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Special guest feature article by Rich
Fields
If not for the 350
engine, would this have been the baseline
Camaro Super Sport?
(Please note: Footnotes are
bookmarked- click on superscript numerals to view)
| Take a good look... Although it
lacks the SS hood, you could be easily fooled by the looks and performance of this '68
L30/M20 coupe... |
 If you are a regular attendee of classic car cruise
and show events, you may have encountered an adamant believer that some first-generation
Camaro Super Sports were manufactured with the 327ci engine. While the claim of a factory
SS-327 Camaro is absolutely untrue - no production Camaro SS's were ever built with
engines smaller than the 350 - there are understandable reasons for the spread of such
rumors, since there was a factory 327 Camaro model with technical specifications
and performance very similar to that of the SS-3501. Included with this 327 were a number of pieces of
high-performance equipment that some have believed were applied only to the SS or Z28.
This is a story that has been largely forgotten --- the details behind an unsung
performance Camaro, the L30/M20 Camaro of 1967-68.
 The 1967-682 RPO (regular production option) combination of the L30
327ci-275HP V8 engine with the M20 4-speed manual transmission created a true
high-performance automobile, in part due to additional components automatically installed
by the factory when the M20 was paired with the L30. The details of this package were
poorly documented and essentially unadvertised; probably only the most discerning people
of the era realized the implications.
The writers and editors of period car enthusiast
magazines rarely delved deeper into available options than the basic promotional
literature supplied by Chevrolet, and the Chevrolet marketers preferred to emphasize the
SS models, or later, the Z28. Serious racers considered the SS and Z28 to be only starting
points, with further modifications required to meet their needs. So it was not well-known
(and still isn't3) that the L30/M20 Camaro was the only regular production Camaro outside
of the SS/Z28 models to receive the heavy-duty "12-bolt" rear-end,
right-side traction bar (in 67), and multi-leaf rear springs (in 68), as well as
additional performance equipment otherwise exclusive to the SS or Z28 lines. The potential
for model confusion is understandable since, without this knowledge, a L30/M20 could
easily be mistaken for a SS-350 stripped of ornamentation (if the 327 was mistaken for a
350), or, if the 327ci engine was recognized as such, the L30/M20 could be interpreted as
evidence of a factory SS-327.
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The above ad ran in many
major enthusiast's magazines. It depicts a 327 coupe in "SS trim" and calls it
an "SS"!!! Could this have added to some of the confusion? I think so...
 RPO L30 "327-275" Engine. A real
performer when combined with RPO M20 four speed transmission.
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If there is any confusion, much
of the blame can probably be assigned to the manufacturer. Chevrolet's long-term
record-keeping policies have proved to be so poor (perhaps deliberately poor) that they
have no permanent individual records of the vehicles produced (GM of Canada is the exception, but Canadian
Camaros were a relatively small number of the total Camaro population.) Chevrolet
files4 have been nearly purged of first generation Camaro
engineering data; old drawing numbers are now being reused on new models with old drawing
files trashed in the process. Little, if any, of the original data remains in Chevrolet
files. Chevrolet has even lost the official translation and/or significance of certain of
their own production codes. |
An example particularly germane to the topic at hand is
the 1967 "4P" Trim/Cowl Tag code. The meaning of codes can now be understood
only by deduction; by acquiring data on a number of vehicles, determining the similarities
and differences, and then attempting to deduce the original meaning of the code. Lacking
an official Chevrolet interpretation, the 4P code was, for a long time, interpreted in
aftermarket Camaro literature as unique to the SS-350. Recently however, a more complete
meaning has been determined by the U.S. Camaro Club. This code is now believed to indicate
a high-performance small-block V-8 application; 5 this includes not only the SS-350 but, for a short period of
time, also the Z28 (until the unique "4L" code was set aside) and the L30/M20. (The extent of application of the "4P" code to 1967 L30/M20s is
still being researched.)
A better understanding
of the significance of the L30/M20 Camaro can be had by first briefly reviewing the
specifications of its close cousin, the SS-350...
The SS-350 Camaro, a.k.a, the L48/M20:
350ci-295HP, 4-speed (base V8 price +
$395.00 in 1968)
 When
Chevrolet introduced the all-new 1967 Camaro on September 29, 1966, the top-of-the-line
Camaro Super Sport was powered only by a new high-performance 350ci-295HP small-block V8.
The 350 engine (in its various forms) would prove to be the last6 and arguably most famous expansion of the overhead-valve,
small-block Chevrolet engine line that began in the 1950's. The previous incarnations, the
327, 283, and 265 (in reverse chronological order) had developed a formidable reputation
for dependable power.
The additional displacement of the 350 was obtained from
the 327 engine block via a new crankshaft7 that increased the 3.25 inch stroke used on the 327 engine to
3.48 inches while retaining the 4.00 inch bore. This new engine debuted in the 1967 Camaro
as part of RPO L48 (the Super Sport, or SS), and would not be made available to the other
Chevrolet lines until the next model year. While the Camaro SS line would soon be
bolstered by a series of 396ci big-block engine options that would push advertised power
ratings to the 325-375HP range, the 350 engine retains a strong identity as the baseline
powerplant of the original Camaro SS, the SS-350.
