More performance for my 1980 L82
Thread Starter
Drifting
Joined: Jan 2006
Posts: 1,540
Likes: 12
From: TX
More performance for my 1980 L82
I have a low mile untouch L82. I am a big performance hands on guy
but want to leave this one looking stock. I know the carbs are really
lean from the factory. The car is way to slow for me. What mods
really help this thing while leaving the stock air cleaner on and stock looking under the hood? Thanks
Has anyone ever tried putting 1.6 roller rockers on, tuning the carb, etc?
Why is this thing such a dog, Ha ha
but want to leave this one looking stock. I know the carbs are really
lean from the factory. The car is way to slow for me. What mods
really help this thing while leaving the stock air cleaner on and stock looking under the hood? Thanks
Has anyone ever tried putting 1.6 roller rockers on, tuning the carb, etc?
Why is this thing such a dog, Ha ha
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Billy, the biggest problems with the L82 were the heads, and exhaust. The cam can even be made more aggressive if the heads are replaced with something that flows better.
Knowing that you want to keep it looking stock, get some iron 64cc heads, maybe after market Vortec heads that are drilled for your stock intake manifold.
Then, install a more aggressive cam and lifter combo, and look into a true dual 2.5" exhaust system with a set of better flowing mufflers.
That'll get you a considerable HP increase without affecting the stock look of the engine.
Knowing that you want to keep it looking stock, get some iron 64cc heads, maybe after market Vortec heads that are drilled for your stock intake manifold.
Then, install a more aggressive cam and lifter combo, and look into a true dual 2.5" exhaust system with a set of better flowing mufflers.
That'll get you a considerable HP increase without affecting the stock look of the engine.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
The heads were the same as L48 heads just with larger valves. They still had poor air flow.
Your compression is correct, but with 64cc heads you'll get around 9.5:1 which is considerably better and you'll still be able to run on pump gas just fine.
The other advantage of the Vortec head design is the flow. Known as the best flowing head GM has put on a stock engine before the LS engines, the Vortec head will flow much better than the stock heads.
Iron Vortec heads can be found by several after market companies for not a lot of money, and the fact that they are usually drilled for both intake manifold styles and both valve cover styles means you can keep that stock appearance while still bumping the compression and increasing intake flow.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I'm fairly certain the L98 heads were aluminum swirl port and your intake would fit them, but they may have smaller chambers. If you can get me casting numbers I can tell you what size the chambers were. They would flow better but you might get too much compression.
Edit: Glen has more info on the L98 heads.
Last edited by Durango_Boy; Nov 17, 2008 at 07:41 PM.
Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
hegazman
If you want more power and the stock look, get yourself a set of fast burn vortec heads modified for higher lift plus a good cam. It will still look fairly stock with a lot more power. Also "Jet Performance" has Q-jet carbs rebuilt for more HP and good off idle response and are fully adjustable.
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
accoirding to this site, the squeeze on the last L-82 was 9.0:1
http://www.corvetteactioncenter.com/...0/80specs.html
'assuming' the L-82 and L-48 shared a similar cylinder head, with different pistons being the difference in compression (as I have been told), putting 64cc heads on that short-block will raise the squeeze to 10.2:1, maybe higher, probably necessitating the use of 93-octane fuel.
I believe the L98 head has 'standard' intake ports, and not vortec-style ports, and have 58cc chambers, and your compression might go through the roof, but they are aluminum, so that may offset the increased squeeze, and allow the continued use of high-octane pump-gas:
besides the L98, they are standard equipment on ZZ4 crate-motors.
Red 69 bought a 1979 L-82 that was slightly modified before he took posession, which now runs low 14-second 1/4-miles in full street-trim:
he might have a few suggestions about making it run to your liking.
http://www.corvetteactioncenter.com/...0/80specs.html
'assuming' the L-82 and L-48 shared a similar cylinder head, with different pistons being the difference in compression (as I have been told), putting 64cc heads on that short-block will raise the squeeze to 10.2:1, maybe higher, probably necessitating the use of 93-octane fuel.
I believe the L98 head has 'standard' intake ports, and not vortec-style ports, and have 58cc chambers, and your compression might go through the roof, but they are aluminum, so that may offset the increased squeeze, and allow the continued use of high-octane pump-gas:
besides the L98, they are standard equipment on ZZ4 crate-motors.
