Firebird 400 “The Boss”

The 400 was equipped with a 4BBL carburetor and dual exhausts and made 330bhp @ 4,800 rpm. Other standard features unique to this model included a 3 speed transmission with floor mounted shifter, chrome air cleaner and valve covers, sports suspension and shocks, heavy-duty battery, a Power Flex Fan, and either red stripe or whitewall tires.

This model is most easily recognized by the twin-scoop hood with “400” emblems located on the rear edge of the hood bulge, front bumper emblem and chrome grill trim.

1968 Firebird 400 H.O.

In 1968 a L74 400 cubic inch H.O. (High Output) variation was introduced. The 400 H.O. option was available at $74.88 over the base 400 and gave you free flowing exhaust ( long branch exhaust manifolds) and a wilder “067” cam on automatics and the 288/302-duration “068” on manuals.

The 400 H.O. was rated at 335hp @ 5000 rpm with a torque rating of 430 ft lbs @ 3400 rpm. The #16 heads had a compression rating of 10.75:1.

Car and Driver March 1968 5 Car comparison – See how the 68 Firebird 400 H.O. compared against the Camaro 396 SS and some other famous muscle cars.

1968 Production Numbers

400 H.O.:  2087  (coupes & convertibles)
400 H.O. Convertibles:   350 *

400 H.O. manual : 1400
400 H.O. auto :    650

400 H.O. Conv w/manual: 250 *
400 H.O. Conv w/auto :  100 *

*  estimate: This number is exaggerated based on a Coupe to Convertible ratio of 15.8%. The majority of 400 H.O. and RAM Air cars ordered were coupes due to their stiffer bodies used for road and track racing which was big in that day.

We can see that this is true by looking at the Ram Air cars. There were only 12 known Ram Air convertibles. If  we used the same coupe to convertible ratio, there would be an estimate of 82 build. We know that is not true.

Research that I have done seems to reviles that the 400 H.O. convertible production numbers are more in line with 10% ratio. That would make the convertibles w/manual 140 and Automatics 65. This would make these cars < 1% production car.

If we believe that a cars survival rate after 45 years is approximately 10%, that would lead to approximately 200 400 H.O.’s with approximately 20 400 H.O. Convertibles.

Additional Production Information


1968 Important Numbers

1968 400 HO Identification Codes
Engine Codequantity BuiltTransmissionHeadscarburetorDistributorIntakeLongbranch Exhaust Manifolds
WQ 1415Manual#16 10.75:1 CR7028271 XP 11114499790140LH-9799495
YW684Automatic#16 10.75:1 CR702826411112709790140LH-9799495