Timing and TDC

[Chryco Psycho]

You are welcome Joe 

[headejm]

Thanks @Chryco Psycho! So I assume each engine build has an optimum initial timing. I know you like to set timing without a timing light but what are the best indicators besides experience and engine sound? Can they be measured? Like vacuum reading, rpm, etc.?

[Chryco Psycho]

adding advance at idle the rpm will increase Vacuum will rise , the engine will become more responsive off idle , less accelerator pump shot needed without having the engine stumble , less traction , go too far & it will not increase rpm & can be hard to start

[HP_Cuda]

 

Had mine set at the high end and it was hard to start, even worse in the winter!

[shawge]

What is the rate of advance added with the vacuum advance? Something like 2 deg / inHg?  And we want to shoot for ~15 deg vacuum advance?

Edit: followed the link to the article, They have a 2 deg / 5 inHg vacuum advance and end up at 14 deg.

[Chryco Psycho]

I have found using the vacuum advance lengthens the advance curve so to run best at higher rpm you have to remove timing at idle , no win ,
the vacuum advance can be adjusted using an allen wrench inside the vacuum hose nipple on the dist & can be changed from approx 15 * to zero , turn the screw CCW to reduce the amount vaccum can add to the curve