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"help" McCulloch Mac 2181 (PRO MAC) "28cc"

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Old 07-06-2006, 06:42 AM
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milne
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Default "help" McCulloch Mac 2181 (PRO MAC) "28cc"

Hey there all,

I’m going to have a go at building a tuned pipe for my Pro Mac 28CC using the following internet site as guidance:

[link=http://www.mh-aerotools.de/airfoils/javapipe_en.htm]DIY TUNE PIPE[/link]
(Need JAVA if you want look at it)

Well I know the CC’s (28) of my PRO MAC but yeah that’s it, according to the program I need:

1. Velocity of Rotation (RPM)
2. Exhaust Port Angle (o)
3. Transfer Port Angle (o)
4. Exhaust Port Area (mm2)
5. Exhaust Gas Temperature (oC)

If anyone knows the data already or can help me find it by explaining or maybe even finding an internet site that would be so awesome !!! The hardest part is the exhaust head attachment as on this particular model they are just clamped on using some dodgy spring system that takes your eyes out when trying to take it off and replacing.

THANKS ALLOT,
milne

"If you require pics don’t hesitate to ask"
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Old 07-06-2006, 07:25 AM
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milne
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Default RE: "help" McCulloch Mac 2181 (PRO MAC) "28cc"



ANYONE able to understand what this all means??
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Old 07-06-2006, 09:04 AM
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Default RE: "help" McCulloch Mac 2181 (PRO MAC) "28cc"

Goodday Milne,
I think that your Pro Mac 28 is a standard Mac 28cc here in the states. I am attaching a picture and port timings. I don't have the port areas, but they are generous. It is a well made motor, tho a bit heavy.

Intake open 62 degrees BTDC
close 62 degrees ATDC
duration 124 degrees

Exhust open 70 degrees BBDC
close 70 degrees ABDC
duration 140 degrees

Transfer open 52 degrees BBDC
close 52 degrees ABDC
duration 104 degrees

Dave
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Old 07-07-2006, 03:53 AM
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milne
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Default RE: "help" McCulloch Mac 2181 (PRO MAC) "28cc"

ok thanks SOOOO much, i now need RPM of the engine? Exhaust Port Area? Exhaust Gas Temp?

Im guessing to find the gas temp you just put a themometer at the exhaust outlet for a min on high revs?
and for the Exhaust Port Area - ive got no idea
and the RPM i wonder if somone has a manual in it or somthing with the specs?

cheers, milne
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