Match Race 1972 ~ 'Duster 340 vs 'GTO 400'

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Had a basically stock 1972 Fire bird Formula 400. Stock other than cam & headers. Gutless. Cool thing about the early Ponchos: all the early ones were set near zero deck. Yanked the stock 1972 7K3 heads off,installed a set of 1968-69 18 castings on it. Compression jumped from 8 to 1,to 10-to 1. This and a moderate narrow lobe center cam. Night and day difference. Cackled& feisty, low and mid range crazy. Nice combo.
 
IIRC 340 A body cars have always been considered to have a favorable power to weight ratio.

I wonder how the 400 Roadrunner did vs the gto.

Same cubes and you would think a similar weight, although the weight for the goat listed above seems kinda light.
 
YY1 said:
IIRC 340 A body cars have always been considered to have a favorable power to weight ratio.

I wonder how the 400 Roadrunner did vs the gto.

Same cubes and you would think a similar weight, although the weight for the goat listed above seems kinda light.
Click to expand...


YY-1,

I thought the shipping weight of the 1972 'GTO 400' would be higher as well.

But, all books list the Hardtop at #3450 lbs.
And the limited production 'Sports Coupe' {Pillar-Post} is listed at #3510 lbs.

These weight numbers are for 'the base' Lemans, without the GTO options.

Add;
* Front Disc Brakes
* Dual Exhaust
* GTO interior
* Power Steering
* Power Assist unit
* Air-Pump
* Radio
* Console

72gto.gif
 
95teetee said:
:butthead:
Click to expand...

I always loved your car and I appreciate installing some options, but my personal taste prefers the plain lid. As was said earlier, nothing personal. Now, don't get me started on the Bird/Daytona.....I'd better put on my bulletproof vest...lol.
 
Abodybomber said:
Had a basically stock 1972 Fire bird Formula 400. Stock other than cam & headers. Gutless. Cool thing about the early Ponchos: all the early ones were set near zero deck. Yanked the stock 1972 7K3 heads off,installed a set of 1968-69 18 castings on it. Compression jumped from 8 to 1,to 10-to 1. This and a moderate narrow lobe center cam. Night and day difference. Cackled& feisty, low and mid range crazy. Nice combo.
Click to expand...

You've been there, so you know how the Poncho's responded. I had a hand in a half dozen or so 400/455 street builds. Not talking race builds, except for one round port, but the untouched "D" port heads just didn't respond to big lift cams. I learned my lesson the hard way with a 70' 400 that I built as a higher rpm engine. Lots of lift, a single plane, and a big carb (850). All I did was take away the torque and the heads just couldn't handle that style of build. Lost bottom end and top end...:banghead:.

As you said, if you didn't have a 10ish to one to begin with, it was gravy to just drop on a set of early 72cc heads to get the comp back. As long as you had the squeeze, a cam with 470"/490" lift and a moderate .050 duration, along with a dual plane to keep the torque up, resulted in a serious street player with a 3.55 or so gear.
 
I know I won't make any friends here talking about Pontiac's, but I'd love to put together a 455 short block with good rods, forged flattops and top it off with a pair of round port 72cc Eddy's. The resulting 12+ compression and some cam would produce a nice bracket engine that should give a 550/550 engine shifted at 6k max.

I'd love to know the combo Steve Caldwell is running in his Ventura?
 
O-M-R

Lots of Pontiacs out there at the Track......Don't get me thinking....

1972 ~ 400/250 HP

Factory Listed Compression...... 8.20 to 1
NHRA Listed Compression........ 9.49 to 1

Pistons................................. Flat-Top w/Notches

Deck Height........................... .000" {'Zero'}

Cylinder Heads {#7K3}............ 'D-Port'
Combustion Chamber............... 96.0 CC's {Factory}
Combustion Chamber............... 85.8 CC's {NHRA Minimum}
Intake Valve........................... 2.11"
Exhaust Valve......................... 1.77"
Intake Flow............................ 200 CFM @ .425" Lift
Exhaust Flow.......................... 155 CFM @ .425" Lift

Note: Milling .048" off the Cylinder Head, will reduce 10.2 CC's, gaining an increase in 1.29 Compression.

Camshaft {P-Code, #9779067}
Lift...................................... .425" / .424"
Duration............................... 273* / 289*
Overlap................................ 54*
Center-Line.......................... 112*
 
The "S" 068 cam was the RAIII cam as I recall. Advertised duration was 288/302. The lift was still in the 420"ish range, but it was a really strong street cam. I think Pontiac even knew that the "D" heads didn't flow at that point. The standard engines in GTO's and Firebirds used the 067 273* that was probably also used in the 72' 400. They really didn't step up their cam specs other then the 68' Ram Air II and then the with the same cam when the 70' RAIV was offered with the 1.6 rockers.
 
O-M-R

We've had several Pontiacs, but never a true Race Car. Only Street Performance Cars.

The 'S' Camshaft was a great Street Bumpstick.

#9779068 = .425"/.424" Lift ~ 288*/302* Duration ~ 63* Overlap

Worked nice with the Automatic.......

