2broke2ride
Addicted to ArboristSite
- Joined
- Jul 20, 2014
- Messages
- 1,862
- Reaction score
- 2,491
These are also available third party from chainsawr.com he gets them from sugar creek supply. Cost about $30.
McCulloch Carburetors
- Thread starter heimannm
- Start date
Help Support Arborist Forum:
These are also available third party from chainsawr.com he gets them from sugar creek supply. Cost about $30.
chy_farm
ArboristSite Guru
Hello Eccentric, thanks to your tip I was able to find this information at the other site, CSCF. It will help me a lot in tinkering this old carb.
Chy
Wojoe51
ArboristSite Lurker
Wojoe51
ArboristSite Lurker
Wojoe51
ArboristSite Lurker
Does anyone know about the primers on the 440s? mine is leaking fuel around the plunger when running - to me if it leaks fuel it can leak air - Seen the name Bob Johnson regarding these but cant find him...
any help would be appreciated
any help would be appreciated
Chainsaw Jim
CJ Saws, LLC
You can remove the primer pump to service it. You likely need to replace the two little o rings and you're good to go.
It's a simple design and easy to work on.
The primers on the large flat back carburetors are non-serviceable. Your only option is to find someone with some NOS ones, or just plug the ports and prime it manually down the throat for cold starting.
The primers on the 10 Series are serviceable, but there are 5 or 6 different versions and you need to know how your is to be configured.
Mark
The primers on the 10 Series are serviceable, but there are 5 or 6 different versions and you need to know how your is to be configured.
Mark
Wojoe51
ArboristSite Lurker
Wojoe51
ArboristSite Lurker
Mark - U mentioned getting a primer from Bob Johnson - I cant seem to locate him on this forum - U got any info on how I could contact Him??
Bob only works by phone 607 638 9297 Eastern time zone.
Mark
Mark
Wojoe51
ArboristSite Lurker
thank you very much
Wojoe51
ArboristSite Lurker
Anyone know where I can get a needle and seat for mac flatback carb???
The seat is not a replaceable item for the carburetors used on saws, the kart carburetors used on the 49, 90, and 91 had a replaceable seat.
The needle used with the replaceable seat is 63038 which I believe is the same as the one used on the saw carburetors without the replaceable seat even though the part number is different (83753 and 87875). 83753 is also used on the MDC carburetor on the Mini Mac saws.
The needle itself is 9/16" long (.562) and has a rubber or Viton tip.
I have some extra needles (used) and a few of the kits with new needles and the metering levers for both the MAC and BDC carburetors; kit part number is 85059 and someone had written the 63038 part number on the package which leads me to believe they are all the same.
Mark
The needle used with the replaceable seat is 63038 which I believe is the same as the one used on the saw carburetors without the replaceable seat even though the part number is different (83753 and 87875). 83753 is also used on the MDC carburetor on the Mini Mac saws.
The needle itself is 9/16" long (.562) and has a rubber or Viton tip.
I have some extra needles (used) and a few of the kits with new needles and the metering levers for both the MAC and BDC carburetors; kit part number is 85059 and someone had written the 63038 part number on the package which leads me to believe they are all the same.
Mark
After looking through some carburetors I have I find some that were removed from saws do indeed have a removeable seat like the kart carburetors. It seems my McCulloch Carburetor Guides are not entirely comprehensive in covering all the carburetor options.
Mark
Mark
Bump
I got a rebuild kit from Bob for my Mac 250 . Got the two 0-rings for the primer also. Still can't get it to start when it is cold. About how many pumps does it take to get the saw to start?
Updating an old thread. Thanks to Parker Jameson (I don't remember the screen name he uses here) I was inspired recently to look into rebuilding some of the primers used on the large McCulloch saws with the MAC/Walbro carburetors.
As others have also observed, the primers tend to leak after a while and often stop pumping as well making the saws hard to start. I had tried a number of times to pull them apart, even tried threading the hole in the end of the plunger to use a small slide hammer but I was never able to get one apart. Someone told me Parker had come up with a solution so I contacted him and he freely shared everything he had learned.
