Help me understand my timing please

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bigtooth

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So, my setup is as follows:
MP 360/390HP magnum crate engine

cam specs.
288°/292° Advertised Duration
(230°/234° Duration @ .050")
0.501"/0.513" Lift

9.0:1 compression.
4 speed car.

I have an MSD Pro billet ready to run distributor with the two heavy springs and the blue bushing in it to limit the mechanical advacnce to 21 degrees on a slow curve.

I'm also running an MSD 6al box.

The thing that gets me is when I look at the initial timing (no vaccum advance) at idle the engine needs around 32 degrees just to idle, any less and it dies. I'm using an old style light, not a dialback light.

From everything I've read this seems really high. That would put the total timing at 53 degrees. The motor seems to run well, it has a bit of a bog off idle but then comes right into it, it doesnt break down in the higher RPM range, and is not obviously pinging.

Does anyone have any ideas why I need so much initial timing to get this thing to idle?
 
You need to verify TDC. Bring #1 piston to TDC using the piston stop method then check the mark on the balancer to see where it lines up with the mark. If it is correct then check that the rotor is pointing to the #1 wire terminal on the cap.

It's possible the balancer ring has slipped or the dizzy is one tooth off.
 
There is a fair amount of noise on the www about timing light problems with MSD. I don't use 'em so am not familiar.

Some systems seem to have a "bypass harness" (optional?) that may solve the problem

It also sticks in my mind that above 3K the MS goes away, so you could conceivably set for total mechanical time and if you are sure of the dist. curve, "figure" initial by subtraction.

I agree, though the very first step is to verify TDC. If you need help post back
 
you can make one or buy one dirt cheap
 

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OK, piston stop. Get, buy make one

Remove the no1 plug, and make sure the piston is "down a ways." Unhook the battery for safety. Install the device. You may have to play with the length of the device some. It is IMPORTANT that you "jam nut" the plunger so that it does not move.

Gently wrench the engine around until it stops on the device. You are NOT trying to "find" TDC, merely stopping the piston somewhere as it comes "up."

When the engine stops, make an accurate mark under TDC on the tab onto the balancer

Now repeat, going CCW

You will now have TWO marks on the balancer you've made, and true TDC will be 1/2 way between, and if the original is accurate, that is where it will be.

Now is a great time to go further and degree your balancer, or measure it for timing tape. Use a narrow, flexible tape to carefully measure around the balancer to obtain an accurate circumference

Now you can either order the proper size timing tape, or figure how many "degrees per inch" and mark off the balancer the appropriate distance.

I usually figure 40* and carefully mark that off, rechecking carefully. USE the tape, not dividers for this first step

Now, you can use dividers to cut the 40* mark in half, for 20, again for 10, etc. Then scribe, and file, the marks into the balancer.

If you are interested in checking vacuum advance, you should degree out to about 55*
 
I'm running the same cam as you in a 402/435 . According to Chrysler, 1-888-528-hemi, my initial should be 15-20, total 32-35.

I'm just getting it on the road after a ton of delays, and I'm running 19 initial and 14 mechanical. Check to see what your msd recommends for your plug gap for 9:1. NGK said for me to use 7938-BKR5E PLUGS.

Starts right up and doesn't kickback, sounds mean.
 
I had the chance to check my balancer for TDC last night, I built a pistion stop and used the method in the video and explained in this thread. Everytyhing looked right on, my center mark was right on my 0 Degree mark. Then I looked at my rotor point, it was pointed almost 180 degrees from the #1 wire, I thought 'a haa', but then realized I was on the exhaust stroke and went around to the 0 mark on the balancer 1 more time and it was almost pointint at the #1 wire, I feel that if I retarted the dizzy back to 0 degrees it would have been right at the wire - does that make sense?

I think I'm getting a little detonation at lower rpms when I try to get on it, I can hear a metalic rattle if I try to aggressivly 'lug' up the RPM's - this is with my vacuum installed, I havent tried driving it without the vacuum hooked up.

Is there an accurate way to tell if my dizzy it one tooth off? When I pull it there is just a flat wedge on the bottom, the gear does not come out so when I stab it in can only go in 1 of 2 ways.

my timing tape kit should be here today from summit, and since my current timing marks only got 30 i'll be able to get a much more accurate reading of where i'm at for a total tonight.
 
It sounds like your ok as far as the install. I'm not familiar with that specific dizzy, but it may be a rotor phasing issue. There's a video i've seen that explains it. Hate to over video you, but i'll find it and post the link just for some more info. Some other members should chime in also that have 1st hand experience.

[ame="http://www.youtube.com/watch?v=aWMlNwGW0tM"]MSD Tech: Rotor Phasing - YouTube[/ame]
 
.hmmm I can't adjust my rotor phase like they illustrate in that video..:-k

This morning I was able to get it to idle down around 25 degress :blob:, BUT I had to turn in the main idle screw on the carb to bring up the rpm so it wouldnt die.

What should I be doing with the idle circuit while setting initial timing?

