Dualling Mac 101B's at Dusk ...............

mcbob · Post by **mcbob** » Wed May 27, 2009 4:08 am

At last we fired up my Twin Mac 101B's man what music to the ears yep i have the odd nut and bolt to tighten but she's a runner and a beauty at that ..............

http://s18.photobucket.com/albums/b108/ ... unning.flv

Enough to make any Mac Man proud, tommorrow we'll start getting the feel of things and check for bugs one engine starts the other real easy so in reality we don't need a second decompressor so i'll change the head back to a standard head.

The engines need checking at revs to see what we getting but hopefully it will be a Torque Monster, we're going to miss the Australian Nationals in Queensland as there on in just over a weeks time anyway that just gives us more time to sort this beast out.

WITH A GRIN FROM EAR TO EAR ............. McBob.

Russ Smith · Post by **Russ Smith** » Wed May 27, 2009 11:32 am

Hey McBob...............How about a Copperhead/101 twin???

That would shake up a few tailfeathers!

mcbob · Post by **mcbob** » Wed May 27, 2009 3:27 pm

Russ Smith wrote:Hey McBob...............How about a Copperhead/101 twin??? That would shake up a few tailfeathers!

Ya must be reading my mind Russ the bit's are being collected now as i write this reply and it will be a centre drive, i have 1 engine here modded to Copperhead standard so i'm looking to build another to make a pigeon pair.

The main thing now is to get the Mac sorted as i'm sure it's sold and i wouldn't like to think i've run myself to a point where i cant build faster saws. Then all i have to do is find some-one with the nuts to drive it.

Mc Bob.

Brian Thomas · Post by **Brian Thomas** » Wed May 27, 2009 5:17 pm

How about a hotsaw with an out board motor . Dave Bonbright (sp) put a Mercury 6 cyl. on a kart .
Brian

mcbob · Post by **mcbob** » Wed May 27, 2009 5:53 pm

Brian Thomas wrote:How about a hotsaw with an out board motor . Dave Bonbright (sp) put a Mercury 6 cyl. on a kart .
Brian

Na wouldn't be able to find a gorrilla big enough to pick it up let alone control it.

Anyway have just bought the second US820 engine SO I'M COMMITTED NOW IN MORE WAYS THAN ONE.

Mc Bob.

John Miller · Post by **John Miller** » Fri May 29, 2009 5:49 pm

Very cool McBob!

Do you have posts or pics elsewhere that show more detail about the parts needed to couple the two together? I'm mostly interested in your throttle linkages & the central clutch.

On another note... Anyone out there care to try to explain to me what our fascination is with 2 or more engines combined in one performance vehicle? From a twin engine kart, the multi Hemi engined dragsters of the 60's, to the incredible combinations of multiple engines created for pulling tractors.

Does two equivalent engines actually double the output? I have often thought that the answer is probably no. For example. If you were able to couple two 10HP Macs perfectly, without any coupling or alignment induced losses. Would the output be the same as one 20HP Mac?

I realize this is a very simplified example for a complicated process, but I'm interested in hearing the opinions of others.

mcbob · Post by **mcbob** » Sat May 30, 2009 7:13 pm

John Miller wrote:Very cool McBob!

Do you have posts or pics elsewhere that show more detail about the parts needed to couple the two together? I'm mostly interested in your throttle linkages & the central clutch.

On another note... Anyone out there care to try to explain to me what our fascination is with 2 or more engines combined in one performance vehicle? From a twin engine kart, the multi Hemi engined dragsters of the 60's, to the incredible combinations of multiple engines created for pulling tractors.

Does two equivalent engines actually double the output? I have often thought that the answer is probably no. For example. If you were able to couple two 10HP Macs perfectly, without any coupling or alignment induced losses. Would the output be the same as one 20HP Mac?

I realize this is a very simplified example for a complicated process, but I'm interested in hearing the opinions of others.

Problem with the method i used to couple my engines is that it ain't 100% efficent so we get a drop in revs but a huge increase in good old fashioned torque this allows us to gear the saw for more chain speed and a more aggressive set to the chain.

I set up the inboard engine with a clutch drum mounted to the flywheel the drum i had made at my local machine shop for $ 60-00 then i left the clutch drum off the outboard engine so when i built the frame the outboard clutch is slid inside and then bolted up via the frame the clutch to drum runout is pretty good for as you hand crank the outer engine there's no drag on the clutch drum and all i have to do is start the outer engine and hey Huston we have lift-off as the outter starts the inner engine instantly. Oh forgot to mention i have a decompressor fitted to the outboard engine.

I too luv the old twin engined dragsters of days gone by they have a sound all there own we didn't get to see many out here in Australia as i found getting to the various drag strips a real pain without a car .......... and Heck man they just look tough !!

For more pics
http://macbobaust.com/twin1.html

Mc Bob.

Dualling Mac 101B's at Dusk ...............

Dualling Mac 101B's at Dusk ...............

Re: Dualling Mac 101B's at Dusk ...............

Re: Dualling Mac 101B's at Dusk ...............

Re: Dualling Mac 101B's at Dusk ...............

Re: Dualling Mac 101B's at Dusk ...............

Re: Dualling Mac 101B's at Dusk ...............

Re: Dualling Mac 101B's at Dusk ...............