Measure to get timing numbers?

[Ronie]

Can someone explain or point me to a thread on how to measure with a ruler to get the timing numbers?

 

[Ronie]

I did find a calculator to figure it out but you need to know the rod length and I can't see anyway to accurately measure it with it in the case.

https://lambretta-images.com/tuningh/port-timing-calculators/

 

[cuinrearview]

I found a page that had some Stihl con-road lengths but I can't remember where. A mm or two doesnt change the heights much at all relatively speaking in these small engines. I am ball-parking the rod length until I have concrete info.

 

[Ronie]

I found a page that had some Stihl con-road lengths but I can't remember where. A mm or two doesnt change the heights much at all relatively speaking in these small engines. I am ball-parking the rod length until I have concrete info.

I'd like to get an accurate transfer timing number on a Poulan 31, They are hard to see with the domed piston and it has a cut out at the transfers. I'm not planning on changing the timing, I'd just like to know what it is.

 

[Ronie]

I found a page that had some Stihl con-road lengths but I can't remember where. A mm or two doesnt change the heights much at all relatively speaking in these small engines. I am ball-parking the rod length until I have concrete info.

Thanks Tim, I just tried eye balling it and I'm only 1.5 degrees off of what I was guesstimating.

 

[Pincher]

Since you have a degree wheel, measure your piston travel from tdc to 90 degrees. Use that measurement and change rod length until it matches the results from the calculator. Should get you really close.

 

[David Young]

I had a thread on this let me see if I can find it...

 

[David Young]

I had a thread on this let me see if I can find it...

https://opeforum.com/threads/linear-measurement-for-port-durations.838/

 

[David Young]

I found a page that had some Stihl con-road lengths but I can't remember where. A mm or two doesnt change the heights much at all relatively speaking in these small engines. I am ball-parking the rod length until I have concrete info.

Like you said. Conrod Length does not typical have a huge impact on numbers. So I just take an educated guess with calipers

 

[Ronie]

I had a thread on this let me see if I can find it...

Nice thread, thanks.