Need Mac carb information Please read

[Terry Bentley]

I would like to know if the flatback and BDC carb diaphram kits are currently being manufactured? I am not interested about someone having them ratholed in their garage, selling NOS on ebay, but new production. If there is not a current source, I want to get them manufactured. If you are interested in any NEW sets, please let me know. I am talking about very near future if possible on availabity. There are plenty of small companies that can turn these fairly easily and in small quantities.

[kevin brown]

Terry,
Any new movement on this project? You can count on me as a interested buyer.
Kevin

[david a luciani]

Hi Terry,

haven't heard from you in a while, still lurking?
anyway i'll be interested in at least 15 mcculloch flatback kits too.
dave

[roger santee]

I would be intereseted in 2 kits
Roger

[Jeff Campbell]

Perry has the hard to find ones:
... no dirt cheap deals there, but he has some of the more hard to find items, look around his website.

...but do note that many of the diaphragms and gaskets are the same as the Walbro kits still sold for the vintage snowmobile market ... mfgsupply.com is a great low cost source (main diaphragms for 3 bucks).


FYI - the Walbro WDA-1 carb is very similar to the carb used on the MC101's (the double pumper BDC carb), many of the WDA-1 carb kits contain all the rebuild parts you need, except for the duck bill. I have purchased many WDA-1 kits for around 10 to 20 bucks. My experience with these after market kits is that I prefer the kits where both the fuel pump and check valve diaphragms are made of a white fiber reinforced material ... many of the kits today have a fuel pump diaphragm made of black thin flimsy material whose check flappers get sucked into the Mac carb plates. (I am referring to diaphrams #22 & 23 in the brochure below). If I remember right (someone should verify this here), the WDA main diaphrams will work in the Mac small flat back and MC91 series BDC carbs ... the hard to find diaphram for these carbs is the fuel pump diaphram, which marmax's kartsandparts.ca does sell.





Also, mfgsupply.com used to see the WDA-1 kits with the correct fuel pump diaphragm for the MC101 carb, here is a link that shows a photo of the kit: .... also I did find a link to a nice pictorial that explains why they had different fuel pump diaphragms, the black flimsy one is used with coil springs behind the flapper check valves , the WDA-1 and Mac double pumper carbs do not use the coil springs and the fuel pump diaphragm has to be a stiffer stronger material in order for those flappers to work right without getting sucked into the carb plate holes. I have seen some universal WDA / WDA-1 kits that come with both types of fuel pump diaphragms.

I have been having trouble finding the correct WDA-1 kits lately, I did just see this online store selling them at a reasonable price (some places are charging over 60 bucks) ... 25 bucks here, but I have not ordered from them, nor do I know if they really have it in stock:

Jeff

[kevin brown]

Jeff,
Thanks for all the info. it is very much appreciated. Any one recommend a rebuilder for the large and small bore Walbro's .. Contacted EC Carbs and they had no interest.
thanks,
Kevin

[david a luciani]

kevin,

you're better off learning how yourself.
mcculloch carbs can be great runners.
but if you can't rebuilt them you'll be lost when they act up at the track.
and they do act up , sometimes alot.

as with any high performance part they are fussy and sometimes experience is the only thing that'll let you fix them.
i know several people who tried to have their carbs rebuilt by someone else.
they then expected to just turn screws to tune the engine trackside.
usually that doesn't work out too good.
several now swear at the mac carbs.

they are pretty basic but stupid things will mess them up.
a little dried gas on the needle tip, flappers not under the tabs,popoff set to low, popoff set too high,swollen duck bill the list is long.
but when you get a good handle on them they're hard runners.

was it me i'd read every thread on the mac carbs in all the forums and pay close attention to what steve has said.
with a little practice you should have no trouble rebuilding your own.
dave

[Chris Marchand]

Kevin, These 35/40 year old Mac carbs are pretty tempermental even when they are rebuilt. Save yourself a lot of headaches and look at the HR series Tiillotson carbs. Put one on adjust it and go !!!!! Chris

[Rob Voska]

"several now swear at the mac carbs." And a lot swear AT the carbs!

[Bob Towarnicki]

Then there are those of us who swear by the carbs. No Michelob Ultra for me!