The LeMans (on the left) has a mild, non-rebuilt 455 with ported & polished 6X heads, c. 9:1 compression, Edelbrock Performer intake, Holley 800 Street Avenger, Comp XE274 cam, making maybe 300-350 horsepower. The Grand Am (right) has a .030 over 455 with Edelbrock heads (87 cc chambers), 10:1 compression, same Comp cam but with 1:65 roller rockers, slightly better Exhaust (H-pipe), Edelbrock Performer RPM intake and Edelbrock 750 carb. About 500 horsepower at the flywheel. The heads make all the difference. The Grand Am has the Flowmaster American Thunder Exhaust system, which has the 50-series mufflers. LeMans has a Summit Exhaust system, which was cheap and went on nice & easy.
Pontiac 455 Crower Camshaft 60210
Stock pontiac 455 with Crower camshaft 60210 and crower vslve springs. Its
obviously wsy too big of a camshaft for the stock 8.5 compression ratio but
it runs with thr timing advanced to 25 degrees.
PONTIAC - "The Super Duty Story" Part 1 of 3
Pontiac had an SD engine program in the late 50s early 60s, and
later/briefly again in 1973/74 with the SD455. This video is regarding the
FIRST Super Duty program.---In only a few years time during the late 50s
early 60s, Pontiac MORE THAN DOUBLED their V8's horsepower output (described
in this video), while using/keeping the same V8 engine block they used thru
1955-81. Even though the same block was kept, from 1955-62 the cubic inch
displacement grew much larger than the initial 287 cuber it started as in
1955. It grew to a 317 347 370 389 and finally a 421 cuber in 1962. It
eventually maxed out at 455 cubes in 1970. By 1970 ALL the other GM
divisions were producing engines at 454 or 455 cubes (500 for Cadillac).
PONTIAC WAS THE ONLY DIVISION still using the same block they used in the
1950s on engines that had a much smaller displacement -- 287 cubes. The
1955 287 displacement would remain the smallest displacement ever used in
the Pontiac V8 block all the way until 1980/81 when a 265V8 was produced.
Since less durability was required for the smaller displacement, the block
was decked/butchered/lightened on the 265/301v8s of 1980/81. Prior to 1980
the block had never been decked/butchered/lightened. The 1980/81 265/301v8
blocks were about 200 pounds lighter than the 1955-79 blocks, and only 25
pounds heavier than a Buick 231V6.
Pontiac running 2009 big cam idle
1964 Pontiac Tempest, 2dr Post, 455 .040 over, 4X heads, Comp XE274
cam,Performer RPM manifold w/ Edelbrock Performer 800cfm, Full Pypes X Exhaust with RacePro mufflers.
Engine has Holley 3130/750 now and different timing set up. Made huge
difference. I could never get the Edelbrock carb to work right. And yes
the Mr Gasket header gasket on the driver side was leaking just 40 minutes
after break in.