L82 DCR: The Ultimate Case for a New Cam in an L82?
11-07-2017, 10:07 AM
#41
Le Mans Master
Lets be realistic here. The L-82 came with a L-46 Cam, 4 bolt main and all forged bottom end. I don't know about this 4* retard business if so that happened in later years. But the 73-74 L82's simply and a head and induction swap and they were virtually L-46's....and no L-48 was touching it. 
The L-48 was an absolute dog in stock trim...The L-82 was acceptable especially with the 4 speed and 3.70 gears, even stock. Before my rebuild of the OEM L-82 in 2014, all I did was 2.5 duals, shorty headers in the mid 2000's, roller tipped 1.52 comp cams rockers, ignition timing adjustment for performance, advanced the L-82 stock cam by 4 degrees when I changed the timing chain and gears in 2012 (lowered peak torque by about 500 revs-Dyno documented before and after), and removed all emissions. The engine performed NOTICEABLY stronger and probs was in the low 6's 0-60 sec range and high 14's in the quarter. Do the same to an L-48 and you could stand on your head and still could not get those times with the same mods on an L48.
Your comment about the internals of the L-82 is also spot on. I reconditioned the L-82 forged crank, L-82 rods, mildly ported the L-82 aluminum intake, and of course bored the 4 bolt main L-82 block when the engine was upgraded (A LOT) in 2014. Ridiculous comparison!
11-07-2017, 10:26 AM
#42
There are two primary ways to make more normally aspirated power: 1) cram more fuel/air into a cylinder with an improved camshaft or 2) get more energy out of each combustion event with higher compression. Doing both is very nice :-)
Simply changing to a set of 58-64cc heads on a L-48 or L-82 wakes them up nicely. A 10.5:1CR L-48 will run with a 8.9CR L-82 on the street. Make that same change to an L-82 and its no contest.
If I had an L-82 I would just change the heads with something that offered more CR and possibly change the cam timing. The only advantage I see to only improving the cam on a 8.9CR L-82 (keeping the 76cc heads) is so I could run any squirrel **** gasoline I wanted without fear of detonation. A cam only change that will add both more fuel/air and measurably increase dynamic CR without negatively affecting peak power will likely require new valve springs and possibly a roller lifter anyway, so that is why I would recommend just the head change (but I am not a professional engine builder so YMMV, .02. YYY).
I added 58cc L98 heads to my 69 ZQ3 (a high compression L48 with 4 bolt) replacing the stock 64cc heads and it is a strong runner for that camshaft. With the 1990-91 L98 .015" head gasket I have 11:1 CR. Gets pretty descent gas mileage too.
Last edited by Dynra Rockets; 11-07-2017 at 11:14 AM.
11-07-2017, 01:28 PM
#43
Burning Brakes
It probably needs to be re-curved.
But I was trying to find out if it was just the distributor work or the cam timing too.
11-07-2017, 01:40 PM
#44
Ignore the initial, check what your total timing is. It's very possible that you are way off on your total timing and that would DEFINITELY mess with your acceleration. disconnect the vacuum line from the distributor and plug it, and get a timing light on your car. Try setting it for 34 degrees advance at 3,000 RPM (or wherever your curve stops, hopefully around there). And see what that does.
11-07-2017, 01:57 PM
#45
Le Mans Master
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I have a 79 L82. I have a set of 66cc combustion chamber Vortec heads for it, tuned port injection, and was looking at a cam which gives 7.81 to 1 dynamic compression ratio with a .060 overbore and those heads. Will I be able to run on 87 octane gas as I do now?
Last edited by Priya; 11-07-2017 at 01:58 PM.
11-07-2017, 03:46 PM
#47
Burning Brakes
Ignore the initial, check what your total timing is. It's very possible that you are way off on your total timing and that would DEFINITELY mess with your acceleration. disconnect the vacuum line from the distributor and plug it, and get a timing light on your car. Try setting it for 34 degrees advance at 3,000 RPM (or wherever your curve stops, hopefully around there). And see what that does.
They have the heads off to resolve the oil usage problem after the engine rebuild.
11-07-2017, 05:40 PM
#48
Had a 76 L82 with Auto. Changed cam to an Isky 264 mega cam, 214-214, .450 lift on a 108 lsa. Big time low and mid range punch! With a 4 speed and some gears the 270 mega cam , 221-221 .465 lift on 108 lsa would make for a fun ride!
11-07-2017, 05:46 PM
#49
Burning Brakes
What make this one better at the low end?
Last edited by LenWoodruff; 11-07-2017 at 05:46 PM.
11-07-2017, 05:54 PM
#50
Had a 1976 L-82, 4-sp
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Royal Canadian Navy
I run 91 but have yet to try a lower octane. I don't put enough miles on the car to worry about the price difference so I err on the higher octane side. I do know, if I disconnect and plug the vac advance, I don't get any pining because my advance is limited to about 34*. I did need to limit my vac advance to 8* for a total of 42* at cruise to prevent pinging. Any further vac advance and it will ping on 91 octane.
Last edited by resdoggie; 11-07-2017 at 05:54 PM.
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Priya (11-07-2017)
11-08-2017, 03:33 PM
#51
11-08-2017, 03:52 PM
#52
Have a friend that put a GM 290hp crate engine in a 75 Camaro but he found that it was a real dog with the L82 cam in it. He did not want to spend more money on a different cam so he installed a set of Rhoads lifters and gained much better low end. They do work , I have used them on 2 different over cammed engines.
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AirBusPilot (11-08-2017)
11-08-2017, 04:36 PM
#53
Burning Brakes
11-08-2017, 04:38 PM
#54
Burning Brakes
Have a friend that put a GM 290hp crate engine in a 75 Camaro but he found that it was a real dog with the L82 cam in it. He did not want to spend more money on a different cam so he installed a set of Rhoads lifters and gained much better low end. They do work , I have used them on 2 different over cammed engines.
11-08-2017, 04:46 PM
#55
Le Mans Master
A set of good small chamber heads really changes things.
A new cam won't help nearly as much without a good set of heads.
You also need to realize how old these cars are and what someone may have done.
I have known my car since new.
11-08-2017, 05:10 PM
#56
Burning Brakes
Distributor timing mainly but advancing the cam factors into it pretty well.
A set of good small chamber heads really changes things.
A new cam won't help nearly as much without a good set of heads.
You also need to realize how old these cars are and what someone may have done.
I have known my car since new.
A set of good small chamber heads really changes things.
A new cam won't help nearly as much without a good set of heads.
You also need to realize how old these cars are and what someone may have done.
I have known my car since new.
11-08-2017, 05:12 PM
#57
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St. Jude Donor '05
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LenWoodruff (11-08-2017)
11-09-2017, 09:03 AM
#58
Le Mans Master
Use your DCR calculator to determine the optimal static compression ratio for the L-82 cam. Are you aiming for say... 7.0-8.0 DCR maybe?
play with it and let me know what you find. :blue angel:
-Mark.
11-09-2017, 11:07 AM
#59
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St. Jude Donor '05
Some guys dont like them cause they cant follow directions
Think they make a hydraulic roller version too, ran the HFT ones in a few cars liked them.