Mc101 carburetor help.
Moderator: Rob Voska
-
ken testa
- Posts: 5
- Joined: Mon Feb 14, 2011 12:10 am
- Vintage Karting items owned: 1965 Hornet Marauder
- User Agreement: Yes
Mc101 carburetor help.
I have a Hornet Kart with twin Mc101 engines. The engines have 4-76 double pumper carbs. It's difficult to keep the carbs. In tune on gasoline. Can these carbs be changed to single pumpers by removing two sections or do I need to buy conversion parts or different carbs. Thanks. Ken
Re: Mc101 carburetor help.
Ken,
Most people are afraid to talk about carbs.
As far as Mc carbs I have seen one guy [Jeff Campbell] who really seems to have a handle on Mc carbs and have heard that Steve O'Hara is good with them also.
A large percentage of people seem to replace the Mc carb with a Tillotson. Tillostons can be purchased new, have parts readily available, and are very consistent in their performance.
US Motor Power http://www.usmotorpower.com sells brand new Tilloston HL series carbs for the WB-820 so it would probably be a safe bet to say that they would also work pretty well of a stock 101 if that's what your motor are. You may also want to consult with http://www.eccarburetors.com about what would be a good carb for your application. Keep in mind also that you will need to change the stock oem manifolds and reed cages to run a HL on a 101 also.
Best bet is to head to your local track and talk to the guys who are running and ask them how, what, and why they run the carbs they do then make your decision on which route you want to take.
R.E.A.R.
Most people are afraid to talk about carbs.
As far as Mc carbs I have seen one guy [Jeff Campbell] who really seems to have a handle on Mc carbs and have heard that Steve O'Hara is good with them also.
A large percentage of people seem to replace the Mc carb with a Tillotson. Tillostons can be purchased new, have parts readily available, and are very consistent in their performance.
US Motor Power http://www.usmotorpower.com sells brand new Tilloston HL series carbs for the WB-820 so it would probably be a safe bet to say that they would also work pretty well of a stock 101 if that's what your motor are. You may also want to consult with http://www.eccarburetors.com about what would be a good carb for your application. Keep in mind also that you will need to change the stock oem manifolds and reed cages to run a HL on a 101 also.
Best bet is to head to your local track and talk to the guys who are running and ask them how, what, and why they run the carbs they do then make your decision on which route you want to take.
R.E.A.R.
-
ken testa
- Posts: 5
- Joined: Mon Feb 14, 2011 12:10 am
- Vintage Karting items owned: 1965 Hornet Marauder
- User Agreement: Yes
Re: Mc101 carburetor help.
Thanks! Ken
-
ted johnson
- Posts: 1685
- Joined: Fri Jun 15, 2007 7:59 am
Re: Mc101 carburetor help.
A lot of guys simply replace the big Walbro with either an HR Tillotson or a 34mm Mikuni. Either choice seems easier to keep in tune. It's a simple change. You need to drill a new 9/64" (.141) pulse hole in the Mac reed cage flange and plug the four little corner holes in the reed. The cast four holes are actually very close to the diameter of a No. 8-32 tap drill, so you can just tap thru the cast holes. Buy four No. 8-32 X 1/8" Lg socket head cap screws, apply JB Weld to the threads and screw them gently into the tapped holes, making sure not to over tighten them in the cheap cast aluminum of the reed. Be sure to wipe off any excess epoxy from around the heads where it squeezes out, and from the bottom surface of the reed. Get some 5/16" O.D. X 1/4" I.D. X 1/4" long bronze bushings from the hardware or from www.mcmaster.com and drop them onto the 1/4" mac carb studs. Place the Tilly gasket on over the bushing spacers and install the carb. Done. The setup runs great. Of course, a GEM V-12 manifold with two 1" Tilly HL's also works very well. My buddy put a just-rebuilt 101D on his Bug for Fremont. He installed a V-12 with two alky HL250's and it ran perfect all weekend with almost no tuning. It was Charlie's first effort with a 101 and it was flawless until the brake pucks disintegrated and I roasted his brake and disc! TJ
-
ken testa
- Posts: 5
- Joined: Mon Feb 14, 2011 12:10 am
- Vintage Karting items owned: 1965 Hornet Marauder
- User Agreement: Yes
Re: Mc101 carburetor help.
