Steve, too bad you need a +.030" piston, I have a near perfect +.010" Mc-6 non pinned thin ring piston from an Mc-6 I was about to assemble. It came off a Bug Wasp I got for Faye.
An unpleasant event lead to me not being able to assemble that engine. The piston, rod, crank, flywheel, the whole engine minus the block are orphans due to the fact a certain short fat bald vintage kart puke made off (stole) with the block. This is the correct Mc-6 rod.
Need Mc 6 piston
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steveohara
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- Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45
Re: Need Mc 6 piston
Scott,
Thanks for the info and the offer on the Mc 6 rod. Your post motivated me to go back and look at some of my motors and I was pleased to find that my 6 has the correct piston and rod as it should since it was never disassembled before I restored it.
I am posting links to some photos of three rods I have here. Based on your info and my other Mc 6, I think the rod on the left is the correct rod for the Mc 6 I am building and I plan to use a 49 piston without spacers to complete the motor and I'll keep looking for a correct piston and change it out some day if I find one.
The rod in the middle is skinny at the top and the beam is a different shape from the 6 rod but it retains the same shape at the big end so it must be the rod used in the 7 and 30. I opened up my Mc 30 and the rods matched but the rod in my Mc 7 is identical except that it has a lube slot in the cap. I'm trying to figure out what engine used that early rod with a lube slot???
The third rod, on the right, is skinny at the top and has a revised shape at the big end.... what model was that rod introduced?? My Mc 40 has a rod that looks the same but it is the wide version at the top so I can't figure out what model engine the rod on the right would belong too???
Last question.... the Mc 2 was a bushing motor and I built mine from parts and used a 91 rod and needles until I found the correct rod and bushing.... are any of the rods in the pictures the correct rod for a Mc 2??
Everyone take a look and share their thoughts.
Steve O'Hara
Thanks for the info and the offer on the Mc 6 rod. Your post motivated me to go back and look at some of my motors and I was pleased to find that my 6 has the correct piston and rod as it should since it was never disassembled before I restored it.
I am posting links to some photos of three rods I have here. Based on your info and my other Mc 6, I think the rod on the left is the correct rod for the Mc 6 I am building and I plan to use a 49 piston without spacers to complete the motor and I'll keep looking for a correct piston and change it out some day if I find one.
The rod in the middle is skinny at the top and the beam is a different shape from the 6 rod but it retains the same shape at the big end so it must be the rod used in the 7 and 30. I opened up my Mc 30 and the rods matched but the rod in my Mc 7 is identical except that it has a lube slot in the cap. I'm trying to figure out what engine used that early rod with a lube slot???
The third rod, on the right, is skinny at the top and has a revised shape at the big end.... what model was that rod introduced?? My Mc 40 has a rod that looks the same but it is the wide version at the top so I can't figure out what model engine the rod on the right would belong too???
Last question.... the Mc 2 was a bushing motor and I built mine from parts and used a 91 rod and needles until I found the correct rod and bushing.... are any of the rods in the pictures the correct rod for a Mc 2??
Everyone take a look and share their thoughts.
Steve O'Hara
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Scott Kneisel
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Lotsa' other Macs - User Agreement: Yes
- Location: Farmington, NY
Re: Need Mc 6 piston
Like Tom's post, the rod on the left is correct for the Mc6.
The middle looks like an Mc20 rod but I am not sure about the right hand one, My guess is that is the latest release of the narrow top rod, maybe Mc40???
I have an Mc7 rod which is again different than any of the three above on the bottom end but has a narrow top. I'll post a pick in a later note.
Not sure what an Mc2 rod looks like. I have an Mc2 block but none of the rest so I'm shooten' from the hip on that. You might want to send a note to Jeff Campbell on that, he put together an Mc2 awhile back and may have the original rod. The one with the slot could be for that engine.
Isn't it amazing all the different configuration of parts in these engines?
Scott
The middle looks like an Mc20 rod but I am not sure about the right hand one, My guess is that is the latest release of the narrow top rod, maybe Mc40???
I have an Mc7 rod which is again different than any of the three above on the bottom end but has a narrow top. I'll post a pick in a later note.
