I am either going to be useing a mallory or a msd distvac advanced dist, I was wondering ho do I achieve the total timing number? do I want the vac advanced hooked up how much do I want and by what rpm? the motor is a 350. what is mec advance and what is vac advance? how do they all work together to get the final 36 to 40 total? how do you set each?thanks

 

The 36 degree "total timing" number doesn't include the vacuum advance, it's just the centrifugal advance plus the base advance.

 

look on the main page of TGO for an article about "high performance HEI ignition" or something along those lines. Written by Damon I think. He lays it out step by step.

 

So if i set the timing to 10 at idle with the vac dissconnected, And say the dist has 20 built in to it, I would then bring it up to 3,000 rpm with the vac still distconnected and I should have thirty at this point? If I would want 38 I would have to set the base at 18? Do i want to check it with the vac hooked up? at all?

 

That's pretty much it. Adjust your centrifugal advance so you've got about 34 degrees or so at 3000 RPM, or sooner if the engine will take it without pinging at WOT.

After that you can adjust the vacuum advance curve to avoid pinging under part throttle.

 

Do i need to check what the timing is when the vac is hooked up? some come with a adjustable vac advance some do not, if they don't come with one how do you adjust it? if you need to buy a adjustable can is it worth it? thanks

 

if they don't come with an adjustable vacuum can - you can't adjust it.

I think it's worth it, having the rate, and amount of vacuum being adjustable there. The Crane one is what I have, and I like it.

Yea, you don't really need to check your timing with a light with your vacuum can hooked up. Unless you want to hook it up to manifold vacuum just to verify how many degrees you're getting max.

Did you read the article I pointed you to? All the info is there, ie, how to adjust it, etc.

 

Yes I read the article, so the dist should be hooked to ported vac, but I can hook it to manifold vac to check total timeing? would i leave it at idle to do this? thanks

 

Well, no. "total" only refers to base, + mechanical advance. But that's just symantics technically.

Yes, you can let it idle, and hook up to manifold vac to find out the max timing you're getting from the vacuum can. timing, subtract your base, is your vacuum timing added.

Assuming lets say you're getting 18" vacuum at idle, and at cruise you might be getting 24", so we're assuming your vac can is maxed out by 18". Or whatever you've got at idle. That way this test will work.

If this amount of timing (could be upwards of 30*), raises your idle speed to where your mechanical advance is kicking in, then again, this is meaningless. You'll have to close your throttle blades until it's below the mechanical advance period. So it can get tricky, but you'll figure it out.