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#26 | |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,717
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Re: how rare is factory AC?
There were no high performance high compression big blocks in the trucks. The only real difference between the 396 and 402 is a .030 overbore. And on the GMC trucks, they list the big block as "400" on the SPID. Same motor. The combination of pistons and combustion chamber dictate compression ratio. Closed chamber heads used different domes than the open chamber but the were all 8.5:1.
I just built a 390hp 427 for my '69. It's also a '69 from a 'vette. 512 2 bolt block and 290 101cc heads. Should be right at 10:1 with the SpeedPro pistons that are the stock replacement spec. I have a second 427 with the same pistons and a set of 781 heads that should put the motor at 9.3:1 because of the 118cc chambers of the later open chamber heads. Quote:
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#27 |
Registered User
Join Date: Jul 2017
Location: herminie, pa
Posts: 313
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Re: how rare is factory AC?
It seems like most of the big block trucks discussed in this thread had automatic transmissions. Was that the preferred way to order a big block truck?
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2009 GMC Sierra 1500 2006 Buick Lacrosse 1987 Chevrolet V10 1972 Chevrolet c20 350/350 1967 Chevrolet Biscayne ls3 swapped |
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#28 |
Registered User
Join Date: Oct 2014
Location: Mesa AZ (Near Phoenix)
Posts: 2,302
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Re: how rare is factory AC?
nice.
I am usually not much of an original guy, but when you find one like ours that's all there, well, that changes things. For me at least. Last thing on earth I want to do is cut this one up or rip out that big block.
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"Life is too short to drive a boring vehicle". Later, Wayne ![]() |
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#29 |
Registered User
Join Date: Oct 2014
Location: Mesa AZ (Near Phoenix)
Posts: 2,302
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Re: how rare is factory AC?
Beautiful truck.
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"Life is too short to drive a boring vehicle". Later, Wayne ![]() |
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#30 | |
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,224
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Re: how rare is factory AC?
Quote:
If you're saying only GMC shows 400, I have two 402 Chevy that show 400 on the SPID. I know little about engines, but I understood heads do contribute to compression. That or perhaps they provision for more compression? Is it possible high performance heads came on a Chevelle and such? On a side, that license plate number is a fluke. Considering they use letters as well, what you figure the odds? It's another reason I chose not to destruct the truck. ![]()
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 07-19-2017 at 12:31 PM. |
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#31 | ||
Senior Member
![]() Join Date: Feb 2009
Location: Northern Nevada
Posts: 7,224
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Re: how rare is factory AC?
Quote:
Quote:
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Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assembly kit for restoring the (a) truck from the ground up. My build thread, and more on the assembly kit https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 07-19-2017 at 01:17 PM. |
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#32 |
Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,717
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Re: how rare is factory AC?
Just saying my experience with big block trucks are just GMC's. Not sure how Chevy did that.
The heads and the pistons together determine the compression ratio. And there was never a higher compression big block in a 67-72 chevy truck. At least from the factory. 70 was the first year of the open chamber head in production (69 ZL-1 had open chamber aluminum heads if memory serves) but only on some engines (hi perf 454 for sure) but I think it was 71 before the 402 Chevelle got the open chamber heads and I think the truck soldiered on with the closed chamber until the arrival of the 454 in 73. That was why gross power outputs were lower in '71 and then the net power measure in '72 really dropped the numbers. Either way GM spec'ed it with no dome closed chamber or small dome open chamber, compression was 8.5:1 for truck 402's. But in the 40+ year history, what's on the truck and what came on the truck but not be the same...
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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#33 |
Registered User
Join Date: Jul 2017
Location: Bee Cave TEXAS
Posts: 6
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Re: how rare is factory AC?
My 67 in high school had AC - and the 72 that I sold 14 years ago also had it - I miss both of them... getting the urge to get another one...
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#34 |
Registered User
Join Date: Aug 2017
Location: Peoria Heights,IL
Posts: 4
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Re: how rare is factory AC?
Sorry to butt in on conversation but was wondering if one might be able to say values on a big block AC truck? A few months ago I bought a 71 long Cheyenne, factory 402, turbo 400 trans, factory AC (everything is there, just not working at the moment). I bought it from a friend and really enjoy the truck, I am just curious as to what values a big block goes for as opposed to a small block? I don't see (in my area) a big difference in pricing
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#35 |
Florida Edition
![]() ![]() Join Date: Oct 2010
Location: Fruitland Park, FL
Posts: 4,025
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Re: how rare is factory AC?
All depends on total package, condition and personal preference.
The deference between long bed big and small blocks might not be much but the deference between short bed big and small blocks is about 150% See attached..
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70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394 |
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#36 |
Registered User
Join Date: Aug 2017
Location: Peoria Heights,IL
Posts: 4
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Re: how rare is factory AC?
Wow that is a beautiful truck! Mine isn't near that condition. Mine isn't restored, it's patina'd and mostly solid....rockers are shot, but other than that, in good shape. Definitely wouldn't bring the money yours would! I'd have a hard time parting ways with it so I guess value doesn't really matter, just something I was curious about. I've seen a few big block trucks in my area that have been LS swapped and it didn't make sense to me of why you'd want to do that to a rare packaged truck
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71 c10 longbed, 402, AC 2011 Silverado 2500 duramax (daily driver) 2013 Rzr 800s (toy that has lost attention since c10 moved in) |
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#37 |
Registered User
![]() Join Date: Sep 2013
Location: Western PA
Posts: 1,295
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Re: how rare is factory AC?
Here's another 1971 BB with AC. It's a SWB Cheyenne too. It's currently in storage, but the original white/ochre/white/ochre paint schema will ride again some day after I finish my other project. One of the great rarities of the C/K-10/20 world.
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#38 |
Registered User
Join Date: Aug 2017
Location: Peoria Heights,IL
Posts: 4
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Re: how rare is factory AC?
I wish mine was a short bed, I really like the stance of those! That last one you posted looks great! Here are a couple photos of mine
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71 c10 longbed, 402, AC 2011 Silverado 2500 duramax (daily driver) 2013 Rzr 800s (toy that has lost attention since c10 moved in) |
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#39 |
Registered User
Join Date: Aug 2017
Location: Peoria Heights,IL
Posts: 4
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Re: how rare is factory AC?
Okay let me try this again....Im having a hard time posting pictures on my phone, so switched to work computer
https://www.flickr.com/photos/151065...posted-public/ https://www.flickr.com/photos/151065...posted-public/ https://www.flickr.com/photos/151065...posted-public/ https://www.flickr.com/photos/151065...posted-public/
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71 c10 longbed, 402, AC 2011 Silverado 2500 duramax (daily driver) 2013 Rzr 800s (toy that has lost attention since c10 moved in) |
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