Trying to get my 327 tuned just right. I know a few of the theories, but here is what I've got:

With tranny in park: Idle 1200RPM, vacuum 20-21", timing set 14BTDC.

Note: The more I advance the timing, the higher the RPMs and vacuum. It looks like it might like 20BTDC!

In drive w/ parking brake: 15-16" Vacuum and idle at 850.

Also of note, the four corner idle screws are nearly fully closed, between 1 & .5 turn to close! My guess is that my transfer slot is too exposed. I was planning on closing the secondaries and run idle off the primaries.

Any thoughts...?
Thanks

Engine: 327, vortec heads, Performer RPM intake, 5/8" 4 hole carb spacer, 268 cam, MSD ignition all around, road demon 625cfm, headers, etc.

Ethan '67 327

Be sure to get the vacuum out of the equation as well as the mechanical advance. Disconnect the vacuum advance and set the timing, using a degreed timing light, with the distributor at full mechanical advance. This is probably at least 3K rpm depending on your spring and weight combination. The total advance number to shoot for is somewhat dependant on the efficiency of the combustion chamber. IE: Good heads will need less advance than stock heads. I would probably start with 38* total. After setting the timing reconnect the vacuum advance to a manifold vacuum source not the timed port on the side of the metering block.

Don't shut off the rear half of your 4 corner idle. 1250 rpm is too high. You have to be idling on the timing curve which will cause problems. Try to get it to idle below 900 rpm as most distributors the mechanical advance curve doesn't start until 900rpm (the initial advance will stay at where you set it at any rpm below 900). Since you are making 15+ vacuum at 850 in gear you should be in good shape idling in neutral around there (maybe lower). Your engine may like 38 degs total advance but until you get control of your carb, set your initial at 14 -16 degs with the vacuum advance disconnected and the port on the carb plugged.

Here's what I posted in another BG thread, ignore the plug comments. You really want to set that carb back like it came out of the box.

Originally posted by DjD:
Here's how I found success with a BG carb. Floats should be in the middle of the site plugs (as opposed to Holley's at the bottom) Next the idle screw(s) need to be adjusted with the carb off the manifold. There are transfer slots in the walls of the throttle bores and with the carb upside down you want adjust the idle screw(s) so .020" of each slot is showing. BG says once these are set you don't want to play with the idle adjustment any further. Now use the rich lean mixture screws to set your idle. All this is straight from the BG manual and video that comes with each carb.

I also suggest if you have made any jetting or power valve changes you go back to the factory setting until you get this thing idling properly.

I don't know where the rapid fire #5 sits in the heat range compared to other plugs but one range colder than stock heat range should be fine for your stroker. Also a blown power valve will create a real rich idle condition.

Edit: That transfer slot is .020" wide so if you adjust the throttle blades so you see a square you will be about right.

Good advise Dennis. FWIW I agree 100%

On the timing thing. I would just set the total timing to 36* and forget about base timing. Set the timing first, then the idle mixture, then the idle speed.

My 750 speed demon also idles best with the idle screws out about 5/8 turn, sounds like yours likes the same setting. Just set them with your vacuum gauge (sounds like you already did) and forget 'em.

Then, if you have to change the idle speed just make sure that you adjust both the primary and secondary idle screws exactly the same amount. I set mine to the .020 like the video says then I adjusted both screws exactly the same amount to get the idle speed I wanted. Mine idles at 1100 in neutral and 900 in gear (lumpy cam). 850 RPM neutral and 700-750 in gear is a good place to be IMO unless you have a lumpy cam, then just raise idle speed until you get a stable idle.

Good luck!