My carbs are stamped 4-76. They are double pumped. Is there any way to tell if they are alcohol or gasoline carbs? Thanks!
Re: Mc101 carburetor help.
Look for "BDC16" or "BDC22" stampings on front of the carb flange where an air cleaner bolts. I have no idea what you have. Also NO you can't just take plates out.
Re: Mc101 carburetor help.
Ken,
Here is a link http://californiavintagekarters.com/ to a site that offers a adaptor so you can bolt a HL Tilloston directly on to your stock McCulloch big carb manifold and reed cage. Click on the Intake Manifolds/ carb-related section for info. Looks fairly simple to make yourself also.
Here is a REAR end look at Charlie's kart that Ted smoked the brakes off of showing Charlie's V-12 set-up, its so pretty its worth another look.
Karting...Made in America.
R.E.A.R.
Here is a link http://californiavintagekarters.com/ to a site that offers a adaptor so you can bolt a HL Tilloston directly on to your stock McCulloch big carb manifold and reed cage. Click on the Intake Manifolds/ carb-related section for info. Looks fairly simple to make yourself also.
Here is a REAR end look at Charlie's kart that Ted smoked the brakes off of showing Charlie's V-12 set-up, its so pretty its worth another look.
Karting...Made in America.
R.E.A.R.
-
ted johnson
- Posts: 1685
- Joined: Fri Jun 15, 2007 7:59 am
Re: Mc101 carburetor help.
Nice pic. I'll make sure Charlie looks at it.
NOW, you remind me that I gotta rebuild Charlie's brake. Those pads had been in that caliper since the early sixties! I was a one-man destruction derby at TBO. I ruined Charlie's caliper and disc, and got my own Max Torque so hot the lining adhesive melted and the linings fell off the shoes! Jim Donovan had it fixed and back in my hands in about a week from the day I sent it to him. He's really a wonder! Ted
NOW, you remind me that I gotta rebuild Charlie's brake. Those pads had been in that caliper since the early sixties! I was a one-man destruction derby at TBO. I ruined Charlie's caliper and disc, and got my own Max Torque so hot the lining adhesive melted and the linings fell off the shoes! Jim Donovan had it fixed and back in my hands in about a week from the day I sent it to him. He's really a wonder! Ted
-
Scott Kneisel
- Posts: 477
- Joined: Mon Mar 24, 2008 7:48 pm
- Vintage Karting items owned: '63 Rupp Grand Prix, 66 Rupp Chappy, Mc6's, Mc8, Mc10's, Mc20's
Lotsa' other Macs - User Agreement: Yes
- Location: Farmington, NY
Re: Mc101 carburetor help.
Ken,
The 101 "double pumper" carbs (BDC16 or BDC24) are supposed to work with either gas or alky according to the Mac literature but in my experience they are very hard to tune on gas like you are finding. The carb is made to deliver a LOT of fuel so squeezing down the needles so it will work with gas is tough. The carbs work pretty well on either Methanol or E85 Ethanol. If you want to run gas I recommend that you either get a couple Tilly HR carbs (EC sells the HR181 new) which can be applied to the stock 101 manifold with minimal modifications or you could get adapter plates (Vince Hughes sells these) and use Tilly HL series carbs. I have run an HL360 carb on my stock 101A and it runs surprisingly well. If you are going to run an HL carb, that is the one I recommend for a 101.
The 101 "double pumper" carbs (BDC16 or BDC24) are supposed to work with either gas or alky according to the Mac literature but in my experience they are very hard to tune on gas like you are finding. The carb is made to deliver a LOT of fuel so squeezing down the needles so it will work with gas is tough. The carbs work pretty well on either Methanol or E85 Ethanol. If you want to run gas I recommend that you either get a couple Tilly HR carbs (EC sells the HR181 new) which can be applied to the stock 101 manifold with minimal modifications or you could get adapter plates (Vince Hughes sells these) and use Tilly HL series carbs. I have run an HL360 carb on my stock 101A and it runs surprisingly well. If you are going to run an HL carb, that is the one I recommend for a 101.