Help idenitifing an engine

Yes indeed, that is the boss you use for EXTERNAL pulse placing impulse signal top side of pump diaphragm. Be sure to plug pulse hole at gasket surface **

tapkoote wrote: I was afraid you might say some thing like that Scott, how ever you can still help.
i have a 257 in peices in front of me, It apears there is an embossed spot on the bottom plate. Which could be drilled and tapped for the line on the intake manifold. It's red at the tip of the pen.

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And hello Ozpluse, you seem to have some knowledge of this motor
but down there isn't everything in reverse?? lol
Seriously, I saw an air boat you built with a pulling prop, when I get further along can I pick your brain some? Looks as if the prop will cool the engine??
Thanks folks
Pat

First question for Scott or anyone else
Went to pull the clutch off, can't tell if it's a left hand thread, the rotor side is right.
Don't want to harm that rotor using it as a hold back, I've got a rattle gun but need to know which way.

Thread direction will be such that the drag on shoes within drum will tighten clutch to crank. So reverse that and it should spin off.

But then again we are talking that McCulloch ???
Strain my brain will you !!

Don't remember specifics, but pretty sure end of crank at clutch end has a BLACK nut threaded onto end of crank, remove it and clutch carrier may be on a taper only requiring a sharp hit with a BRASS hammer on cranks end to pop it off ... again not sure ? only been 25 years ago.

Probably engineering 101 Scott
whish I'd gone on in school instead of the Army, But Army Aviation tought me some thing also.
The one I've got is gold"ish" colored and stamped with marks my old eyes can't make out, thats why I suspect it's left handed.
Thats on the clutch end, the one on the pull end(rotor) is black and right handed.
Also found on another site a partcial pic. of an engine which could be the one, and is left handed.
How ever his mac is a 310 and claims to be 35CC's, his buddy volumed his same motor at 40cc's.
So another ? for U
could my 320be smaller because it was only a 10 inch bar?????
NOW WE'RE DIGG'N
Pat

tapkoote wrote: Probably engineering 101 Scott
whish I'd gone on in school instead of the Army, But Army Aviation tought me some thing also.
The one I've got is gold"ish" colored and stamped with marks my old eyes can't make out, thats why I suspect it's left handed.
Thats on the clutch end, the one on the pull end(rotor) is black and right handed.
Also found on another site a partcial pic. of an engine which could be the one, and is left handed.
How ever his mac is a 310 and claims to be 35CC's, his buddy volumed his same motor at 40cc's.
So another ? for U
could my 320be smaller because it was only a 10 inch bar?????
NOW WE'RE DIGG'N
Pat

If that clutch side is a NUT by it's self holding down the carrier, likely carrier on a taper like I said. Nut also likely LH threaded on.

Mac made a 310, 320, 330, 340 series ... Primarily was handle configuration changes pending application. As for the displacement mid 30 cc give or take ???

Ya know ... GOOGLE SEARCHES are your friend !
search.yahoo.com/r/_ylt=A0oGdU...s-/170374630253

The thread was LH
the carrier wasn't on a tapered shaft but running on roller bearings.
Thanks for the link, no I didn't check ebay
craigs list had 0 help
should be in good shape from here, however there is a click when the motor rolls over to top center.
We'll see
Pat

Scott
another picture to look at
This piston is rather scuffed up, the cylinder shows wear but no real damage.
I'm going to polish it up and try it, what do you think was the cause? Did it get too hot?
The bearings seem tight, I can't detect any end to end play.
Question, the ring groves dont have any pins, could that clicking have been the end of a ring in a port?

Yup, Roller bearing mains and a fracture cap rod.
Piston been seized for sure !!
No ring index pin because cylinder uses small ports and Ex is bridged.

Those roller bearing mains ARE NOT going to like axial loads being engine by design was to ONLY have radial loads of chain being spun.

More you show and memory returns on these engines have to say likely not a good candidate for a boat application with prop in water or air pusher/puller either

Thanks again Scott
Learned something there, being a tinkerholic also.
I have a war era 2cly/2 stroke power head off a 9.8 Johnson out board.
And wondered why the exhaust port had those"bridges" now I know.
Not one to give up on a bad idea, I'd have to devise a drive system to relieve the axial load on this
engine and/or gear it way down and run a paddle wheel.
Me thinks the air boat is out.
Pat

Hi nice old motor and for part go here www.rearenginekarts.com/mcculloch%20parts.htm