McCulloch Mini and Small CC Chainsaw's

[heimannm]

The welch plug covering the check valve on the MDC carburetors is indeed 7/16".

The other one over the L ports is 1/2".

Mark

 

[gumneck]

The welch plug covering the check valve on the MDC carburetors is indeed 7/16".

The other one over the L ports is 1/2".

Mark

Hey Mark, I went back thru my cob webbed brain and remember you sent me a 1/2" one a couple years back. Is there a part no you could share as I have another mm6 I'm going through.

 

[heimannm]

68560 is the McCulloch PN.

https://www.jackssmallengines.com/j...wd6n8gdy5wg47xoy42iyxnvz3w1jmdxuaauj4ealw_wcb
https://www.amazon.com/Stens-615-67...E2jhDMvo5BUAV9U7R5YGLBf_YapiIxz4aAiD1EALw_wcB
Let me know if you'd like just one, I'm sure I could spare one.

Mark

 

[gumneck]

68560 is the McCulloch PN.

https://www.jackssmallengines.com/j...wd6n8gdy5wg47xoy42iyxnvz3w1jmdxuaauj4ealw_wcb
https://www.amazon.com/Stens-615-67...E2jhDMvo5BUAV9U7R5YGLBf_YapiIxz4aAiD1EALw_wcB
Let me know if you'd like just one, I'm sure I could spare one.

Mark

Thanks Mark but I'll buy some from your links. Looks like the Jacks link for part no 881718 may be the 1/2" plug. That's the one I need. thanks again.

 

[gumneck]

I looked up the part no's on ebay and the 881718 specs showed as 5/16, and the 615675 specs to 7/16. So I kept on hunting and found on McMaster-Carr a plug that fits 0.502 (I assume it means fits the inside hole as it specs ID 1/2") , seems like they would also give OD of the actual plug. Anyway, I'm going to try this unless there's a better source. Seems crazy to spend 16 bucks on it but if it works I can sell the rest on EBAY and make ones of dollars then retire.

https://www.mcmaster.com/products/w...2/material~18-8-stainless-steel/height~0-075/

 

[heimannm]

Sorry about that, I Googled 1/2" welch plug and those were the items that popped up.

I have extra 1/2" if you want to avoid McMaster-Carr shipping expenses.

I will try to find some better PN's to work from for the various sizes.

Mark

 

[gumneck]

Dont give it a second thought Mark, I appreciate your help. You need to maintain your supply...you may get a flood of minimacs coming in.

 

[heimannm]

I have tried to search and come up with some more universal part numbers for the 1/2" welch plugs but to no avail.

If I come up with something I will report back.

Mark

 

[gumneck]

I have tried to search and come up with some more universal part numbers for the 1/2" welch plugs but to no avail.

If I come up with something I will report back.

Mark

Tks @mark.
I received the McMaster Carr plugs. My calipers battery is dead so I can't measure the new plugs yet. But looks like it was a bust....these new ones are thick as nickles.
New plugs on the right each pic.

 

[gumneck]

Just thought that maybe I'll run the bottom across some sandpaper for an hour or so and try it anyway.

 

[turmlos]

I did something similar, only I used a flat file. Got me out of a bind.

 

[heimannm]

I bought a batch of the steel ones from McMaster-Carr which are about 0.061" thick, checking the others I have on hand I found some aluminum ones that are 0.063" thick, some steel ones around 0.038" thick, and some thinner steel ones that are 0.028" thick.

I guess I can always look at the depth of the pockets where the welch plugs fit and try to use up the thicker ones in deeper pockets...

Mark

 

[gumneck]

Worked on mine with a file for about 20 minutes. Middle one is the result so far, far left is the McMasterCarr unfiled, and the oem is far right. Tape on both fingers is recommended.

Then I read yr post Mark and for some reason thought, why not search up aluminum welch plugs. All previous searches included size, Walbro, MCCulloch, small carb, even diff spellings as they are also Welsh plugs. Well, maybe this will work out as it was the first web link that popped up. So no prices given, But I'll call Hubbards tmrw.

https://www.hubbardspring.com/product/expansion-plugs-aluminum/
And maybe this is an option, aluminum and 1/2" but doesn't give other details like thickness.

https://www.carburetor-parts.com/expansion-plug-85-58

 

[gumneck]

I'm wondering even if I file it down to the exact size of the original aluminum one that it may be difficult to seat it in the bore without having to use a giant hammer to get the steel one to expand outwards enough. So I'm not going to chance destroying something else.

Another although a bit pricey option.
https://www.seastrom-mfg.com/productdetails.aspx?productNumber=5790-206

 

[gumneck]

To update my post with findings. The Hubbards Spring Co. would have to have an order of 100 to run and they are $2.68 each as they do not have any in stock.

The Mikes carb shop link has 1/2" aluminum but a warehouse person measured and they are thicker than .0302, more like .064. But they are $6.85 for 10. Being aluminum, they should file down much quicker with less blood from my finger tip.

 

[MAC 7-10]

Mark, in your experiences does it make a difference which type plug material for welch plugs in carbs? I've found .032 steel in most M D C carbs that I have rebuilt ,was wondering about expansion and contraction with aluminum plugs. I got a quote from Hubbard minimum order was $50.00 for qnty 20.. I think most rebuild kits are using .032 steel in the smaller plugs., would hate to order the wrong material at those prices

 

[heimannm]

I don't think the material makes much difference, I have found mostly steel ones used in the MDC's and mostly aluminum in the SDC's. The temperature change is actually minimal so I don't believe the different thermal expansion rates would have any impact. The body of the carburetor is aluminum so if anything, aluminum welch plugs would more closely match the expansion or contraction of the holes.

If the counterbore in the body of the carburetor is deep enough I would not hesitate to use the thicker welch plugs and save my thinner ones for carburetors with a more shallow counterbore.

Mark

 

[turmlos]

I can't compare to Mark, but I'll give my two cents.

I don't think plug expansion & contraction should be an issue. The pot metal or aluminum carburetor body should expand and contract at about the same rate I would imagine. I'm relatively new to the chainsaw world, but the vast majority of small engine carburetors I've rebuilt utilize aluminum plugs.

EDIT: He beat me to it.

 

[turmlos]

I rescued this little guy from my buddy's scrap pile. It was a dirty mess with several parts missing. The cylinder was full of oil and the spark plug hole was stripped out. I went over the oiler and freed up the ball in the check valve. I also Helicoil'ed the cylinder, and consequently the original taper plug would no longer seal. I ended up going with a standard CJ8 plug with a crush washer. I need to modify the rear handle a bit so I can remove the larger plug easily. Of course I rebuilt the carburetor, it had a Zama so I lucked out there. The chain tensioner was missing so I modified a different one I had. She runs great! I may even invest in an uncracked air filter cover. I epoxied the old one for now.

 

[heimannm]

Let me know if you go searching for a new AF cover, I have both new and used available, probably yellow and black as wel.

Mark