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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!
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| | | | Joined: Jun 2012 Posts: 76 Shop Shark | | Shop Shark Joined: Jun 2012 Posts: 76 | Can anyone confirm the correct location for the sending unit to be installed in engine? Is it the driver side rear most head bolt on top? 1950 216 engine
Last edited by 1965t5; 12/31/2015 2:16 AM.
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 |
Denny G
Sandwich, IL
| | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | So no one is confused, the sending units are normally pipe thread.
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: Jan 2010 Posts: 4,263 Shop Shark | | Shop Shark Joined: Jan 2010 Posts: 4,263 | Straight thread on the 1950 216 mechanical sender | | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | 1956 was the first year for pipe thread, for the new electric sending unit design.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Right Dave and the thread in the 216 head is 5/8-18 not a pipe
thread. Big discussion on that just last week, and those
pictures I linked to illustrate that.
Even though the pitch of a nominal 3/8 NPT is 18 threads per
inch, it is a tapered thread and the 216 sender socket
is UNF which is a straight thread. The tap drill for both
the 3/8 NPT and the 5/8-18 are both 37/64" this is where the
confusion often comes into play.
dg
Last edited by Denny Graham; 12/31/2015 7:38 PM.
Denny G
Sandwich, IL
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | As a philosopher (not you) once asked, Denny: "why would GM ever do that?" | | | | | Joined: Jan 2010 Posts: 4,263 Shop Shark | | Shop Shark Joined: Jan 2010 Posts: 4,263 | Ran into this issue when I was trying to install an aftermarket electric sender that was 1/8 pipe.
Had to make my own adapter
Ran a 5/8 18 UNF die over a 3/8 brass adapter.
I will never forget that size, got the info from pre68dave
The later heads pipe size is alot larger than 3/8 pipe | | | | | Joined: Mar 2010 Posts: 10,271 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,271 | Does that 5/8-18 hole in the 216 head have a smaller diameter tapered portion at the bottom that mates up with stock temperature gauge bulb/nut?
Carl
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Feb 2001 Posts: 1,096 'Bolter | | 'Bolter Joined: Feb 2001 Posts: 1,096 | Yes the taper is the seal face for the unit. | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | Sorry for the misinformation.
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: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Tks Dusty, and that Tim, is the reason "why would GM ever do that?"
The sender bulb being fixed to a capillary tube meant that it
couldn't be turned so they used the same principal as a flared
tube and flare nut, with a straight thread to seal the bulb
into the seat. And GM wasn't the only one using that was to
install mechanical temp gauges, it was quite common before
the advent of electrical gauges.
dg
Last edited by Denny Graham; 01/01/2016 12:18 PM.
Denny G
Sandwich, IL
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