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Old 03-18-2004, 07:11 PM   #1
Mountain Man
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What HP did a stock 402 have?

Does anyone know what the stock HP rating was for the stock 71/72 402 block. Also, was this a good engine?
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Old 03-18-2004, 07:14 PM   #2
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Also, is Ochre and white a collectable color, would it be a crime to paint a different color.
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Old 03-18-2004, 07:18 PM   #3
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HP would have been 240 net, not sure on the TQ. Good motor.

Ochre and white is a very nice color, i have it on my '72 C10 (ochre body, full trim, and a white roof) and i love the way it looks. Think it is my favorite color on these trucks.

Its not really that collectible though, fairly common color. I don't think any of the colors availabe on these trucks are collectable, except maybe Coral Ice Pink.....

It is your truck so paint it a different color if you want, but i would wait. Ochre has a reputation of growing on you after a few months
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Old 03-18-2004, 07:56 PM   #4
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Yellow72Custom - would you have a picture.
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Old 03-18-2004, 08:17 PM   #5
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Here's an Ochre and White truck that I snapped at a cruze night last year...

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Old 03-18-2004, 08:20 PM   #6
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It's kind of confusing, because if you look in nada it gives you credit for 402 with 310hp and other books list the hp at 210,so I'd like to know too.
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Old 03-18-2004, 08:58 PM   #7
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If I was a betting truck owner I would say 310hp...I think the brochures also state 310hp...Anyone got a brochure? All my truck reference stuff is boxed up as I'm in the process of moving.
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Old 03-18-2004, 09:26 PM   #8
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Mountain Man
In 1971 the 400 V/8 was listed in the GM data package as:

Gross Horsepower 300 @ 4800 rpm
Net Horsepower 240 @ 4400 rpm
Gross Torque @ lb-ft 400 @ 3200 rpm
Net Torque lb-ft 340 @ 3200rpm
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Old 03-18-2004, 09:27 PM   #9
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While looking up the info for my 70 GMC on my motors #'s it showed 310 hp. There is a Ochre / White GMC near me.
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Old 03-18-2004, 09:28 PM   #10
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I second the 240hp, that is for a half ton pickup from 1972.
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Old 03-18-2004, 09:30 PM   #11
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In 71 and 72 they were designed to run on unleaded gas. Which reduced horsepower.
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Old 03-18-2004, 09:30 PM   #12
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71 Chevy Ochre / White
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Old 03-18-2004, 10:47 PM   #13
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Here is a pic of mine:


It looks kinda dark in this pic, but it is about the exact shade of the C20 posted above this.
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'97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg
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Old 03-18-2004, 10:49 PM   #14
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Good observation super72...
I forgot but the 71 and 72 BB's were reduced in hp in order to use unleaded gas...
I'll bet a hot fudge sundae that the 1970 402 BB was rated at 310hp...
Any takers?

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Old 03-18-2004, 11:28 PM   #15
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What HP was in the 72' 402BB?
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Old 03-18-2004, 11:58 PM   #16
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i believe the 72 402 was rated around the 240 mark for a manual tranny and about 210 with auto
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Old 03-19-2004, 12:11 AM   #17
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Also remember this was near the end of the muscle car era. The insurance companies were starting to hit the high horsepower engines a lot harder. I believe they started measuring the horsepower differently to keep insurance rates down. It had something to do with measuring at the end of the transmission or rearend instead of the flywheel. This gave a lower number. I am sure there was some drop because of the unleaded gas, but I think most of it was smoke and mirrors measurements to keep rates lower. Anybody else remember this?
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Old 03-19-2004, 12:16 AM   #18
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In 72 they started measuring net HP at the rear wheels, previously it was listed as Gross HP or Engine HP.
That is my understanding of the big HP drop for 1972.

My dad's 72 ran regular gas, so did his 76. The 78 was his first unleaded only truck.

My 72 shop manual specs the 402 as 210 hp. No mention of a 240 version.

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Old 03-19-2004, 07:44 AM   #19
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The '71 GM Chevrolet Truck Service manual states 300 h.p @ 4800 RPM & torque 400 @ 3200 RPM ( 402 engine)
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Old 03-20-2004, 04:32 AM   #20
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I was thinking, that the main reason that the HP numbers were lower in 71-72 was due to new emissions requirements, and that the 'modification' to the engines was to retard the timing.
I could be wrong of course, but that is what I have read in a few books. On the other hand, I didn't think unleaded fuel became standard until 1976, but again, I am too young to verify this. I was 4.
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Old 03-20-2004, 11:37 PM   #21
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The differnce is Net and Gross HP, Gross HP was used up until 1971. Net HP is the HP of the engine as it is installed in the vehicle, with all accessories (water pump, alternator, PS, air cleaner, exhasut manifolds, mufflers, ect) attached. Gross HP was just the motor, and sometimes they would run high octane fuel, advance the timing, ect., to make the enigne look more powerful on paper.

I doubt you would see much, if any, difference in performance between a 1971 402 rated at gross 310 HP, compared to a 1972 402 rated at 240 net HP
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'70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck.
'97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg
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