L82 DCR: The Ultimate Case for a New Cam in an L82?
11-27-2017, 05:51 PM
#101
Le Mans Master
Member Since: Dec 2009
Location: Saskatoon Saskatchewan
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I find it hard to believe that just doing those things would make an L48 more powerful than an L82. I also don't believe recurving the distributor is going to give you an additional 50 hp.
I recurved the distributor on my L82 and bumped the initial advance from 0 degrees to the 10 BTDC its supposed to be at and its an improvement, but not 50 hp improvement.
11-29-2017, 03:17 AM
#106
Drifting
Member Since: Aug 2015
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C3 of Year Finalist (track prepared) 2019
Heads, cam and intake on both and they'll be the same (assuming same replacement components and compression ratio) The forged bottom end and 4 bolt mains aren't worth any hp...
11-29-2017, 09:12 AM
#107
Le Mans Master
11-29-2017, 10:29 AM
#109
11-29-2017, 11:24 AM
#110
Le Mans Master
In 1980, L48 also got the L82 aluminum intake.
Last edited by TedH; 11-29-2017 at 11:26 AM.
11-29-2017, 12:05 PM
#111
Le Mans Master
Member Since: Dec 2009
Location: Saskatoon Saskatchewan
Posts: 6,397
Received 640 Likes
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Assuming flat-top pistons added to the L48 along with bigger valves, no performance difference from L82. Most 'Performance' rebuild kits for 350 introduce the flat-top (with reliefs) hypereutectic pistons (Sealed Power H345NP if I recall correctly in my kit). Benefit of the lower CR is you can run more initial and total advance to compensate.
In 1980, L48 also got the L82 aluminum intake.
In 1980, L48 also got the L82 aluminum intake.
First you were talking just adding "heads, cam, and intake", now you're talking adding new pistons and a full rebuild on top of that. That's called "moving the goal posts".
Of course if you remove everything that makes an L48 an L48 and substitute the same parts an L82 has you'll get the same performance.
11-29-2017, 01:51 PM
#112
Le Mans Master
The bottom line is that both can make great power with matched components including heads, cams (roller preferred), intake, compression, etc BUT the L-82 is definitely a MUCH better base to start with the 4 bolt main, forged crankshaft, forged rods, aluminum L-82 intake, etc.....
With my rebuilt/upgrade on the OEM L-82 355 I reused/reconditioned the Forged L-82 crank, reused/reconditioned the L-82 rods, mildly ported the aluminum L-82 intake, reused the dual snorkel air intake, and obviously the 4 bolt main L-82 block...engine makes about 425-450 gross HP with AFR 180 heads and Howard's Roller cam.
With my rebuilt/upgrade on the OEM L-82 355 I reused/reconditioned the Forged L-82 crank, reused/reconditioned the L-82 rods, mildly ported the aluminum L-82 intake, reused the dual snorkel air intake, and obviously the 4 bolt main L-82 block...engine makes about 425-450 gross HP with AFR 180 heads and Howard's Roller cam.
Last edited by jb78L-82; 11-29-2017 at 01:55 PM.
11-29-2017, 02:12 PM
#113
Le Mans Master
First you were talking just adding "heads, cam, and intake", now you're talking adding new pistons and a full rebuild on top of that. That's called "moving the goal posts".
Of course if you remove everything that makes an L48 an L48 and substitute the same parts an L82 has you'll get the same performance.
Of course if you remove everything that makes an L48 an L48 and substitute the same parts an L82 has you'll get the same performance.
It is amazing what a distributor recurve can do to waken a small block. Stock, advance curve is for emissions compliance. Recurve for power can add 50hp!!! Accomplished with an Accel performance replacement HEI and performance curve.
Along with better heads, cam, intake, carb jetting, headers/exhaust, compression and you get all kinds of complimentary benefits.
Toss in a 700R4 with lower 1st gear and non-stock 3.54 gears in back and it gets really fun.
Last edited by TedH; 11-29-2017 at 02:23 PM.
