Dacksoldier

What is the physical difference between an 1978 L48 and same year L82?? can you make a L48 perform just like an L82??

mrvette

Short answer, no, not really, heads, cam, pistons, and some say also the block is 4 bolt mains for the L82.....
which will not mean much for hotrodding for street use....

in fact the late 70's heads are rather poor no matter which engine....thin castings....lo flow rates, which suited the mild cams, but limit performance....then there are the cat *** trophic converter requirements, and single exhaust...the list is long, and the cures vary wildly depending on your local .gov inspections....

Oldguard 7

Yes it can be done but as the previous poster mentioned,you would have to get better flowing heads. The L82 cam is the same as the L46 engine. Pistons in the L82 engine are forged with a single trough relief.

Scott Marzahl

Not only are the pistons forged but so is the crank for a stronger bottom end. Basically if you want to swap heads, cam and intake you can make a very good running L-48 assuming that the short block is in good condition.

martinsw

Why even try? L82 only had what, 220 hp vice 185 for l48. Better just to gut out the l48 and build up the sbc using aftermarket parts and get a lot more than 220 hp IMHO. the two bolt main should handle well over 400 hp shouldn't it?

dstaley

Yep, well over 400hp - especially with quality (ARP) bolts or studs.

The Vortec head swap is very popular, and will nearly double the original L48 power output with the right intake, camshaft, headers, and dual exhaust. 360hp is well within reach, forget about 220hp.

Enersis

my buddies motor in his camaro is 2 bolt, with 600 hp, i wouldn't do it, but its holding up just fine.

Dacksoldier

well the reason i want to keep the L48 cuz its matching number.. but i'm thinking against that now and if i can just find a 427 or 502 that my friends dad gets rid of all the time(he does super comp drag racing)

kk now my question is can i put a 427 or 502 in a 1978 L48 vette?
i'm guessing that its easily possible.

dstaley

Sure, the chassis was designed to accept big blocks and little was changed between the early 70's and your 78. There is a wealth of information on this forum about the details, but the motor mounts will simply bolt up. You'll have to work through details like alternator and power steering brackets, A/C compressor brackets (if you intend to keep/install it), and the radiator fan shroud. Hood clearance will need careful attention too.

7T1vette

If your buddy's Dad is 'done' with a 502, it's because it is WORN OUT! Don't put an abused, tired engine in your car...you'll just be asking for trouble.

dstaley

And, you know this HOW?

That's one good reason for being 'done' with it, but others are: changes in rules, different car, wanting to compete in different class, wants new/bigger flavor-of-the-month engine, etc...

I bought a 396 from a buddy that was "done" with it in his T-bucket. He wanted a 454. There was no sensible reason for it, he just wanted it. I bought another one from a different friend that sold the car but the new owner wanted only a roller.

Give the guy a break, there are a wealth of reasons why a engine may retired from a particular application but be perfectly suitable for a street car/play toy for many years in the future. At the least, it may be a perfectly suitable core for a rebuild project (if that's Dacksoldier's intent).

EDIT: Dacksoldier should certainly be aware that the engine might be tired/worn out, but if this guy is truly a friend he should be pretty well informed about the situation and have some idea about the condition of the engine.

1980 blue L48

I did not know that the heads were different, in the 78s?

martinsw

Just keep your L48 matching number block and put on different heads, cam, intake and headers / dual exhaust. You can get to good hp numbers and still have your 'l48' block between the motor mounts. You can keep your take offs to return back to stock if, and when, ever desired.

A few years ago I wanted more power from my stock L48 1979 - ended up putting in an LS1 and T56 and have never regretted it. I was on the fence though to just keep my L48 block and rebuild with crank, rods, pistons, cam, heads (would've been less expensive and not taken as long)....not entired sure why, but still have the numbers matching L48 and TH350 in the shed (seriuosly doubt they will ever get back in their original home)

jakesindy

78 L48 and L82 head casting #,s are the same

RonR80

All I did was swapped Cam ,intake, true dual exhaust, recurved distributor, on my L-48 and on the dyno I pulled 221 hp at the wheels .This was cheap and quick to do , and cheap too! Ron

68FireBird

Ron,

Which cam and intake did you use? Did you upgrade to headers?

I'm thinking about the same approach with my stock 76 L82

Scott Marzahl

68Firebird,
Regarding your plan for the XE-262 cam and keeping your existing valve springs. You will need to call Pioneer and verify the spring rate with them, but I will venture to say that you will need to run the Comp Cams matching springs. Pioneer calls the RV-943-4 a .490" Z-28 spring and I do not see a spring rate for them. The Comp XE Cams require the use of a pretty stout spring due to their fast ramp rates. These are Comp 981-16 which are rated at 370 pounds/inch. The GM Z-28 and off-road springs are around the 300-325 pounds/inch rate.

377

I have a 73 L-82 it has a steel crank/x rods/forged flat top 2 valve releif pistons /4 bolt block 6 qt oil pan trap door/windage tray and the cam is the 350 350 hp . head are 202 valves /guild plates/screw in studs. basically its a lt1 with less compression and a hydraulic cam. its a #matching car. but yes you can make the same or more power no problem. hope this helps

dstaley

What did it come with stock?

377

thats the stock untouched # matching engine