** bonus question :newb:

My old man gave me an older Sun Pro tune up kit, it contains the timing light, vacuum gauge and a tachometer, the tach has the same inductor hook up as the light. What is the right plug wire to put this on or does it matter? If its #1 can I run the tach and the light at the same time?

thanks guys!!
 
So is it kosher to increase the fuel at idle if it allows the engine to idle with less advance? the plugs did look lean, could this be why the engine needed so much advance to idle? Lean condition?
 
No, work them "up" together, back and forth

Use as much initial time as you can without kickback on the starter. You can also get an idea by using a vacuum gauge, time at idle for max vacuum

Then adjust the speed screws "within reason"

Then adjust mixture for best/ highest/ smooth idle, readjusting the speed screw if necessary. On a new setup you may have to do this a couple of times

HAVE YOU determined TDC is correct yet?

YOU SHOULD consider what was posted about rotor phasing. There could be something wrong in the distributor mechanically or electrically. For example, those of us using GM HEI modules, if you hook the distributor pickup reversed, it will wrongly affect rotor phase.

You should at least consider checking rotor phase especially since you are having timing trouble.

And do some Googling about MSD and timing light troubles. I don't know if it applies to your setup, probably only to the digi MSD boxes.

If all else fails AFTER you have verified TDC scare up a known working ignition to put in there, even a points dist. or a Mopar breakerless system.
 
Yes, i've confirmed TDC - its good. I'm not sure how to check rotor phasing with out one of those cool caps shown in ricks video.
This thing seem to start without a problem no matter how much initial you give it. I've seen the initial as high as 40 and it still starts without kickback.

I'll keep playing with it. I wanted to try the largest bushing in the dizzy, limiting the mechanical advance to 18, with some lighter springs I may have to fab a way to limit the mechanical even more because MSD doesnt offer any larger bushings the the 18 degrees one if I want to run more initial.
 
Sorry i haven't posted today, things got crazy this morning and then the wife's car battery took a poop.....lol. I'm gonna read thru the thread again and see if any pops in to my head. 67Dart273 knows alot about how these ign systems work, so i have to defer to him on the real technical matters. Timing is always the first issue that need to be addessed in the tuning process, but since it's gone this far, what carb and intake (M1 single plane?) are you running?
 
Rck you give me too much credit. I'm not really familiar with MSD stuff except in a general theory way.

To check rotor phase, it's not a "cool cap" LOL. All you need to do is get a hole in the cap anyway you can. Saw, heavy gunfire, drill, etc. Old caps are obviously preferred, why chop up a new cap? If "that thing" uses any kind of stander cap?? you might even score a used one from a buddy.

Generally, on a dist with vacuum advance, the rotor will be "as far" from one end (retard) of the cap contact as it is when the vacuum can is all in on the other end (advanced) but the rotor should still be at LEAST "corner to corner" from it's contact to the cap.

Mechanical advance should NOT change rotor phase except for maybe a tiny bit due to shaft wear, etc.

If you run an engine very long, as a few thousand miles, you can usually see rotor phase problems easily ---there will be short carbon tracks leading up to or from the cap contacts inside the cap.
 
Wow guys, thank you both for taking the time to help me out. I will try to find an old cap to check the phase.
the intake is an M1 and the carb is a 750 holley w/ vaccum secondaries.

I just tried to order some of the 10 and 14 degree stop bushings from Don Gould at FBO, man what a cool guy! He was more then happy to talk to me and offer some advice, he sounded very familiar with my crate motor and ignition system.

Basically he said my motor DOES want about 30 degrees initial, but i cant get it all out of turning the dizzy cause I'll end up with way to much total and hard hot starting, he told me to try the following:

1) put the black bushing (18 degrees)in the dizzy, and adjust the car to have a total of 34 degrees, all in by 3300rpm.
2) the initial will now be down to 16, so I must run the vacuum advance to manifold vacuum, this will allow the timing to come up at idle and drop as the rpms go up and the mechanical takes over

I think this makes some sense and am going to give it a shot also

again, thanks for the ideas guys
 
67Dart273, i just read in some of MSD's material that they specifically check and set phasing on the pro billet dizzy because it's difficult to change. For what ever that's worth...lol. I think your correct to try a swap and make sure it's a dist. problem.
I hate to bring this up this early in the process, but i'm wondering how old/miles are on it and could cam timing be involved. Also it looks like the concensus is that the magnum heads only require 32-34 total to make the best power.
 
Well I bought the car and it supposeily only had ~5k miles on the motor, but who really knows, I have not done a compression test yet. Yikes, i'm trying not to think that could be the problem
 
bigtooth said:
Well I bought the car and it supposeily only had ~5k miles on the motor, but who really knows, I have not done a compression test yet. Yikes, i'm trying not to think that could be the problem
Click to expand...

Don't worry, i doubt it is a problem. It was just that it seemed like everything was shifted off the scale to one side and i was just thinking of things that may cause it. Getting the distributor and timing straight will most likely fix the problem.

P.S. sometimes i tend to think outloud too much:D.
 
this timing setup seems to working great, now onto the carb.
34 degrees total, making the initial ~16 and running the vacuum advance to the manifold.

thanks!
 
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