11-29-2017, 02:25 PM
#114
Le Mans Master
The bottom line is that both can make great power with matched components including heads, cams (roller preferred), intake, compression, etc BUT the L-82 is definitely a MUCH better base to start with the 4 bolt main, forged crankshaft, forged rods, aluminum L-82 intake, etc.....
With my rebuilt/upgrade on the OEM L-82 355 I reused/reconditioned the Forged L-82 crank, reused/reconditioned the L-82 rods, mildly ported the aluminum L-82 intake, reused the dual snorkel air intake, and obviously the 4 bolt main L-82 block...engine makes about 425-450 gross HP with AFR 180 heads and Howard's Roller cam.
With my rebuilt/upgrade on the OEM L-82 355 I reused/reconditioned the Forged L-82 crank, reused/reconditioned the L-82 rods, mildly ported the aluminum L-82 intake, reused the dual snorkel air intake, and obviously the 4 bolt main L-82 block...engine makes about 425-450 gross HP with AFR 180 heads and Howard's Roller cam.
Last edited by TedH; 11-30-2017 at 12:13 PM.
12-21-2017, 01:11 PM
#115
wow, quite the debate
I stumbled onto this particular string as I was looking for recommendations on a good head to go with the generally stock '80 L82 I have. I've been to this site many times but this is the first string that begged me to jump in. I haven't read every post in it, but forgive me if some of what I'll post has already been debated. To start, I've owned my '80 L82 since 1980 - yes, first owner. I was 21 when I bought it. To put that era in perspective - 13.4% loan rate, inflation exceeding 10%, unemployment to match. What I had going for me was a brand new engineering degree that plopped me into the oil field at a time when the price of oil had gone from $11/barrel to $42 in under a year. Hence the ability for a farm kid to afford a brand new vette.
Now, I've seen in this a lot of argument about I raced this X yr L82 with my Y yr whatever. Well are we talking about the 205 hp car of 1975 or the 230 of 1980? Also, auto or manual, 3.07's or 3.55's or what? Huge difference in these. Let's just say they all did well for the time but, as many have suggested, there's a lot better cams around today in the mild street rod class today. I've also seen some statements that these cars, especially the auto's couldn't smoke 'em up out of the hole. I beg to differ as being 21 it was the first thing with it. Yes, you had to brake stand up to about 2000 RPM, but it was happy to oblige with 255/15R60 tires and 307 gearing at least with the benefit of the highest power L82 that was ever restricted by a cat. Going further with this, after leaving the oil field and going back to the farm I spent a weekend a barn putting on a set of long tube headers. I didn't have any additional parts for the exhaust, but obviously had to check out the difference. I figured a quick run up the road wouldn't hurt (unlike a few years earlier when I got pulled over in the open header '32 flat head V8 Ford Roadster rod my brother and I still own - but that's for some other forum I guess). Hitting the gas without a brake stand put the tires into full spin mode. Backing off to let them grab and then hitting the floor while still moving smoked them up again. So the cam seemed to do fine when not being strangled by a single pipe exhaust with a cat.
Fast forward to 1990 and kid 2 had arrived and it was time for a daddy car which translated into a Delta 88 (that was an Olds for those too young to remember). But I kept the vette around for fun and drove it up until 2004 at which point it went on hiatus. The only mod in all that time was to add roller tip rockers since I had to go into the valve train to put in new seals. So about 2 yr's ago I finally started some refurbishment. Part of this involved a rebuild of the carb which included proper set up for the cam. This was important as the carb was not in anyway tuned for the cam. It was set up for emissions, 100%. As far as I read in these posts no one mentioned the carb issues with these engines. But it's kind of critical to the low performance off the line for the smog controlled L82's. Now, at the risk of setting off another debate, I will say that the Q-jet is a marvel of engineering. Yes it can hold a candle to electronic FI, but that's like saying an abacus can't compete with a digital calculator. True enough. But that's not the point. The abacus will still get the right answer if you know how to properly set it up. And the q-jet will get the right fuel mixture over most of the RPM range if you're willing to throw a little gas out the tail pipes. But that's the rub since in the mid-70's that became a non-starter, no pun intended. Those carbs were set extremely lean pulled the power down. That famous q-jet bog people rightfully gripe about was a symptom of this.
