Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => McCulloch => Topic started by: martyinmi on November 04, 2012, 09:55:00 pm

Title: Swapping Cranks and Cylinders
Post by: martyinmi on November 04, 2012, 09:55:00 pm
I want more cubes from my new to me Mac 250. Will the crank from a 1-75 (1.625 stroke vs 1.375) fit into the 250 crank housing? Is the bolt pattern for the cylinders the same? They both share the same bore @ 2.125, as do many of the older Macs. Those components would jump me from 80 to 95 cc's. If the internals from a 1-75 won't fit, will the internals from a 1-70 fit? The crank and cylinder from it would take me up to 87 cc's.

I'm aware that the 250 is not considered a hot saw, but I love the looks of it and the way it sounds. Also, about 5 years back I watched one out cut an 046 at a farm show up north. I made up my mind that someday I'd have one and I'd get it running well enough to out run my brothers John Deere (82 cc Efco).

Al is already aware of my dilemma, but I was hoping a few of you other experts might be able to help me out too.

Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 05, 2012, 04:24:27 am
Probabley if it would work you'd jamb the piston through the top of the head deck .

You can get into all kinds of problems .Like for instance clearance on the stuffer .On a Mac 125 for example they  use a special six splined screw on the rod because believe it or not a standard grade 8 #10-32 socket head will hit the stuffer .That just one of many problems you might encounter .

Although I'm not exactly certain I'd imagine talking a standard 250 at 80 cc as to a super 250 at 87 cc ,they most likely used a shorter rod .I'd have to wade through a ton of IPL's to be certain .
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 05, 2012, 04:43:01 am
Couple more points .You obviously have not really looked at the design because this is not a removable cylinder type engine like a Stihl .

By and large all McCullochs are cast as a block .The reed valve models it's all one assembly and the 10 series and Mini Macs it's a clam shell design .There is no swapping cylinders although on the cast iron liner types they can be over bored but you'd have 6 times as much as the saw is worth to have it done .

Facts : A 250 was made basically in the early 60's when the transition was from heavy old gear drives that weighed a ton to lighter direct drive saws .Now they will cut no doubt about that and can be modified .However is the cost and frustration worth it ?

An 82 CC J-D branded saw will run at RPM's that would shake that old reed valver apart .It produces it's power like a Chevy 350 at RPM while a reeder reachs peak ,like a Ford 390 at lower RPM .

If you  want a Mac that could stand up to the BIL's saw for speed get an 850,805, SP 81 .I'm not trying to be pessimistic  just the facts as I see them .
Title: Re: Swapping Cranks and Cylinders
Post by: martyinmi on November 05, 2012, 06:34:41 am
I am going to mod this one! I've actually got another 250 powerhead on the way that is supposed to run well. I'll also find a 1-70 or a 1-75 and do some swapping...if it will work ??? I have a mill and the necessary tooling to bore the cylinder. I just don't care to start welding on the crank to stroke it like we do on our antique pulling tractors if a crank swap will work.

Remember Al, you got myself and many others in to this souped-up-saw thing. Now the way I see things, you need to help me out along the way. ;D

Time for work. Thanks
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 05, 2012, 08:43:26 am
Maybe so on Stihls .However other than a piped mini Mac and a finely tuned and slightly altered 6-10 with a larger carb I've never done a thing other than rebuild and restore them .

I wish you a lot of luck,go for it.

Oh I'll do that super 44 one of these days which is just an intact  pile of parts that Dan Henry sent me .It's kind of low on the priority list though .
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 06, 2012, 02:51:52 pm
A little fly in the ointment .According to the IPL's the super 250 uses a ball bearing on the clutch side while a standard 250 uses a needle bearing .Which is not to say you can't use a needle with a super crank providing the shaft size is the same ,dunno .

