The one millionth timing question

[AMXguy]

I got a spring kit and messed around until I think I have a decent curve, or not I don't know. I was getting some pre ignition at the 2000-2500 rpm range under full throttle in my 440 because all my timing was coming in at 2000 rpm. soooo I played with springs until I now have 11 at idle,15 at 1500, 25 at 2000 and all in at 36 at 2500. BUT to get this I have to use the vac advance which I just read doesn't count in the total timing? that doesn't make sense? my vac isn't doing anything until about 2200 then it helps up to the 36 at 2500. I know this is a screwed up question the way I discribe it but I can't go test drive the car because the roads are a mess for a few more months, anyone care to tell me if I'm probably ok or if I need to change anything?

[dodge freak 2]

Not sure I follow you but heres what I know.

If you put in both light springs and you get pinging at say 2500 rpms and the total timing is right, then you should swap 1 heavy spring in and keep 1 light spring and see if it goes away then.

If you have no heavy springs then you can double up the light springs, just make sure the hoops are going the same way. I am using 2 light springs on one side and just 1 light spring on the other side. It fits so good you can not tell by looking down at the springs one side has 2 springs on the same posts

[quagmire]

Depending on how big of a cam you have it is very possible that the vacuum advance wont do much at lower RPM's because you wont make enough vacuum.  Do you have the line hooked up to a timed vacuum source?  The advance could be sticking too.  Vacuum advance will not do anything for total timing at WOT, because you will not be generating vacuum.  That is why initial and total have to be dialed in w/o the vacuum line hooked up.  Vacuum advance adds timing under light load/throttle conditions, it is used to improve fuel economy and improve drivability only.

[AMXguy]

 Yes I think I have the vac on the right port. but if you had 36 total without the vac hooked up then added the vac at 10 or so to bring you in around 46 + - wouldn't than be too much?  am I wrong in thinking keeping the vac advance down under full throttle would help my detenation issues?  getting my total all in by 2000 isn't working, and I can't seem to find a combination of springs to get it right without using the vac advance. 

[quagmire]

Well the thing about using the vacuum advance is it doesnt work under full throttle.  If you are having full throttle detonation issues the vacuum advance is not the problem.  You should be able to get 36 degrees out of that distributor w/o vacuum advance.  Under light load you can run much higher advance, so 46 degrees is probably not going to hurt anything.  Are you sure your timing marks are accurate?  Maybe the balancer outer ring has slipped.

[AMXguy]

I was getting 36 out of it with no vac advance hooked up but the problem is it was coming in to fast. none of the spring combinations I've tried will give me 36 total without coming in to early, now I'm getting about 25 mechanlcal at 2500 and I'm bringing it up to 36 with vac advance. if I understand right 25 isn't going to be enough mechanical? I have an adjustable vac so I could bring it up to 45 or whatever but that's not going to solve anything when the vac is dumped . is being a little short on mechanical advance going to make a noticable difference in performance you think?

[Aussie Challenger]

  Plug your vac advance up and get the mechanical working properly first.   

  When everything is working then re-connect the vac advance, it is adjustable also.

  Vac advance is basically for economy, it can give a little quicker take off in an auto trans equiped car.   

[Chryco Psycho]

sometimes using the vacuum advance helps , it can bring the curve in sooner & can be limited by inserting an allen wrench through the vacuum nipple & turning counterclockwise , each tun is approx 1* & you have approx 14 turns total

[AMXguy]

So if I have 10 initial + 15 mechanical all in at 2500 for a total of 25, then add say 10 of vac to bring it up to 35 will I get decent power and not burn valves? I could add even more vac advance but as has been said that does no good at WOT. I have every spring mopar performance makes but I just can't seem to find a combination to get 30 or more total without it coming in too soon, unless I get the last 10 from the vac advance. if this isn't going to work I may have to send my distibutor off and get it curved, the way it cam new giving me 32 at 2000 with no vac advance hooked up wasn't working for sure so I have to do something.

[LAA66]

 I went the lazy man's way and sent mine to FBO too have the distriutor inspected and the curve done. It made a big differance in response and power.

[Chryco Psycho]

Sounds about right AMX ,  + it will retard the timing at WOT a little so detonation should not happen

[AMXguy]

Sweet I'll try it when the roads clear this spring.  I can live with a little less power I just didn't want the fun of heating and burnt valves .