The Search for a "Good" McCulloch BDC carb duckbill - by Jeff Campbell   Elder Rubber Company (ERC) has built new duckbill tooling to produce gasoline resistant duckbills. These new duckbills will be made from a BUNA-N material, and will be available for the 2005 season.

ERC Duckbill running at idle ..........................................ERC Duckbill running at full throttle

Track Testing Results

EPDM showing 12% swelling after 1 hour of track time

ERC Duckbill swelled very little (only 1%) after a 1 hour track run

On track running of the new ERC duckbills went well. Feedback is that the motors responded well and ran very normally throughout rpm range. Measurements taken before and after running showed only about 1% swelling, a 12 fold reduction over previously available EPDM rubber duckbills.

Gasoline Soak Test

ERC Duckbill new, dry...................ERC duckbill after Gasoline/Klotz soak

36 hour gasoline/Klotz swell soaking test results show a reasonable 9% swell in these new ERC duckbills. That is a huge improvement over the 40% seen with SBR and EPDM rubber materials!!!!

Old Portion of Duckbill search article:

Yes, all 4 of the duckbills in the above photo were the same size prior to soaking, after a 6 hour soak, the EPDM and SBR duckbills soaked in Methanol/Klotz(KL100), showed no signficant swelling compared to dry duckbills. The duckbills soaked in Gas/Klotz(KL200) swelled a lot, the EPDM part was the worst at 43%, the SBR duckbill swelled 39%. OK - if you are running methanol, readily available EPDM duckbills used in automotive brake master cylinder applications should work fine. Where to get them, there are several distributors selling small quatities, for one try Elder Rubber (just ask for the McCulloch kart motor duckbills, they will know what  you are asking about). I did spend considerable time talking and meeting with Vernay, they are the ones that actually make all the 6 "tit" duckbills for the automotive industry, part number VA3131. They sell them in EPDM and SBR rubber, but refused to give me a quote for fuel resistant materials, even at high volume, they wanted no part of it. If anyone else wants to try, good luck!