Same block (but 2 bolt vs 4 bolt main). Different cam but same carb (different air cleaner and calibrations). Crank is forged and different pistons and fluxed rods. Also has pushrod guides, different heads (sometimes), different compression ratio, different ignition maps (early years?), different damper. Not an exhaustive (and I may be in error on some things) list but those are the immediate differences I can recall off hand. Keep in mind that differences may vary from year to year since the L48 was in production 12 years and the L82 for 8 of those years.

Also the L82 was more a mid and late 70s option since it was intro'd in '73. Prior to that the the L46 was it's predecessor in '69-70.

If not worried about originality one can always build up most any L48 or NOM - that's the beauty of a SB V8.

 

I was wondering about the 2-4 bolt main. thanks for that answer. I do plan on building a strong motor, but I don't plan on getting crazy (probably about 300hp as a goal). I want a car that I can drive anywhere and anytime. The 4 bolt might be a bit stronger, but probably not enought for me to worry about.

thanks for the replies so far

tom

 

I completely agree.

The L48 is a great engine - it can be left alone or just tweaked w/ a modern cam and better ignition curve and maybe pistons (or hot rodded to your heart's content).

 

If your not to concerned about originality and you just want to have fun and drive dont get hung up on L82-L48.Id rather have a good strong car with an L48 than a basket case L82.As already stated the 48 can be built up quite well.

 

my l-48 is now a stroker and all is well

 

In 78 the L48 compression ratio is lower. Dished pistons instead of flat tops.

I think this holds true for all L48's

 

If you stick with the years when both were avaialble at the same time to compare side by side, you would see that L-48's came with 2 bolt mains, cast iron crank, base (smaller) harmonic damper, lower compression cast pistons, base configuration rods, no windage tray, smaller valve heads, no guideplates, pressed in rocker studs, base model cam, stamped steel base engine valve covers, base model pulleys, and a lower redline on the tach. Some differences in the carb and distributor calibration.

All of those things were different for the L-82 as it came with 4 bolt mains, forged steel crank, larger HP harmonic damper, higher compression forged pistons, special inspected and surface preped rods, windage tray mounted on the main cap stud bolts, larger valve heads, pushrod guideplates, screw-in studs, special HP cam, cast aluminum finned valve covers, deep groove pulleys for higher RPM, higher redline on the tach, and the calibration differences mentioned above. Some years had special intake manifolds while other years the base Vette got the L-82 intake manifold.

That is the basic stuff.

You can modify an L-48 without fear as the original configuration has a substantial factor of safety built into it. The L-82 has some nice goodies in it already so you have a better base to start with for basic upgrades if you desire. If you are going to modify it heavily then it probably does not matter which one you start with as most of the GM stuff will end up in boxes on your garage floor.

-Mark.

 

Have a 78 L-82 4 speed 3.70 rear. Been a good motor. After 119K,have only pulled intake due to ERG valve cooking gasket (at 90,000 miles)resulting in fouling of no.8 plug.Trying to squeeze another 30,000-40,000 out of it before rebuild....being held captive in Calif,so my options are few..thinking 5 speed at re-build,maybe....

 

To see the differences for '73, the first year for the L82, just check out The '73 Spot below. Go to Technical Info and then select L48 - L82 Compairson

Had nothing to do with trim, was strictly an engine package.

 

stingr69 pretty much said it all. The cam in the L82 was/is almost identical to the cam in the L46, which was the 350/350 option in the early seventies. There used to be a website called l-82.com but it appears to be gone.

I have a 78 L-82 with the close ratio 4 and 3.70 gears. Runs great and I love the motor. In the era of smog motors, it's really pretty good.

 

I have a'75 L-82 4 speed in a somewhat modified state. The previous owner did a half-assed job rebuilding it. So, long story short, it spun the 1 and 5 bearings. Ouch, what a sounds that makes.

Anyway, I just reveiced it back after after a complete rebuild and all i can say is WOW.

Some of the stats:

.060 over, forged pistons, moly rings, machined crank .295 cam, lifters, valve job, roller rockers, edelbrock dp manifold, holley 600 cfm, and other miscellaneous updates.

I've been running it with a straight chambered dual exhaust. After the rebuild it sounds sick, almost like a big block. Nice crackle from the exhaust now.

 

In OCT 2002 we were in South Boston,Va in our Vette.Left Calif right at 100,000 miles and returned home with another 7,000.Really enjoyed tooling down the Blue Ridge Parkway,3.70 gears and all....two duffle bags and her make-up case...

 

Both the L46 and L82 ran the same 962 cam actually. Great cam that has stood the test of time but being 35 years old might be able to do better w/ a modern profile like maybe one of the dual profiles. Still a 962 cam works great dropped in an otherwise stock L48. Keep in mind that it's so-called '350' horse status is from the pre '72 era of grossly overrated gross HP ratings. The L48s 929 cam should produce more torque at lower RPMs w/ a smooth idle.


Probably too much gears for me personally but that sounds like a really nice combo on that '78!

 

Keep in mind that it's so-called '350' horse status is from the pre '72 era of grossly overrated gross HP ratings.

What is a good ballpark figure for the L46 in real world net HP?

 

just build what ever you got for more power.....an L82 is what a 190 HP engine? so what? it may have been top dog in the smog laden mid 70s but now its just an old under powered SBC. don't worry about 2 bolt or 4 bolt mains built what you got if you want more power, you can easily outperform an L82.

 

I really appreciate all of the replies. I am sure over the next year or so, I will be asking a ton of questions. But mostly I plan sitting back and reading.

Thanks again to all of you

tom

 

You're kidding aren't you????? The interior has nothing to do with whether you have a L-48 or a L-82. The deluxe interior package could of been ordered with either engine.