Timing Adjustment

ok, after two months of messing around I finally got a working ECU and the truck is running again. It actually seems to be performing better than I remember it ever being. However, I figured just to be thorough I would check/adjust the timing with the cheapo timing light I ordered and using the dashboard tach instead of a handheld. It went pretty well but there were two things that I'm not certain are correct.

When my truck has warmed up it idles nicely at 750 rpm, exactly what the VECI says. However, the VECI also states that the 750 rpm is with the test jumper installed. When I install the test jumper the engine speeds up to maybe 800-830 rpm. So, should I trust the tach and lower the idle speed (maybe whoever set it previously didn't know to ground the test connector) or since the Haynes manual says the dashboard tach isn't accurate enough for setting the idle speed should I assume it's close enough and let it be? Or is it worth getting an accurate handheld tach?

The timing was just under 6

I rotated the engine on the B2200 with a 21mm socket and then painted the mark white.

On the B2200 I found it easier to pull the AC belt off to better see the timing scale.

No, 1 degree off isn't worth setting, within the limits.

I thought about rotating it manually but couldn't remember how so I just tried without paint and was happy it worked. Sounds like I didn't need to adjust the timing anyway.

Thanks for your reply.

I noticed you're in AZ. I grew up in tucson and loved it but was happy to have nicer weather when I moved. I'll never go back without AC.

Yep, a few of us here are in AZ. Luckily, the AC in these trucks works pretty well (or I would've moved on long ago).