If you're read the vette shop manuals of the time for setting up the idle on the q-jet you'll that you are to drill out the plugs which prevent Joe Public from messing with his idle mixture. Then turn them out either 2 or 2.5 turns. Then set up fixturing to inject propane into the air flow and adjust the propane until watching the RPM rise to peak value and then drop. And if this peak value was in some spec'd range, then you left the idle screws as they were or adjusted a little to get to the right range. So basically the approach was to intentionally fuel starve the engine at idle. How starved where they? Well on the rebuild naturally the ilde mixture plugs were drilled out. Getting the idle mixture set required opening the screws 4.5 turns, basically twice what the factory setting was. Is there any wonder that off idle these cars bogged even with accelerator pumps and part throttle circuits in them.
In case you're wondering about the effect of this one change I'll describe my first experience with it. The car as it is now is back to the stock exhaust but sans cat. I was sitting in the driveway where I was limited as the car was not yet registered (never seemed to worry me when I was 21). After warming up and running up and down the drive way a couple times, I figured I give it a partial tromp - no brake stand, not to the floor. It easily broke the tires loose and kept them there. I could barely get off the gas and on the brake before getting to the sidewalk.
So, I'll go back and say I totally agree it is not the best cam you can get today nor was it well matched to the heads. But it is a solid cam. And unless you plan on hitting the track, it will allow a kick in the but if the chains are taken off of it. and that brings me to the real point of my post - again, for those of know the song "Alice's Restaurant" I'll just say - "you remember Alice, she's the one this song's about". I'm not in a hurry to tear into the engine too deep for now. It has about 90k on it and isn't smoking or knocking. So I'd just like to drive it for a time. I do want to drop a set of heads on it that get the static compression up to about 10 (64 cc chamber?) where this cam wants to live I believe and and to let it breath. So recommendations would be appreciated - either specific make/model or just specs to look for. And thanks for indulging my ramblings as a first time user.
Now, I've seen in this a lot of argument about I raced this X yr L82 with my Y yr whatever. Well are we talking about the 205 hp car of 1975 or the 230 of 1980? Also, auto or manual, 3.07's or 3.55's or what? Huge difference in these. Let's just say they all did well for the time but, as many have suggested, there's a lot better cams around today in the mild street rod class today. I've also seen some statements that these cars, especially the auto's couldn't smoke 'em up out of the hole. I beg to differ as being 21 it was the first thing with it. Yes, you had to brake stand up to about 2000 RPM, but it was happy to oblige with 255/15R60 tires and 307 gearing at least with the benefit of the highest power L82 that was ever restricted by a cat. Going further with this, after leaving the oil field and going back to the farm I spent a weekend a barn putting on a set of long tube headers. I didn't have any additional parts for the exhaust, but obviously had to check out the difference. I figured a quick run up the road wouldn't hurt (unlike a few years earlier when I got pulled over in the open header '32 flat head V8 Ford Roadster rod my brother and I still own - but that's for some other forum I guess). Hitting the gas without a brake stand put the tires into full spin mode. Backing off to let them grab and then hitting the floor while still moving smoked them up again. So the cam seemed to do fine when not being strangled by a single pipe exhaust with a cat.
Fast forward to 1990 and kid 2 had arrived and it was time for a daddy car which translated into a Delta 88 (that was an Olds for those too young to remember). But I kept the vette around for fun and drove it up until 2004 at which point it went on hiatus. The only mod in all that time was to add roller tip rockers since I had to go into the valve train to put in new seals. So about 2 yr's ago I finally started some refurbishment. Part of this involved a rebuild of the carb which included proper set up for the cam. This was important as the carb was not in anyway tuned for the cam. It was set up for emissions, 100%. As far as I read in these posts no one mentioned the carb issues with these engines. But it's kind of critical to the low performance off the line for the smog controlled L82's. Now, at the risk of setting off another debate, I will say that the Q-jet is a marvel of engineering. Yes it can hold a candle to electronic FI, but that's like saying an abacus can't compete with a digital calculator. True enough. But that's not the point. The abacus will still get the right answer if you know how to properly set it up. And the q-jet will get the right fuel mixture over most of the RPM range if you're willing to throw a little gas out the tail pipes. But that's the rub since in the mid-70's that became a non-starter, no pun intended. Those carbs were set extremely lean pulled the power down. That famous q-jet bog people rightfully gripe about was a symptom of this.