An I-70,Super 44a is a right hand start saw which uses a right thread nut so you don't spin the clutch off starting it ,keyed clutch which has a tendency to tear out the keyway which is why in later years Mac used just the taper to hold the clutch,no key .A standard 250 uses a left hand thread screwed on clutch .

Now then  the rods on a 250 and a super are the same which I assumed them not to be  but they list a different piston so I assume if you use a standard 250 piston with a long throw crank  you'd  chunk it through the head deck .

I-75 have no idea .It's not on my micro film nor in the big black book that weighs 20 pounds .According to Mike Acres site they only made it a year .So reading between the lines it's rare as a hens tooth .

Now before you get the idea you can take a crank from a 650 gear drive here's that deal .They are also rare as a hens tooth .That I know of they were made for 10 months .I have one,Mike Acres has one and there are only two others I've heard of .Besides being a geardrive that crankshaft is not designed to run a direct drive clutch .
Title: Re: Swapping Cranks and Cylinders
Post by: martyinmi on November 06, 2012, 06:56:15 pm
Thanks for the legwork Al. I really appreciate it!
If push comes to shove I'll just weld up the crank myself and have it offset ground. If I add a quarter inch stroke I'd need to shorten the rod an eighth inch or so. I've done both(crank welding and rod lengthening/shortening) many times.
An old trucker (late 60's) came in my office and commented on the 250 saw in the back of my pickup. He seemed to know a lot about them. He said that he thought a reed  engine would tolerate the extra stroke much better than a piston ported one. What do you think about that?
You wouldn't know where I might find a set of rings for it, would you? I'm calling chainswr tomorrow to see what they might have.
Thanks again!
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 07, 2012, 07:43:33 am
They pop up on flea bay every so often but are often oversized ,left over new oldstock .

FWIW I turned a set of rings out of tool steel for a Mac 125 but never finish them because I found a set for 14 bucks .It can be done but it takes hours and hours of tedious machine work .

Now if you are serious about all this why don't you just bolt that block up in a face plate and cut the head deck off .Make another head and punch the iron liner out or make a new one .

If you really want to go whole hog find a kart piston .Wiseco made them for the 101's that were 100 thou over sized .Of course it would just be easier to find a 101 rather than all that fiddling around but they are very proud of those things as far as price .
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 07, 2012, 07:52:20 am
More ramblings .If you go to Mike Acres site and look up 125 Mac ,that all yellow saw is mine .

Rebuilt from a chrome liner worn out 125 .New iron cylinder sleeve ported pretty much stock with slightly wider transfers .Some people have hours in rebuilding saws ,some days .That one was literally weeks .Ya know as of yet I haven't even ran it long enough to seat the rings .

So what I'm trying to say is a project such as you are undertaking probabley takes on the challange of proving you can do it .However instead of the weeks I had in the 125 project you are going to have months .
Title: Re: Swapping Cranks and Cylinders
Post by: martyinmi on November 07, 2012, 07:16:58 pm
Stroking a crank is very easy, as is shortening a rod. I've taken WC Allis Chalmers cranks (4.0" stroke stock) and added two inches to the stroke. That usually takes about a full day of welding. The compression height is so tall on those old tractors that we can usually add stroke, go to an automotive style piston, and then actually make the rods longer than they were stock. I usually buy 8 SB Chevy rods(5 bucks each), strategically cut them, weld them back together, box them in for strength, then balance each end.
As far as the welding of the crank and shortening of the rod goes, I can't see that taking even a day. A machine shop a few towns over can grind it(the crank) for me for 50-80 bucks. So far the biggest hold ups right now appear to finding a set of rings and reeds. Chainswr can't help me, and I'm not finding anything on fleabey.
And speaking of reeds, if I get a fog of gas near the inlet of the carb at WOT, thats usually an indication of reeds not sealing properly, isn't it?
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 07, 2012, 09:33:08 pm
Say what now 2" of stroke on a WC Allis .Just so you know I've turned a few wrenchs on the old orange tractors .If I recall correctly a WC is a square engine ,4" bore 4" stroke .Now just where pray tell did you put the other two inches because it won't fit .There isn't two inchs left even with stroke 6 to one pistons .Plus there's not enough meat on the crank to add two inchs .Plus two inchs the crank throw  would hit the bottom the the cylinder .What rod did you use  to weld the crank throw ?

