Anyone here want to help me build an engine (Or two)?

[John Miller]

O.K. Guys,

I have a few McCulloch pieces, parts, and pieces of parts, that I will list below.

Now I know that there is at least one great McCulloch engine waiting to emerge from this pile. Possibly even 2 or 3. I've never built a McCulloch engine & almost everything that I know of them (Maybe I should have written "What little I know of them") has come from this site, McBob's site, plus a few others.

What I'm looking for is some guidance from one or more of you guys that are real sharp on what parts can be mixed & matched to build a performance engine. What I need from this engine is reliability, reasonable longevity, must run on pump gas & be fit with a recoil starter for all starting purposes. I would prefer that it does not require much more than average maintenance. Low end power output would be preferable to a high winder, within reason.

Here is the list:

Mc30 (0022)
This engine looks to be complete, but has an Mc20 shroud on it. Has a recoil starter & builds compression. Has small flatback carb that is bolted to a strange box looking intake manifold that is partially painted a red/orange color.

Mc70 (973)
This engine is not complete. I have a block, cylinder, head assembly with a piston, rod & crank in place. The cover behind the flywheel is in place along with the flywheel & coil. There is also an exhaust stub type pipe bolted to the exhaust port. The flywheel is missing one cooling fin. The crankshaft has a chip busted out of it where it looks like a keyway once was. The crankcase cover is missing along with all the intake manifold pieces. Ports look to be unaltered & crankshaft/piston assembly rotate freely. I cannot sense any lateral play at either end of crank by hand alone.

Mc15 (22923)
This is what appears to be a complete saw that has been disassembled for restoration purposes. Cylinder shows evidence of crosshatch pattern on walls, piston is very clean with very little carbon build up or discoloration. No evidence of piston skirt/cylinder wall scoring. Rings look clean & rotate freely in ring lands. Connecting rod looks good other than discoloration on small end that I’m assuming is from heating that end to press fit the wrist pin. Crank looks good other than there is a bearing that seems to be very stuck onto the crank. Previous owner was unable to remove the bearing. The flywheel has two broken fins.

One of my many questions is. Why does the Mc15 have 3 exhaust ports in the casting but only the outer two are actually drilled? Should the center one be opened up for a performance application?

I also have a few loose parts. I have 2 removable cylinder heads that I do not know how to identify. There is an inner & outer blower shroud assembly. I have one extra flywheel without any broken fins. I have a couple of aftermarket intake manifolds including a GEM dual carb stuffer & a few Tillotson carbs. I also have one of the big McCulloch carbs.

There is also two other chainsaw power-heads to draw from if needed. One is an I-85 & the other is an overstrike block that had a 44 with a 55 stamped over the top. The serial # is 3774.

So, What do you all think. Anything interesting here to build? Any stroker combinations? I’m looking forward to any replies. Thanks.

[John Miller]

Is there anything that can be done with a flywheel that has a broken fin or two?

I have one flywheel that is missing two fins. It just so happens that if I removed every other fin, as in leave one - cut one - leave one - cut one, the two broken ones are spaced accordingly. I suspect that someone has tried this in the past to gain a few RPM. I'd like to know the results, the difficulties faced in re-balancing the flywheel & if there was still enough cooling available.

[david a luciani]

ho boy,

that's a big list
kinda tired i just got back from fremont by way of mi but your question is a good one.
the mc 30 is a nice motor.
the shroud is special to mc20's and alot of people could use it.
it'll work on the thirty but if it's nice is worth a bit.
you should sell that and replace with the more common mc30-101 shroud they all fit.
the manifold sounds like a go power.
a good mc10 manifold fair for the thirty theres better matches but it will work.
if you want i may be willing to work a trade as i need one more gopower for my mc10's.
the motor sounds tight.you may only need to check the torques and seal it up.
really important check the torque on the crank rod bolts.
my mc9 died because i didn't check.
the recoil start was on many if not all the mccullochs.
theres a reason they were replaced.
the compression on these puppies is BIG so pulling them can be really hard if not impossible.
but if you insist replace the recoil rope and have at it.

the mc70 is too far gone for a newbe.
it may be good but the crank needs a new keyway cut or the old one repaired or the crank replaced.
all require removal of the crank.
an involved job that takes alot of experience.
if you want to try it'll take about two pages of advise to get you through without wrecking the motor.
these motors are compression fit and need heat to disassemble.
ask before you try we'll help if you wanna be brave.

the mc15
a good motor for casual play
it'll run well missing that port.
far better than if you try to drill in the missing port.
if you mess up the port height the motor will be ruined.
if it's apart you may already have a problem.
the crank parts are heat fitted and if they're forced apart the "pinch" built into the components may be ruined.the same goes for the bearing on the crank.
that you can see the bearing tells me the motor may have been forced apart by someone.

the saws you have are interesting.
some of the s44/55 are usable on early mc motors.
the head -inner /outer fan housing, coil ,flywheel con rod and various nuts and bolts.
the same goes for the 1-85.

if you want to trade or sell both those are interesting to me.
pm me your phone number and we can chat.

the flywheel can be used but they are common enough not to bother.
i have plenty if you need one.

lastly i'm posting mc torques on all the sites tonight. read them and use them.

hope this helps
dave

[John Miller]

I appreciate the replies & PM's that I have received, but I'm not interested in selling the parts that I have collected at this time.

I would really like to make use of them & enjoy them. I do not want to risk damaging anything due to my lack of knowledge. So that was the motivation for my post in the first place.