If you're read the vette shop manuals of the time for setting up the idle on the q-jet you'll that you are to drill out the plugs which prevent Joe Public from messing with his idle mixture. Then turn them out either 2 or 2.5 turns. Then set up fixturing to inject propane into the air flow and adjust the propane until watching the RPM rise to peak value and then drop. And if this peak value was in some spec'd range, then you left the idle screws as they were or adjusted a little to get to the right range. So basically the approach was to intentionally fuel starve the engine at idle. How starved where they? Well on the rebuild naturally the ilde mixture plugs were drilled out. Getting the idle mixture set required opening the screws 4.5 turns, basically twice what the factory setting was. Is there any wonder that off idle these cars bogged even with accelerator pumps and part throttle circuits in them.
In case you're wondering about the effect of this one change I'll describe my first experience with it. The car as it is now is back to the stock exhaust but sans cat. I was sitting in the driveway where I was limited as the car was not yet registered (never seemed to worry me when I was 21). After warming up and running up and down the drive way a couple times, I figured I give it a partial tromp - no brake stand, not to the floor. It easily broke the tires loose and kept them there. I could barely get off the gas and on the brake before getting to the sidewalk.
So, I'll go back and say I totally agree it is not the best cam you can get today nor was it well matched to the heads. But it is a solid cam. And unless you plan on hitting the track, it will allow a kick in the but if the chains are taken off of it. and that brings me to the real point of my post - again, for those of know the song "Alice's Restaurant" I'll just say - "you remember Alice, she's the one this song's about". I'm not in a hurry to tear into the engine too deep for now. It has about 90k on it and isn't smoking or knocking. So I'd just like to drive it for a time. I do want to drop a set of heads on it that get the static compression up to about 10 (64 cc chamber?) where this cam wants to live I believe and and to let it breath. So recommendations would be appreciated - either specific make/model or just specs to look for. And thanks for indulging my ramblings as a first time user.
12-22-2017, 12:06 PM
#116
Le Mans Master
I stumbled onto this particular string as I was looking for recommendations on a good head to go with the generally stock '80 L82 I have. I've been to this site many times but this is the first string that begged me to jump in. I haven't read every post in it, but forgive me if some of what I'll post has already been debated. To start, I've owned my '80 L82 since 1980 - yes, first owner. I was 21 when I bought it. To put that era in perspective - 13.4% loan rate, inflation exceeding 10%, unemployment to match. What I had going for me was a brand new engineering degree that plopped me into the oil field at a time when the price of oil had gone from $11/barrel to $42 in under a year. Hence the ability for a farm kid to afford a brand new vette.
Now, I've seen in this a lot of argument about I raced this X yr L82 with my Y yr whatever. Well are we talking about the 205 hp car of 1975 or the 230 of 1980? Also, auto or manual, 3.07's or 3.55's or what? Huge difference in these. Let's just say they all did well for the time but, as many have suggested, there's a lot better cams around today in the mild street rod class today. I've also seen some statements that these cars, especially the auto's couldn't smoke 'em up out of the hole. I beg to differ as being 21 it was the first thing with it. Yes, you had to brake stand up to about 2000 RPM, but it was happy to oblige with 255/15R60 tires and 307 gearing at least with the benefit of the highest power L82 that was ever restricted by a cat. Going further with this, after leaving the oil field and going back to the farm I spent a weekend a barn putting on a set of long tube headers. I didn't have any additional parts for the exhaust, but obviously had to check out the difference. I figured a quick run up the road wouldn't hurt (unlike a few years earlier when I got pulled over in the open header '32 flat head V8 Ford Roadster rod my brother and I still own - but that's for some other forum I guess). Hitting the gas without a brake stand put the tires into full spin mode. Backing off to let them grab and then hitting the floor while still moving smoked them up again. So the cam seemed to do fine when not being strangled by a single pipe exhaust with a cat.