Red 69 bought a 1979 L-82 that was slightly modified before he took posession, which now runs low 14-second 1/4-miles in full street-trim:
he might have a few suggestions about making it run to your liking.
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Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Red 69 bought a 1979 L-82 that was slightly modified before he took posession, which now runs low 14-second 1/4-miles in full street-trim:
he might have a few suggestions about making it run to your liking.
I'm no engine guru, but I will pass to you what others on this forum have told me. If you are looking for performance, forget about those
L-82 heads. Power is made with good heads and a cam to match. My stock 350 with ported L-82 heads and 327-350 cam runs low 14's. It has a 3:73 rear gear turning 26.75 tall Nitto DR's.
I have a pair of Vortec heads I bought from Durango Boy that will be replacing the L-82 heads as soon as they arrive. My intake will be replaced with an Air-Gap and Holley 650 DP.
As stated, some Vortec heads are drilled to accept perimeter valve covers to maintain the Gen 1 appearance. If you don't want to go this route, ask Glen about his latest mods. He made his cam work better with 1.6 ratio rockers and shed the cross-fire intake for a 650 DP Holley. As stated, Jet Performance has built Q-jets available. Making the stock exhaust true duals won't hurt performance either.
he might have a few suggestions about making it run to your liking.
I'm no engine guru, but I will pass to you what others on this forum have told me. If you are looking for performance, forget about those
L-82 heads. Power is made with good heads and a cam to match. My stock 350 with ported L-82 heads and 327-350 cam runs low 14's. It has a 3:73 rear gear turning 26.75 tall Nitto DR's.
I have a pair of Vortec heads I bought from Durango Boy that will be replacing the L-82 heads as soon as they arrive. My intake will be replaced with an Air-Gap and Holley 650 DP.
As stated, some Vortec heads are drilled to accept perimeter valve covers to maintain the Gen 1 appearance. If you don't want to go this route, ask Glen about his latest mods. He made his cam work better with 1.6 ratio rockers and shed the cross-fire intake for a 650 DP Holley. As stated, Jet Performance has built Q-jets available. Making the stock exhaust true duals won't hurt performance either.
Le Mans Master
Joined: Mar 2004
Posts: 7,502
Likes: 1,510
From: Little Rock AR
This '80 L-82 looks rather stock but runs a lot harder than stock.
Dart Iron Eagle 64cc Heads, stock L-82 cam, .015" steel shim head gasket, stock cast iron rams horn manifolds, true dual exhaust without the catalytic converter, ignition recurve, and the stock Q-jet with a few Lars mods to richen the mix a tad.
This combination will get you 10.4 C/R and runs fine on pump gas.
It is basicly backdated to be a '69 350/350 with better than stock flowing heads.
-Mark.
Last edited by stingr69; Nov 18, 2008 at 02:42 AM.
Le Mans Master
Joined: Oct 2007
Posts: 7,456
Likes: 977
From: RI, Now Franklin/Nashville TN
For big power increases, the heads are the way to go. As noted above, 9:1 compression for the L-82 versus 8.5:1 for the L-48, bigger valves, much more aggressive cam in the L-82. If you want to avoid changing heads, you may want to consider what I have done which are very basic power changes: K&N air cleaner in stock housing on top of 4175 Holley, EGR plate (no EGR), 180 thermostat versus 195 originally, 1.5 roller rockers, high performance coil (hypertech with crane performance module) and Mcjacks shorty headers (no AIR pump and hardware) with 2.5 in true duals and Monza turbo mufflers. Much Much better performance than stock L-82 and looks basically stock and sounds great. Very similar power to early 70's SB's but not the power gains from changing heads and cam but the car moves when revved but I have a 4 spd not an automatic like in your 80 L-82. Since it sounds very stock, I would not be changing heads etc since it sounds pristine.
Race Director
Joined: Jan 2003
Posts: 15,176
Likes: 88
From: State of Confusion
http://forums.corvetteforum.com/c3-t...rag-strip.html
I'm very surprised that the stock cam wants to pull easily to & above 5000 RPM with full exhaust, which could be a result of the 1.6:1 rocker-arms.
