This is the thread you want. Honestly it should be a sticky.

 

I'd start a new thread. The best thing you can do with an L48 is replace it with a crate engine.

Pull it out of the car, and place it next to a cheap LS-based engine from an early 2000s Silverado. Take them both apart. If your L48 is anything like the original engine in my 79, you'll stop right there. With only 60,000 miles, it was toast. Not worth rebuilding, not worth selling on Facebook (I couldn't even get $200- for it). The LS will come apart and go back together like LEGOs.

Don't waste time on a Gen 1 SBC, unless you really really need to have the original engine in your car. There are SO many better options out there, and cheaper, too. I just picked up a complete, running, 6.0L LQ9 (native roller cam, coil-per-plug ignition, EFI, and light, aluminum heads) for less than the price of a single AFR head. You'll need two heads on that L48 to go any further, and would still have a carb to tune (or delete).

 

This is solid advice^^^^ from a guy who did want to keep his OEM 78 L-82 4 speed with 3.70 gears original as much as possible.

Back in 2014 with me doing most of the work except the machine work for the short block (boring .030, reconditioning the L-82 rods, reconditioning the L-82 forged crank, and assembling the short block with my purchased JE forged racing pistons), me purchasing the AFR heads/Howards roller cam kit, reusing/porting the aluminum L-82 intake, reusing the Holley 4175 on the car since 1985, oil pump/everything else including a new RAM clutch kit, and various other parts and issues, the total cost was $5,500 using top parts I selected for my L-82 engine goal . I pulled and installed the motor myself with some help.

Is a 355/383 crate engine less expensive than my end product with similar power and built with the same precision and quality products? Probably not, BUT much easier.

Going with an LS configuration in a C3 is a completely different direction. No question that an LS is extremely cheap power for short money but the question you have to ask yourself is that C2/C3 really still true in some extent to the original intention by GM/Duntov 50-60 years ago? Not saying it is wrong but just not a C3 any longer to me, my opinion only.

When I get into my 78 with the rebuilt/upgrade 355 L-82 GEN 1 SBC, it still feels, smells, sounds and drives like a C3 just with more power than L79/L46/LT-1 by a lot and handles/steers like a C3, just much better, with all the changes and tweaks to the OEM suspension/steering/brakes I have done over the last 40 years BUT with the OEM design in mind.

Depends on what you are aiming to achieve............

 

I just freshened an original 79' L-82 and stuck it in a 73' C10....ran great.....first completely bone stock sbc I think I have ever built...I even reused the 45 year old L-82 camshaft as it mic'd out perfect (44,000 mile engine I bought from a forum member) .it will peel the 255/75/15's right off the rim LOL....I sold him this freshened L-82 for $3500 carb to pan.....it beats the **** out of a crate engine....and is all GM....

Realistically....on a strict budget....the best thing to do to a L-82 is pull the heads and clean up the bowls really well and the port match....get a good "Z/28" spring kit, properly check and installnthe correct length Trend pushrods....use a 1.6 rocker arm....roller tip is fine....install a 2101 Performer....and a pair of long tube headers with a good 2.5" exhaust....jet and curve it.....it will throw about 275 to the tire....good for low 14's....or better depending on the setup....about 360 flywheel horsepower....and they run well.....get 15-16 mpg with a Q-Jet.....
If you can afford it....have the heads clipped .030 when they are off and use a .015 head gasket.....this will get you to about 9.7:1.....
The alternative is to find a pair of 69-70' 186 (LT-1,DZ,L-46)heads with the 64cc chamber and do the same thing to them (no milling).....the L-82 cam loves compression and it will respond another 15hp.....
This is assuming of course that all of your equipment is in top condition.....you can still do this **** dirt cheap.....I still do occasionally as it satisfies by bohemian need to build **** with more brains and attention to detail as opposed to throwing new parts at it....
The L-82 is also the strongest small block GM ever made....it shares nut and bolt the exact same short block as the fabled LT-1.....so after all of your upgrades....you still want more power....bolt a 175hp shot of NOS on it.....for 550hp....instantly....the engine will take every bit of it.....all forged components.
11's with a backyard sbc and a little spray....we used to do it all of the time in the 90's....I used to freeze when I saw a rubber bumper Vette at the junkyard back then....to see if it had the tell tale dual snorkle air cleaner....and the letters on the hood.....I could buy these for $200 back then....take them apart and put a timing chain....rings, bearings, intake and Comp rocker arms on it....sell it to a buddy and they would go fast!