Fast forward to 1990 and kid 2 had arrived and it was time for a daddy car which translated into a Delta 88 (that was an Olds for those too young to remember). But I kept the vette around for fun and drove it up until 2004 at which point it went on hiatus. The only mod in all that time was to add roller tip rockers since I had to go into the valve train to put in new seals. So about 2 yr's ago I finally started some refurbishment. Part of this involved a rebuild of the carb which included proper set up for the cam. This was important as the carb was not in anyway tuned for the cam. It was set up for emissions, 100%. As far as I read in these posts no one mentioned the carb issues with these engines. But it's kind of critical to the low performance off the line for the smog controlled L82's. Now, at the risk of setting off another debate, I will say that the Q-jet is a marvel of engineering. Yes it can hold a candle to electronic FI, but that's like saying an abacus can't compete with a digital calculator. True enough. But that's not the point. The abacus will still get the right answer if you know how to properly set it up. And the q-jet will get the right fuel mixture over most of the RPM range if you're willing to throw a little gas out the tail pipes. But that's the rub since in the mid-70's that became a non-starter, no pun intended. Those carbs were set extremely lean pulled the power down. That famous q-jet bog people rightfully gripe about was a symptom of this.
If you're read the vette shop manuals of the time for setting up the idle on the q-jet you'll that you are to drill out the plugs which prevent Joe Public from messing with his idle mixture. Then turn them out either 2 or 2.5 turns. Then set up fixturing to inject propane into the air flow and adjust the propane until watching the RPM rise to peak value and then drop. And if this peak value was in some spec'd range, then you left the idle screws as they were or adjusted a little to get to the right range. So basically the approach was to intentionally fuel starve the engine at idle. How starved where they? Well on the rebuild naturally the ilde mixture plugs were drilled out. Getting the idle mixture set required opening the screws 4.5 turns, basically twice what the factory setting was. Is there any wonder that off idle these cars bogged even with accelerator pumps and part throttle circuits in them.
In case you're wondering about the effect of this one change I'll describe my first experience with it. The car as it is now is back to the stock exhaust but sans cat. I was sitting in the driveway where I was limited as the car was not yet registered (never seemed to worry me when I was 21). After warming up and running up and down the drive way a couple times, I figured I give it a partial tromp - no brake stand, not to the floor. It easily broke the tires loose and kept them there. I could barely get off the gas and on the brake before getting to the sidewalk.
So, I'll go back and say I totally agree it is not the best cam you can get today nor was it well matched to the heads. But it is a solid cam. And unless you plan on hitting the track, it will allow a kick in the but if the chains are taken off of it. and that brings me to the real point of my post - again, for those of know the song "Alice's Restaurant" I'll just say - "you remember Alice, she's the one this song's about". I'm not in a hurry to tear into the engine too deep for now. It has about 90k on it and isn't smoking or knocking. So I'd just like to drive it for a time. I do want to drop a set of heads on it that get the static compression up to about 10 (64 cc chamber?) where this cam wants to live I believe and and to let it breath. So recommendations would be appreciated - either specific make/model or just specs to look for. And thanks for indulging my ramblings as a first time user.