To get the primer apart, the key is to drill a hole in the back end directly in the center, and press it apart. He used a 3/16" drill but I went slightly smaller so I could tap it for a 10-32 set screw to seal it back up when the work was complete.
Parker recommended using a 1/2" drive socket to hold the primer which work perfectly with the 1/2" square aluminum body of the primer. Be sure to drill the hole dead center so you can press squarely on the plunger to get it apart.
Parker's press set up using a vise.
I made some special tools for this project starting with this to work in my small arbor press. I made a few modifications to the press a while back including drilling a 3/8" diameter hole in the center of the ram to serve as a tool holder. I used a short section of a #25 drill bit for the punch portion and made the body long enough that I could grip it with a pair of pliers to give it a twist as needed when I pull it out of the ram.
Once the primer as been pressed apart you can see the simple arrangement inside. Since this was not intended to be a serviceable parts there are no official names or part numbers for the components so I have applied some for the sake of clarity. There is only one o-ring used in the location shown, and the cup or v seal has completely disintegrated into tar.
When I disassembled several primers for rebuilding I noticed two different plungers (one steel, one aluminum) that utilize two different cups or v seals.
Digging through my assortment of McCulloch parts I found two different cups / v seals that were apparently the same as the ones used in the primers. Both of these are used in the manual oilers on different front tank saws. 24104 matches up with the cup on the aluminum plunger and 67116 matches with the cup on the steel plunger.
After removing all of the old deteriorated cups and o-rings it is time to reassemble. As I mentioned, I tapped the back of the primer body to accept a 10-32 set screw, Parker has the ability to weld aluminum so he simply welded the body closed.
The cup, 1 o-ring, and gland installed on the aluminum plunger.
It is important to get the gland pressed in to the correct depth in order to achieve a good seal with the o-ring (after all, the main reason to go to all this effort is to stop the leaking...). Too deep and the o-ring between the gland and the retaining ring will roll back a forth, not deep enough and the o-ring will be compressed and will prevent the plunger from operating freely. To achieve this, I made special arbor tool to seat the gland in the correct position.
To be continued...
Mark
As others have also observed, the primers tend to leak after a while and often stop pumping as well making the saws hard to start. I had tried a number of times to pull them apart, even tried threading the hole in the end of the plunger to use a small slide hammer but I was never able to get one apart. Someone told me Parker had come up with a solution so I contacted him and he freely shared everything he had learned.
To get the primer apart, the key is to drill a hole in the back end directly in the center, and press it apart. He used a 3/16" drill but I went slightly smaller so I could tap it for a 10-32 set screw to seal it back up when the work was complete.
Parker recommended using a 1/2" drive socket to hold the primer which work perfectly with the 1/2" square aluminum body of the primer. Be sure to drill the hole dead center so you can press squarely on the plunger to get it apart.
Parker's press set up using a vise.
I made some special tools for this project starting with this to work in my small arbor press. I made a few modifications to the press a while back including drilling a 3/8" diameter hole in the center of the ram to serve as a tool holder. I used a short section of a #25 drill bit for the punch portion and made the body long enough that I could grip it with a pair of pliers to give it a twist as needed when I pull it out of the ram.
Once the primer as been pressed apart you can see the simple arrangement inside. Since this was not intended to be a serviceable parts there are no official names or part numbers for the components so I have applied some for the sake of clarity. There is only one o-ring used in the location shown, and the cup or v seal has completely disintegrated into tar.
When I disassembled several primers for rebuilding I noticed two different plungers (one steel, one aluminum) that utilize two different cups or v seals.
Digging through my assortment of McCulloch parts I found two different cups / v seals that were apparently the same as the ones used in the primers. Both of these are used in the manual oilers on different front tank saws. 24104 matches up with the cup on the aluminum plunger and 67116 matches with the cup on the steel plunger.