During the first two years of the Camaro, RPO L48 was
more than just the new 350ci engine; it was a true option package that pulled
together a balanced collection of performance components and added a special trim package
for visual distintion8. While certain performance components (dual exhaust, for example)
were also available to many non-SS models via separate RPOs, other components (like the
traction bar, heavy-duty clutch, and multi-leaf springs) were restricted to Camaro models
internally designated by Chevrolet as high-performance vehicles and could not be
specifically ordered as a separate option9. Not counting non-functional special interior and exterior trim
(SS badges, SS hood, SS paint stripe, chrome-plated engine trim, etc.), the 1967-68
RPO L48 added eight high-performance component groups to the baseline vehicle:
- A heavy-duty rear-end based on a larger, 8.875
inch diameter, ring gear suitable for high-torque engines. This rear-end is commonly
called the "12-bolt," after the number of bolts on the ring-gear (as well as on
the cover). The standard rear-end of this era was "10-bolt" rear end with a
8.125 inch diameter ring-gear10.
- Heavy-duty driveshaft universal joints, suitable
for high-torque engines.
- Significant suspension improvements: stiffer
springs (multi-leaf rear springs in 1968) teamed with heavy-duty shocks and, with 1967
manual transmissions, a rear axle radius rod (a.k.a., traction bar).
- A low-RPM, high torque, starter motor, needed for
high-compression ratio engines and upgraded from the baseline starter.
- A two-piece rear brake line with
rear brake proportioning valve to improve pressure distribution between front and rear
brakes. (1968 only. 1967 Camaros featured this only on air conditioned cars and disc brake
cars. *See Illustration below.)
- A dual-exhaust system with 2-1/4 inch pipes for
improved power.
- Wider profile 70-series tires: D70x14 in 1967 and
F70x14 in 1968, as compared to the standard D78x14 tires used in both years.
- Heavy-duty, larger diameter (11.0-inch) clutch,
suitable for high-torque engines. (Obviously only for use with manual transmissions.)
Having reviewed the
performance features of the SS-350 Camaro, let’s look at the top-of-the-line
327-powered Camaro.
The L30/M20 Camaro:
327ci-275HP, 4-speed (base V8 price +
$331.00 in 1968, with N10 dual exhaust & PY5 F70x14 tires)
While the L48 package got top billing, the
less-publicized optional upgrade to the base 327 engine, RPO L30, boosted performance of
the base 327ci V8 from 210HP to 275HP. When the L30 engine was combined with the M20
4-speed manual transmission, and only in this case, Chevrolet considered the result
to have crossed the line into high-performance territory and added to the package a number
of high-performance components, including identical (or near-identical) matches to the
first five of the eight SS-350 performance component categories... Similarly to the 67-68 Z28, the L30/M20 was
outfitted with the smaller, 10.4-inch diameter clutch, and the larger clutch used on the
L48/M20 could not be separately ordered. Though not a heavy-duty clutch in the same sense
as the 11.0-inch SS clutch, with the L30/M20 combination the pressure plate on the
10.4-inch clutch was upgraded to a more durable lining. When the dual exhaust
system (RPO N61 in 67; RPO N10 in 68) and wider-profile tires (such as RPO PY5 in 68) were
added to the L30/M20 option, the result was a truly functional 327 equivalent of the
SS-350. The L30/M20 with N10/PY5 add-ons could be had for a 1968 list price of $331.00,
$64.00 less than the SS-350 L48/M20 and enough difference to pay for an additional
high-performance option like positraction, with change left over. Budget-minded
performance enthusiasts who were in-the-know could optimize their fun by adding additional
options to the L30/M20 Camaro to meet their specific needs, rather than by selecting the
SS-350.
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Above..
The L30/M20 and L48 face off... So close in so many ways!! |
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In addition to the clutch, the other
significant difference between the L48 and L30/M20 was the M20 transmission. M20 was
not the name of the transmission, it was the functional designation for any
standard ratio 4-speed. Unfortunately, Chevrolet yoked the L30 to the less-desirable
cast-iron-bodied Saginaw 4-speed, heavier by some 14 lbs. than the Muncie aluminum-bodied
4-speed11 that was placed behind
the L48. Just for the L30 application, the Saginaw 4-speed was
beefed-up slightly by the substitution of heavy-duty bearings for the standard bearings in
both the clutch-gear shaft bearing and rear mainshaft bearing locations.
The increased weight of the Saginaw was offset by the
lower weight of the standard, and arguably better-looking, hood used on the L30/M20, as
compared to the much heavier SS hood with its non-functional "window-dressing"
hump and ornaments. The 1968 L30/M20 with N10 exhaust is documented12 as being a total of 29 lbs. lighter than the L48/M20, though a
few pounds of this margin would be eaten away if the PY5 wide-track tires were added to
the 327 powered car. While data that would allow a comparison of vertical Center of
Gravity (CG) coordinates are not available at this time, the L30/M20/N10 may have enjoyed
a slight handling advantage from a lowered CG due to the mass shift combination of the
much lighter hood and the slightly heavier transmission.
