Mac 1-50 MC5 conversion
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Re: Mac 1-50 MC5 conversion
I just got a cheapy set of files from H/F and they are all very small and their are like 10 of them to choose from in different patterns. They arent the hardest materials but for the 5 bucks I paid for the whole set its worth going through a set or two. Also I had asked earlier about using the MC6 crank and it throwing off port timing because of the lengthened stroke, any body care to fill me in on that?
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Re: Mac 1-50 MC5 conversion
i had written a long reply to that but i decided it was a bit mean sounding so i trashed it as i wasn't trying to be mean.
basically you won't hurt the motor using a mc6 crank.
mcculloch did it when they effectively stroked the mc5 and called it a mc6.
at first they just crossed or restamped mc5 blocks they also made mc5/6 stamped blocks.
this was discussed ages ago so your research should now include some back reading in the forums.
you should start at the beginning of this forum and read every post that has to do with mc5 or mc6.
many of your questions have been answered before.
hope that doesn't seem mean just my two cents.
now the bad news,as far as i know the mc6 was the only engine that mcculloch installed the long crank with ROLLER BEARINGS 1.5 stroke in, as a result they are very rare.
there are mcculloch long crank 1.5 strokes out there but they use BALL BEARING and won't fit in your block without expensive machining.
as this is supposed to be a low buck job to stay in your parameters you need to find a cheap mc250 with a tapered crank or make a modified saw clutch work.
leave the stroke alone with this one.
if you want to make mc6 equivilant saw to kart motor ask and i will list which ones will work.
i just sold a fixed head one to my buddy at TBO for 50$ ready to build so they're cheap even from a vintage karter.
i also bought the equivilant of a mc91 a mc 500 saw that i paid 15$ for from a scrap yard.
can't get cheaper than that.
the motor has the ports and tapered crank basically i removed the saw bits and now have a fixed head mc91.
dave
basically you won't hurt the motor using a mc6 crank.
mcculloch did it when they effectively stroked the mc5 and called it a mc6.
at first they just crossed or restamped mc5 blocks they also made mc5/6 stamped blocks.
this was discussed ages ago so your research should now include some back reading in the forums.
you should start at the beginning of this forum and read every post that has to do with mc5 or mc6.
many of your questions have been answered before.
hope that doesn't seem mean just my two cents.
now the bad news,as far as i know the mc6 was the only engine that mcculloch installed the long crank with ROLLER BEARINGS 1.5 stroke in, as a result they are very rare.
there are mcculloch long crank 1.5 strokes out there but they use BALL BEARING and won't fit in your block without expensive machining.
as this is supposed to be a low buck job to stay in your parameters you need to find a cheap mc250 with a tapered crank or make a modified saw clutch work.
leave the stroke alone with this one.
if you want to make mc6 equivilant saw to kart motor ask and i will list which ones will work.
i just sold a fixed head one to my buddy at TBO for 50$ ready to build so they're cheap even from a vintage karter.
i also bought the equivilant of a mc91 a mc 500 saw that i paid 15$ for from a scrap yard.
can't get cheaper than that.
the motor has the ports and tapered crank basically i removed the saw bits and now have a fixed head mc91.
dave
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Re: Mac 1-50 MC5 conversion
Mike,
Dave is right, it is VERY hard to find a MC6 crank, and if you do, it will cost you a fortune.
It is true that the longer stroke will effectively change your port timing ... its like raising your ports. On the MC5 look-a-like motor I built, I did not raise the transfers and hardly raised the exhaust port .... since the longer stroke MC6 crank that I installed would effectively do that job for me. If you want to stroke your motor, there are many of the 1.635" stroke cranks out there (needle bearing PTO with tapered end) ... but with this much longer stroke, the top ring on most pistons starts popping out the top of the block! There were some pistons made that had the ring grooves lowered on them (for highly stroked motors), I think the later MC10 pistons were like that. I also have seen pistons where someone cut a new pair of ring grooves lower on the piston (one between the existing ones, and another below the lowest one). I haven't tried it yet, but I wanted to try building a motor from a saw block with a 1.635" stroke crank, and simply leave the top ring off the piston.
