[6pack] Proper starting rpm

[Sally or Dick Taylor]

Eric---Your math is correct, of course, as is the revolutions per spark event. My curiosity got the better of me so I went out and disconnected all of the plug wires and held one of them to ground. Cranking the engine for 10 seconds, I counted 15 sparks at the plug wire. Looks like my particular engine spins around 180 rpm with the starter motor.
I really enjoy these types of discussions!

Dick


-----Original Message-----
From: Brits'n'Pieces (Eric Frenken)
Sent: Monday, December 15, 2008 11:58 PM
To: 'Sally or Dick Taylor', 'Stephen Lindquist', 6pack at autox.team.net
Subject: RE: [6pack] Proper starting rpm

Dick, 150 rpm makes 2.5 rps (rotations per second). That is 12.5 rotations
per 5 secs. A 4-stroke engine has 1 ignition every 2 rotations per cylinder.
That makes approx. 6 flashes during 5 secs of cranking per wire. So, a rule
of thumb would be 1 flash/sec, maybe a bit more.

Best regards

Eric
www.brits-n-pieces.com

-----Original Message-----
From: 6pack-bounces at autox.team.net [mailto:6pack-bounces at autox.team.net] On
Behalf Of Sally or Dick Taylor
Sent: Tuesday, December 16, 2008 8:36 AM
To: Stephen Lindquist; 6pack at autox.team.net
Subject: Re: [6pack] Proper starting rpm

Steve---If you have a good, steady spark from the coil wire to ground, then
things are probably OK from the points to the coil neg. If you can't get
spark to the plug wires, then the rotor is suspect. Or something in the cap
area.

The no-start could be timing related, but you should still be seeing spark
from the plug wires. Approx. 12 flashes during five seconds of cranking, per
wire.

My best guess for crankshaft rpm when using the starter motor would be
around 150 rpm. A lot depends on how much drag is from motor parts,
compression,  oil viscosity and the like.

Dick