Join Date: Oct 2005
Location: bc, canada
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Re: Dauntless Stall Issue
Well Gary, the bright side of this whole exercise is that you will know how to trouble shoot and tune up an older carburated GM engine really well by the time this is all over.
I need to mention that you can get a backfire even on carburator related hesitation, so don't discount the carb just yet.
However, the next things to look for are in the ignition circuit. You need to make sure all the basics are there before you can carry on. If equipped with points, check point gap, use a dwell meter if possible. Make sure the distributor flyweights are working well, you should be able to move them away from the center post maually, and you should see the center post rotate ahead when you do this.
Check the rotor for cracks, any pencil line arcing to ground, etc.
Check cap for cracks, pencil line arcing between terminals or to cap edge.
Check all wires, no corrosion allowed, resistance should be within acceptable limits.
Plugs should be gapped to spec, and in good shape, if unsure, replace.
Check coil tower, there should be no traces of arcing between the secondary and the primary terminals. The tower needs to be very clean, the insulator boots on the h.t. wire need to be in good shape. Make sure the wire seats into the tower at the cap and the coil fully.
When running unit, check with a timing light, make sure timing is ok, make sure vacccuum addvance is working, make sure mechanical advance is working. Run at RPM. the timing should be 20+ degrees. Check again for vaccuum leaks, use a vaccuum guage, vaccuum should be about 17 to 20 In. when timing and carburetor are adjusted properly.
The other possibility. although remote, is that your harmonic balancer may have slipped, this may mean that your timing marks are out to lunch. You may want to time so that you get the highest possible vaccuum reading, then see if problem persists. But do not drive it this way for any length of time, today's fuels will give you lots of preignition when timing is set this way.
Good luck, Merry Christmas