Not sure what an Mc2 rod looks like. I have an Mc2 block but none of the rest so I'm shooten' from the hip on that. You might want to send a note to Jeff Campbell on that, he put together an Mc2 awhile back and may have the original rod. The one with the slot could be for that engine.
Isn't it amazing all the different configuration of parts in these engines?
Scott
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Scott Kneisel
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Re: Need Mc 6 piston
OK, here we go...
The one on the left is an Mc6, the narrow top middle came out of an Mc20 that was never apart and the narrow top on the rt came out of an Mc7 that was rebuilt ? many tines so I don't know if it is original.
The rod on the rt is more rigid but has holes on the inside of the bore, maybe for lubrication.
Anybody have any info? This is a cool thread.
The one on the left is an Mc6, the narrow top middle came out of an Mc20 that was never apart and the narrow top on the rt came out of an Mc7 that was rebuilt ? many tines so I don't know if it is original.
The rod on the rt is more rigid but has holes on the inside of the bore, maybe for lubrication.
Anybody have any info? This is a cool thread.
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steveohara
- Posts: 411
- Joined: Thu Jul 19, 2007 2:29 am
- Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45
Re: Need Mc 6 piston
Well thank God for cordless impact wrenches otherwise my arm would be numb by now. After opening up all of my motors from the 5 through the 45 here is what I found...
The rod in Tom's pics and the left in my photos and Scott's photos is the rod used in the Mc 5 and 6.
For the Mac 20 they changed the mold and made the beam slightly lighter and rounded the top and narrowed it down to .310 wide. The basic shape and bolt spacing at the big end remained the same. Both of my 20s have that rod and I know one has never been disassembled.
My Mc30 has the same rod as the 20 but my Mc 7 has a real mystery rod... it is identical to the two Mc 20s and the Mc 30 except that it has a lube slot in the cap. Caveat... my 7 has been built up from parts and was not a complete motor when I got it... no telling where that rod originated. My first thought was that the lube slot was a late introduction in the model run but that would make me expect that the lube slot would continue into the revised rod used in the Mc 40 and 8 models. But, the 40 and 8 rods feature a revised big end with narrower bolt spacing and the streamlined shape like the rod in my photos on the right and a wide top section for the wrist pin but no lube slot in the caps. That makes the rod in my pics on the right another anomoly.... I can't see where it fell in the progression as it looks like a 40 rod but it is skinny at the top.
My all original 45 and 9 both have rods identical to the 40 rod with the lube slot added.
So, over just a few years we find the 5/6 version, the 20 version with and without the lube slot, the 40 version with skinny and wide tops and the 45/9 version. Six different configurations and we haven't even talked about the funny looking rod at the far right in Scott's pictures.
Interesting to see how much experimenting they were doing in those early years. Very likely a result of rapidly increasing stresses being applied as the racers figured out how to make the engines produce more power and rev much higher.
I'm inclined to wonder if there is really any absolute correct configuration for some of the earliest motors... they seem to have just thrown together whatever they had.
Not to change the subject, but I am working on a Mc 7 now that clearly had the ribs under the intake manifold and they were neatly machined away. My other Mc 7 clearly came from a mold that did not have the ribs so which is the correct Mc 7???
Steve O'Hara
The rod in Tom's pics and the left in my photos and Scott's photos is the rod used in the Mc 5 and 6.
For the Mac 20 they changed the mold and made the beam slightly lighter and rounded the top and narrowed it down to .310 wide. The basic shape and bolt spacing at the big end remained the same. Both of my 20s have that rod and I know one has never been disassembled.
My Mc30 has the same rod as the 20 but my Mc 7 has a real mystery rod... it is identical to the two Mc 20s and the Mc 30 except that it has a lube slot in the cap. Caveat... my 7 has been built up from parts and was not a complete motor when I got it... no telling where that rod originated. My first thought was that the lube slot was a late introduction in the model run but that would make me expect that the lube slot would continue into the revised rod used in the Mc 40 and 8 models. But, the 40 and 8 rods feature a revised big end with narrower bolt spacing and the streamlined shape like the rod in my photos on the right and a wide top section for the wrist pin but no lube slot in the caps. That makes the rod in my pics on the right another anomoly.... I can't see where it fell in the progression as it looks like a 40 rod but it is skinny at the top.