The information on the Mc15 is troubling. What should I be looking for to determine if it has been damaged? I have the ability to post pics if that would be helpful. I actually have a fairly high level of mechanical aptitude & have performed a "Blueprint" type build on a big block V-8 engine in the past.

[mcbob]

The information on the Mc15 is troubling. What should I be looking for to determine if it has been damaged? I have the ability to post pics if that would be helpful. I actually have a fairly high level of mechanical aptitude & have performed a "Blueprint" type build on a big block V-8 engine in the past.

John the Mac 15 is a detuned engne hense the undrilled centre exhaust port now providing that when you look at the piston through the exhaust port it appears clean and not all scored up then you may only need to change the bottom reed valve plate to a bottom kart style stuffer and change the intake side to a more approprate kart system now the only thing that will cause a little grief is that the Mac 15 has a stepped crank and not a tapered one i have seen conversions available to fit a max-torque style of clutch ..... oh and don't forget it's 80cc so maybe you might have to drive it bearfooted to save a little weight.

Mc Bob.

[John Miller]

ho boy,
<snip>

the mc15...

...if it's apart you may already have a problem.
the crank parts are heat fitted and if they're forced apart the "pinch" built into the components may be ruined.the same goes for the bearing on the crank.
that you can see the bearing tells me the motor may have been forced apart by someone.

<snip>

dave

This is what I was referring to as troubling information. What do I need to check to determine if any damage has been done?

Does anyone know of any books or web-sites that chronicle the history & development of the various McCulloch engine models?

I'm also very interested in some form of technical guides and/or books on the proper procedures to inspect & rebuild these engines. I doubt that I will be able to search eBay daily for copies of the various vintage Kart magazines from back in the day. Besides, these types of magazines really deserve to be purchased by avid collectors. Not some guy that just enjoys working on old engines.

[ted johnson]

John, I've built and disassembled literally hundreds of Macs over the past 50 years, and almost none have ever required heat to take them apart. I've never taken an Mc15 apart, but most of the small Mac saws have a needle PTO side bearing, and the crank just slips out. Usually the point plate side ball bearing will come out with hand pressure and a little wiggling. Sometimes screwing a nut onto the end of the crank until it's flush with the end of the threads and GENTLY tapping with a brass hammer will get the bearing out of the plate. Rarely gentle heat is needed. The crank bearing is a transition fit onto the crank, and sometimes a little heat is needed to persuade it off. Don't expect much performance from the Mac 15! It's a small displacement engine and with the center exhaust port undrilled, it won't have much output. It WILL be a good, reliable fun motor! Have fun, and don't fear reassembling it yourself with a bit of care. Reinstalling the point plate side ball bearing is best done by gently heating the plate and pushing the crank and bearing in by hand. Be careful not to overheat the seal (not over 250 degrees in the wife's toaster oven...), and take care not to invert the seal lip when putting the crank in. TJ

[david a luciani]

Ted,
will all due respect these motors are built with a tension fit and wiggling will wreck that if done enough.
heating the engine to about 250 is easily done and recommended by mcculloch and every other builder i've talked with.
unless the crank was turned down (a common practice in the day) both bearings should pinch a little.
if you do take them apart this way i'm sure the first time or two would be doable but many of the motors i have need new inner covers because that basic heating s.o.p. was skipped.
the pinch holds the crank in position and a out of line crank is not a happy one in my world.

john,

the damage will come if someone forced the motor apart.
the tension fit around the ball bearing is your important area.
if the bearing goes in and out with no effort the pinch is no good.
sometimes locktite will help .
if it's loose the bearing will start walking when the engine is running.
at even 9000 rpm's the motor will gradually waste out the fit even more,
then all sorts of exciting things happen when the crank and rod get out of line.

i prefer to heat the bearing and freeze the crank.
one shrinks and one expands.
they go together real easy then.
zero banging usually.
then heat the cover and freeze the crank and bearing.
assemble them
then heat the block and freeze the crank-bearing-cover unit.
on the last be sure to put the inner gasket in place as really bad language results when you realize you forgot that right when you hear the click of the metal locking together.

also i have a pretty good basic hot rod engine book i just got.
theres around twenty pages in it that explains mcculloch engine rebuild stuff.
Mike Savin wrote it in 1975 and it's pretty good.
if you'd like a copy i can maybe scan it and send a pdf.
if you want a photostat version i'll need a couple of dollars to get it copied at kinko's as my machine broke and i'm not buying another.
dave

[ted johnson]

David, I agree completely with the heat/cold method of getting the bearings on and off the crank, but it's almost never required to get the bearings in and out of the block or crankcase cover. Rebuilders I know just push them together. Most bearings will come off the crank with a small puller, and since you're almost certainly going to replace the bearings with a rebuild, the 250 degree heat/freeze method almost always allows the bearing to fall onto the crank. My latest 101 has a NOS crankcase cover, and a very little used block, and the crank and bearing installed with a gentle hand press, as usual. I hadn't built a Mac in several years, so I called Terry Ives for refreshment; he said that most of them push together with hand pressure, and he was right. Dad and I built countless Mac kart engines and saws over the years as dealers with never a failure. If you encounter a stubborn one, treat it accordingly. Anyhow, as they say, "to each his own". BTW, Benders go together just as easily. TJ

[david a luciani]

Ted,
i like to learn something new every day.
and disputing Terry would be silly.
basically i'm cautious with these motors as there's no corner store to get parts from.
most of the parts i'm dealing with are used and have not had an easy life.
so i take the longer road when i build the macs.
my main point was to stop new guys from reaching for the ball pean hammer and ice tongs when breaking down these motors.
dave