Need some help guys. Don't know much about this engine, the guy I bought it from didn't know either. 350 chevy, medium cam and headers. I just put on an Edelbrock crossram intake with 2 Holley 450s. Runs like a banshee. I'd like your opinions on where to set timing at idle. It's vaccuum advance. It runs really good at 8 BTDC but the idle increases as I push it more advanced. But I don't know what I might be gaining or losing by advancing too far??? So, what ya think is best for timing at idle? Thanks guys....

A pair of fours...

Yes, as you advance the timing the idle speed will increase. So lower the idle adjustments on the carb,..or do I not understand the issue?

Reverse your thinking.
Set the upper end of the curve for max performace/economy...that is the important bit
Then leave the intail where it 'falls' and adjust mixtures Sec and primary butterflys for best idle...

I guess I really didn't ask my question well. I just don't know how much advance I should be setting at idle. I don't have any guages or anything to tell me what total advance is. Just wanted to know what you guys would suggest as to advance at idle............

Thanks,

You shaouldn't have any advance at idle, except for initial advance. Unless, the non-stock camshaft needs more timing to produce an acceptable idle speed.

Some use full-time vacuum for this purpose. Otherwise as suggested, shoot for total timing at upper rpm, then let engine idle and see/view timing at idle.

A vacuum gauge is the best tuning tool, along with common sense, but you already knew it.

Give it as much initial as it will take. 8* sounds low, I would try 10-12*. You need a timing light to set the advance. After you set the advance, you may need to lower the idle speed.

You also need to figure out how much timing is in the distributor. Do some searches for the procedure.

Greg - a typical sbc 350 will want between 32-36 degs of total advance (btdc). Total advance is directly related to initial (idle if you wish) advance. If you increase the initial by 2 degs it also increases the total by 2... How do you know you have 8 degs of advance at idle? You would use the same tools for checking total timing you use to check the initial.

Now trying to keep it simple and not go into the whole initial/total and mechanical/vacuum timing thing. You say your car runs great so why mess with it? If you must play, add or remove timing in 2 deg increments and test it by going for a drive. Listen for pinging under load and at WOT. Also watch for starting problems as you advance and overheating if you retard the inital at idle... As you advance the the initial the idle will increase as already stated so just turn the throttle adjustment screw to bring it back down. Always check your timing after doing this, if you are idling on the curve the timing will change and you might need to reset the timing.

Last bit from me is to always know where you started, check and write down where the timing is and verify how many partial turns you make to any screws so you can put it back... Again though if it runs good now, don't mess with it. Seat of the pants isn't very accurate so the track where you can make timed runs is the best place to do performance tuning...

I guess I really didn't ask my question well. I just don't know how much advance I should be setting at idle. I don't have any guages or anything to tell me what total advance is.

So u are unable to make a curve mapped on graph paper.
BEFORE even touching anything u MUST have a timing light.
Quick Fix/improvement:
As a general rule of thumb, for a basically stock engine, with orginal dizzy.
Keep the intial at stock or increase at the most about 2 deg.
Source a set of lighter springs..These can be from dizzys in a wrecking yard, (most ford mopar springs are also interchangeable) and or purchase a set from the local speed shop.
Replace 1 spring with a lighter spring...feel how the car responds from standing start.
Replace the other spring and repeat...
Keep an ear out for detonation and ping...if u hear any go back 1 or 2 steps.

It is may experiance in Ford, Chev and Holden engines, the changing to a lighter spring, (faster curve) even in a hit 'n miss fashon makes a suprisingly big difference.

Guys, thanks for everything. I just wish I knew more about this engine. I have a timing light but no other stuff. I've just been reading stuff about running hot and other things, guess it makes me a bit freaky. This is in a '68 Camaro that I just cruise Sunday afternoons in. A rather fast cruise whenever possible of course. A buddy said to push the advance as far as I can get away with without pinging but I'm not so sure about that. So, I've given you guys very little to work with but as much info as I have. I guess if it runs GOOD, and stays at 190 degrees I should be happy???

Thanks guys,