On the engine stand right now is an original 355 LT-1....I stuck 70' pistons in it(.125 dome)for 10.3:1....it has 71' 487 heads ported by me with Stainless valves, three angle valve job, ARP studs, Isky Z/28 springs, Trend 7.750 long pushrods, Comp 1.6 Magnum roller tip rockers,Cloyes true roller and a nasty Isky 292Mega cam with 108lsa 4degrees advanced....factory high rise and a bone stock lower end complete with a M55A "Z/28" pump....(what GM used not HV)
With headers and a 750HP carb....it should throw 320 to the tire...400 flywheel horsepower.....and even with the hydraulic cam will rev to 6700rpm....fun engine...that sounds nasty AF....a L-82 on steriods....but I kept 75% of the original GM parts in/on this engine....toss that around for a minute.
I am going to try a 650HP on this engine too to see if it helps signal downstairs where real people drive...
This is the third "cheater" or "vintage look" sbc I have built in the lastncouple ofnyears and there seems to be a market for it....IDK....what does the forum think?

Anyway...OP....your cam is plenty for now.

Jebby

 

100% agree that the L-82 is a tremendous platform, pretty much the last of the Gen 1 SBC built really stout from GM. I was one of those die hards in 2014 that wanted to retain as much as possible from how the engine was conceived and built by GM in October 1977 for my engine.

My original intent back in 2014 on the OEM L-82 engine with 65,000 miles on it was to refresh it with cam and heads but when I removed the stock 882 heads I discovered some issues. I bought the car in 1983 with 35,000 miles on it, and is typical with used cars with performance, this being an L-82 4 speed 3.70 gears with the gymkhana sport suspension option along with AC (no other options-no power windows, no power door locks, no rear defroster, no tilt steering column, no anything), the car was abused and street raced, probably.

As you can see from the engine pics above, it was well maintained by me during its life but who knows before. Today, it pretty much looks like an OEM L-82 with the dual snorkel air intake still in place and most external GM parts visible like the heavy duty fan and clutch for the L-82 AC cars but the addition of the AFR eliminator aluminum heads and 1 7/8 inch LTH headers, obviously, are not stock, along with 2.5 inch dual exhaust with C4 Corvette Borla Type S mufflers. Running a howards roller cam with .525 lift/LSA 110, duration 219/225 motor should be good for around 450 Gross HP with 10.2-10.3 compression...Looks like a 78 L-82 4 speed but runs like a beast when pedal is down......

 

Jebby
Good to hear from you again!
Always love your wisdom!

The LT-1 you are building now sounds exactly like the '70 I raced for 27 years.
The only 3 non-stock parts in that engine were ARP rod bolts, stiffer off-road Z28 valve springs and an old school DZ302 / Fuelie 30-30 solid cam. That one had 254* duration on a solid vs your 244 on a hydraulic. Yours is actually probably just a touch wilder. The Idle did sound nasty!

Mine saw 6800rpm dozens of times every weekend on an autocross, over likely 1000 events. If I wanted to hold on and not shift I would rev it to 7200.
That engine was tough as nails, and 97% stock. Loved that engine!

Rev'd it for for 20k hard racing miles. And got 15 mpg on the turnpike at 65-70 mph with 355 gears at ~3000 rpm.
I always guess-timated 390-400HP based on times. 106mph in the Qtr. This was mostly 80s & 90s. Hi 13s with a horrible launch.

It was a little soft until 2800 when the cam kicked in, hard! Although I always wondered whether that surge could have been the OEM Holley, at the point where the idle circuit cut out, and the main circuit cut in. 'Cuz it always stunk at idle. We did not have AFR gauges in the 80s, and nobody cared how it ran off idle.

An L82 is the same engine, short block anyway, if you can get the compression back!

And JB78L82's engine is basically the same with much better AFR heads. So his makes 50 more HP even with a milder and more streetable cam.

High RPM small blocks are such a blast to drive!