If that thing would have two inchs left to play with and a 4 inch stroke it would only have a compression ratio of 2 to 1 and stoke it's 6 or 6.5 to 1 .Standard high comp domed pistons raise  to 8.5 to 1 .Some flat top high comps  will bump it to 9 to 1.Those are rare to find . 

Now just explain how you did that .Now are you pulling my leg per chance ?

Holman and Moody speed shop out of Indainapolis built one up that was dynoing over 200 HP .I only managed to get 45 myself but that's a lot more than the original 23 HP .

I will say this though a WC is by far the best puller in the under 3,000 Lb class . ;)
Title: Re: Swapping Cranks and Cylinders
Post by: martyinmi on November 08, 2012, 06:38:00 am
Nope, not pullin' your leg Al. I'll explain in more detail tonight when I get home from work. One guy from Mi is taking an "M" Farmall engines and making 700 ci out of them-with well over 200 naturally aspirated hp. Another from Mo has gotten over 1500 ci's out of a Moline GVI. Gotta run.
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 08, 2012, 07:18:19 am
Well get some pictures is all I can say .
Title: Re: Swapping Cranks and Cylinders
Post by: brokenbudget on November 08, 2012, 08:01:26 am
yup need pics. those farmall m tractors are only about 250ci. stock. pretty hard to believe somebody trippling the ci. out of an already very tight block. been into quite a few of them as they are a very common tractor around here. i know the bottom of the piston at bdc is about an 1/8" of an inch from the weight at it's closest point, something to do with that loooooooong 5" stroke ;). the piston uses ALL the cylinder, so there isn't much room for added lenght. besides the fact these like to let go if they even hear somebody say the rpm sounds a little high. anything over 2000rpm, the rattle themselves apart. violently, leaving big ol holes in the block from the exiting rods :-\
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 08, 2012, 09:05:42 am
They used to somehow use a d-17 crank or the whole d-17 engine in a WC .Of course that was when you could buy them for scrap prices .

The D-17 was a 4.25 stroke as oppossed to 4" on the WC .Over bore piston went out to 4.125 as oppossed to 4" stock .They reground the cam and used larger valves out of something ,dunno myself .They used a either a WD or WD 45 manifold as oppossed to the side exit under the hood disstilate manifold the WC came with .Ported polished head of course .Drilled out carb and all that stuff .

High comp pistons because Allis used a d shaped combustion chamber and milling the head really wouldn't work so well .

All that then they ran only about half the water in the radiator and took every bit of weight off they could to get it below 3,000 pounds with the driver on them .I've even seen 100 pound teenage girls run them because their 250 pound father would put it over weight .No crank, no starter they had to pull start them and only carry about 2 gallons of fuel .

Sanctioned pulls you could only run 20 percent over on RPMs and 20 over dynoed HP for the winner .They had sneaky ways of last minute detuning though .

Money pulls they actually had a "protest  " rule just like NHRA had at the drag strips ."hot farm stock " you could get away with about any thing put pure stock they really got anal about .

You know it really doesn't make any diff if the thing put out 500 HP  if you can't put the power on the ground it doesn't do you any good .

Take a hundred dollar WC ,put 3 grand in it and pull 200 feet after driving three states away .Didn't make sense then,doesn't make sense now .

The whole thing became such a pain in the behind listening to cry babys I just gave it up for a lost cause .--and it was John-Deeres not AC ,that was my old friends then 67 years old .I built it he ran it ,only local though .
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 08, 2012, 09:10:39 am
Here's a flash from the past .Younger Al ,no gray whiskers and arm like a gorrilla with a temper to match .I'm trying to pull about 5,000 pounds dead weight .I think I moved about 5 feet before I spun out .

