1980 L82 4-Speed Controversy
08-03-2011, 02:32 PM
#21
08-03-2011, 03:25 PM
#22
Le Mans Master
As stated there were no L-82 4 speeds in 1980. One other place to check for the authenticity of an L-82 engine is the tach which should say L-82 in the body of the tach and also redline at 6,000 RPM s not 5,500-5,600 rpm for the L-48. No L-82 tach probably a swapped in engine! Vin tag can also be forged!
The 80 L-82 is the only year that could not be had with a manual transmission!
The 80 L-82 is the only year that could not be had with a manual transmission!
08-03-2011, 03:45 PM
#23
Le Mans Master
Another issue is there is no way that GM sold an L-82 with a 4 speed legally if the first ones were not produced until March 80 since that would be 6 months into the 80 Production! Approximately 5,000 L-82's were produced in 1980 as an FYI.
Another way to verify if the motor is an L-82 is to pull the oil pan and check for a 4 bolt main cap- 2 bolt-L-48. Pull the valve covers and check for 2.02 exhaust valve size on the L-82 heads. Lastly, you can maybe do a compression check and if the compression is under 8.5 : 1 it cups also indicate an L-48 assuming the engine is not too worn or if the compression is over 8.5:1 it most probably an l-82. can't think of anything else offhand!*
Another way to verify if the motor is an L-82 is to pull the oil pan and check for a 4 bolt main cap- 2 bolt-L-48. Pull the valve covers and check for 2.02 exhaust valve size on the L-82 heads. Lastly, you can maybe do a compression check and if the compression is under 8.5 : 1 it cups also indicate an L-48 assuming the engine is not too worn or if the compression is over 8.5:1 it most probably an l-82. can't think of anything else offhand!*
08-03-2011, 03:57 PM
#24
My understanding (which may of course be entirely wrong) is that in the US they started using the 'primary metering rod control solenoids' in '81 on some 5.0 and / or 5.7L QJs, and on all by / before '85 (?).
In non-Vettes, the only 5.7L available here in '85 was the LM1 Police Special 'B' car. The 'B', 'G' and 'F' cars could only have a 5.0 L max. and my '85 LG4 did did not have that feature or any kind of 'computer control' for that or the distributor.
Last edited by Rich's'78; 08-03-2011 at 04:00 PM.
08-03-2011, 04:07 PM
#25
[QUOTE=jb78L-82;1578310539] Another way to verify if the motor is an L-82 is to pull the oil pan and check for a 4 bolt main cap- 2 bolt-L-48. Pull the valve covers and check for 2.02 exhaust valve size on the L-82 heads. 
QUOTE]
Another thing is L-82s used pushrod guideplates, although they could be had, like the larger valves, by just swapping the heads. If you are going to pull a head, L-48s had dished pistons, while L-82s did not.
QUOTE]Another thing is L-82s used pushrod guideplates, although they could be had, like the larger valves, by just swapping the heads. If you are going to pull a head, L-48s had dished pistons, while L-82s did not.
08-03-2011, 04:09 PM
#26
My understanding (which may of course be entirely wrong) is that in the US they started using the 'primary metering rod control solenoids' in '81 on some QJs, and on all by / before '85 (?).
The only 5.7L available here in '85 was the LM1 Police Special 'B' car. The 'B', 'G' and 'F' cars could only have a 5.0 L max. and my '85 LG4 did did not have that feature or any kind of 'computer control' for that or the distributor.
Huh?
08-03-2011, 05:00 PM
#29
Burning Brakes
I'll add a little fuel to the fire. Just found in a book that listed engine code ZBD for 1980 Hi Perf. 350 eng. (L-82) w/m.t. But since they were never built, I would think either engine or trans swap. Engine codes for 1980 were ZCA,ZAM,ZAK,ZBD,ZBC.
08-03-2011, 06:18 PM
#31
Race Director
Starting with the September 1979 edition of the Corvette Parts Books, there are 5 engine 1980 engine suffix codes listed. Besides ZCA (CA 305), ZAM (Federal L-48 4sp), ZAC (Fed L-48 auto) and ZBC (Fed L-82 auto); ZBD was included for the Federal emission L-82 4 speed. Chevrolet never removed the L-82 4 speed suffix code from subsequent editions of the Parts Book, which is why the code shows up places like The Corvette Black Book.
GM expected to be able to build and sell 4 speed equipped L-82's in 1980. As such, a suffix code was assigned to the combination. After it was cancelled, GM never bothered eliminating it from their system.
Often things like suffix codes, get determined months or more before production actually begins. For various reasons, things change, but it doesn't mean the old info gets expunged. There are other known suffix codes, for engines that didn't make it to production. The best known of those is probably the 1970 LS-7 454 codes of CZL & CZN.
