...Also in the tech forum, so whichever one takes off first.

Hey guys, I just had a quick question. I've been browsing the carb section for carb/ignition tuning and have some great ideas on what i should be running as to base/mechanical/advance, but i can't make sense of what I have now...

I am running 11* initial. I am using a rebuilt HEI w/ a proform HEI tuneup kit. The little slip of paper is rather vague, and that's what is confusing me.

I am running the silver springs. Paper says the curve starts at 600rpm, and is in by 2800 RPM, and it says curves are based on a 24* mechanical advance at the crankshaft. This is where I am lost.

Would that mean I have 35* of advance, with the curve coming in at 600? I'm understanding that's coming in too fast?

I have read around here and some big names say the curve shouldn't come in till after 1000rpm, and all in by 3000?

Anyone willing to clear this up I would be grateful. I have also looked into getting an MSD advance set, out of my MSD catalog, in which they have about half a dozen charts comparing springs and mechanical advance.

Thanks in advance, hope this makes sense.

 

What they mean is that the centrifugal advance will BEGIN to kick up off of the initial setting (11* BTDC) at 600 RPMs and reach full advance of 35* (11 initial + 24* centrifugal = 35* total) by 2800.

However.... trust NOBODYS paper specs. You need to play with everything and test it yourself with a dial-back timing light and a tach to see what's ACTUALLY happening and when.

24* centrifugal advance is a lot for a stock-style HEI. Most poop out around 20* depending on the centerplate in it, mostly.

600 RPMs is awful low for a timing advance curve to begin, too.

TEST FOR YOURSELF! That's what I've done for years. You are almost certain to find that it's very different than what the piece of paper tells you it should be.

 

hmmm...that's what i was thinking too. close enough not to hurt anything, but still leaving more to be desired.

my car idles at around 800rpm in park, so the advance has already started?