My all original 45 and 9 both have rods identical to the 40 rod with the lube slot added.
So, over just a few years we find the 5/6 version, the 20 version with and without the lube slot, the 40 version with skinny and wide tops and the 45/9 version. Six different configurations and we haven't even talked about the funny looking rod at the far right in Scott's pictures.
Interesting to see how much experimenting they were doing in those early years. Very likely a result of rapidly increasing stresses being applied as the racers figured out how to make the engines produce more power and rev much higher.
I'm inclined to wonder if there is really any absolute correct configuration for some of the earliest motors... they seem to have just thrown together whatever they had.
Not to change the subject, but I am working on a Mc 7 now that clearly had the ribs under the intake manifold and they were neatly machined away. My other Mc 7 clearly came from a mold that did not have the ribs so which is the correct Mc 7???
Steve O'Hara
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Scott Kneisel
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- Location: Farmington, NY
Re: Need Mc 6 piston
Interesting you should mention the Mc7 blocks.
I have one and have rebuilt several with the ribs machined like Steve said and I have another un-modified block that has the Mc7 stamp and has no ribs and is identical to the Mc8 blocks. I think when they changed the mold over to the Mc8 they were still in production for the Mc7 so they just used the 8 blocks and stamped them for the 7.
I think both are correct but the one with the machined ribs is more common. Again, you never know what you are gonna get, McCulloch pretty much did what they wanted to back when they were building so many kart engines.
I have one and have rebuilt several with the ribs machined like Steve said and I have another un-modified block that has the Mc7 stamp and has no ribs and is identical to the Mc8 blocks. I think when they changed the mold over to the Mc8 they were still in production for the Mc7 so they just used the 8 blocks and stamped them for the 7.
I think both are correct but the one with the machined ribs is more common. Again, you never know what you are gonna get, McCulloch pretty much did what they wanted to back when they were building so many kart engines.
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ted johnson
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Re: Need Mc 6 piston
Scott, we've noticed the rib thing on more than one Mac block of the Mc7 denomination. That's why I had no hesitation in using an Mc9 block when I built the twin Mc7's for Charlie's Van Tech. We've even seen an Mc6 stamped block that's obviously original, which has four mounting bosses on the PTO side. Merry Christmas, all. Ted
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Scott Kneisel
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Re: Need Mc 6 piston
Thanks Ted and Merry Christmas to you also and all on this forum.
Steve,
I'll bet that "odd" rod on the right is a #47782 Mc8 rod that someone ground the top thin like Ted mentioned so it would fit in the narrow boss piston.
Here are the numbers given in the IPL's:
Mc 5, Mc6 & Mc10: #55009
Mc7, Mc30 & Mc20: #48905 Thin top
Mc8, Mc40 - #47782 Like the Mc9 rod but no slot
Mc9, 45, 90 and on up: #47903 (there were many versions of this number though)
Scott
Steve,
I'll bet that "odd" rod on the right is a #47782 Mc8 rod that someone ground the top thin like Ted mentioned so it would fit in the narrow boss piston.
Here are the numbers given in the IPL's:
Mc 5, Mc6 & Mc10: #55009
Mc7, Mc30 & Mc20: #48905 Thin top
Mc8, Mc40 - #47782 Like the Mc9 rod but no slot
Mc9, 45, 90 and on up: #47903 (there were many versions of this number though)
Scott
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ted johnson
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Re: Need Mc 6 piston
Scott, we'll be in shirtsleeves. It's supposed to be 66 Sunday! Nike sitting mocked in the garage, wish you could see it, even tho it has the dreaded 610 Bender on it! Ted
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Tom Smith
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1961 Max-Torque Special triple
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Re: Need Mc 6 piston
Nothing to do with pistons but here's a Mac rod that you don't see very often, I forgot what it's from. It has the wide wrist pin boss and the wide rod bolt spacing (pre mc-10 stroker rod) yet has the later style beam section. The holes are also 90 degrees from the normal rod.