Melting Slicks
Joined: Jul 2006
Posts: 2,291
Likes: 493
From: Salmon Arm, BC
I ran 1.6 rockers on my vortec headded 350 with .534" lift (?? can't remember exactly but very close to that). I used comp 1.6 self guided rollers, and I needed to drill out the pushrod hole to 1/2" to get clearance for the pushrod. Those vortecs are great heads for the money.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The answer here is just about always heads and cam - together - for a stock upgrade.
The additional lift from a 1.6 swap won't buy much with the stock heads as you're already at the top of the flow capability. You'd be increasing the stock .450/.460 lift (already a pretty healthy cam) by 1.067 and I suspect you'll hit coil bind at that lift with the stock springs. You gain a slight increase in duration too - but it's trivial.
I'd invest in a good port of the existing heads or an aftermarket. As noted the GMPP stock Vortecs are by far the best bang for the buck - but would also require a manifold swap or a redrill of the heads (generally not cost-effective). Something in the 180cc range.
An L-82 shouldn't be a "dog"; before you touch anything I'd invest in a good tune.
All IMHO :-D
The additional lift from a 1.6 swap won't buy much with the stock heads as you're already at the top of the flow capability. You'd be increasing the stock .450/.460 lift (already a pretty healthy cam) by 1.067 and I suspect you'll hit coil bind at that lift with the stock springs. You gain a slight increase in duration too - but it's trivial.
I'd invest in a good port of the existing heads or an aftermarket. As noted the GMPP stock Vortecs are by far the best bang for the buck - but would also require a manifold swap or a redrill of the heads (generally not cost-effective). Something in the 180cc range.
An L-82 shouldn't be a "dog"; before you touch anything I'd invest in a good tune.
All IMHO :-D
Last edited by billla; Nov 18, 2008 at 06:07 PM.
Melting Slicks
Joined: Apr 2002
Posts: 2,337
Likes: 14
From: Norfolk VA
I agree with some of the others. The L-82 cam is a good camshaft (used in the L46 350/350 engine) and with smaller combustion chamber heads will wake it up a little. You can get a little more agressive camshaft.
Instructor
Joined: Aug 2005
Posts: 209
Likes: 8
From: Hollywood FL
'80 L-82s aren't all that common and it was the last year for that engine. Have you considered saving the stock motor in a bag and going for a crate motor? Maybe a Fastburn 350 or a ZZ383? It's a bit more pricey, but you'll get it done in one shot and get as much HP as you're looking for.
Thread Starter
Drifting
Joined: Jan 2006
Posts: 1,540
Likes: 12
From: TX
The answer here is just about always heads and cam - together - for a stock upgrade.
The additional lift from a 1.6 swap won't buy much with the stock heads as you're already at the top of the flow capability. You'd be increasing the stock .450/.460 lift (already a pretty healthy cam) by 1.067 and I suspect you'll hit coil bind at that lift with the stock springs. You gain a slight increase in duration too - but it's trivial.
I'd invest in a good port of the existing heads or an aftermarket. As noted the GMPP stock Vortecs are by far the best bang for the buck - but would also require a manifold swap or a redrill of the heads (generally not cost-effective). Something in the 180cc range.
An L-82 shouldn't be a "dog"; before you touch anything I'd invest in a good tune.
All IMHO :-D
The additional lift from a 1.6 swap won't buy much with the stock heads as you're already at the top of the flow capability. You'd be increasing the stock .450/.460 lift (already a pretty healthy cam) by 1.067 and I suspect you'll hit coil bind at that lift with the stock springs. You gain a slight increase in duration too - but it's trivial.
I'd invest in a good port of the existing heads or an aftermarket. As noted the GMPP stock Vortecs are by far the best bang for the buck - but would also require a manifold swap or a redrill of the heads (generally not cost-effective). Something in the 180cc range.
An L-82 shouldn't be a "dog"; before you touch anything I'd invest in a good tune.
All IMHO :-D
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Given that reality I'd agree that likely the best option would be setting aside the L82 and putting in a hot crate engine - maybe something "retro" like a red-hot 383 painted Chevy Orange and looking stock-ish.