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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
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| | | | Joined: Apr 2009 Posts: 88 Shop Shark | | Shop Shark Joined: Apr 2009 Posts: 88 | I am starting to restore my 640 with a 471 and 5 and 3 trans. I am going to start by making sure the motor is okay and then I am going to replace the 5 speed with a 610 road ranger I have. Also does anyone know if they made a turbo 471? I will be in need of a few small parts like a factory air gauge or have mine restored. I will post pics when I get them.
Thanks
Brad | | | | | Joined: Jan 2008 Posts: 4,964 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,964 | Detroit did offer a 471 turbo version, but it will require different pistons and head. A turbo upped the hp by about 30. | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | How are the Pistons different(compression ratio?) and head different?
I have a 630 with a 503 gasser and need a water pump and some other small parts, was thinking of putting a 4-71 in it.
Thanks,
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: May 2005 Posts: 8,878 . | | . Joined: May 2005 Posts: 8,878 | Pistons and liners are usually different between turbo and natural Detroits. The compression ratio, sometimes port height, and probably where the rings are on the piston.
Head casting may or may not be the same, valve seat inserts are different, usually the valves, and sometimes springs too.
While you could just add a turbo to an N engine you'll have better long term results by starting with a real T engine, especially if you plan to work it hard. | | |
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