Difference between 70 71 72 ?
Le Mans Master
Joined: Jan 2007
Posts: 5,485
Likes: 7
From: Peekskill NY
I just looked at ondagawood's '72 project yesterday, and noticed that it has front seat belt retractors under the carpeting, whereas my '70 doesn't have them, but does have chrome holding clips attached to each seat to hold the lap belts neatly in place.
How about the '71 configuration?
How about the '71 configuration?
Also the Alternator mounting bracket & exhaust manifold design changed on the 72 SB. It bolts to the head & water pump. 70-71 bolts to the water pump & exhaust manifold.
Pro
Joined: Oct 2004
Posts: 624
Likes: 24
From: Shoreline WA
My guess is a 1971. You realize this is a 10-year-old thread? No comments for a decade. Anyway, the fender badge shouldn't be there, no gauges on the wiper door, and inboard backup lens missing. Front air dam? May or may not be a big block. Still, it's a beautiful car! Wish mine looked that clean.
Race Director
Joined: Oct 2008
Posts: 19,141
Likes: 1,667
From: Long Island
Front Grill
70 studs for mounting , hole in turn signal case for fiber optic - Amber lenses
71 screws for mounting , hole in turn signal case for fiber optic - amber lenses]
72 screws for mounting , no hole in turn signal case for fiber - no fiber optic - clear lenses. amber bulb,
70 studs for mounting , hole in turn signal case for fiber optic - Amber lenses
71 screws for mounting , hole in turn signal case for fiber optic - amber lenses]
72 screws for mounting , no hole in turn signal case for fiber - no fiber optic - clear lenses. amber bulb,
Melting Slicks
Joined: Dec 2016
Posts: 3,193
Likes: 184
From: Central Bucks County, Pennsylvania
My guess is a 1971. You realize this is a 10-year-old thread? No comments for a decade. Anyway, the fender badge shouldn't be there, no gauges on the wiper door, and inboard backup lens missing. Front air dam? May or may not be a big block. Still, it's a beautiful car! Wish mine looked that clean.
Also, I believe the rear view mirror (inside), changed in 72, from polished to a black finish.
The Blue interior changed to a darker Blue for just 71 and 72.
In later production 71 the leather seats had pleats running side to side instead of fore and aft.
Fuel filler door hardware (seen when you open filler door) changed in 71 to make filling easier.
I know there are a few more things, but it will come to me later
Last edited by Z06LMB; Feb 2, 2019 at 04:16 AM.
4th Gear
Joined: Sep 2017
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From: Marietta Ga.
Burning Brakes
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1967 Pedal Car Champion
Joined: Mar 2020
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From: US-PNW
It's a very old thread, but since it's reopened by 3 or 4 replies:
I won't dispute that the HP was lowered each year, but you two are mixing apples and oranges. To say the HP went from 390 to 270 is terribly misleading. For '70 GM used gross horsepower and for '72 GM used net horsepower. The ratings method was in transition in '71 and is the only year GM specified the ratings using both methods (365 gross/285 net).
A few years ago I had my original stock '72 454 rebuilt. The compression was raised to about 9:1 or 9.5:1 but all else was very close to factory components (.030" over, hydraulic flat tappet "RV" cam, original heads w/new guides and valves). The dyno came in at something right about 395hp. 1/2 point of compression may account for a slight bump but it wouldn't be all that significant and certainly not 120 hp (270 to 390) as indicated in your quotes.
It's been stated here on CF that quite a bit of detuning of the ignition for emissions will account for a good part of the HP loss.
A few years ago I had my original stock '72 454 rebuilt. The compression was raised to about 9:1 or 9.5:1 but all else was very close to factory components (.030" over, hydraulic flat tappet "RV" cam, original heads w/new guides and valves). The dyno came in at something right about 395hp. 1/2 point of compression may account for a slight bump but it wouldn't be all that significant and certainly not 120 hp (270 to 390) as indicated in your quotes.
It's been stated here on CF that quite a bit of detuning of the ignition for emissions will account for a good part of the HP loss.
For '70, the LS-5 had 10.25CR (390 gross hp);
For '71 & '72 the LS-5 had 8.5CR (365 gross hp).
You can see that much more is going on for that 25 hp loss than just compression ratio when my 454 jumped back up to ~395 w/a slight compression bump but tuned for performance by my builder. There was a lot going on politically in this time period with emissions and insurance regulations such that the Big 3 were detuning and downplaying horsepower.
For '71 & '72 the LS-5 had 8.5CR (365 gross hp).