After removing all of the old deteriorated cups and o-rings it is time to reassemble. As I mentioned, I tapped the back of the primer body to accept a 10-32 set screw, Parker has the ability to weld aluminum so he simply welded the body closed.
The cup, 1 o-ring, and gland installed on the aluminum plunger.
It is important to get the gland pressed in to the correct depth in order to achieve a good seal with the o-ring (after all, the main reason to go to all this effort is to stop the leaking...). Too deep and the o-ring between the gland and the retaining ring will roll back a forth, not deep enough and the o-ring will be compressed and will prevent the plunger from operating freely. To achieve this, I made special arbor tool to seat the gland in the correct position.
To be continued...
Mark
Ready to press the plunger into the pump body.
Done
I made another tool to press the ring in place flush with the primer body. Here you can see the o-ring tucked into the primer body, the ring in position, the the tool used to press it home.
After assembly, I work the plunger on the primer to make sure it move freely, some of them can be a bit sticky at first but it seems like 10 cycles or more and they work freely. I use a little air tool oil on the rubber parts as I am assembling the primers. Once I am convinced they work freely, I install the 10-32 set screw in the back with some red LocTite to make sure they stay sealed.
I wanted a simple way to test the primers before and after servicing, before to determine if they are operable and/or leaking, and after to insure proper operation. I had an old carburetor body on hand without the throttle shaft so I simply added a nipple to supply pressure and plugged the fuel passage. You can see that this one was certainly leaking before the rebuild.
After rebuilding I used a container with SeaFoam for testing, the SeaFoam seems to have a little oil in it and does not stink up the shop like using mixed fuel would.
No leaks.
I didn't attempt to make a video, but you can see the stain on the shop towel from the primer pumping fuel. They move quite a lot in a few pumps one they are primed.
Mark
Done
I made another tool to press the ring in place flush with the primer body. Here you can see the o-ring tucked into the primer body, the ring in position, the the tool used to press it home.
After assembly, I work the plunger on the primer to make sure it move freely, some of them can be a bit sticky at first but it seems like 10 cycles or more and they work freely. I use a little air tool oil on the rubber parts as I am assembling the primers. Once I am convinced they work freely, I install the 10-32 set screw in the back with some red LocTite to make sure they stay sealed.
I wanted a simple way to test the primers before and after servicing, before to determine if they are operable and/or leaking, and after to insure proper operation. I had an old carburetor body on hand without the throttle shaft so I simply added a nipple to supply pressure and plugged the fuel passage. You can see that this one was certainly leaking before the rebuild.
After rebuilding I used a container with SeaFoam for testing, the SeaFoam seems to have a little oil in it and does not stink up the shop like using mixed fuel would.
No leaks.
I didn't attempt to make a video, but you can see the stain on the shop towel from the primer pumping fuel. They move quite a lot in a few pumps one they are primed.
Mark
The aluminum plungers with the 24104 cup seem to be a near fool proof repair. The steel plungers with 67116 cup caused me some problems...one would pump but would not hold pressure (leaks through the primer discharge port) and the other would hold pressure but would not pump. Because the dimensions are different you cannot use the 24104 on the steel plunger. I replaced the cup with a #010 o-ring on the non pumper and now it pumps, but still leaks through the discharge port. Conferring with Parker he noted that using a slightly stiffer spring for the check valve in the carburetor body would correct that. Ideally the primer check valve will but just slightly higher pressure than the carburetor pop-off setting but not so high that it make the primer hard to operate. H located some Tillotson HL metering springs that are just the right pressure so I have them on order now. For those that may not be familiar with the check valve, it is just a spring, check ball, and the same rubber seat as use in the Tillotson HL carburetors. I use #010 o-rings to seal the primer to the body of the carburetor.
Once I receive the new springs and do some additional testing I will report back.
Mark
Once I receive the new springs and do some additional testing I will report back.
Mark
Im not trying to be smart Mark but is one port feed and the other prime out put?
I was wondering if it would be possible to put brass nipples in those and use a primer bulb?
