Big Rod.....................Uhhh....I'm lost!?!
sorry
6s6

at wrote:

It would be lower but I don't understand what you're trying to do.
Say at 800 rpm you're getting 4 degrees centrifugal advance so you dial  in 11 degrees btdc static to get your 15. At 1500 rpm you may be getting 20 degrees cent advance so you would dial in 5 degrees atdc static. If your advance tops out at 3000 rpm you would never get to 36 degrees. If it is still climbing you could get more depending on rpm.

 I can understand your confusion.
Here is some background.
The Engine is a 302 crate engine that was supplied to me with the carb adjusted as well as the timing preset at 3000 rpm to 36 degrees. I am assuming they set it at that rpm because of the rpm fluctuation at the lower normal 800 rpm (caused by cam). (clear as mud eh.)
 Any way I was re-tuning it, setting 15* static at 1500 rpm
 when I began wondering where it would end up at the 3000 rpm point. I’m using 1500 rpm because that is where it is idling in park with a c4, about 950 rpm when in gear with the brake applied.

 

Nasty65 wrote:

I'd suggest setting total timing where you want it, typically it will be "all in" by 3k-4k rpm, and let the initial fall where it may as long as you don't run into hard starting problems.  Then just adjust the throttle to the rpm it wants to idle at.  If your timing is set too low at upper rpms it can result in poor performance and overheating issues.

Yes, I'm in agreement.
Thanks for the replies.

Rod

I always set total at 4000 to 5000 rpm to make sure everything is out at that rev level. 35 to 36 degrees seems to suit most set ups for the small block Ford. Once in a while I see one that likes more, sometimes as much as 41 degrees. I always run a plug cut with new plugs when I get one that is that high to be sure I am not getting any detonation issues.

I do not run any vacuum advance, only mechanical. The cams I run are not kind to vacuum controls. I even have one set up with no mechanical either, I had to use an electronic box to retard for starting. It is an awesome set-up.

Rod wrote:

If 15* base timing is set at 800rpm resulting in 36* timing at 3000 rpm, is the 3000 rpm higher or lower if base is reset to 15* at 1500rpm?

I'm thinking the 3000 timing would be lower with the 1500 reset .

Rod

I'm not sure what you're getting at, but here are a couple of links that may be of help:

http://www.gofastforless.com/ignition/advance.htm
http://classicinlines.com/spark.asp

Don't know your situation but as these articles indicate, unless you have a very special situation, a car driven on the street will be more responsive, get better gas mileage, and easier to drive with vacuum advance.