MAC 84 W/ANDY B PARABOLIC PIPE TUNED LENGTH

rbarile · Feb 19, 2015

Got a Mac 84 & Andy B. old parabolic pipe. Need pipe length for setting up for a twin A. B.hull. Will be running 1667s . I will be bench run first with a aero prop . What would be a good target rpm?? 23 to 25 m or more??

Also only have one Andy B s old pipe. Will the AA pipe match or do I need to buy a matching set?

Appreciate some help Rich B

Ray Sametz · Feb 19, 2015

Richie, good to hear from you, old goat. I'd start at 11-3/4. Aero prop ain't going to do squat. Wait till waters soft and what prop you running.

Don Ferrette · Feb 19, 2015

Do not over prop the MAC 84s, let 'em rev! 1667s cut to 64mm and cupped up were the hot ticket when I ran them. Set the pipes at 11" and let 'er rip.

rbarile · Feb 19, 2015

Hi ! Ray, will run a 9 - 10 carbon fiber prop. and some others to run , have been doing planes for a time, but got the bug for boats again from looking at the twin races on you tube and reading Charlis S. and his twin evil. I had the two mac 84 s so I decided to give it a go.

What about the pipes can I use one old and one new , will it be a match.

When I get the hull I'll run a post on it, getting one of the hybrid type with struts on the hull bottom.

Rich B.

Andy Brown · Feb 19, 2015

Rich,

Post a pic of your pipe if you can. There are two different AB pipes that look similar. A 67 and an 84 and some guys get them confused.

There is a good chance someone here has a match for you.

Andy

Ray Sametz · Feb 19, 2015

rbarile said:
Hi ! Ray, will run a 9 - 10 carbon fiber prop. and some others to run , have been doing planes for a time, but got the bug for boats again from looking at the twin races on you tube and reading Charlis S. and his twin evil. I had the two mac 84 s so I decided to give it a go.

What about the pipes can I use one old and one new , will it be a match.

When I get the hull I'll run a post on it, getting one of the hybrid type with struts on the hull bottom.

Rich B.

9-10 carbon fiber prop???? Like Andy said post pics of pipes. Good to have you back, your stuff was always fast.

rbarile · Feb 20, 2015

Andy , uploaded photos from gallery on pipe and my upgrade to the mac 84s for twin.

Could not figure out how to upload on the post so did by the gallery.

As you can see I made a J.A. type sleeve and cut case to base , lip is same as stock sleeve.

Want to bench run to see how piston wares in made it a little to tight.

The pipe has a stinger of 540 od , about 1 inch long I have a sleeve on it , from when the 67 was

in scale boat. Will this pipe be a match for AA pipes.

thanks rich b.

Andy Brown · Feb 21, 2015

Rich, That is the 84 pipe. I'm not sure the AA is exactly the same.

I was wondering about that liner. Do both engines have the same liner?

rbarile · Feb 21, 2015

Both engine are the same, only have one ready to run. Wanted to do one first, and run to see if my piston fit

is correct. Have not done it in such a long time, was difficult to get in the mode. Wish the macs could be

reversed on the exhaust to make an easer bench run. Do you know approx. what rpm to look for on the bench.

Wanted to make the setup for the twin as painless as possible.

Plan to run 1667s have a lot of them from when I ran 90 class SG rigger. Whats the best pitch?

Will have to match a few.

rich b.

rbarile · Feb 21, 2015

How do I get photos on the post??

rich b.

Ray Sametz · Feb 21, 2015

Richie, click more reply options. Type post, then click browse, select pic, then click attach this file. Then hit Add reply..........

rbarile · Feb 21, 2015

Pic on up grade of Mac 84 Made sleeve/piston and head , all else is stock. Will be putting them

in A B twin hull and will post when its in..

Had three mac s one had the top of the case cracked, hoping these two stay to gether,

I thought having a J A type liner would even out the stress on the upper end, and maybe

cure the problem any input?????

Rich B

MAC 84 W/ANDY B PARABOLIC PIPE TUNED LENGTH

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