Merc switchbox part #???

[mxz]

Guys, I noticed one of my switchboxes on my 1981 225 2.4 Merc seems to be the wrong part #. The part # is 322-5524 A1. Does this belong on my 2.4??? The other one is the correct 322-7778 A1.

Thanks

[mxz]

ttt

[MTCM]

The part: 322-5524 A1 has been substituted with: 7778A12


Looks like one of your boxes has been replaced with one bearing the "new" P/N.

No worries

[mxz]

Thanks!!!

[sosmerc]

You should check to make sure both of your bias circuits have the same resistance reading. Resistance from the white/black terminal to ground should be the same for each box. High rpm "race" boxes have a different spec than "stock" boxes. I don't have the numbers in front of me at the moment, but I think the stock boxes have a higher resistance number. Just make sure both boxes are reading the same, or close anyway.

[sosmerc]

I found the spec.....
15,000 ohms for standard switchbox
9600 ohms for racing units

This is resistance between the white/black post and ground (with the white/black wire disconnected). If this reading is way off on either switchbox you will end up with a timing problem and potential for serious engine damage.

[mxz]

sosmerc,
Thanks for the info!