View Full Version : mac point gap&any timing tricks?
01-25-2005, 07:42 AM
any info on how to time and any tricks to time the old mac i'm hope to get the kb-2 flying soon... :confused:
01-25-2005, 09:55 AM
Guy, you live close to one of the best Mac Mech around. Mike Gaspard and Rod Reed. Rick W has some instructions for the CDI unit which times the same except for the number of degrees. Mike will probably email you the word file with the instructions. If not let me know and I will send you what I have in the Mac Manuel and Ricks doc.
01-25-2005, 04:36 PM
Breaker Point Gap >018 in.
Timing > 25 BTDC
01-25-2005, 06:03 PM
Timing should be 21 deg BTDC
This will help keep the motor cooler!
01-25-2005, 06:29 PM
25º BTDC was called for in the original overhaul manuals, but that was for the Army, and they were not concerned with long-term duration.
The old manual I have on hand (Bill Parsons Gyros) calls for .022" breaker point clearance in the assembly section, but in the front table of limits, it calls for .018". :confused:
My other manuals are at the hangar, so I can't compare them.
The Parsons version calls for 22º BTDC on magneto timing.
My CDI unit (made by some guy in Ohio :) ) is set at 21º BTDC.
01-25-2005, 06:32 PM
Points what are those for?
Some guy from Ohio doesn`t use them!
01-25-2005, 07:40 PM
so without degree marks how is the magneto set at 21 btdc?
01-25-2005, 08:13 PM
Guy, You will need a dial indicater that screws into the #1 cyl sparkplug hole.With this type of tool you can find TDC then back the engine up to .100 - .125 BTDC.STOP THERE!Do Not move the prop!
The points in the mag should just start to open at that setting.You will rotate the mag case to get the points to move.(not the crankshaft)You will need a magneto buzz box hooked to the p-lead to determine when the points open.If you don`t have the tools to do this timing procedure contact Mike or Rod there in LA.
01-26-2005, 05:06 AM
Guy, you need to put some money in a cookie jar and save up for a CDI from Rick. It will eliminate you cleaning filing points. It will give you a good hot spark to burn the 2 cycle fuel. It is probably the best improvement that can be made to a Mac. (just a suggestion)
01-26-2005, 05:11 AM
I forgot that Rick had a good price on plugs not too long ago. He may have a few left. you better hurry before those LA. boys buy them all up.
01-26-2005, 08:16 AM
yes i got some plugs from rick but i have a rebuilt magneto assn from r&d so ,but i have a few subrau ea-81 car pull outs for sale or trade?anyway i could load the gyro on it's trailer if mike or rod would be interested in timing it?thanks
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