74, L82 350, changing cam
Thread Starter
Heel & Toe
Joined: Jun 2011
Posts: 15
Likes: 0
From: Elida OH
74, L82 350, changing cam
We want to increase the horsepower on our 74 corvette. So far Jegs Elderbrock #60899 is the one we are looking at. Any suggestions would be greatly appreciated.
Instructor
Joined: Apr 2011
Posts: 151
Likes: 1
From: Cedar Springs MI
It runs pretty good considering stock heads and low compression. be careful not to get one that is 2 big for what you have. Thats why I went fairly mild. If you go big you will want to get a stall converter, gear change, better heads, headers, duals etc
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The stock L82 cam is actually pretty decent for an "old skool" cam, and well-matched to the heads. If the engine is stock (intake/exhaust manifolds, etc.) I wouldn't look to a cam swap to have that big of an impact.
Racer
Joined: May 2001
Posts: 401
Likes: 0
From: Carlsbad CA
Before I went with the TPI manifold I looked at just doing a cam swap, and everything I found said that there was almost no difference in performance for my '74 L82 with a cam change only. I waited until I could afford to do cam and heads at the same time. For the swap I went with Trick Flow heads and a Comp XE268 cam and noticed a huge difference in the top end.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
That cam is the same as the 350 HP 350 CI cam used in 1969-70 L46. These engines were pulling 350 HP through a stock cast iron low rise intake and quadrajet. Best performance increase would be a free flowing exhaust with headers, better intake and a good flowing set of aluminum 64cc heads.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
That cam is the same as the 350 HP 350 CI cam used in 1969-70 L46. These engines were pulling 350 HP through a stock cast iron low rise intake and quadrajet. Best performance increase would be a free flowing exhaust with headers, better intake and a good flowing set of aluminum 64cc heads.Ahhh, nah not my thoughts, I would think opening valves further is a power increase and you can do this with a higher lift cam and way cheaper.
You guys love to spend people's money don't ya?
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
So leave the same lift cam and spend money on a new set of $1000 heads only to have the valves open exactly the same amount as the old ones??
Ahhh, nah not my thoughts, I would think opening valves further is a power increase and you can do this with a higher lift cam and way cheaper.
You guys love to spend people's money don't ya?
Ahhh, nah not my thoughts, I would think opening valves further is a power increase and you can do this with a higher lift cam and way cheaper.
You guys love to spend people's money don't ya?
At the same time, better heads would get a lot out of this cam. It's an old-style lobe, but it's still a decent cam. If one head flows 185 CFM @ .450 lift, and another flows 235 CFM @ .450 lift...then the new head is going to make far more power with the same cam.
An engine is an air pump; the more air you can flow the better - but it doesn't make any sense to address one part of the flow path...intake without headers, cam without heads that can flow, etc. The best money for the OP is a tune, followed by exhaust, followed by intake...then getting into the engine. Also, outside of forced induction it's not possible to force air into an engine; it will only take what it needs. This is why a too-big carb also ends up creating soggy throttle response.
A smart choice is a lot cheaper than making a lot of changes that don't make more power
Last edited by billla; Apr 18, 2012 at 09:14 PM.
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
I changed just the cam out on my 77 L48 with the stock heads and gained 1/2 second in the 1/8.
Not that it was fast but it was a 1/2 second faster.
I know heads are the heart of performance but I think there is room for improvement in the cam first and for cheaper.
Not that it was fast but it was a 1/2 second faster.
I know heads are the heart of performance but I think there is room for improvement in the cam first and for cheaper.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
There's no one-size-fits-all recommendation - what's true in one case isn't true in another. In this case, the heads won't deliver more than what the cam is getting out of them.
Last edited by billla; Apr 18, 2012 at 09:23 PM.
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
Im glad you agree with me. Thanks!
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
A head flows what it flows based on the runners, etc. This is what a flow bench tests...and there's no cam involved in that process. And there isn't any "potential" beyond about .450 lift in the stock L82 heads...which is what the OP already has. You can put a .650 lift cam with those heads...and they're not going to flow more.
Your lack of understanding of head flow is what drove you to buy a set of S/R heads expecting "big power gains".
We'll have to hope your "guidance" doesn't cost anyone else here as much money as it already cost you 
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
No, Tim, it doesn't. And no, Tim, I don't.
A head flows what it flows based on the runners, etc. This is what a flow bench tests...and there's no cam involved in that process. And there isn't any "potential" beyond about .450 lift in the stock L82 heads...which is what the OP already has. You can put a .650 lift cam with those heads...and they're not going to flow more.
Your lack of understanding of head flow is what drove you to buy a set of S/R heads expecting "big power gains". We'll have to hope your "guidance" doesn't cost anyone else here as much money as it already cost you
A head flows what it flows based on the runners, etc. This is what a flow bench tests...and there's no cam involved in that process. And there isn't any "potential" beyond about .450 lift in the stock L82 heads...which is what the OP already has. You can put a .650 lift cam with those heads...and they're not going to flow more.
Your lack of understanding of head flow is what drove you to buy a set of S/R heads expecting "big power gains".
We'll have to hope your "guidance" doesn't cost anyone else here as much money as it already cost you And yes you agreeing with my choice of a World torquer S/R heads is a wise choice because they will gain and engine 30 to 70 horsepower.
I think you and I are really seeing eye to eye on this and im glad you finally are stepping up to team with me.
