Timing Question - Third Generation F-Body Message Boards

mavcar38 · 10-29-2009, 09:13 AM

I just fired up my new crate 350, 330 hp engine up yesterday. Im having some difficulty setting the timing. It has a holley 4brl electric choke carb, hei distributor. Mild cam. Plugs are gapped at .45 What should my timing be set at?
Thanks for the help

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Bobbyz · 10-29-2009, 11:28 AM

I would say 12* initial for starters

Damon · 10-29-2009, 10:59 PM

Agreed. About 10-12* initial should put you in the ballpark.

Remember to check this with the vacuum advance disconnected and plugged and the idle speed very low to make sure you're not getting the centrifugal advance kicking in a few degrees of additional timing, which would give you a false base timing reading.

Fionnla · 10-29-2009, 11:48 PM

12 degrees advance is where I set mine, seems to run the best there.
GM suggest 10 degrees. I hook my distibutor vacumn advance line to the timed vacumn hose connection on the carb after setting the timing.
My 350 is setup with the Edelbrock Airgap RPM manifold with a Barry Grant Speed Demon 650 Dbl Pumper with electric choke and MSD Dist & Control box. Runs great. I have a Speed Demon 650 with vacumn secondarys and electric choke. It ran fine, but the I like the Dbl Pumper with the Stall converter. Good Luck with your 350, I'm sure you'll love it once you get it setup.

mavcar38 · 11-02-2009, 09:47 PM

Cool, thanks for the help. Im not the greatest at setting carbs up. Ive always had tpi prior to this. In the process of breaking the motor in now. One problem Im having is when the car is in drive with the brake on every so often it will jump and sound like it wants to cut off.....its strange...is this timing or a idle/mixture issue?

vortec350s10 · 11-03-2009, 02:01 PM

If you have your timing set at what everyone is saying, I wouln't think it would be that. Which vacuum port on your carb do you have distributor connected up to? If your distributor sees no vacuum at idle, I would have to say your idle mixture could be a little on the lean side. I have your same engine with a lot of hours and hours tuning it, PM me if you need anything. I've tried a lot of stuff on mine. Adjust your idle mixture for maximum vacuum at idle to get it real close. Experiment with switching your distributor vacuum advance from ported to full manifold vacuum too if you want it to advance more at idle. Mine likes to have vacuum on it at idle. Idles a lot cleaner and smoother. While cruising mine didn't have enough throttle blade opening to allow vacuum to start pulling though the ported port for vacuum advance, so I gotta keep mine on full vacuum. Sorry didn't explain the best, gotta get back to work, so made it quick.