in theory..timing at cranking speed question?

[2cycle]

I was just doing some reading in the Evinrude forum, and someone noted that the difference in "actual" degrees from "true" WOT max advance and cranking speed is about 4 degrees. It was stated that for this reason, the timing at max advance at cranking speed should be set 4 degrees "less" to make up for the actual difference from the actual setting at high RPMs. I always thought that, for example, 21 degrees at cranking speed is more akin to 18-19 degrees at actual WOT. Or is it the other way around?: Is 21 at cranking speed more akin to 23-24 at actual WOT with the system "sped" up? This is a generalized question, but if we had to be model specific I have an inline 6 that I set at 21 degrees at crankinng speed. Thanks for the replies!

 

[andy6374]

Re: in theory..timing at cranking speed question?

Unless you have a spark advance module or an ECU of some sort that "modulates" the timing, the timing doesn't change. When you throttle up and the trigger "advances", it advances the same distance aka the same amount of degrees whether the engine is cranking or running at WOT.<br /><br />But like I said if you have a module which controls these sorts of things that retard and advance the timing then what you are saying is true.<br /><br />For example on my merc...<br />If you set the max spark advance to 22 degrees BTDC at cranking speed this will result in 20 degrees BTDC at 5400 RPMs and 26 degrees BTDC over 5600 RPMs. <br /><br />However my module is disconnected so the timing is timing however you set it.

 

[2cycle]

Re: in theory..timing at cranking speed question?

Andy,<br /><br />Thanks for the clarification. That makes sense. I just wanted to make sure I wasn't in danger of melting a piston over a few degrees or misunderstanding.