On a dead weight it's just like a horse pull ,only ten feet gets it  not like 200 feet with a transfer sled .
Title: Re: Swapping Cranks and Cylinders
Post by: martyinmi on November 08, 2012, 06:49:01 pm
D-17 is a 4.5" stroke. And they don't have a combustion chamber built in to the head, only a small spark plug pocket. They are a simple head to cc to figure static compression ratios. You could be thinking of the LeRoi line of engines that AC bought. A lot of those parts were interchangeable-including the heads. The D-17 is usually the block of choice when building a stroker WC. That or a Gleaner combine engine. The biggest crank I've ever welded up for a WC puller was a 6.25". Need to add about 1 inch of pure weld to one side of the rod journal to gain almost 2" of stroke.
My wife's WC puller is a very small engine by today's standards. It started out as a 226 combine engine. It's now a 4.53 bore and a 5.57 stroke(359 cubes), and about 110-115 hp @ 540 pto rpm.
If you care to see what's going on in the antique tractor pulling world, go to Yesterdays and scroll down until you find the tractor pulling discussion forum. Sounds like you've been away from it for a long time, and things certainly have changed. We used to follow the national circuit( for about 7 or 8 years, but we stopped two years ago when my in-laws decided they were getting too old for all the work involved. It has became painfully obvious to us that it was a huge waste of money chasing points to win a jacket- and thats saying you win. My wife has two national championship jackets over the years, one in Division 2, and one in Division 3. I have one from Division 3, and one from Division 4(open class). We figured between fuel,entry fees,missed time from work,motels,broken parts,racing fuel,etc., we would spend 12-15 k every year in our travels.

The lightest WC I've ever seen pull weighed 2750, and it was a huge waste of time because there was no weight left over for balance. Most clubs limit a WC to no lighter than 3500#. My wife pulls hers in the 3750, 4000, and 4250# classes.

As far as the big "M" motors, a fella by the name of Gary Baker from Manchester,Mi builds the biggest ones in the country. Some people aren't impressed when you tell them that a 700 ci engine only makes 270 hp, until you tell them that it makes it at 1400 rpm and they start to figure the torque at that rpm. Do the math(I'll do it-it's over 1000pounds of torque). It's quite Impressive to say the least! These engines cost in excess of 20k!!

As far as pictures go, how many do you want? We have hundreds, as well as hours of videos.

Edit: Almost forgot. We still pull dead weight- only not like you did. The blocks(usually 500 lbs.) are added one at a time, and we try to see who can pull the highest percentage of their combined(3500 lb tractor plus operator pulling 7000 lbs =200%). My beautiful bride pulls a '38 JD "A" . I usually pull our E-3 Co Op.

And you are right about the crybabies. It gets much,much worse at a National level :'( :'( :'(
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 08, 2012, 07:22:49 pm
All well and good but just how pray tell do you first weld 2" onto a rod and both keep the pins aligned perectly straight and in parrellism with no twist .Those are forged steel as you know .

Secondly just how do you lay two inchs of weld  on a crankshaft without it first warping and not causing internal stesses. Those are cast iron crankshafts made long before ductile or nodular iron was even thought of .If you did use pure nickle rod you'd have a hundred bucks worth of rod on each journal .

At 6 to 1 comp on a 4 inch stroke you'd have approx .8 inch of free space at top dead center .Where does the other 1.2 inch of piston go .It can't go into the head even if you could carve that much combustion chamber out and if you did the top two rings would be in free air because they wouldn't be in the cylinder any more .

Explain to me just how you have enough room in the crankcase to swing another 2 inchs of crankshaft .Not to menton with all this welding how does one redrill the oil holes because the original oil channal hole from rod to main would no longer align being 2 inchs off center .Unfortunately you can't curve a drill in steel like they do hydrafracting for natural gas .

