Datsun Roadster Forum-311s.org

putting the carbs onto the studs on the intake. I have the correct, smaller nuts. Not sure if a lock washer was/is used originally. input please.

My numbers matching ‘66 put together by Ross has them. Not sure if original or not. Hope that helps.

In very high tension locations such as rods, main bearing caps, heads etc. the torque is high enough that no lock washer is needed. The stretch of the bolt is what makes it impossible for the nut to back off. In lower tension locations lock washers of different types are used. The carburetor insulators would crush with the torque needed to rely upon bolt stretch.

I use a lock and a flat as in the picture above.

C.Costine wrote: Mon Aug 24, 2020 7:37 am In very high tension locations such as rods, main bearing caps, heads etc. the torque is high enough that no lock washer is needed. The stretch of the bolt is what makes it impossible for the nut to back off. In lower tension locations lock washers of different types are used. The carburetor insulators would crush with the torque needed to rely upon bolt stretch.

I'm familiar with Clamp Load, the force that a bolt produces when tightened. Was wanting to know what washers were original. Pat

Pretty much certain it is as shown in the photo by Devo above flat washer, lock washer, nut.

You mentioned smaller nuts though, that puzzled me. A 66 is all SAE&USS so the nut should be 5/16 SAE, 1/2" wrench size.

If you have nuts with 12mm flats, those are 8mm metric which is a mis-match for your engine. (Doesn't really matter other than requiring a metric wrench for your 66, but if you are trying to be 100% correct, you need 5/16 nuts w/1/2" flats.

If you look at the parts manual it is interesting. The old rubber type insulators show flat, lock and bolt to the manifold. For carbs just lock and nut to insulator. Then in usual Datsun fashion in figure two they show the new insulator and stud but of course not the nut and washer. I hate these parts manuals, they all seem to be different.

So I guess you extrapolate flat,lock and nut. Personally I just don't put lock washers against aluminum so it can dig in to the surface even when it shows to. Who knows, maybe I'll be sorry someday.