681 crossflow

[rdssdi]

What is the thread size for the electric temp sender for the early (681) crossflow?

It appears to be 3/8 BSP. Is this correct?

Who sells 3/8 BSP temp senders. AC (UK) temp gauge.

Bob

[peteleo]

Bob,

It should be 3/8" tappered by 28. P/N: D1FZ-10884B with a round end connection. When new they read 350 Ohms. Faulty temp senders will read a higher resistance that indicate a lower reading on the gauge when actually the eng. temp is higher.
Found one on ebay item # 290607678995

Pete

[rdssdi]

This is the sender that I removed from the engine. Would 3/8 x 28 be a BSP thread? I know that a 3/8 NPT is different. Slightly larger will not thread in.

[rdssdi]

The threads cannot be 28 tpi as you indicated. The original sender which threads in nicely, are approx. 20TPI. As 3/8 NPT does not fit I assume it is 3/8 BSP ( which is 19 tpi?) and possibly straight threads not tapered.

[peteleo]

I remember now that this comes off your TVR.

What you have there is either a Smiths or AC sender. Size: 3/8W ( British Standard) nut. Thread size: 5/8 x 18.

These units require a brass washer. Smiths or AC are approx. 500 ohms.

What is wrong with your sender ?

[rdssdi]

Could be the 5/8 x 18 thread but what I cannot understand is that all the specialist suppliers list the early crossflow temp senders as 1/4NPT. Certainly not what this is. I do not believe that TVR would modify the opening in the head to accept a different thread size.

The original has a cracked insulator and has 0 ohm when tested.

I have not seen any 5/8W threaded senders. Any idea where they came from besides a Cortina?

Bob

[peteleo]

All MK2 Cortinas imported to N.America have the 3/8"x28 or 1/4NPT temp senders which match the temp gauge.

TVR may have modified the head to accept the larger senders for the Lucas or Jaeger gauges.

EnFos before approx. '66 used the 5/8"x18 AC or Smiths senders.

There should be a manuf. p/n on your sender. I may have one.

[rdssdi]

The P/N on the sender is partially obliterated. I can make out 8 ? 6195 AC Made in England.

I have ordered a smiths sender with the same threads. The AC appears to use the same ohmic range. I used 94 ohms which gave an 80 deg c reading. -Scale is 40 deg C to 110 deg C. That appears to be the 10-180 ohm sender.

I am surprised that TVR would modify anything that required machine work. It is more their style to use some goofy adapter using over the counter auto parts.

Bob