Mac BDC's on US820's

[mcbob]

I recall some time back Gordon Daux showed a BDC 14 i think adapted to a US820 intake manifold
My question is will the BDC 16 or 23 ALKY carb flow enough fuel to suit these modded 820's

McBob

[Rob Voska]

I'm sure it will but why not use a HR series Tillotson? Why would you run alky in a saw that you have to pull start? To get more power from alky you would need to raise the compression more than you would gas.

[mcbob]

I have Tilly HR's here but set for petrol but i have plenty of spare BDC 16 and 22/23 to use .... ever tried push starting a chainsaw Rob ?
Anyway all my saws run decompressor valves.

Mc Bob.

[steveohara]

Bob,

The BDC 16 carb will work great on a WB820 and will have no problem providing all the fuel the motor can use even running 100% alky. Setup properly, the BDC 16 can be a better carb than any Tilley for kart racing applications due to the widely misunderstood duck bill circuit. That being said, the advantages that the duck bill circuit offer would not be of much use in a chain saw application since you use a narrow power band with your saws.
Regards,
Steve O'Hara

[mcbob]

Thanks Steve ...................... Bob

[Carl Haydt]

Hey Bob,Here's a different approach to running a big Mac carb on a 820. All you do is graft a stock Mac manifold top to the West Bend bottom! This was done long before the "Copperheads" were even thought of. Boy if this isn't a "McBender" part I don't know what is! Carl

[mcbob]

Thanks Carl yep thats much the same as our mate Gordon Daux posted up here ages ago but i have two gem v-12's that i wish to bolt the BDC's too i only need to find another single large bore carb top for one of my manifolds .....................

Bob.

[louie figone]

Bob, Terry Ives has the large single carb adapter that you need for the V12 manifold. Will Rogers cast and machines them and Ives sells them.

Louie

[mcbob]

Thanks Louie .................... Bob.