As Dave pointed out there are a lot of nice fixed head saw motors out there with large displacement and tapered PTO cranks. Personally, I don't like working with the fixed head blocks... it takes equipment I don't have to bore / hone them and its hard to get in there to do porting. ... but back in the day, guys used to convert these fixed head blocks to removable head blocks ... I have never tried it, has anyone else? I can see some difficulties with coming up with a way to thread in all the cylinder head bolts ... any advice?
Jeff
Dave is right, it is VERY hard to find a MC6 crank, and if you do, it will cost you a fortune.
It is true that the longer stroke will effectively change your port timing ... its like raising your ports. On the MC5 look-a-like motor I built, I did not raise the transfers and hardly raised the exhaust port .... since the longer stroke MC6 crank that I installed would effectively do that job for me. If you want to stroke your motor, there are many of the 1.635" stroke cranks out there (needle bearing PTO with tapered end) ... but with this much longer stroke, the top ring on most pistons starts popping out the top of the block! There were some pistons made that had the ring grooves lowered on them (for highly stroked motors), I think the later MC10 pistons were like that. I also have seen pistons where someone cut a new pair of ring grooves lower on the piston (one between the existing ones, and another below the lowest one). I haven't tried it yet, but I wanted to try building a motor from a saw block with a 1.635" stroke crank, and simply leave the top ring off the piston.
As Dave pointed out there are a lot of nice fixed head saw motors out there with large displacement and tapered PTO cranks. Personally, I don't like working with the fixed head blocks... it takes equipment I don't have to bore / hone them and its hard to get in there to do porting. ... but back in the day, guys used to convert these fixed head blocks to removable head blocks ... I have never tried it, has anyone else? I can see some difficulties with coming up with a way to thread in all the cylinder head bolts ... any advice?
Jeff
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Re: Mac 1-50 MC5 conversion
Hey, Jeff. Back in '61 or '62, Dad had a 6.3 inch saw block de-headed by Russell. Of course, the bolt holes had to be tapped into the aluminum, as Russell said there wasn't sufficient material for Helicoils. The beast blew head gaskets regularly, until it trenched the block enough that we could no longer surface it for a gasket. I consider it a failure, though there may be others who had a better experience. TJ
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Re: Mac 1-50 MC5 conversion
I recall some of the fellas were reluctant to run a rod with a solid cap in a mac. I have one of these from a 1- 50 in mint condition for a spare to my mc 45. Is it ok to carefully grind (or mill) a shallow relief on each side of the cap's bottom (like on a power products) so more of the needles see oil? Or would this weaken the cap even with small radii in the corners? All this experimenting on extinct motors scares me sometimes, but i still love it!
Regards, bill
Regards, bill
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Re: Mac 1-50 MC5 conversion
Jeff,
on the saw motors my preference is to leave them stock if they have fixed heads.
especially if it's a newbe.
the rebore issue is a problem.
i'm actually thinking on pricing a blind hone but i think theres a few guys that'll do it now.
Bill,
many guys will tell you that the slot in the rod is useless and weakens the motor.
not true and not what you asked.
but for the recoerd they are the same strenth at least with the slotted one maybe being more durable because of oil.
but that's at max rpm every weekend something we don't really do much of anymore
for our purposes just run little heavy with your oil and leave the rod alone.
cutting a slot could "relieve" the metal tension and the rod will be out of round.
NOT a good plan.
dave
on the saw motors my preference is to leave them stock if they have fixed heads.
especially if it's a newbe.
the rebore issue is a problem.
i'm actually thinking on pricing a blind hone but i think theres a few guys that'll do it now.