Identifying an L30/M20:
The L30/M20 Camaro was contained, as was the 1967 Z28
(base V8 price + $663.60 including the Z28 required M21/J50/J52 options), in a package
with no tell-tale external badging. To the undiscerning eye the L30/M20 is just another
plain-jane Camaro. The only way to verify an original L30/M20, without the original paper
documentation, is to check as many of the performance components as possible. The
best-case scenario would find a suitably date-coded, matching-number, 327ci-275HP engine
of the proper block casting number that is stamped with the manual transmission engine
model code (MK or ML in 1967; EA in 1968). This L30 engine should be teamed to a suitably
date-coded and matching number 4-speed Saginaw transmission assembled of castings with the
proper numbers. If either engine or transmission have been replaced, L30/M20 verification
will require checking the date-code on the 12-bolt rear end; to supplement this one should
attempt to locate as many of the other performance components as possible, especially the
traction bar (1967) or multi-leaf rear springs and rear brake proportioning valve (1968).
Shown below is the
two-piece rear brake line with rear brake proportioning valve to improve pressure
distribution between front and rear brakes. (1968 only. 1967 Camaros featured this only on
air conditioned cars and disc brake cars.
 If most of
these components are missing (many are often missing due to modifications made over the
years), including more than one of the three key drivetrain items (engine, transmission,
rear-end), the claim of a real L30/M20 may be difficult to reliably establish.
If you have one of these difficult cases,
contact the author for help with additional identifying features.
How Many...?
How many L30/M20s were built? While Chevrolet records
document how many of each individual option was sold, we don't at this time have
any record of how many option combinations like the L30/M20 were sold. However, we
can make an educated guess, based on transmission usage, from the data shown in the table
below13. The L30 predominately drove either the standard Saginaw 3-speed
manual, the M35 PowerGlide two-speed automatic, or the "close ratio" M20 Saginaw
4-speed manual. The total number of these three transmissions sold in Camaros in model
years 1967-68 was approximately 430,458. Dividing this into the number of M20s sold
(Saginaw + Muncie), 80,967, gives us a rough estimate (perhaps a significant
over-estimate, since we are including the Muncies in the M20 arithmetic) of the number of
L30s mounted to M20 transmissions; just under 19% (18.81%). Multiplying this factor by the
number of L30s sold indicates that a maximum of 8835 L30/M20 Camaros were produced for
both years; less than 2% of all Camaros built in these years. Interestingly enough,
production quantities this low put the rarity of the L30/M20 on a par with models like the
1967-69 SS with the L78 396ci-375HP engine (9464 built) or the 1968-69 SS with the L34
396ci-350HP engine (4597 built), and significantly more rare than most other production
models, even the SS-350 or Z28. If this estimate is reasonably close, only the L89
aluminum-head 396-powered SS (583), or the various low-volume COPO models would be
significantly rarer. Given the relative lack of respect that this poorly appreciated
option combination has enjoyed, these thirty years later it is likely that surviving
original L30/M20s are counted in the hundreds rather than the thousands14.
CAMARO PRODUCTION QUANTITIES:
| |
1967 |
1968 |
Both Years
(+1969) |
% Total |
| Total Vehicles:
|
220,906 |
235,147 |
456,053 |
100 |
| |
|
|
|
|
| Engines
Subtotals: |
|
|
|
|
| L48
(350ci-295HP) |
29,270 |
12,496 |
41,766+22,339 |
9.16 |
| L30
(327ci-275HP) |
25,287 |
21,686 |
46,973 |
10.30 |
| L35
(396ci-325HP) |
4,003 |
10,773 |
14,776+6752 |
3.24 |
| L34
(396ci-350HP) |
--- |
2,579 |
2579+2018 |
0.57 |
| L78
(396ci-375HP) |
1,138 |
4,575 |
5713+4889 |
1.25 |
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|
|
|
|
| Transmissions:
|
|
|
|
|
| M20 (4-speed manual) |
45,806 |
35,161 |
80,967 |
17.75 |
| Std 3-speed manual |
48,506 |
51,093 |
99,599 |
21.84 |
| MB1 (2-speed semi-automatic) |
--- |
3,099 |
3,099 |
0.68 |
| M13 (special 3-speed manual) |
681 |
752 |
1,433 |
0.31 |
| M21 (4-speed manual) |
1,733 |
11,134 |
12,867 |
2.82 |
| M22 (4-speed manual) |
--- |
1,277 |
1,277 |
0.28 |
| M35 (PowerGlide automatic) |
122,727 |
127,165 |
249,892 |
54.79 |
| M40 (TurboHydraMatic automatic) |
1,453 |
5,466 |
6,919 |
1.52 |
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|
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| L30/M20 Estimate: |
4,756? |
4,079? |
8,835? |
1.94? |
.Please click here to go to Part Two
View foot notes and read about
the Author...
 Questions and comments regarding this
article are welcome and encouraged.
Please click on image to email Rich Fields..
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