I bought a new timing light some recommended; the Innova 5568. Nice and works well; but was surprised that the instructions were for ****. Being old school my old light did one thing check initial timing. With the added features there was more to learn and some sifting on the web helped; but still kinda foggy information and confirmed this with two buddies that have done a whole lot of car work for eons. What I gathered is this dials in timing adjusting the strobe pattern and give you, or actually confirm, what the timing is when say it's beyond what the indicator plate provides by finding the timing matching TDC. And also by dialing in timing, for full advance, gives you what total advance is at various RPM's that is to mate the balancer mark to the indicator to TDC. Anyhow, this is what I gather. My problem is when I connect the vacuum advance, the mark is whacked out nowhere near the TDC and motor stumbles (that's what I'm trying to get rid of). So this is a problem I'm thinking is advance adjustment or curve is off. Does my description of the timing confirmation jive with those of you who are versed on this? Thanks! Hope I've given you ample details.
Timing Light School
- Thread starter Ron H
- Start date
Frank Mopar
Well-Known Member
69L48Z27
Well-Known Member
Your vacuum advance should not be doing anything at idle. I’ll open the great manifold vs ported vacuum debate. Vacuum advance was intended off idle while cruising. Some found the running it off straight manifold vacuum was good for them. That’s fine. If you have a stock setup you don’t wasn’t any vacuum advance coming in at idle IMO.
What is your timing at idle, advance disconnected? What RPM? What is your timing with advance hooked up?
What is your timing at idle, advance disconnected? What RPM? What is your timing with advance hooked up?
Frank Mopar
Well-Known Member
I have a mild cam in the poly 318 with solid lifters, bored out .60. Timing is at 12 advanced. Runs like a clock without the advance connected. Stumbling occurs only with vac adv connected starts at around 2200RPM. If I used this new timing light correctly, I found total in the area of 30 at 2500 RPM; but when connecting advance, the mark is way off at 2500. I'm sure there's more to this and will check the links provided...thanks again...while I stay on the hunt!
Ironbuilt
Well-Known Member
This might help.
Many vac cans have a allen head adjustment 9/32 I think inside the hose nipple. Cant recall what direction clockwise or counter will raise were /when it pulls more advance.
It may be adjusted all one way/ bottomed out. I am pretty sure the adjustable cans have a hex head looking shape.
Lefty71
Well-Known Member
You need to be sure you know how to check and set timing on a vacuum advanced distributor type motor with a basic light first, then it will be easier to understand the dial-in style. That sounds a little critical, but it's true and not meant to sound that way. Anyway, another important consideration is that if you are using that light on an MSD or multi-spark type ignition box, it's going to be very erratic until you rev the motor up to 3,000rpm plus to get single sparks from the box. If that's the case, you'll probably need to get a MSD compatible dial-in light (they do exist) and try again. HTH, Lefty71
There's more to my story that likely raised the great questions and tips here. I put in a mopar electronic ig years ago but two years ago motor was totally rebuilt with some mod's. Come to find after wanting to do some tricks to hep it up a bit off the line was the idea to trick the advance with lighter springs. I took two steps forward that may have been a goof. First I came to find that my advance was dead anyway so had to get a new can and since this was off put in lighter springs. Maybe shoulda left that alone and set this up before doing springs. Just a guess. In any case with a 'working' advance this created the stumbling problem at around 3k rpm, so adjusted timing. This got me getting stumbling at around 2000rpm. Meantime my old timing light took a dump (I only had it 40 years lol). So then got one with added perks as I described. The nifty thing is the light gives the ability to verify timing at initial and also total that I had to read up on and I gather I'm doing this correctly...I think. For example, if your timing is more radically advanced, off what the indicator plate identifies, you set the light to say 15 degrees...then you check this by the location of your timing mark to the TDC mark. If they're meeting you confirm it's 15. For total, then you set the light to say 25 and rev engine up to 2500-3000rpm to again see if the marks are lining up. If not, as in my case, I reset the light to 30 and found marks were aligning to indicate total is 30. Of course the advance adj being whacked out is another animal to contend with and my read up with the links sent is a tricky deal to figure this out then get it right. Ahh...so I'm thinking.
Similar threads
