tran-zam.com
1970 Engine Options
  Tran-Zam Home
     
  1970 Links
    Exterior Details
    Exterior Moldings
    Interiors
    Wheels
    Options
    Interesting Facts
    Firebird Gallery
     
  Firebird Information
    Spotter's Guide
    Color Guide
    Hood Bird Guide
    1970 Home
    1971 Home
    1972 Home
    1973 Home
    1974 Home
    1975 Home
    1976 Home
    1977 Home
    1978 Home
    1979 Home
    1980 Home
    1981 Home
     
 
1970 Engine Options
Engine ID Codes
UPC Code Type Source Displacement Bore & Stroke Carb Compression HP/RPM Torque/RPM Manual Automatic
L22 Inline 6 Chevrolet 250 3.88 x 3.53 1bbl 8.5:1 155@4200 235@1600 ZB ZG
L30 V-8 Pontiac 350 3.88 x 3.75 2bbl 8.8:1 255@4600 355@2800 WU YU
L65 V-8 Pontiac 400 4.12 x 3.75 2bbl 8.8:1 265@4600 397@2400 - XX
L78 V-8 Pontiac 400 4.12 x 3.75 4bbl 10.25:1 330@4800 430@3000 WT YS
L74 V-8 Pontiac 400 Ram Air III 4.12 x 3.75 4bbl 10.5:1 335@5000 430@3400 WS YZ
L67 V-8 Pontiac 400 Ram Air IV 4.12 x 3.75 4bbl 10.75:1 345@5400 430@3700 WH XN
 
     
 
Identifying a Pontiac Engine
For 1970 Pontiac would no longer produce 6 cylinder engines for the Firebird so the Chevy 250 cid inline 6 was used replacing the innovative overhead cam 6 cylinder produced by Pontiac in the previous years.  This was one of the first years that GM installed engines made in other divisions into Pontiacs, a practice that would continue until 1982 when all engines would be the same across all GM lines.  Most V-8 engines installed in Second generation Firebirds were produced by Pontiac and most were built upon the same basic block. Therefore it is very difficult to tell the difference between a 350, 400, and 455 block since all were of the same basic design.  The only sure way to tell whether you are buying a high performance block versus a "grocery getter" is to look at the engine stampings.  On 6 cylinder models the two letter code (see Engine Options above) is stamped near the distributor mounting pad.  On all others it is stamped below the passenger side cylinder head on the front of the engine. Some nuances are present on each engine shown below that can help to identify the engine. The most easily identifyable characteristics are easily changesd so check the codes before you buy.
     
 
The Chevy built 250 cid inline 6 was used from 1970 to 1975. The 6 cylinder lacked power to haul the heavy Firebird so as a result only 3134 were installed in 1970 base Firebirds, or 6.4% of total production.
  
Shown above is a typical Pontiac V-8.  Pontiac V-8s were always based upon the same basic block design and 350 blocks were nearly the same as the basic 400 block and even the 455 block used in later year Firebirds.  The Ram Air III and Ram Air IV appeared very similar to 350/400/455 blocks but they were different, mostly in block strength.  The best way to tell them apart is to look at the ID codes stamped on the engine block itself just below the passenger cylinder head. 
     
 

L22 250 cid Inline 6 Cylinder

The inline 6 was only available on the Base Firebird and installed in only 3134 Firebirds.  Since most of these were used as daily drivers they are extremly rare.  The photo above is actually from a 1973 Firebird, the closest year that could be found. The block is painted in Chevy Orange and is bvelieved to be correct.. 

 

L30 Pontiac 350 cid V-8

A 350 cid Pontiac block installed in an Esprit.  By looking at it you would be hard pressed to say that this is not a 400.  The only sure way is to look for the engine code numbers (shown at the top of this page in the engine table).  The 350 and 2 barrel 400 both had blue valve covers and a single snorkel from the air cleaner.
     
 
L78 Formula 400 Standard Engine  
L74 Ram Air III - Formula Option
Shown above is the standard Formula 400 4 bbl engine.  An interesting feature is that the air cleaner had two snorkel air intakes for breathing air into the engine. This is often mistaken as being incorrect but all Formula 400's from 1970 to 1972 had them.  The correctness is verified by the 1970 Firebird Sales brochure that states in the Formula description "An engine that breaths better can work harder with less strain.  So the air cleaner on our 400 V-8 has two snorkels instead of one." The valve covers were polished aluminum.  The example shown also has air conditioning.  On Pontiac engines the air compressor is always installed on the passenger side.
  
When the Formula was ordered with the Trans Ams Ram Air III engine the hood scoops became functional.  To get the cold air into the carburetor a different air cleaner asemble was used as shown above.  Under the hood two round rubber boots were installed to seal the openings on the air cleaner snorkels to the inlets on the hood.  The photo shows the correct engine blue, a light metallic blue, for 1970.  Once again the valve covers were polished aluminum. 
 
Trans Am Ram Air III   Trans Am Ram Air IV
The Trans Am's Ram Air III engine was identical to the Formula's except the air cleaner which obviously had to carry the Trans Ams signature hood scoop.  From 1970 to 1972 the hood scoop on Trans Am was function with a flap on the back opened by a solenoid when the car was running.  Note that the air cleaner had only one snorke shown almost hidden to the right.  Natural Alumnum valve covers were agin present.
   The Trans Ams Ram Air IV was offerred by Pontiac only through the back door in a fashion that could be considered similar to the famous COPO process used to sell big block powered Camaros.  This engine was intended for drag racing and was not on the dealer's standard order sheet.  This engine looks very much the same as a Ram Air III but inside it had all round port heads and exhaust versus the D port in the Ram Air III. Visually the dual snorkels in the air cleaner are the only tell-tale clue that this was a Ram Air IV.  Pontiac did not apply decals to the shaker scoop as shown here.  You may also tell by the long branch exhaust manifolds if you can squeeze a look underneath.