08-03-2011, 06:51 PM
#32
Race Director
Not to mention it's a 1.60 exh valve, with a 2.02 intake valve. 
But you would see the guide plates in there...
Could also measure the lift of the cam and determine whether or not it has an L82 cam. Intake lift is ~.390 on an L48, ~.440 on an L-82.
But you would see the guide plates in there... Could also measure the lift of the cam and determine whether or not it has an L82 cam. Intake lift is ~.390 on an L48, ~.440 on an L-82.
08-03-2011, 07:15 PM
#34
Le Mans Master
Another issue is there is no way that GM sold an L-82 with a 4 speed legally if the first ones were not produced until March 80 since that would be 6 months into the 80 Production! Approximately 5,000 L-82's were produced in 1980 as an FYI.
Another way to verify if the motor is an L-82 is to pull the oil pan and check for a 4 bolt main cap- 2 bolt-L-48. Pull the valve covers and check for 2.02 exhaust valve size on the L-82 heads. Lastly, y ou can maybe do a compression check and if the compression is under 8.5 : 1 it cups also indicate an L-48 assuming the engine is not too worn or if the compression is over 8.5:1 it most probably an l-82. can't think of anything else offhand!*
Another way to verify if the motor is an L-82 is to pull the oil pan and check for a 4 bolt main cap- 2 bolt-L-48. Pull the valve covers and check for 2.02 exhaust valve size on the L-82 heads. Lastly, y ou can maybe do a compression check and if the compression is under 8.5 : 1 it cups also indicate an L-48 assuming the engine is not too worn or if the compression is over 8.5:1 it most probably an l-82. can't think of anything else offhand!*
08-03-2011, 07:20 PM
#35
08-03-2011, 07:37 PM
#36
Le Mans Master
Does it say "L-82" on the tach and does it redline @6,000 RPM? I would think that the easiest way to determine if it is an L-82 is to drop the oil pan and see if it is a 4 bolt main.
This article may be of some help-the 74-80 L-82's were essentially all the same, the differences from year to year are primarily the type of exhaust and mufflers run on each year engine:
http://www.superchevy.com/technical/...ver/index.html
Without taking the engine apart as noted above compression ratio and valve train differences would be difficult to determine.
This article may be of some help-the 74-80 L-82's were essentially all the same, the differences from year to year are primarily the type of exhaust and mufflers run on each year engine:
http://www.superchevy.com/technical/...ver/index.html
Without taking the engine apart as noted above compression ratio and valve train differences would be difficult to determine.
08-03-2011, 11:02 PM
#37
Le Mans Master
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Does it say "L-82" on the tach and does it redline @6,000 RPM? I would think that the easiest way to determine if it is an L-82 is to drop the oil pan and see if it is a 4 bolt main.
This article may be of some help-the 74-80 L-82's were essentially all the same, the differences from year to year are primarily the type of exhaust and mufflers run on each year engine:
http://www.superchevy.com/technical/...ver/index.html
Without taking the engine apart as noted above compression ratio and valve train differences would be difficult to determine.
This article may be of some help-the 74-80 L-82's were essentially all the same, the differences from year to year are primarily the type of exhaust and mufflers run on each year engine:
http://www.superchevy.com/technical/...ver/index.html
Without taking the engine apart as noted above compression ratio and valve train differences would be difficult to determine.
Scott
08-04-2011, 04:51 AM
#38
Safety Car
Sorry to raise a dead thread, but while looking to purchase my first L82, I came across something I cannot explain. I responded to an add for a 1980 L82 4speed and asked for the numbers--
VIN: 1Z878AS439989
Motor: Z0718ZBC S439989
The VIN reads L48, but the motor reads L82 and the numbers do match. Are these possible to forge?
VIN: 1Z878AS439989
Motor: Z0718ZBC S439989
The VIN reads L48, but the motor reads L82 and the numbers do match. Are these possible to forge?
Problem is verification...not sure if there exists a published source for Q'Jet carb broadcast codes for 1980.
08-04-2011, 07:50 AM
#39
Race Director
17080204 - L48 Automatic
17080207 - L48 Manual
17080208 - L82 Automatic
17080204 - LG4 Automatic (CA 305)
17080217 - LG4 Automatic (CA 305)
Note that there is no published part number for an L-82 manual.
Each Q-Jet also had a 4 digit Julian date code. The first 3 digits are the day of the year, and the last one is the year. A 1980 carb dated 3659, would have made on Dec. 31, 1979.
1980 Corvette service replacement carbs carry these numbers:
17066422 - L48 Automatic
17066425 - L48 Manual
17080228 - L82 Automatic
17066436 - LG4 Automatic
Service replacement carbs are dated the same as OEM carbs.
