New Glass packs on the Mac

dabkb2

Dave Bacon
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Very nice Mark, I like the starter also.
 

Passin' Thru

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Mark, please don't feel ill for what I am about to say, I ain't trying to be critical but I think you should consider the following;
If it wuz me, I would lower the mufflers down beside the keel tube and connect them to the manifolds with stainless steel flex tubing. J.C. Whitney has it. This would allow the engine to rock around without slinging the mufflers from side-to-side like a dog shaking a rat. As it is at the moment something will soon break and what breaks off could go thru the prop.:sorry:
Also lowering the mufflers will put the exaust pulses outside the propeller arc.
The extended distance between the ports and mufflers should help your torque in the upper RPM range.:yo:
I love the workmanship and the starter!:peace:
 

Mark Spies

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I have tried both ways and did not like the flex. When I had it setup that way the shake started to elongate the mount holes in the exhaust port. I have 4130 tube sleeves between each exhaust port so the wall will not break in due to tighten the bolts to hold the pipes on. The way we have it now with the braces off both the starter mount and across each glass pack it allows it to move as one and the chances of it breaking we think are lessened . We plan on testing and make sure all is well. Thank You for your input....
 

dabkb2

Dave Bacon
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I do not know what the differences might be, but the glass packs I used were mounted on the keel. There was some vibration but not enough to cause a problem.

Did you make the starter set up? I would like to have one but do not have acsees to a mill.
 

scandtours

scandtours
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I agree with Passin’ Thru (as per post three above) but whatever we say the engine sounds really very sweet.
I used to have Ron Menzies’s muffler system on mine, (photo below,) it worked very well too but, this sounds even better. If I watch the video once more maybe I will go back to the McCulloch………:whoo:
 

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Mark Spies

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David, The starter and exhaust manifolds we made by Steve Weir. He made it for a 72 Mac he had. I bought the engine and setup from him. Steve did a beautiful job. You may want to contact him at [email protected]. I should have copied the plates etc but got caught up in the build I forgot...
 

Timchick

Tim Chick
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Very nice setup. Love the electric starter setup. Do you think you'll have to change the jets since you changed mufflers?
 

Mark Spies

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Tim I am running a 70 main jet at this time. I had a 69 main with the cool cowls on and when I put the exhaust with the Freon can I went to the 70 main. I was not able to fly it Saturday had a bad cross wind. On the static run she made 4000 rpm and about 800 on the exhaust temp on the #4 jug.
 

Mark Spies

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FYI We do not have plans of the starter setup. Neither Steve nor myself copied them. I may in the future take it off and copy it. It is a perfect setup and would work on any Mac. Now if someone wants to pay me 1,000000 I will do it tomorrow...Lol
 

Brent Drake

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The glass packs do not have enough back pressure. I'm certain your loosing around 10-20hp from you setup.
 

Gyro28866

David McCutchen
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this is Marions' setup - from an earlier post
I think/maybe the flywheel is from a 40hp Johnson outboard???
 

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dabkb2

Dave Bacon
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That is what I noticed, but there was still plenty of power and I liked it not so loud.
 
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