If you drilled straight from main  to rod  the hole would come out  the side of the rod journal .Not to mention you'd break the drill once you hit the weld metal .On that the new journal would only be held by about 1/4 of the base metal connecting it to the crank throw unless you burn another 150 bucks worth of rod per journal building up the throws . Oh sorry I forgot to mention I work in an automotive engine plant and know how crankshafts are made .

So Marty explain away . ;)
Title: Re: Swapping Cranks and Cylinders
Post by: martyinmi on November 08, 2012, 08:58:26 pm
Alright, Al, here goes:

The easiest way to weld two rod halves together that I've found is to use an old disc brake rotor with the center cut out. I turn down a piece of round stock to the big end diameter(1.995 for a SB Chevy) and drill a hole through it and the rotor, mount the rod half to it, and using my mill to digitally measure, bolt it directly to the rotor, then use an old wrist pin for the the small end and fasten it where it needs to be to get the correct length. Then I am able to weld both sides, as well as box it in for extra strength. Very simple to do. You use two rods cut strategically and welded together to make one longer one.

Before welding a crank, we weld in boat loads of bracing anywhere we think it could possibly move. And remember, we are only welding one side of the journal, not all the way around, and for every 1 inch of weld applied, you gain 2" of stroke, and as far as I know and have seen, all old IHC and Allis cranks are steel, not cast iron. And as far as internal stresses added after welding goes, well, they are there for sure. I've never worried about them, and not one of my cranks has ever broke. I have had one rod failure, but thankfully it was on my own tractor. Most of the guys who build antique pulling motors for a living send their welded components in to either have them normalized or cryogenically(don't have spell check for that one) treated. 

Remember what those old pistons looked like? The CD(compression Distance) on some of them were more than 3". We use either custom pistons or find automotive ones that have the CD we want. When you add 2" of stroke, the piston is going up 1" higher and down 1" lower.

Getting that extra mass to swing sometimes means grinding big pockets out of the inside of the crankcase. On the WC blocks the inside measures a little narrower than the 17's, so much over 5.5" stroke and 2" rods requires cuts all the way through on the manifold side of the block. The hardest item to clear in an antique stroker is usually the cam. We end up with two flat spots where all 4 rods swing, and sometimes the cam gets ground pretty thin.

And back to the crank, we weld a short piece of thick walled 1/4"ductile iron pipe right on top of the oil hole, which also acts as a guide when applying the build up of weld. Remember Al, one inch of weld translates into 2" of stroke. And obviously, we use a wire feed. I use Spool Arc 83 wire.

As a rule, all stock reciprocating items are usually not used in antique stroker applications. You gotta wrap your head around that one first. Forget what the old pistons looked like and picture what the newer, modern ones look like.

Any more questions feel free to shoot away. Better yet, the next time you're going to be in central Mi, pm me,pop over, and I'll be happy to pull the access panel off from the side of my MM 335 and show you what an old school stroked motor looks like. That one is 4.125 bore and 6.5 stroke and 110 hp @ 540. It was around 30 hp in it's stock form. ;)

Title: Re: Swapping Cranks and Cylinders
Post by: martyinmi on November 09, 2012, 06:21:04 am
Hey Al,
   There will be an indoor pull in Wauseon, Ohio on Thanksgiving weekend. I'm having knee surgery the day before Thanksgiving, so I won't pull, but I'm thinking of coming down on Saturday to watch. How for away are you?

We also have one in Tallmage Ohio in a few months. Which one are you closer to?
Title: Re: Swapping Cranks and Cylinders
Post by: Al Smith on November 09, 2012, 06:23:19 am
Well Marty assuming those methods work then I see no reason you shouldn't be able to turn a 250 Mac into a hotty .Fact if you're real successful as it's assumed you will be once you get it done trot on down to Chardon Ohio come spring time .You can run it against the fastest saws on the east coast if not the world . ;)