Torque Specifications for The PB Engine

[Canadian PB Kid]

I got a call from the fellow doing the babbit work on my PB engine and he's asked if I could find the torque specs for the mains, rods and head. I checked specifications section in the instruction book and the parts catalogue but I didn't see this info. Am I looking in the wrong section? 

Would anyone have the torque specifications for the head nuts, connecting rod caps and main bearing caps for the PB? 

 

Thanking in advance!

 

Dave

 

STAY SAFE!

 

[Bloo]

At the time the PB was made, torque wrenches were not yet common in the automotive world. On some cars, you can look at a later version of the same engine, but I don't think that helps with the PB.

 

@ply33 do you know anything about this?

[Canadian PB Kid]

2 hours ago, Bloo said:

At the time the PB was made, torque wrenches were not yet common in the automotive world. On some cars, you can look at a later version of the same engine, but I don't think that helps with the PB.

 

@ply33 do you know anything about this?

Yes, I thought it was unusual that these torque specs were omitted when all other clearances were included in the reference books. Hopefully someone will have the updated specs recorded and be able to share them. 

 

STAY SAFE!  

[ply33]

I think @Bloo has it correct. I do not have an extensive library, but from what I have the earliest shop or repair manuals with torque specifications were published in the 1940s. Since the Plymouth 6 cylinder engines in the early 1940s as basically the same as the 1935 engine (and similar to the 1933 & 1934 engines) those later books sometimes give values for the engines from the mid-1930s. See: https://www.ply33.com/Repair/torque

 

For the 1932 and earlier vehicles I have never seen published torque specifications.

 

However all is not lost as there are published torque specifications for fasteners based on size, thread pitch and grade. My “go to” for that information is a mid-1980s Machinery’s Handbook which is simply a huge fine print reference book for machinists with all sorts of information about machining and assembling mechanical things. So you can look up the bolts, studs, nuts, etc. by size and see what the torque values are. I haven’t checked but I bet there is a later edition of that book available new or you could pick up an old one from some used book vendors.

 

The caution there is that I suspect that lots of things that now use grade 4, 5 or stronger fasteners probably used grade 1 or grade 2 back in those days. For example the compression ratio of the 1932 engine is probably about 1/2 of that for a modern engine so they did not need as much clamping force to seal the head and might have used common grade 1 or 2 studs, not special hardened ones. If you still have the original fasteners then you might be able to test them for hardness and guess what grade they were so you know what to look up in the machinist’s handbook.

[keiser31]

16 hours ago, Canadian PB Kid said:

I got a call from the fellow doing the babbit work on my PB engine and he's asked if I could find the torque specs for the mains, rods and head. I checked specifications section in the instruction book and the parts catalogue but I didn't see this info. Am I looking in the wrong section? 

Would anyone have the torque specifications for the head nuts, connecting rod caps and main bearing caps for the PB? 

 

Thanking in advance!

 

Dave

 

STAY SAFE!

 

This may help....

[keiser31]

Got these from an old mechanic for my 1931 Dodge Brothers DH6....

[Bloo]

If I'm not mistaken, the PB is a four cylinder engine. It is unlikely to be related to the sixes.

 

 

[TTR]

Another option could be to research what, if anything, some other manufacturers of similar size/type engines (i.e. 4-cyl. with similar bore/stroke, compression, crank journal diameters, etc) suggested for torque specs during late ‘20s/early ‘30s.

Edited October 20, 2021 by TTR (see edit history)

[Canadian PB Kid]

Thank you keiser31 for posting these, it helped getting and figuring out the info required... we are going with 60-65lbs for the head and the rest will be by general torque recommendations...   

 

Thanks to all who took the time to chime in and assist in clarifying this info....  my research indicates Chrysler patented the first beam torque wrench in 1938 and then sold the patent in 1940.... interesting....

 

Dave,

STAY SAFE!