1967 Pontiac GTO idle speeds and other trivia

[rodneybeauchamp]

Hi? Can someone advise the correct fast idle speed and normal idle speed for the GTO with 400cu in motor. A/C car specs preferred.

 

Does the hood mounted tachometer read left to right or right to left? What is the red line marked at.

Does the His / Hers automatic shift hold gears 1-2-3 without shifting?

 

thank you

Rodney 😊😊😊😊😊😊

[rocketraider]

Don't have your exact idle specs but 1100 rpm fast idle and 650 curb idle are common on mid-60s GM cars. I cannot remember if Pontiac used an idle speed solenoid on A/C cars. Been years since I've owned one.

 

Every hood tach I'm familiar with sweeps left to right with zero at the left. Different engines will use different rpm ranges and redlines. Some 0-6000, others go to 7 or 8 thousand. All depends on the car's original engine usage.

 

The Hurst Dual/Gate (correct name, His-and-Hers came out of the original 1963 sales brochure) operates thusly: in the PRNDSL (left side) gate, the transmission shifts thru 1-2-3 in D and will hold 1st or 2nd in L or S.

 

Put the shift lever in the 3-2-1 (right) gate and it functions as a ratchet shifter. Start in 1, when you're ready to shift push the shift lever forward and sharply to the right against the stop and it will lock in 2. Shift 2-3 same way and it will lock in 3. The idea behind the Dual/Gate is to prevent a botched 2-3 shift where you'd go too far, hit neutral and over-rev the engine.

 

I can't find a good youtube of anyone actually shifting a Dual/Gate the way it's meant to be used, but here's one of Pontiac's in-house ratchet shifter they used starting 1970.

 

 

[Str8-8-Dave]

Rodney- I had 68 and 69 GTO's with 400 cu in motors, the 69 was a RA IV automatic without air.  The 68 was a 400 HO with air.  These idle speeds are from memory, may not be exact.  The 68 A/C on idle was around 750-800 in neutral, should not be below 600 in gear.  Fast idle was around 1200-1250 rpm cold, A/C off.

 

The Hurst Dual Gate shifter with gate closed only allows access to park, reverse, neutral and drive, it will allow fully automatic upshifts in drive.  Gate open then allows access to second which when left in that position will  only lock out drive.  If you come to a stop with the gate open second position the car should downshift to first and allow automatic upshift from first to second.   Selecting low gear or first gear will hold the trans in low gear, no upshifts. 

 

I never had a hood tach but it does read from left to right, needle moves clockwise as engine speed increases.  Typically redline starts at 5500.

 

Milt Schornack installing the 400 HO in my 68 GTO after working his magic.  Milt Schornack

was MR Royal Bobcat GTO and campaigned cars for GM and Royal Pontiac.

 

I wanted my GTO to look bone stock under the hood but still pack a little extra wallop.  It

had a crank ground 0.060" to lengthen stroke 0.120" giving 406 cu in and had a roller cam,

custom calibrated Quadrajet carburetor, custom curved distributor, higher stall torque converter

and reworked trans valve body.  It would easily rev to 6,500 and chriped modern radial tires on

the 1-2 shift...  The A/C was restored and functional.

 

This car's interior was a mess requiring rewiring, restoration of Rally Gauge Pack and I had

to find an 8-track player and replace an aftermarket wheel with the correct sports wheel

to get the car back to the build sheet specs.

 

The car was probably a secretary's car, it was originally built with PMD pancake wheel covers

and whitewall tires which led the unwary to think it was a cream puff. 

Edited July 18, 2021 by Str8-8-Dave
Add pictures and text (see edit history)

[rodneybeauchamp]

Wow. This is amazing stuff. Many many thanks to you both. I lusted after a ‘67 GTO years back but never happened when I was into Pontiac.

 

FYI am writing an Automotive fiction novel and one main character has a ‘67 GTO so it features prominently. I want the details to be accurate for the reader so information you both provided and video Glenn provided about the his/hers shifter are gold. If it didn’t come as an option someone fitted it. It makes for an exciting action scene.
 

Dave, those photos of your restoration underway are magic as they give me lots of accurate details that I can pop in.

 

The idle specs are important as when you start these GM engines,  they immediately go to fast idle. So the shifts into reverse and drive in the automatic transmission are always going to jolt the driver.

 

I enjoy reading but a pet peeve is books that gloss over technical things or leave them out or worse get it wrong because the author didn’t research. Anyone can describe stone walls and green trees or a picture on the wall. 
 

So having the “ GTO driver slow and pull over left, then make a wide U turn. Gunning the big 400 back up the highway, slamming the his/hers shifter into second and chirping the tyres as the needle sweeps the hood mounted tachometer” is probably a bit more exciting as well as being technically correct!

 

many many many thanks

Rodney 😊😊😊😊😊😊😊😊