How's that movie quote go?
Something about
" 7000 RPM "

 

I was going to put a 30-30 in this for authentic sound......but the owner and I got to talking and he said he didn't want to lash valves......I don't blame him but I also told him the the "sewing machine" sound would be gone.....but the Isky 292 MEGA is ground on a 108 lobe center and the ramps.....although not as tight as the newer grinds (which can have break-in issues) the lobes are waaaaay tighter than the 30-30.......which the lobes are so long it cannot be lashed at TDC! GM knew their heads sucked.....so they engineered the biggest longest cam that they thought would work and put it on a 114 lobe center......for better idle vacuum....it is a lumpy dude but gives up a lot.....it makes pretty good power but their are better choices with less duration......the Isky is one of them......with 10.3:1 it will sound great.....and believe it or not....that hydraulic will rev to 6700+.....but I think the party will be over at 6500.....
The Isky will have a much better torque curve from 3000-on......I am also using a 1.6 Comp Magnum rocker, ARP stud, the Isky spring, and premium pushrods.....and that is how it will get to close to 7000rpm by keeping valvetrain flex and harmonics down.....even on the ancient setup, it all matters.....lift will be .534/.534 with the 1.6.
It will be very fun cruiser engine with 3.70 gears and a 2.56 low 4 speed......I have used the 292 in many engines and the Comp version too which is on a 110......for a "large" cam....they run amazingly well all over and makes a better sound than any other cam I have ever used on the street in a stock block SBC.

I am building a version of a LT-1 myself and have the twin to this short block on a stand for myself. This one will be near identical but will have a pair of 180cc Edelbrock E-Street heads I picked up cheap.....ported by me of course....with a 1.6 Comp full roller rocker. I expect 425 hp from that one with a stock LT-1 intake and my own modified 750HP Holley.....I may put this in my 72' and see how I like it.......maybe break out a 125 shot of NOS on it......as the rearend, suspension, half shafts are all new......the 406 will probably go in my wife's 82' Z/28.....or just keep it on a stand I always wanted a stout 355 in that car......the 406 is pure muscle everywhere, but I want something that revs higher and makes less torque off the bottom....

Jebby

 

Yeah I built mine way back in '79. The car is long one, but I would almost love to build another, with way more modern tech like AFR heads etc. etc.
I have no doubt on the 425+HP !

Instead I have my LS6 roller cam clone, which will never have that sewing machine sound, or that high RPM scream,
But I have never owned a BB, and all the extra TQ should be fun!

Sigh..if only I had room for two.

 

Ok a couple more points here net vs gross horsepower aside the NHRA factored the L-82 at 315 horsepower because it obviously made over 225 horsepower. A good reason the LT-1 made more power than the 350/350 was the LT-1 had a vastly better intake manifold and no it didn't have a quadrajet either. I had a 78 pace car L-82 4 speed advanced stock cam 1.6 rockers LT-1 intake headers and dual exhaust brand new car and.never got beat by an LT-1 Corvette on the street oh and I had a 750 double pumper. Now put this thread together and write a book.
Funny how the L-82 is probably. The engine we talk about the most.

 

more Compression accounts for most horsepower differences.
depends on which year.
70-back LT-1 had lots more compression than 71-up
All L-82 had large chamber & less compression than 70-back LT-1; also less scr than 70-back ZQ3 aka L48.

70-back base ZQ3 had same cam as did smog 77 L48; but the earlier motor had Lots more compression.

 

I guess I failed to mention my pace car had a set of then new angle plug heads which would have taken my compression to right about 10-1 which equalized things alot plus those heads flowed alot better. The point is set up properly that engine could run very well.

 

Did your pace car deliver new with angle plug heads; or were angle plug heads installed post-delivery ?

 

NHRA factored at 315 HP Gross sounds about right.
Compare to 71 LT1 at 330 HP.

Gross means headers and optimum tune. Main difference here is intake and Holley. Easily 15 HP.
That puts a fictitous 71 L82 at 260 net, with stock 71 car dual exhaust.
That drops to 225 for later cars do to the horrendously restrictive single "can" cats, a 35 HP drop.
So now you know how to push it to 315 HP gross. with 9:1 CR.
Increase compression and add modern head ports & combustion chambers and you have another 40-50+ HP. Call it 365 now.
Add back the LT-1 intake & Holley and you're at least at 390. Gross.
With headers and really good 2.5" exhaust and mufflers.
With stock L82 driving manners.

So how much is enough?
It doesn't matter the L82s short block can take it.
'Til you cross 6500 RPM often anyway.
.