Bill,
many guys will tell you that the slot in the rod is useless and weakens the motor.
not true and not what you asked.
but for the recoerd they are the same strenth at least with the slotted one maybe being more durable because of oil.
but that's at max rpm every weekend something we don't really do much of anymore
for our purposes just run little heavy with your oil and leave the rod alone.
cutting a slot could "relieve" the metal tension and the rod will be out of round.
NOT a good plan.
dave
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Re: Mac 1-50 MC5 conversion
Mike,
back to an earlier question.
i had a donor cover for parts you'll need to get one.
i bet if yo ask there'll be a few available as everyone seems to have at least one thats broke bad.
anyway you cut off the bump carefully.
you'll notice that the back inside is curved .
do your best to keep that on the cover as it'll be usful.
what i did was remove the lump and leave a ridge in the lumps shape.
i then HAND filed off the ridge.
after that i cut a big chunk out of the donor cover.
i removed the top edeg but left some of the curve.
i cut around the starter cover bolt hole though.
now comes the tricky part.
you need to scrib the missing shape onto the donor part.
cut the excess away leaving at least 1/4 inch past the scrib mark.
then its file and fit time.
carefully file the edge down to a knife edge reversing the curve in the cover.
when you get close and it fits pretty good you need to file or dremel cut the step into the cover and the piece so the lock together.
when you're done the donor part is flush with the top surface of the cover.
wash the parts with brake cleaner mix j.b. weld epoxy up and clamp overnight.
rest is standard body work.
hope this helps it's easier than it sounds .
see the few pix i took.
dave
back to an earlier question.
i finally got some time (read got off my lazy butt!!) and modified my mc 1-50 saw cover.I will need to cut the fan cover because it has a huge circular thing that when I dismanted the engine it seemed to have no purpose.
i had a donor cover for parts you'll need to get one.
i bet if yo ask there'll be a few available as everyone seems to have at least one thats broke bad.
anyway you cut off the bump carefully.
you'll notice that the back inside is curved .
do your best to keep that on the cover as it'll be usful.
what i did was remove the lump and leave a ridge in the lumps shape.
i then HAND filed off the ridge.
after that i cut a big chunk out of the donor cover.
i removed the top edeg but left some of the curve.
i cut around the starter cover bolt hole though.
now comes the tricky part.
you need to scrib the missing shape onto the donor part.
cut the excess away leaving at least 1/4 inch past the scrib mark.
then its file and fit time.
carefully file the edge down to a knife edge reversing the curve in the cover.
when you get close and it fits pretty good you need to file or dremel cut the step into the cover and the piece so the lock together.
when you're done the donor part is flush with the top surface of the cover.
wash the parts with brake cleaner mix j.b. weld epoxy up and clamp overnight.
rest is standard body work.
hope this helps it's easier than it sounds .
see the few pix i took.
dave
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Re: Mac 1-50 MC5 conversion
here's two more
dave
dave
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Re: Mac 1-50 MC5 conversion
Wow thats great info thank you very much. Hey I was going through the WKA website and came across your name in the standings for enduro I beleive?
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Re: Mac 1-50 MC5 conversion
ummm,i heard that.
so maybe i am but it doesn't mean much.
heres what went on.
my buddy Bill called me and said get down to jersey i have a margay set up for you.
i went but because of work got there 1/2 hour before race.
signed in and ran to the track.
hadn't ever been on the kart or track first enduro race too.
was field of seven four finished.
i was forth.
in my defense i was running a mc91 and everyone else was foriegn or mc101.
anyway Bill was first but light so he dq'd that made me third sorta if you just look at the books.
BUT i had FUN most important part!!!
dave
so maybe i am but it doesn't mean much.
heres what went on.
my buddy Bill called me and said get down to jersey i have a margay set up for you.
i went but because of work got there 1/2 hour before race.
signed in and ran to the track.
hadn't ever been on the kart or track first enduro race too.
was field of seven four finished.
i was forth.
in my defense i was running a mc91 and everyone else was foriegn or mc101.
anyway Bill was first but light so he dq'd that made me third sorta if you just look at the books.
BUT i had FUN most important part!!!
dave
