so i have a 350 with about 10 to 1 comp, camel hump heads edelbrock performer cam and intake and 600 carb, and with the vacuum advance disconnected, i set the timing at 10 degrees, is that about right? also i should run the drivers side port for my advance right? cause it has vacuum at idle, or should i be using the other one?

 

It depends on the cam. I'm assuming you aren't using the stock cam because it ain't gonna like 10:1 C/R. The combustion chamber shape in the later (after '67) heads will tolerate a good bit of advance. The amount of advance that the centrifugal weights in the distributor provide also figures into it.
The vaccum source OHpinions run about 50/50 ported verses straight manifold vacuum. I prefer straight.
With 10:1 C/R I would start with 6 degrees and adjust it up from there, listening for the engine to ping. It may ping at 6, again depending on the cam.

 

What does OHpinions mean anyway??

But yea, you'll have to play with it. More timing, load the engine hard at low RPM at operating temp, does it knock? Nope, add more. Yep, take 2 off and try again. Then if it won't idle because it doesn't have enough timing, throw on vacuum advance, if it does idle fine (without having the carb bores opened enough to give a long flat spot off idle...) then you can just use ported.

 

its got the performer cam like i said haha, but anyways i dont remember the exact spec but like 218 218 duration and like 420 442 lift, i started it up and got it to operating temp, took off the vac advance, and then i put the timing light on it and set it at about 10*, then connected the advance and set the carb, has nice response and idles, nice, but the furthest ive drove the car yet is about 15 mph, never got out of 1st gear, no plates or insurance yet so i cant go to far, so would i have it set about right?

 

Close enough. The only thing it'd be lacking now is a bit of HP. Wait until you can drive it harder, then you can fine tune it.

 

Unfortunately, timing shuoldn't be a matter of opinoin, but rather what the
engine responds to best.

Depending on what you're trying to accomplish (best fuel economy, best power, etc.), you will find the timing curves are going to differ quite a bit.
If you put a little effort into the tuning the curve, you can get the best of
both worlds (especially if you have an adjustable vacuum advance canister
on the distributor).

You will have to road test, or track test the car to find the best timing
curve. A dyno works well too.

 

and that's a matter of opinion What I want out of my car (and therefore how I get it) is different from what you want out of your car (and how you get it).

 

"OHpinion" is my way of highlighting that some people will say that you should "definately" use ported and some will say you should "definately" use "straight" manifold vacuum.
Neither is incorrect.
It's becomes a matter of "OHpinion" when one is correct for one setup and the other is correct for another setup.

 

That sounds exactly like "Tune by Committee" (French Grimes), where you
ask a question to a group of people. Which ever response gets the majority
is the way you will set the engine.

 

well now im confused, i read the tech article about timing, and it says start with 12 to 18*, and that most small block Chevy's like 32-38* total, but then at the bottom, it says your good in the ball park of 45-50* total, so which should i shoot for? i always thought that it would be good at like 36 or 38*, so should i start over and set it up with like 12? also it says to stick with ported advance, which means i have no vacuum advance at idle, so set it at 12* at idle?

also im looking at this distributor from accel, on summits site its like 119.95, so does it come with adjustable vacuum advance or not? prolly not so i would have to buy the crane kit right?

 

At wide open, mechanical advance + initial, your combo tends to like timing
to fall between 35-39 degrees.

The 45-50 degrees you are referring to is part throttle cruise with vacuum
connected. This is a total of mechanical + initial + vacuum.

Under moderator loads, and part throttle, the engine can accept more timing;
that is where you are getting the difference in full advance timing from.

Shoot for a starting point of 36 degrees total at 4000 RPM. You can tweak
it on the dyno, or track.

The total is what is most important. Let the initial fall where it may, and then
you can adjust the timing curve, and vacuum to come in and out where the
engine likes best.