<VV> VirtualVairs Digest, Vol 18, Issue 62, Msg 9 - Dwell School

[WillSmithTFPOCAllenTexas]

- - DWELL SCHOOL IS NOW IN SESSION - -
[DO NOT read this if you already know this]
DWELL - the degrees of distributor shaft rotation that the points are CLOSED which provides a ground path for the coil primary winding. The longer [clock time] the points remain closed the higher the primary winding magnetic saturation, and the fatter the spark at the sparkplug which occurs when the points open. A dwell meter shows the average of the 6 dwell periods [6 cyl]. Worn distributor shaft/bushings will cause erratic dwell and erratic engine running. Dwell meter setting is more accurate than gap setting.

TIP 1 -  when installing new points set the Dwell for the lowest setting specified...as the points rubbing block wears away the dwell will become longer which will allow the coil to produce a fatter spark which will better overcome the increased plug gap caused by erosion which will help reduce misfire as the plugs become worn. [NOTE: I doubt any CORSA owner today lets their engine get that far out of tune]. REMEMBER - Set Dwell before setting Timing; set timing at the recommended idle RPM to prevent the mechanical advance from activating and be sure to unplug the vac hose from the distributor and plug it with a golf tee or similar tapered item [don't use a screw or bolt...they can leak and/or damage the inside of the hose and cause an incorrect setting during timing or a problem when driving.

TIP 2 - Ground the coil "-" terminal with a jumper wire when cranking and not wanting the engine to start [compression test, etc.]. This method prevents the coil from possibly arcing internally and damaging itself which can happen if the coil tower secondary wire is removed rather than grounding the "-" terminal.

TIP 3 - Set Corvair Dwell with a meter...connect the dwellmeter to the "-" coil terminal and ground, remove distributor cap and rotor, crank engine, set dwell.

TIP 4 - Leave the ignition "ON" with the engine not running and IF the points are closed the primary winding will be energized, get hot, expand the cooling oil inside the coil and cause the coil to explode and blow its oil all over your pretty, clean engine. That's why there's an ACC position on the Ignition Switch which leaves the coil out of the circuit. [NOTE: The engine will not start until the coil is replaced. ha]

TIP 5 - To set your timing without a timing light... set the timing mark by hand to the timing spec preferred, connect a 12v test light to the coil "-" terminal and ground, loosen distributor and remove distributor cap, ignition switch in Run position, rotate distributor until test light turns "ON" [points open/plug fires].

Dwell school is now over!

Have a GREAT American Day!

Will Smith, "The Fresh Prince of Corvair"
WANTED: great condition, rust free '66 Monza vert, pg, 110, white top, for parade duty and taking kids for a ride in something they've never seen, and also for playing "Find The Motor".

Message: 9
Date: Sun, 16 Jul 2006 11:42:40 -0400
From: jwcorvair at aol.com
Subject: Re: <VV> 67 110/pg w/AC Update-Dwell

 On my Vairs, both late and earlies, I would often need to set my gap to .012 to get the dwell in the proper range. I've always thought that this was too low, so would set my gap to .016, which gave me about 28 degrees of dwell. I've confirmed the dwell reading with other dwell meters, so it wasn't an issue with my meter. I've often wondered why the dwell would be so far off after setting the gap. Perhaps the distributer lobes were worn, but I'm not certain. Also, I have wondered if it is better to set by gap or by dwell. I think by dwell, because we are looking for the duration of the open points, but if too close, then the points may not create enough gap for a proper spark.
 
Joe White (62 sedan, 66 Porvair)
CORSA, RMC