connecting rod screw socket sizes 25/35hp

[johnyrude200]

I’ve been tearing down several of these motors (about 10 in the last couple of days that were all seized up, going into the parts bins for winter work), and was wondering what is the specific name (and if possible size) of the connecting rod screws for this family of motors.

I don’t have anything in my toolbox in terms of normal hex sockets which fit these screws snugly enough to grab (they spin and strip them, tried metric and english sizes but NO-GO on either).

I’ve just drilled out the screws with some cobalt bits to get the cranks loose where salvageable, but those can only handle this much drilling for so long, and cobalt aren’t exactly cheap bits either.

Any help would be appreciated! The heads of these screws look like stars but with many, many splines on them. (say 10-15 splines, I can count/post a pic if nobody knows off the top of their head).

[frankr]

Nothing special, they take a 5/16", 12-point, thin wall socket.

[billw]

A lot of times, Craftsman sockets (and probably the Chinese Tool Store ones) will not be up to this task and will round out. Snap On has a 3/8" drive, 5/16" socket, 12 point, that is very durable. You have to grind the wall a bit more thin, though. Here is a used one on eBay:

http://www.ebay.com/itm/SNAP-ON-5-16-SO … 99&vxp=mtr

Another better one. I think this is the same as the one I have owned for years.

http://www.ebay.com/itm/New-Snap-on-GSF … 88&vxp=mtr

Long live American manufacturing!

[fleetwin]

the rod sockets are available from OMC/BRP as well.

[johnyrude200]

Thank you! Will be adding that to my 2015 write-offs on the ‘ol tax return 😎 😎 😎 😎 😎 😎

On this same topic, I went through a batch of the older 18/20/25 blocks last week, and for the badly stuck ones, I couldn’t free up the connecting rod screws and had to drill them out to salvage the cranks. I literally bent/twisted my allen wrenches. The ‘good’ blocks, the screws freed up normally with little effort.

I tried heating them up with a propane torch and using blaster, but no luck. Any recommendations/tricks on getting these suckers loose? Or is it just a matter of a little beefier allen wrench?

[frankr]

Allen socket on impact wrench normally will get ’em out.

[johnyrude200]

I’ll give it a try on the next pesky one!

[billw]

Again, Craftsman stuff will often fall short. Get something like Mac or Snap-On 3/8" drive socket.

Long live American manufacturing!

[chris-p]

yeah,forget the allen keys. Impact gun and allen socket will pop em in a quick sec!

[jeff-register]

Use a battery powered driver to get them off without too much heat.

[Author]

Posts