 

Hey there! I started this crazy thread just wondering if the cam was good enough. The answer is...kinda. LSA, lift and dur are all good but the flat tappet and having to use stupid special oil and then I would have had to change springs on my new heads. So...out it goes. Here is the rundown of what I went with:
AFR 195/64 heads
Dougs 1-3/4 tube headers
Pypes exhaust
Howards Hyd Roller dur@050 225 int./231 exh, lift 0.500 int./0.510 exh, LSA 112
PRW 1.6 rockers
Performer Intake (had to for hood clearance!)
McLeod Clutch
Rebuilt Q-Jet
Pertronix Flamethrower ignition

 

Angle plug heads never came from the factory they were an over the counter only part so yes I installed them.

 

Sounds like a much improved combo over a stock L82!
That is a pretty well scienced out combo. And will run better than my LT-1 ever did.
The AFR heads are top notch.
My only thought is that with their excellent exhaust flow, and a good Pypes exhaust, you do not really need a split duration cam.
They are for restrictive exhaust cars.
I would assume you will see no HP advantage to it. And it will have all the downsides of larger duration, more overlap etc.
Now it is only a +6 split.
But I would think a 225/225 112 would run just as well, and drive slightly better.
It all depends on what you are looking for. Sound, powerband, etc.

But I would not just rebuild that QJet, i would seriously have Lars recalibrate the cruise circuit.
Increased overlap drops the vacuum level, and affects the cruise mixture.
Either tune it with an AFR gauge, or let Lars do it.
QJets are very finely calibrated, and very sensitive to changes as well.
There are only a handful of people worldwide, who have the knowledge, and the parts, to tune the AFR on a Qjet.

For the absolute best running combo you can get, I would speak to Mike Jones for a cam profile, and Lars about the QJet.
Just check out what amazing results Stingr69 has been able to get with his Jones cam /Lars QJet combo.

Those two have forgotten more than what the rest of us ever knew!

For example, an idle vac drop from 15 to 13" might be expected and might sound OK to many. This does not sound like a lot. But for a finely calibrated QJet that could mean 15% less fuel at low cruise. A lot leaner. Holleys tend to run much richer at cruise, on purpose, and cover up this sort of thing, and so they are much more accomodating to cam swaps. Go too lean and it will stumble and misfire. That is the main reason why so many Holley lovers bad mouth QJets. QJets need to be calibrated for the cam cruise vacuum. Holleys are actually even more difficult to tune low cruise, you have to change IFRs and air bleeds, or drill things out. At least on QJets you just change jets and rods and taper. But you have to be able to get the parts.

 

Lotsa nice parts, except for PRW.
Suggest don't run Chinesium valvetrain; PRW rockers are ChiCom. Usually, ya get what ya pay for; or get something less than expected.

 

Might be late if you all ready have the parts for your build, but as others have noted, pretty stout selection for your build.

I heard the same about the AFR 180 64CC heads I run about using a single duration roller cam versus the split duration, but honestly, I would be hard pressed to imagine that my 355 L-82 would run noticeable better if I had run the roller cam with 225/225 duration versus my 219/225 that I currently have in the motor, with the emphasis for the street, low end grunt and strong mid range torque which is where my L-82 355 really shines. Either 219/225 duration or 225/225 would be my choice, not any higher, for a street engine, along with 110 LSA versus 112 or higher to concentrate the power band. If it was me, looking back 12 years now on my combo, I would shoot for more lift than I currently run .525/.525 lift, but closer to .530 with 225/225 duration, LSA 110.

Lastly, I was strongly encouraged to run AFR 180's NOT the 195's for a 355 since the 180's theoretically have better low and mid rpm air velocity along with stronger throttle response. Not that the AFR 195's are a problem, but for optimal power with strong low end grunt, BIG mid range torque, and sub 6,000 RPM HP, the AFR 180's appeared to be the better choice over the 195's for my 355.

Just some thoughts from my real world experience.....

 

Billet aluminum is billet aluminum is billet aluminum.they ain't stamped from Chinese steel

 

Thanks man. I love hearing everyone's builds. Yeah I have everything already bought. I mean...is this gonna run ok? What should I look out for when putting it on?
I'm a busy realtor so the demolition phase is taking a minute or three longer than I'd hoped.
Haven't bought the exhaust yet. Still on the fence