Now, I've seen in this a lot of argument about I raced this X yr L82 with my Y yr whatever. Well are we talking about the 205 hp car of 1975 or the 230 of 1980? Also, auto or manual, 3.07's or 3.55's or what? Huge difference in these. Let's just say they all did well for the time but, as many have suggested, there's a lot better cams around today in the mild street rod class today. I've also seen some statements that these cars, especially the auto's couldn't smoke 'em up out of the hole. I beg to differ as being 21 it was the first thing with it. Yes, you had to brake stand up to about 2000 RPM, but it was happy to oblige with 255/15R60 tires and 307 gearing at least with the benefit of the highest power L82 that was ever restricted by a cat. Going further with this, after leaving the oil field and going back to the farm I spent a weekend a barn putting on a set of long tube headers. I didn't have any additional parts for the exhaust, but obviously had to check out the difference. I figured a quick run up the road wouldn't hurt (unlike a few years earlier when I got pulled over in the open header '32 flat head V8 Ford Roadster rod my brother and I still own - but that's for some other forum I guess). Hitting the gas without a brake stand put the tires into full spin mode. Backing off to let them grab and then hitting the floor while still moving smoked them up again. So the cam seemed to do fine when not being strangled by a single pipe exhaust with a cat.
Fast forward to 1990 and kid 2 had arrived and it was time for a daddy car which translated into a Delta 88 (that was an Olds for those too young to remember). But I kept the vette around for fun and drove it up until 2004 at which point it went on hiatus. The only mod in all that time was to add roller tip rockers since I had to go into the valve train to put in new seals. So about 2 yr's ago I finally started some refurbishment. Part of this involved a rebuild of the carb which included proper set up for the cam. This was important as the carb was not in anyway tuned for the cam. It was set up for emissions, 100%. As far as I read in these posts no one mentioned the carb issues with these engines. But it's kind of critical to the low performance off the line for the smog controlled L82's. Now, at the risk of setting off another debate, I will say that the Q-jet is a marvel of engineering. Yes it can hold a candle to electronic FI, but that's like saying an abacus can't compete with a digital calculator. True enough. But that's not the point. The abacus will still get the right answer if you know how to properly set it up. And the q-jet will get the right fuel mixture over most of the RPM range if you're willing to throw a little gas out the tail pipes. But that's the rub since in the mid-70's that became a non-starter, no pun intended. Those carbs were set extremely lean pulled the power down. That famous q-jet bog people rightfully gripe about was a symptom of this.
If you're read the vette shop manuals of the time for setting up the idle on the q-jet you'll that you are to drill out the plugs which prevent Joe Public from messing with his idle mixture. Then turn them out either 2 or 2.5 turns. Then set up fixturing to inject propane into the air flow and adjust the propane until watching the RPM rise to peak value and then drop. And if this peak value was in some spec'd range, then you left the idle screws as they were or adjusted a little to get to the right range. So basically the approach was to intentionally fuel starve the engine at idle. How starved where they? Well on the rebuild naturally the ilde mixture plugs were drilled out. Getting the idle mixture set required opening the screws 4.5 turns, basically twice what the factory setting was. Is there any wonder that off idle these cars bogged even with accelerator pumps and part throttle circuits in them.
In case you're wondering about the effect of this one change I'll describe my first experience with it. The car as it is now is back to the stock exhaust but sans cat. I was sitting in the driveway where I was limited as the car was not yet registered (never seemed to worry me when I was 21). After warming up and running up and down the drive way a couple times, I figured I give it a partial tromp - no brake stand, not to the floor. It easily broke the tires loose and kept them there. I could barely get off the gas and on the brake before getting to the sidewalk.
So, I'll go back and say I totally agree it is not the best cam you can get today nor was it well matched to the heads. But it is a solid cam. And unless you plan on hitting the track, it will allow a kick in the but if the chains are taken off of it. and that brings me to the real point of my post - again, for those of know the song "Alice's Restaurant" I'll just say - "you remember Alice, she's the one this song's about". I'm not in a hurry to tear into the engine too deep for now. It has about 90k on it and isn't smoking or knocking. So I'd just like to drive it for a time. I do want to drop a set of heads on it that get the static compression up to about 10 (64 cc chamber?) where this cam wants to live I believe and and to let it breath. So recommendations would be appreciated - either specific make/model or just specs to look for. And thanks for indulging my ramblings as a first time user.
I will say a slide rule is more accurate than a computer ,because you can verify your computations.
12-22-2017, 06:14 PM
#117