Timing with a vacuum gauge

perko said

Hi all,
I've been trying to time my 318 after I put on a new carb and intake but I think that the balancer has slipped or something because I can't even see the timing mark with my gun.

I've seen some information about timing an engine with a vacuum gauge on the internet so I gave it a try. I adjusted the distributor to max vacuum (about 22) and then brought it back a little to about 20-21.

My question is have i done this correctly? Is this an accurate enough way to time the engine that i can move on to tuning the carb and stuff? Or do i need to find another way to make sure I get this right? Thanks!

Click to expand...

You have found what the engine wants for it's initial timing. Now you need to limit the total timing by reducing the amount of mechanical advance in the distributor.

There are at least two ways to do that. One is to use the limiter plate offered by Four Seconds Flat. The other is to weld up the slots in the mechanical advance portion of your distributor and then file the slot to obtain less mechanical advance. I'm guessing you target timing will be anywhere from anywhere between 34 to 36 degrees total including your new higher initial timing plus your vacuum advance rate.

Once you get the initial and mechanical advance done, you can adjust your vacuum advance to get greater efficiency at steady state cruising.

There's a great article about this process on the Four Seconds Flat website.