McCulloch CP 70 Walbro SDC Carburetor Rebuild

This video is pretty much a step by step process to rebuild and restore your Walbro SDC carburetor to like new condition. Get an $8 rebuild kit and save yourself a couple hundred bucks in shop fees to get your saw running like new.

[@flmulcahy]

This man really knows his stuff.

[@elwellboy]

Hope you found it helpful. Thanks for watching and commenting.

[@E4RTH5T4R]

Valuable info, thanks for uploading and sharing your knowledge. So thankful the SDC carb kits are still available and a tribute to the enduring toughness of the old Mac saws. Great video Sir :)

[@elwellboy]

Thanks for watching. Glad you enjoyed the video.

[@afleetcommand]

Thank you for building and posting this video, very relevant to me! Trying to get a Pro Mac 700 I acquired to run... its ALL NOS parts from cylinder to carb....but it won't run. Started fine at first, then after some running went into a fuel starvation set of symptoms. Now won't run. SO started with fuel line & filter, pulled the carb. didn't see anything obvious, so will now follow your steps as instinct says even though everything is no hours...its been sitting for a decade. :) Either way, thank you.

[@elwellboy]

Sorry I'm just now getting a reply to you. I see the same symptoms on these old saws that haven't been run in a long time. If you haven't already taken the carb apart, I bet you'll find that the metering diaphragm is gunked up. Sometimes - if you're lucky - you can clean the crap off the diaphragm and the metering chamber and get away with a quick/easy fix. Good luck.

[@roncase7166]

I was really interested in the metering valve adjustment but you didn't show the important stuff.

[@elwellboy]

If by metering valve you mean the high and lo speed adjustment needles (which are the only "valves" on these carbs), I start by backing those off 1 turn. They then have to be adjusted while the saw is running - ideally under load which was not the focus of this video. What I view as important stuff in rebuilding these carbs is not losing any parts and putting everything back together correctly which is what I was showing in the video. Thanks for watching and commenting.

[@magicone9327]

Why is there two pump diaphragms? One black and one light see thru brown?

[@elwellboy]

They work together to create the suction to supply fuel. The brown one has an opening over the fuel supply to let the fuel in. Hope that helps. Thanks for watching and commenting.

[@captainsledge7554]

Looks like one my friend is selling in salem indiana. Im buying it prolly. Also the sdc was used in homelite till early 90s. And iirc husky and 10-10S saws had sdc till the late 90s

[@elwellboy]

Yep - there are millions of those SDCs out there. A great and very simple carb. Easy to rebuild and will last forever. Thanks for watching and commenting.

[@davidschaub271]

Looking for check valve under small plug, ideas? Not in kits

[@elwellboy]

Is that the very small screen and lock ring? Sometimes they are in kits but not always. If they are in the kits, I'll use them and save the old. I'll look to see if I have an extra and reply to this. Thanks for watching and commenting.

[@davidschaub271]

@@elwellboy thanks I think this has a diaphragm and a piece that goes over it , not totally sure

[@elwellboy]

@@davidschaub271 Hmmm - perhaps. I was looking at the carb parts list and under the small welch plug looked like that small screen and keeper ring. It's been awhile. I'd probably have to take one apart to be sure.

[@davidschaub271]

@elwellboy that's true but mine is a little different, my carb is sdc 65 , thank you

[@davidschaub271]

@@elwellboy I just did a search and sdc 65 parts diagram looks different that what I have, my saw is pro mac 1010 , carb has build date of 10/76

[@86FxBdyCpe]

A carburetor rebuild video that doesn't actually show you the process, totally useless!

[@elwellboy]

The only thing not shown is using a screwdriver. Most people - including me and a bunch of other viewers/commenters - apparently know how to remove and install screws and don't need to see it on a video. Instead, I prefer to focus on those things that might be a bit more technical than using a screwdriver. Thanks for watching and commenting.

[@outboardfixer]

Christ, if your not going to show the assembly what is the point of the video....OK...here it is assembled.....what the hell is THAT???

[@elwellboy]

The only thing not shown is using a screwdriver. Most people - including me and a bunch of other viewers/commenters - apparently know how to remove and install screws and don't need to see it on a video. Instead, I prefer to focus on those things that might be a bit more technical than using a screwdriver. Thanks for watching and commenting.

[@outboardfixer]

@@elwellboy Oh, I see...What happens if you have the metering valve to high or low? What happens if you don't have your gaskets in the proper order? What happens if you don't get the welch plugs in tight? What happens if you don't get that little spring under the metering valve in properly? What happens if you don't get the diaphragm HOOKED into the metering valve? All that is taken care of by touching a screwdriver to it??

[@davidsmith8126]

Agree. You imho need to just film the ENTIRE process. Dissassembly cleaning, reassembly inbits entirety.