Melting Slicks
Joined: Dec 2009
Posts: 3,233
Likes: 657
From: Thunder Bay
I built a couple of motors years ago in which I swapped IN an L82 cam. You'll find it in the Chevy power book under 3896962. It has .450 lift and 222 deg duration at .050". Those are pretty decent numbers for a street cam. Put your money in heads, headers, and intake. If your cam is in good condition, leave it. Its fine.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Yes thats exactly what Im saying is a 450 lift cam needs changed out to a bigger one. But I think your choice of 650 lift is a little too much even for me i think you should rethink that choice before costing someone money for a bad choice from you.
And yes you agreeing with my choice of a World torquer S/R heads is a wise choice because they will gain and engine 30 to 70 horsepower.
I think you and I are really seeing eye to eye on this and im glad you finally are stepping up to team with me.
And yes you agreeing with my choice of a World torquer S/R heads is a wise choice because they will gain and engine 30 to 70 horsepower.
I think you and I are really seeing eye to eye on this and im glad you finally are stepping up to team with me.
As for those heads - gosh, if there's that much power, then why did you sell them? How much did you get for them?
Folks I hope some of the information was useful, I'm out. "Team Tim" is once again down to one person ;-)
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
I would swap heads cam & intake, afr 180's, little over mild cam & performer rpm air gap intake, should net you the performance you want. I personaly bought the beter head the 2nd time around & would suggest this the place not to save money. Jmo.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Flow numbers on 882 heads.
Chevy 882 Iron CCM 151/59 (port sizes)
70/58 @ .100 lift
125/108 @ .200 Lift
175/135 @ .300 lift
204/141 @ .400 lift
205/142 @ .500 lift
206/142 @ .600 lift
Flow on AFR 195 eliminator
75/57 @ .100 lift
139/113 @ .200 lift
198/160 @ .300 lift
250/190 @ .400 lift
277/207 @ .500 lift
292/216 @ .600 lift
295/220 @ .700 lift
All heads hit a certain lift that, once your there the flow flattens out. No sense in lifting the valve past that point. No power advantage. At that point only more duration will fill the cylider more. More duration reduces bottom end torque, raises the operating range of the cam and hydraulic lifters limit maximum RPM. The L82 cam with 222 duration is feeding those heads all they will take without killing bottom end power. Exhaust will give the OP more power than a new cam due to the weak exhaust port and single duration cam. An intake with bigger ports won't help a lot either. The 882 head intake port is only 151 CC. Heads and an intake will make a noticable difference. Tim's increase in 1/8 mile times comes from more duration. The L48 cam is weak. Comparing the two cams.
L48 cam specs. .390/.410 lift, 196/202 duration @ .050
L82 cam specs. .450/.460 Lift, 222/222 duration @ .050
Chevy 882 Iron CCM 151/59 (port sizes)
70/58 @ .100 lift
125/108 @ .200 Lift
175/135 @ .300 lift
204/141 @ .400 lift
205/142 @ .500 lift
206/142 @ .600 lift
Flow on AFR 195 eliminator
75/57 @ .100 lift
139/113 @ .200 lift
198/160 @ .300 lift
250/190 @ .400 lift
277/207 @ .500 lift
292/216 @ .600 lift
295/220 @ .700 lift
All heads hit a certain lift that, once your there the flow flattens out. No sense in lifting the valve past that point. No power advantage. At that point only more duration will fill the cylider more. More duration reduces bottom end torque, raises the operating range of the cam and hydraulic lifters limit maximum RPM. The L82 cam with 222 duration is feeding those heads all they will take without killing bottom end power. Exhaust will give the OP more power than a new cam due to the weak exhaust port and single duration cam. An intake with bigger ports won't help a lot either. The 882 head intake port is only 151 CC. Heads and an intake will make a noticable difference. Tim's increase in 1/8 mile times comes from more duration. The L48 cam is weak. Comparing the two cams.
L48 cam specs. .390/.410 lift, 196/202 duration @ .050
L82 cam specs. .450/.460 Lift, 222/222 duration @ .050
Last edited by 63mako; Apr 18, 2012 at 10:52 PM.
Safety Car
Joined: Oct 2000
Posts: 3,593
Likes: 103
From: Southern Indiana
*chuckle* Tim, I didn't go through this little exercise for you - you've proven you choose not to learn anything. I went through it for the other folks on here that might be interested in why the recommendation from so many folks is that the cam/heads combo is fine as it is. if it was up to you experts on here everybody would be running 400 lift cams and 2 barrel carbs. If you're running the cam in your .sig with stock L48 heads...then you've shown that you really just don't get this stuff.
As for those heads - gosh, if there's that much power, then why did you sell them? How much did you get for them?
Folks I hope some of the information was useful, I'm out. "Team Tim" is once again down to one person ;-)
As for those heads - gosh, if there's that much power, then why did you sell them? How much did you get for them?
Folks I hope some of the information was useful, I'm out. "Team Tim" is once again down to one person ;-)
I knew you would like the cam I had it really wakes the car up verses the stock junk, thanks for the recommendation!
My World heads, I still have them, I turned down $900 for them because I knew they are worth more, I will use them on a future hotrod with my .040 over 4 bolt main block.
You go on and check out for the night i'll answer questions for you until you get back buddie!
Oh yea one more thing, did you think anymore about that V6 swap in your vette that you PMd me about the other day? I think it would be a great idea that you could brag about to your friend.