Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: bullerd on September 30, 2017, 01:51:26 pm

Title: 018C Carburetor Replacement Question
Post by: bullerd on September 30, 2017, 01:51:26 pm
I am trying to replace the original Zama C1Q-S43A carburetor with an aftermarket carburetor.  They look identical, except that the Metering Chamber Cover on my original model is flat, while the cover on the replacement (which is an S57B) has what looks like a fuel or air port on it.  I've attached an image from the Zama catalog that shows the two parts; my old one is on the right and the new one is on the left.  My question is, can I make the new carb work with my Stihl 018C either by figuring out what to do with that "port" or by using my old carb's flat metering chamber cover on the new carb?

Title: Re: 018C Carburetor Replacement Question
Post by: Cut4fun . on September 30, 2017, 08:08:26 pm
@660magnum I think Jim just did a 180 carb swap maybe.
Title: Re: 018C Carburetor Replacement Question
Post by: 660magnum on September 30, 2017, 10:35:42 pm
You can go several different ways . . .

You could just put the new carb on - snorkel and all - and forget about it (you may have to shorten the snorkel to clear the air filter?),

You can put the old flat plate on your new carb,

or 

You can get the new type air filter with the snorkel hole
Title: Re: 018C Carburetor Replacement Question
Post by: bullerd on October 01, 2017, 01:15:42 am
Thanks so much for the quick and thorough reply.  Will figure out which will work best and give it a go.

Just curious; what's the purpose of the "snorkel"?
Title: Re: 018C Carburetor Replacement Question
Post by: DNX800 on October 01, 2017, 03:17:10 am
The snorkel on the end cover is for the compensating feature. This is for holding the air/fuel mixture for a longer time near the optimum level where it is tuned when the air filter gets more and more clogged with dust. Without compensating feature and a clogged air filter the saw would run to rich and the power would go down.
Title: Re: 018C Carburetor Replacement Question
Post by: 660magnum on October 01, 2017, 07:09:02 am
My experience with these engines is that the power goes down either way if the filter gets plugged.

It is actually a EPA thingy to keep the engine from smoking when the filter starts to plug up.
Title: Re: 018C Carburetor Replacement Question
Post by: 660magnum on October 01, 2017, 07:16:32 am
In your continuing use of your 018C, keep in mind that there is a lot of commonality between the 018 series, MS180, 025 series, and the MS250.
Title: Re: 018C Carburetor Replacement Question
Post by: bullerd on October 03, 2017, 05:22:47 pm
Thank you to all that replied (and for the info about similar models).  I took the metering chamber cover off my old carburetor (C1Q-S43A), installed it onto my new carburetor (C1Q-S57), put it back together, and it started up almost immediately.  Adjusted the idle screw (it was wide open), and it's running like it's brand new!

I am so floored by the community of experts here, willing to help...thank you all again.