Datsun Roadster Forum-311s.org

We’ll gang,

Blew the motor in my 67.5, while driving back from Sarasota. Ended pulling the motor and gonna swap with another 67.5
Come to find out I think I had a 68 motor and tranny.
Air injection bracket on left motor mount. And injection ports on head, Plugged engine drain port on left side.
The tranny is different as well.
The interesting part is the different reverse switches

Well while pilling the blown 68 motor you notice switch on the right with black plate and 2 tabs (25310-14600) 1/2-20
And the left out of the (maybe working 67.5) with broken tab and white cap. 9/16-18

The problem is the thread size is different
I need the 9/16-18 or how to fix the broken tab.

Does anyone know of a different part number with the same tread?

I can’t help with the part numbers, but you should be able to solder new spade (tab) terminals to the old switch. You could also solder short wires directly to the switch and then crimp quick disconnects to them.

According to CarPartsManual.com for Part Numbers, see the following links:
https://www.carpartsmanual.com/datsun/s ... 1600-(r16)
For the 4-Speed, Early (to Sept '67) Fig #97
https://www.carpartsmanual.com/datsun/s ... 0-(r16)/97
For the 4-Speed, Late (from Oct '67) Fig #98
https://www.carpartsmanual.com/datsun/s ... 0-(r16)/98

For the 5-Speed:
https://www.carpartsmanual.com/datsun/s ... 2000-(u20)
Fig #11
https://www.carpartsmanual.com/datsun/s ... 0-(u20)/11
I hope this helps,
Mike

I suspect that the one you think is 9/16-18 is actually a 14mm-1.5 late model (68-70) reverse lamp switch. Dean has them here:

https://datsunparts.com/collections/ele ... amp-switch

If you read the text in the description, it tells you that the late model switch is 14mm-1.5 which is very close to 9/16 SAE. I think the 1/2-20 switch is the 65-67 switch as the parts manual indicates.

DEV, I think that sounds about right, I actually measured 3 of the larger, used ones I have, all three measured at 0.547" or 13.893 mm....

Why did the engine seize?

I suspect oil pressure. Not sure. Pulled the motor, the valves look good through the ports but the crank WILL NOT turn at the pulley. Gonna swap the motors, the tranny was rough going into 2nd gear, so I can drive. Then pull apart the motor with my sons.

Jujuman wrote: Sat Nov 30, 2024 10:52 am I suspect oil pressure. Not sure. Pulled the motor, the valves look good through the ports but the crank WILL NOT turn at the pulley. Gonna swap the motors, the tranny was rough going into 2nd gear, so I can drive. Then pull apart the motor with my sons.

Interesting... please do let us know. The Oil pumps are very simple and robust. I'm sure mine has seen 300k and independent inspections have always given it a good bill of health. Did it happen while drving? Any warning signs before? Whenever something catastrophic like this happens to a members engine it's always helpful to know why, so thank you!

Hope the newer motor works well!

So we were driving back from Sarasota ( 50+ miles) and noticed some loss of power and an odd sound. Stopped and checked oil level. Good. Ran about 5 miles more and stalled at light. Towed back home. Started up ok. Couple days later tried to drive to the garage made it a mile and heard a clunk and engine cut out. Pushed to the side waited an hour for the tow and would not turn by the starter. Eventually got it to my storage shed/shop and pulled motor.
No oil in antifreeze and the valves look straight and tight through the ports. But will not turn by wrench. I’ll drain the oil and pull the pan and take photos. But I suspect not good things.
But silver lining. I wanted to build a 2L clone and have just about everything except the SS license plate surround.
14 yrs of amassing parts.

Glad you were able to find an upside! Sounds like you may have lost a rod bearing. Thanks for posting!