you can,t always tell by looking

grumpyvette

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back when I was in college studying hard to get a degree I had a couple rather close , gear head friends named LARRY, CARLOS and MIKE!
now Carlos was one sharp guy and his dad was well off so he had co-signed for carlos to purchase a 1968 corvette with a 4 speed , 4.11:1 rear gears,and a big block
L71 427 cu. in. 435hp Engine , and carlos paid to have the car modified with the extra cost optional at the time L88 cam installed.
he had headers and a side exhaust and roller rockers.
this resulted in what we thought at the time was an exceptionally fast car, and we had a great deal of fun smoking the tires, on the rare occasions when Carlos would let me drive, (he had a great deal of fun doing the same thing)
l71a.jpg

l71b.jpg

l71c.jpg

l71d.JPG

Larry had a 1963 impala at that time with a rather radical,sounding over camed , but not very fast small block, and Mike owned a formula 400 1967 fire-bird
with a 4 speed. I was very impressed with this Fire bird it was a deep metallic olive color,
1967fb2.jpg

1967fb3.jpg

it had the first 4 wheel disc brakes Id ever seen on a fire bird,(modified Z28 I think)it had lakewood traction bars , it had Harland sharp roller rockers, it had a vertex magneto, tall cast valve covers, 600 cfm dual quads and the first rocker stud girdle Id ever seen.,and while I had a good transportation car in the rambler and a project car I was building with what eventually would be a really nice big block chevy engine, in the 1965 lemans the lemans was about a year or more from being completed and I eventually got a screaming good deal on a similar formula 400 fire bird to what mike owned.
there was an abandoned WWII air strip near the college campus at the time so we frequently met after class to run down the 1.5 mile main run way and chase each other around a few trash cans , we set out to mark a oval amateur race course. at that time I was still putting together my 1965 lemans and was driving the 1965 rambler flat head 6 cylinder... so It was really no contest, at that time I was dead last in performance,
before I got out of high school, I had a job, but I could not afford to do much more than afford gas and maintain a 1965 rambler I used for transportation.
rambler.jpg

I could hardly wait to get up the coin required to sell that flat head 6 cylinder car, but looking back, it was good dependable transportation, I wish I still owned!
I traded that in as soon as I could for a formula 400 firebird

1967Firebird.jpg

1967fb1.jpg

and shortly after bought a 1965 lemans as a project car
65gtoa.jpg

now you might think that the corvette was way faster than all the other cars and there was zero doubt he could smoke the tires rather easily and he sure had plenty of female attention driving it, but the truth was that the formula 400 fire bird Mike own was almost as fast, because Mikes best friend owned a tire shop down in miami and was a retired nascar racer. I don,t remember everything that was done but the guys tire shop name was BOBBY JOHNS TIRES and who ever was helping Mike had access too a great many 421 Pontiac engine parts, because both the corvette and the Pontiac were running low 12 second 1/4 mile times and the vette was only a little faster, just rarely getting within a tenth of breaking into the 11s
I was always rather amazed at the reaction of people because we frequently hung out at a couple drive-in restaurant parking lots where we would go at nite to swap lies trade parts and occasionally set up races for $50-$100 and Larry's healthy sounding but very heavy and rather slow impala always seemed to draw a few on-looker, and everyone assumed his car was far faster than it really was., few people wanted too race Carlos,s corvette, it was just assumed to be an 11 second car. but Mike frequently made a good deal of cash in those races because no one would believe a fire bird was nearly that fast.

all these cars look like clones to the first cars I owned
It took me several years and lots of mods and I eventually blew the 400 engine in the fire bird I owned and I eventually built a killer 496 big block engine for the 1965 lemans that eventually allowed me to beat carlos. but by that time carlos was married and Larry was in jail for something to do with drugs and Mike moved out of state when he got a large promotion and a great job.
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All Poncho 421's had 4- bolt main caps on center 3 mains.
3-1/4 " Mains.
Full length windage tray.
17 degree valve inclination cylinder heads.
Most had Forged steel 6-5/8" center to center Connecting rods not Arma steel Cast.
5/64, 5/64, 3/16 piston ring package.
40psi oil pump.
If 421 HO 60 psi pump.
2-3 Motor mount boss blocks.
Direct bolt in drop into a 1967 -69 Firebird.
None would ever know a 4" inch crank stroke Poncho in place.
I would. Have to look at the rear distributor boss.
A raised 1 inch Tall Pyramid cast in place.
Called the Transfer Lug by Pontiac assembly line crews.
A street racing menace the Formula 400 bird.
421 Cubes.....
Even better with the 421 HO Long branch exhaust manufolds & special Oul filter adapter block.


BR
 
421'S never had the engine displacement casted on outside of the block unlike poncho 400-455.
Makes them near impossible to spot other than by guys like You & Me Grumpy.

BR
 
389/421 Has a shorter crankshaft snout.
Different Harmonic balancer used than 1967-up engines.
Solid Crankshaft Hub. Bolt on Vibration dampner ring with lower crank pulley.
4-bolt water pump timing cover, or 9-bolt water pump timing cover.

How did I do on my Pontiac V8 engine quiz Grumpy ???
Next question.

BR
 
87vette81big said:
389/421 Has a shorter crankshaft snout.
Different Harmonic balancer used than 1967-up engines.
Solid Crankshaft Hub. Bolt on Vibration dampner ring with lower crank pulley.
4-bolt water pump timing cover, or 9-bolt water pump timing cover.

How did I do on my Pontiac V8 engine quiz Grumpy ???
Next question.

BR
GREAT! Id let you work on anything I built, your obviously familiar with those engines

POWER TO WEIGHT CALCULATIONS
http://vexer.com/automotive-tools/1-4-mile-ET-HP-MPH-calculator

http://www.wallaceracing.com/et-hp-mph.php

https://robrobinette.com/et.htm

http://www.ajdesigner.com/fl_horsepower_elapsed_time/horsepower_elapsed_time.php

http://www.tuneruniversity.com/blog/2012/03/power-to-weight-ratio/
 
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