timing question

[junkfixr]

I set my base timing (spout out) around 10 degrees BTDC and drove the truck for a few weeks. Typical, sluggish 2.9 engine but runs super smooth.

I can advance the timing just slightly a couple of degrees and it's very light on it's feet. Plenty of get up and go, smooth throughout the entire pedal, but... it has a slight "pop" accasionally at idle, and sometimes a little sputter under a load at high idle. No spark knock or pinging.

Am I hurting anything ? Mileage ? It seems to have no happy medium. Either I live with a slight pop while idling, or set the timing to where it idles smoothly and live with a sluggish truck. Any suggestions ? Thoughts ? The engine has just under 160,000 miles now.

Thanks in advance,

Kevin

 

[a31ford]

TFI has gone south, is my bet.

 

[junkfixr]

runs good

at 12 degrees BTDC, but just has a slight miss/shimmy at idle. I've got the feeling I'm just slightly too high in time to get a good idle. Considering the mileage, would you suspect a valve deposit? Is it possible I'm just a little too advanced in time to get a smooth idle?

I'm gonna try a little higher (89) octane and put some 44 heat range plugs in place of the 42's. May not make any difference, but it's a cheap experiment. Anyone else have an experience like this ?