Converting a mcculloch saw to a mc49 kart motor

[David Luciani]

Chris Brown,

Brian Thomas wrote:
There will be needle bearings on the rod . Don't loose any . Make sure the rod cap goes on the same way it came off .

Brian

not sure how ill ever get those all back in properlly but i figure ill worry about that when the time comes




 
Dennis Turk,

Chris ,
Please don't sand blast your castings.  Glass bead blasting is OK but not sand.

I use Mr. Muscle oven cleaner to strip the paint off castings before I glass bead blast them.  Spray it on let is work overnight and rinse the next day.  Blow dry and glass bead blast.    I also screw bolts in to ever threaded hole so I don't get glass beads in the threads.  One or two glass beads in a thread and you have a jammed thread and then its stripped threads next thing is a heli coil.

Turk

Chris Brown,

oops, your right. actually thats what my dad gave me a bucket of and said use this. for some reason i call all blasting media sand. just like i call all mortars and adhesives to install tile with Glue, that drives the other setters nuts

thanks for the tip though, my dad didnt actually tell me why not or what the bucket was. and i didnt want to show him the motor seeing santa will be bringing him the very same motor this year, if i can finish it in time

im deeper into one of these motors more than i have ever been now, im a bit nervous to get it all back together properlly but hoping you guys wont give up on me.

Dennis T. ,
thanks for the advice, in case i can not find mr. muscle in my area i was wondering if nearly any oven cleaner will work or if i just hold out for mr. muscle

Grumpy Dave,

how neat .never heard of using mr muscle to strip mcculloch paint.
it is by far THE worst paint to remove from engines for whatever reason.

chris,
these motors aren't particularly hard to build.
  steve m. even has great success with them
the biggest thing is to count those needle bearings.
except for rare cases like the d44 ALL mcculloch motors have 24 needle bearings on the crank to con rod.
DO NOT assume you lost one if you haver less.
FIND IT as they will destroy the motor if they are hiding in the port areas.

if you are bead blasting the motor tape all the openings into the inside of the block first.
i used to blow that off and just clean the block after but that's a horrible S.O.P. and i quit that after maybe three engines.
first it's ALOT more work to clean them after second one grain of media can really wreck your day if it gets into the piston area.

when you re-assemble you can either oil soak you gaskets for a good seal or use silicone.
on the stuffer and side cover i like to use silicone for a good seal.
intakes i always oil soak as they come on and off alot.
on any bolts going into the aluminum block i use black rtv silicone near the head and partially on the threads to secure the bolt and seal the thread holes which sometimes penetrate the block.
the bolts that are on the motor i toss as they are junk.
my personal preference is all allen head bolts with the metric washer Scott k. supplied the specs below.
it's much easier to work on engine later and new fasteners is always a good engine building S.O.P.
notes from an email from Scott K.
Engine hardware.....OK, here goes:
Stuffer bolts - 4ea 1/4-20 x 1.25" Grade 5Stuffer nuts - 4ea 1/4-20 locknuts   (centerlock distorted thread nuts)
Side cover bolts - 6ea 10-24 x 3/4" ( Hex Socket head [Allen head]
)Fan cover bolts (90 series) - 4ea 10-24 x 1" (Hex Socket Head)
(Mc10) - 3ea 10-24 x 1 1/4" (Hex Socket Head)Fan cover nuts - 10-24 Nylock nuts
Head Bolts   (90 series) - 6ea 10-24 x 1 3/8" (Hex Socket Head)
 Head Bolts (Mc10) - 5 ea 10-24 x 1 1/4" (Hex Socket Head) 1ea 10-24 x 2 1/4" (Hex Socket Head)
Head Nuts - 10-24 steel lock nuts (I reuse the old ones, can't find good dups)
Intake Manifold- 4ea 10-24 x 1" (Hex Socket Head)Coil Bolts- 2ea 10-24 x 1" (Hex Socket Head)
Points bolt- 1ea 8-32 x 1/2" (SS Hex Socket Head)
Condenser Bolt 1ea 8-32 x 1/2" (SS Hex Socket Head)
Rod Bolts - Buy 101spline bolts or Holochrome 10-32 x 3/4"
Flywheel nut - 7/16-18 Steel Lock Nut - save the old ones if in good condition.
Washers - Small OD #10 washers (I use M5 metric grade 8.8 washers, they are same size as McCulloch used. Regular SAE #10 washers #10 split lock washers.  #8 SAE washers for ignition

OK, that is all I can think of. You can get all this stuff at McMaster Carr  http://www.mcmaster.com/# with exception of the 101 rod bolts if you want them you are on your own. I always use the high strength Holochrome bolts and have never had a problem. McMaster Carr is an excellent source if you have never been on their site.

Bolt Depot (http://www.boltdepot.com/Default.aspx)in Boston is also a good source but they do not have the steel lock nuts I listed above and their shipping tends to be higher than McMaster Carr.

to reassemble you'll need to either borrow or buy an inch pound torque wrench NOT the common ft pound torque wrench.
heres your torque value you'll need:

So heres the torque values for a mc motor as set forth by Mike Savin in his booklet "Speed Secrets and Tuning Tips"

torque value for each part
Coil/lamination Screws ------------55-60 inch pounds
Condenser screws ----------------30-35 inch pounds
Con rod - mc49 mc 91 -------------105-110 inch pounds *
Con rod - mc101 ---------------90-95 inch pounds *
*a master mc builder told me told that 101 rod bolts with 85-90 inch pounds and red loctite is bullet proof
and torquing to 110 results in cracked caps.i myself do 85-90 inch pounds
Crankcase End Cover Screws --------60-65 inch pounds
Crankcase Bottom screws (stuffer) -------- --95-100 inch pounds
Cylinder Head Screws -------- --55-60 inch pounds
Exhaust Header Screws -------- ----55-60 inch pounds
Fan Housing Screws ----------------55-60 inch pounds
Flywheel nut ----------------------300-360 inch pounds
Spark plug -----------------------216-264 inch pounds
Clutch Nut ------------------------ 260-300 inch pounds

Bonus info:
the following piston to cylinder clearances are recommended
mc49 series .0045 to .0055 inches
mc91 series .0065 to .0075 inches
mc101 series .0070 to .0100 inches

hope this helps
grumpy dave