1954 Bigtwin 25 help please

[kodibass]

I am re-ringing a 1954 bigtwin 25 hp sn# 25916-11093 and got the new rings in the mail the package they came in says p/n 379121 they seem a bit big I think they will compress & go in the cylinder ok, but was wondering if some one could check the p/n# for me, I have a cd-manual for it but not a parts manual, thanks kb

 

[HighTrim]

Re: 1954 Bigtwin 25 help please

I dont have an Evinrude manual handy, but for a '54 Johnson the original part number was 302533 superseeded to 378421, not sure right now if that superseedes more.

Easy enough to check the ring gap once installed in the bore, which should be done anyways.

 

[F_R]

Re: 1954 Bigtwin 25 help please

Confirming, the parts book for model 25916 shows part number 302533 which was for one ring. It is superseeded by 378421 which is the part number for a set of 3 rings, and still a good number to this day. I have no idea what 379121 is, nor can I find any record of that number anywhere.

Put them in the cylinder and check the end gap. Other possible gotchas are width of the ring (clearance in the groove) and height of the ring (inner diameter vs outer diameter), and the type of the notch for the locating pin.

 

[kodibass]

Re: 1954 Bigtwin 25 help please

Yep I could not find this p/n as well, but they came from seaway marine are NOS as the packages are very old, stained, and from the era, #s very hard to read on the packages, How can I tell about the notch for the locating pin? thanks kb,, man I thought this was gonna be a simple re-ring'' darn

 

[F_R]

Re: 1954 Bigtwin 25 help please

You just have to use reasoning. Just make sure the notch is wide enough (actually a bit more than wide enough) for the diameter of the locating pin. Pin sizes have evolved over the years. You can use a wide notch with a skinny pin but not vice-versa. Also make sure the pin isn't holding the ring up too high. You probably are ok, but it never hurts to be careful.