Saturday Night - entertainment....F-4

banjoman09

Well-known Member
Back again! I have been on the Studebaker truck for weeks- trying to get it done so I took a break this evening to try and time my F-4 mag...still:) 1.5 hrs and I quit..im ready to say .......*********. I line up the flywheel with the mark...then turn the strip to no.1 in the cap....then push it together and find two wholes that line up on the coupler..and bolt it together. Role the flywheel back to me and then ahead to the timing mark...snaps everytime about 2" past the timing mark...then I take bolts out and turn the mag a few wholes and it is worse.....uhhhhg. Not fun..time to relax tonight.
 
wish i had a quiet helichopper and would come and land beside it and do that in the dark while your sleeping. probably be gone in 15 minutes before you woke up, like a bank robber just in and out. lol.
 
Forgive me if this is telling you what you already know; can't remember what methods you were following from previous posts.
Assuming your magneto is 21447-D or 26335-D, keep in mind that the magneto has a 35° spark range. If you do not retard it fully to set the timing, you will have headaches.

Do you have a copy of the Blue Ribbon Service Training Course for Magnetos? Very useful. Page 12 gives you correct timing for the distributor gears in the magneto itself.

The instructions for timing an F4 magneto to an engine are as follows (From the Magneto book and F12 book 3434):
"With the breaker points cleaned and adjusted replace breaker housing cover, move the lever end up as high as it will go and remove the cover. This places the breaker assembly in full retard position with ground contact against breaker stop. In this position the magneto will deliver no spark.
Secure the magneto in place on the magneto bracket by inserting the magneto base screws loosely in the magneto. Do not use base screws longer than the originals as they will damage the magneto.
Place No. 1 piston of engine on firing dead center… Then line up 'DC' mark on flywheel with mark on flywheel housing.
Release the impulse coupling. This makes it inoperative. Remove the two coupling cap screws and shims. Take off distributor block. Grasp the magneto half of adjustment coupling and rotate it clockwise (as viewed from coupling end) until distributor disk is under the distributor block terminal marked No. 1 and the breaker points are just beginning to open.
The magneto is now correctly timed.
Without changing this position, replace the magneto drive coupling cap screws and shims. The coupling is so made that only two holes line up exactly opposite each other; the cap screws must not be forced or the setting will be incorrect.
Tighten magneto down in place on magneto bracket, replace distributor block and breaker housing cover.

Further:
"With the spark fully retarded, unhook and slide the impulse coupling cover away from the magneto and crank the engine until the breaker points are just beginning to open, with the impulse coupling disengaged and No. 1 piston coming up on the compression stroke. If the engine is timed correctly, the D.C. No. 1 mark will be in line with the timing mark on the flywheel housing."

I have some diagrams, which may be useful if you would like them. E-mail is open.
SadFarmall
 
Ok....you say email is "open" but at the bottom of the page it says "no email" and also when I click on it. Im not very familiar
with all of this yet. I do understand your posting and will try again after lunch today; I think my main problem is when I try to
set everything the impulse is engaged and I dont know how to dis-engage it sitting in upright position? I can lay it on its side
on my bench...but...it has no "hook" to lift on this one. Thanks.
 
I can give you my address and put my dog in the barn- helicopter might wake me..maybe drive...Ill pay your gas! :)
 
no- havent taken anything apart; just the cap off the back to check the rotor strip. No bale hook on this one; my book says put a nail in oil hole but havent figured that out yet either! Thanks.
 
You can turn the mag backwards so the impulse doesn't catch. Then get it where the points are just breaking. If the engine is on TDC, put the 2 bolts in the holes that match. simple.
 
That didnt work! With the timing mark on flywheel lined up with mark on housing; mag loose from mount I rotated mag"backwards " til points open(with strip toward no 1 on cap) put it together and now the points are open when I rotate engine to left when the marks line up! If I go past TDC, then bring flywheel back to mark they start to open at mark....but not going the other way. Someone call me when you have time...if I dont answer I will call you back. Thanks. 620 388 3556.
 
I believe you need to be in Modern View on the forum to see the e-mail link.
As to the impulse coupling:
A timing hook is provided on the earlier types of F-type impulse coupling… The timing hook has been removed from the later magnetos and the oil cup position has been changed in the impulse housing to a point where it can be used for a double purpose. First, to furnish an opening for lubricating the impulse coupling and, second, to furnish an opening through which the main pawl may be lifted to allow rotation of the magneto without the impulse action during the timing operation.
SadFarmall
11520.jpg

11521.jpg
 
Why are you turning the engine? Leave it at TDC. Pay attention to which side of the cam the points open. Turn it backwards so the impulse can't catch, then forewords to where the points are ready to break. That is when the spark happens, not when the points are fully open. Then put 2 bolts in 2 holes that line up.
 
Ok....I see now....so you need to hold the pawl "up" with nail while you turn it? It is spring loaded? Thanks for the
illustration- very helpful.
 
if your asking me... im in central alberta canada. have no idea where banjo man is from. thats why i said helicopter but i might need a plane! but dont think he will pay for gas for it.lol.
 
Guess that wont work.......im in central Kansas! I did spend some time today and feel good about the timing now- the points "snap" when the two marks are in line:) Now I have a new brush for the mag(that I broke) on its way-maybe Wednesday...so hope all is coming together! Thanks!
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top