new timing light new question

70gto · 04-26-2008, 01:25 PM

I decided to check my 70 gto timing with a new light that has the advance dial. I run points. Well I first moved my vac advance to the manifold, and capped the carb. Checked dwell at 30 degrees. Adjusted idle to 1050 idle and about 900 in gear. I run a Ramair 4 cam so it needs a little more to idle right . By turning the timing light knob when the line hits 0 on the balancer I am at 30 degrees per the knob on the timing light. Is this about right?

I went to check it by disconnecting and plugging the vac advance but it ran real rough back fired and by the time I turned it off I fouled number 1 plug. In fact the timing light would not work with the back fireing. I pulled the plug cleaned it , checked wires and decided to call it a day. Needed to get to T ball game.

I see the tuning sticky in this thread, I followed that and one on another GTO site, I did vac check the advance it does work, and I pulled the cap and rotor to visually check it out. It is missing the bushing under neath mentioned in the sticky and runs 2 silver springs. So I just want to know how close am i with the timing at 30 degrees with vac hooked up?

Rukee · 04-26-2008, 08:38 PM

If you read the sticky, Lars suggests 36* total advance @ about 2500-2800RPM. Disregard what the timing is at idle.
GTO Tuning and Setup Tips

70gto · 04-27-2008, 09:52 AM

Well he is doing it with advance disconnected, I had problems when i pulled the advance off. Plus that seems a little hi for a pontiac, I believe he is using a chevy . I was trying 32 to 34 at 2100 before the back fire , I just was curious what base idle at 30 degrees means.

Rukee · 04-27-2008, 11:23 AM

You want to check total advance with the hose on , and then just let the timing at an idle end up were ever it wants to be (as long as it starts okay without hitting hard) with the total at 36* @ 3000RPMs.
A chevy engine runs a bit more timing, total advance at about 38-40* at 3000RPMs.