Liam's 1932 Cammy

[Liam.Plant]

I am finally back from vacation and have started inventorying my basket case engine. During the summer I databased the entire 1931 & 1932 Illustrated Spares list (and Supplemental) for Model 4F.

The person who took the engine apart did me no favors in that the connecting rods were not labeled. Here's what I'm looking at:

The 1932 Supplemental indicates that there is a special connecting rod on Cylinder 3 (and a special bearing, but I have not gotten that far yet). It does not, however, indicate what the difference is and I can see none. Here is a photo... the rods, bushings, nuts, nut locking washers and Big End Retaining discs are grouped ... each rod was in a separate bag, containing all of the parts on top of, and to the right of it. There are a LOT of Small End Bushings.... not sure if that gives any clues....

I can work on engines, but I have never built one, so purchasing a basket case was likely not the best decision that I've ever made. Without the photos that I take upon disassembly, and my labeling, I'm struggling. I want to think that the person who disassembled the engine packed the relevant connecting rod pieces together, but unfortunately I don't know who that person was. If it is cylinder 3 that also has no Big End Nut or Retaining Disc, then I COULD assume that the one on the right is Cylinder 3, but I would feel much better if somebody could tell me how to properly differentiate that rod from the others.

The same thing was done with the Main Bearings. They were all in one bag and I cannot tell them apart.... they seem to be the same thickness and diameter, with 9 bearing balls between the races. The only thing that appears different is that one bearing has 2 markings on the inner race, and the others do not. Again, if somebody could let me know if I'm on the right track, or what the difference should be, I would greatly appreciate it!

[Liam.Plant]

Can anybody please tell me what the difference is supposed to be between the connecting rod on Cylinder 3 of a 1932 SQ4, versus the other three (as per the 1932 Supplemental Parts list)?

[paul.jameson]

The fundamental difference is that cylinders Nos 1,2 and 4 have overhung big ends whereas No 3 has a conventional big end so as to enable the drive to be taken from it. Looking at your photo, it would suggest that the 3 conrods with associated nuts, retaining discs and locking washers are from Nos 1,2 and 4 while the one lacking the nut, retaining disc and locking washer is No 3. By the time the later OHC Fours were produced (1933-36), the big end bearing for No 3 was larger in diameter than the other 3, presumably to strengthen the crankpin which took all the drive load. Such a difference in diameter is not obvious from your photo but may be there.
Before seeing your postings I was not aware of the change in one of the big ends for 1932 and the implication that, in 1931, all 4 big ends were the same size. Presumably, the new bearing was needed as a result of the increase in power going through that crankpin following the increase in capacity from 500cc to 600cc.

There may, just possibly, be clues about your engine in the factory Despatch Book. If you let me have your engine number, by private message or email to the address on the inside front cover of Cheval de Fer, I will look it up for you.

Paul

[Liam.Plant]

Done. Thanks Paul