From: "'Hugh Boultbee' via Chrysler 300 Club International" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Date: Sat, 2 Nov 2024 08:49:28 +0000 (UTC)
According to my own personally gathered up spreadsheet of thread data, the following probably applies here:
• 3/8 (approximately) x 27 tpi (threads per inch) ought to be 1/8 NPT, which is a pipe fitting or fluid seal type of relatively fine thread form that in ‘real’ dimensions is slightly larger than 3/8" (outside diameter 0.405") • Note - the British ‘pipe thread’ equivalent is 1/8 BSP (28 tpi @ 0.383" outside diameter) • 1/8 BSP and 1/8 NPT are thus very similar to each other (the same situation applies for other sizes) but fittings in those two threads do not interchange • Special note 1 - ½ BSP and ½ NPT are both 14 tpi and the same diameter (0.825”) • Special note 2 - 3/4 BSP and ¾ NPT are both 14 tpi and the same diameter (1.04”) • Special note 3 – However, BSP has thread angle 55° and NPT has thread angle 60° , as per BSW (55°) versus UNC (60°), which usually have the same tpi and will usually be interchangeable in practice, apart from at ½”, where their tpi values do not match • Special note 4 – all other BSP/NPT ‘pipe’ sizes seem to have non-matching tpi values
Hugh
On Friday 1 November 2024 at 12:44:32 GMT, Bob Merritt <bob@xxxxxxxxxxxxx> wrote:
3/8 x 27 and .375" long.
The one I pulled is brass.
3/8 x 27???? Yes, I double checked.
I had not heard of 27" thread before but
I see you can get taps and dies that size
so it does exist........
Bob
On 10/31/2024 9:50 PM, 'Marilyn James' via Chrysler 300 Club International wrote:
Can anyone tell me thread size and bolt size for the drain plug on my 61G. Any help would be greatly appreciated.