I'm setting my timing (again).
I've done it before but when Lars says to disconnect the Vac Advance I wasnt plugging the vac port on the carb. (I timed the car 2 months ago and just now realized I didnt plug the port :rolleyes: )
Now here's where I'm at.
Remove the springs and disconnect Vac advance (plugged port on carb)
Set timing light to 36 and revved motor. Set timing mark to 36 while revving.
Put back springs. Checked to make sure It would hit 36 while revving.
Hooked up Vac advance.

Does this sound right?
How steady is the timing mark supposed to be? Looks kinda jumpy when revving.
Any help appreciated.

 

Have you shimmed your distributor? End play in the shaft can cause jumpy timing. If you haven't done this, I'd recommend buying one of Lars' recurve kits.

 

Stewart -
You don't need to plug the vacuum port - an open vac port won't affect the timing in any way, so you can just yank the vac hose off and leave it off while doing the timing check. You do need to hook it up and/or plug it in order to properly set idle mixtures and idle speed.

Remember that you can only use the spring removal timing method if you have a point-style distributor - do not remove the springs off of an HEI as the HEI will go into an artificially over-advanced condition with the springs removed. If you have a point-style dstributor, you can remove the springs to observe the total timing at a very low rpm: with the springs removed, the distributor will slam into a fully advanced condition at or below 1500 rpm - no need to really rev it up (that's the reason for removing the springs). This fully advanced condition may show a little bit of timing scatter due to the weights flopping around a little, but it shouldn't be too bad. If you are set up with a nice soft set of springs that allow full centrifugal advance at or below 3000 rpm, just leave the springs on and rev the engine up to 3000 or until the advance pegs out. Yes, you set the timing light at 36 and line up the timing line on the balancer with the "0" mark on the tab with the advance pegged out (vac advance disconnected). Once done, you can hook up the vacuum advance and rev it again with the vac hooked up: if you're running the right vacuum advance unit, the total combined timing with the centrifugal and the vacuum all slammed in should not exceed 52. Set the light to 52 and verify it.

 

As always, thanks Lars

 

Lars,
On my 75 it would have the HEI ignition. If I leave the springs connected, do I still set the timing light to 36 degrees and what RPM do I rev to?
Thanks :confused: :confused:

 

but but but but!!!..... Captain Obious just wants to mention that you can pull the hose off the vacuum advance can, no problem, but you must plug the port or hose on the carb side or you will have a big sucking vacuum leak!! :) MJ

 

MN -
Yes, but at any rpm above idle the small vacuum leak has no effect on engine operation or the timing. So you can just yank the hose, rev the engine, and set the timing. No need to waste any time plugging the little vacuum nipple - the small leak has no effect on the timing operation or engine operation above idle. Really...

 

Does amyone have a link to Lar's timing paper ? I need to recurve my distributor maybe this weekend and wouldn't mind have his paper handy ;)

TIA :cheers:

 

Mike, its @ http://www.corvettefaq.com
Find it on the same page as how to install your chevy dist.

 

Thanks, I'm sure it'll come in handy ;) .