 
69 Cuda 440 said:
O-M-R

We've had several Pontiacs, but never a true Race Car. Only Street Performance Cars.

The 'S' Camshaft was a great Street Bumpstick.

#9779068 = .425"/.424" Lift ~ 288*/302* Duration ~ 63* Overlap

Worked nice with the Automatic.......
Click to expand...

I loved that cam. I put it in a 70' GP 400 i built for a co-worker. Even with a stock converter and 2.93? gears, it ran really strong with a good carb/dizzy tune. I think I have a pic or two of that car, but the're in the bedroom where "mama" is sleeping...lol.
 
OldmanRick said:
I know I won't make any friends here talking about Pontiac's, but I'd love to put together a 455 short block with good rods, forged flattops and top it off with a pair of round port 72cc Eddy's. The resulting 12+ compression and some cam would produce a nice bracket engine that should give a 550/550 engine shifted at 6k max.

I'd love to know the combo Steve Caldwell is running in his Ventura?
Click to expand...

:cheers:
 
I'd like to see one of these comparisons for a '72 Buick GS Stage 1 & a '72 GTX. That would be interesting :)
 
Part of the problem with the GTO was the weight of that body. The other was the the later 400 block was a real dog..... The late 60's 455 on the other hand was not. Put that drive train into a lighter car and you have something quick. Like many others here I do have and have had cars outside of Ma Mopar. I recently built a (brand X) 1969 Chevy Nova SS but did not use chevy for power. Instead I went with a 1968 455 Pontiac GTO block, with 78 6X heads (bored and stroked to 500 cubes) anyway enough of the specs. The thing is a monster in the light weight nova body. Point is the reason for the slow times of the later 400 is the later smog era 400 was a real dog. Partially due to compression and also the heads used. There was a high performance head and higher compression available on the firebird that was not a dog at all.
 
1972 Pontiac 400/250 HP

Cylinder Head..... 7K3

This 'D-Port' Cylinder Head was actually pretty decent for Mild to Mid-Range Performance and Street Use.

They had a pretty good flow-rate through the ports.
Intake = 206 CFM @ .500" Lift
Exhaust = 161 CFM @ .500" Lift

On the 1972 400/240 HP Engine, they came with 'Screw-In Studs' and 'High Load-Rate' Dual Valve Springs.

You could also mill the Hell out of them, and take as much as .070" off the Head surface.

.0048" = 1 CC
1 CC = +.12 Compression Gain
 
1972 'Duster 340'

The book states, the 1972 'Duster 340' was 'not' available with a rear Deck Spoiler
or Hood Scoops from the factory.
 
Deke,

1972 Pontiac GTO

Production Numbers

* 400/250 HP ............... 4922
* 455/250 HP ................ 240
* 455/300 HP 'HO' ......... 645

Motor Trend tested a 455/300 HP 'HO' ~ 4-Speed {M-22 Close-Ratio} ~ w/3.55 Gears 'Safe-T-Track'

Performance Results...... 15.40 @ 92.0 MPH

Pontiac Reported........... 14.60 @ 95.2 MPH

579_1972_Pontiac-29_low_res.jpeg
 
I don't know if growing up around low altitude tracks made a difference, but some of these test times are pathetic. I personally know of a 71' HO automatic that went 14.50's with nothing more then L60 tires. The 71/72 HO Birds were pretty deep in the 14's also. All I know is, if I had a confirmed low 15sec car, i would have avoided like the plaque racing those cars on the street.

Just some trivia, not that it matters on this site, but all the 70' to 72' 455 powered GTO's and Firebirds used the Chevy 12 Bolt rear instead of the Pontiac 10 Bolt.
 
The ultimate burnout car when I was in high school? 72' GTO convertible, standard 455, auto, with a "open" 3.07 gear. No "power braking" needed.....Just mash the pedal and completely incinerate the right rear tire. Shifted right into second, speedo hovering at 90, and 150+ feet later, $20 less tread on the tire.:D
 
O-M-R,

The 1972 GTO with the 455/250 HP {L-75} 'D-Port' Engine was an 'Automatic Only' option.

Engine Code 'L-75'........... Low Compression = 8.2 to 1

Cylinder Heads...'7M5'..... 114 CC's and Pressed-In Studs

No Horsepower.................. 250 HP @ 3700 RPM's
Massive Low-End Torque.... 470 Ft/Lbs. @ 3200 RPM's

If you wanted Horsepower Performance, everybody said to stay away from that 'GOAT'.

It was designed for Stump-Pulling/Low-End Torque, for the GTO 'option' Tow Package.

 
I honestly didn't remember about the 4spd availability, but it looks by your spec sheet that it is the case.

Thinking about these cars from so long ago, if I was ever to have one, i think my preference would be a 1970 455/360, Auto, loaded. Air, windows, tilt, cruise.....the works. Speed would be secondary. Kind of a Pontiac version of the "Gentlemen's hotrod".
 
Here's Pontiac's attempt at a "new" style spoiler on the 72's. Termed the "Ducktail" by some, it only made it onto a few cars before it was almost immediately discontinued. Rare today...yes. Looks...i wouldn't have a problem passing on it.
 

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