Dizzy Timing on a Z

[Ron Earp]

I can’t figure out this dizzy situation. I sent my dizzy off to a fellow to have it recurved. I've used him before, I trust him, and I know others that have used him too. I asked for about 22-24 degrees advance all in at about 3k. He was not able to get that, he got 24.5 advance all in at 3k

I got the dizzy and installed it. Got the car idling at 800 RPM and set the timing with a dial back light at 8-10 degrees initial timing. Dial back is set at zero, so the light is reading actual ignition timing. I only have one timing mark, a big fat line, so this is easy. I made the timing mark and have used it for a couple of months. It was made by setting the motor at TDC and scribing a big fat line at 0. Degree wheel was used for cam/crank timing.

Alright, rev up motor to like 4k. Timing scale goes to 20 degrees and the mark is way off scale. I dial the light up to 32-34 degrees but this does not bring the pointer back to zero. I dial some more. I have to dial the light up to about 42-43 degrees, roughly, to get the pointer back to zero.

This doesn’t make sense to me. Everything I’ve ever done is set the total advance with a dial back light, but in this case it is telling me that I’ve got about 42-43 degrees of total timing, which is about 10 more than I wanted.

How can this be if the dizzy only advances about 24.5 degrees? 24.5 plus about 8-10 initial should be about 33-34, which is what I need. But that doesn’t seem to be the case. This dizzy seems to be just like my old one which is going to require like zero initial, or worse timing at ATDC, to run right on advance. This leads to poor starting and almost impossible hot starting.

Ideas?

My thoughts:

*Dizzy advance is not at 24.5 degrees as I was told
*Timing light is FUBAR
*My head is screwed up and I should be dialing back to my initial advance to get total timing, in this case dialing back to 8-10 degrees.

Ron

[Conover]

And people say computer controlled cars are scary, I bet that thing has a carburetter too huh?

It's unlikely that the timing light is wacked.
It is possible that the advance on the dizzy is not right,
the head wacked thing, I'm not sure, what do you get if you set the initial timing to 0btdc? If you set it to zero and spin it up and you get 24.5 or whatever, than it's right. if you spin it up and you get 35 than you got too much, it is a race car after all, though, so hard starting is kinda normal, well, at least with race cars that run on mechanical controls. maybe buy a can of ether?

[dspillrat]

Ron,
I have welded mine up solid/fixed, no advance.

Hard to start ,runs like crap at idle, but don't have to worry about stuff bouncing around in the dizzy.....

With the richness those 260s run at idle, you should have easier time firing up anyway!!!!

[mom'sZ]

This thread caught my eye becuse I'm working on my ignition right now. Not to long ago I started a thread about my 77. You might remember the thread Ron, you posted in it. But anyhow to sort of agree with dave or not really yet because I'm not done and so don't know the results yet but I was planning on gutting the distributor of both the vacumn and centrifical advance as per Keith's (katman) suggestion. I don't think it was in my ignition thread or maybe was, but I swear I recall Keith saying gut the thing and lock it down at 32 or maybe 34 but that's it.
Now as far as your scenerio above, I had to read it three or four times before it made total sense to me, but something is screwy. I'm the kind of guy who wouldn't be able to sleep until I figured it out. I think maybe the distributor is not advancing the promised amount. (or is it to much) Do you know a shop with a distributor machine? They aren't as common as they used to be, but it would tell you what the dizzy was doing without the car influencing the situation.

[Ron Earp]

I’m not sure what is going on, but I want to find out. It is a simple mechanical issue.

I do remember the lock it down thread and I do have a locked dizzy as a kit spare. Dave Brown helped me build one at Roebling about three weeks ago during the down time. I have not tried it, but it is locked, no vacuum advance, and could be set at 32-34 degrees as David and you suggest.

But, I worry about starting, more specifically hot starting.

My car WILL NOT hot start with the old dizzy configuration. That is, initial timing at 8 degrees ATDC that I had to set it so the advance was correct at 32-34 degrees BTDC at 3k and up. That old dizzy had far too much advance which is why I sent it off to be re-curved. The hot start issue sucks because I have to be careful of when I take the car to grid and how long it idles. Get to 180F, turn it off and most times you are SOL for a restart. How many SE racers have pushed old 38 around in the paddock, raise your hand?

Now, if I lock it at 34 degrees what will happen with my hot start problem? David says his is hard to start now when cold, what about when hot?

I bought a new dial back timing light. Tonight I’ll set the timing at idle at 0 degrees, then give it RPM and measure the total advance with the new timing light. That should tell me what I need to know and as far as I know is “fool proof”. If I get more than 24.5 degrees of advance, what the dizzy builder said he checked it out to be, then I think we have a problem with his methodology (he has an advance machine, he does this for a living).

I want to solve the problem because I think proper timing at idle could really help with the hot start issue. While my “old” setup raced fine, it left a lot to be desired for idling due to the timing being so retarded.

R

[seckerich]

Set the light at your desired total timing on the dial. Rev the motor to 4000 or enough to have it all in and adjust the dist. until the line is at Zero. You should now have the desired total advance you need. It is probably already advanced at idle speed and you are just adding to the error. Just a thought.

[mom'sZ]

OK, here is one more idea (and I kind of figured you were a I'll figure this out if it kills me kind of guy) that is not a band aid solution. I got interested in megasquirt because my car is fuel injected. I'd have to run a separate one if I wanted to control ignition with it, but I'm pretty sure you can control things like start up, idle and lower RPMs varing the timing. You can use stock or msd or whatever. You have a table, RPMs on one axis and ignition advance on the other, fill in the amount. Just a thought (it's what I'm going to try) Oh $h*t, did I just give away the secret plan?

[kthomas]

Me thinks your dizzy guy screwed the pooch.

Take all the springs and weights out of the thing and lock the upper and lower shaft together. Set it at 34 and fuggetaboutit.

[Ron Earp]

Hey Steve,

That is what I basically did last night. I am going to try again tonight with a new light to verify. If I set it at 34 at 4k and let it come back to idle it'd be timed at like 2 ATDC. I need to verify this, I could have made a mistake. I needed a second light anyhow, one for home and one for trailer.

Congrats on that win!

----

Keith,

I think you are right, dizzy guy might have too much advance.

I can lock at 34 BTDC - how about hot/cold starts, will it be an issue in your experience?

----

Momz,

You could do similar things with MSD's adjustable timing control. Might not be legal to have that adjustable controller in the cockpit though. Essentally with MSDs adjustable timing control you could lock that dizzy at 34 and retard it for starting. They sell a variety of products that can help out with this sort of thing. MSD has a digital box that would do all that too.

This would fix it too:
http://www.msdignition.com/tc_7.htm


Ron

[mom'sZ]

that thing a ma jiggy you linked to is pretty cool.
Question: why would the adjustible controller be illegal if in the cockpit. I understand it would be driver adjustable during a race, but I though ignition was basically free. Is it a non IT specific rule?
Anyhow, let us know what happens because now I'm curious

[Ron Earp]

It has been awhile since I read the IT rules on ignition timing. I think the retard like I pasted would be legal, but I can't remember of some of the other adjustable products they sell would be legal or not.

I'd like to avoid adding another piece. I checked the timing again and the dizzy is definitely advancing about 35 degrees or so. This should be solvable without additional pieces, I just need this thing curved correctly.

R

[kthomas]

We ran a D.L.Potter recurved distributor (beautiful, but not necessary) for years and eventually moved to the "locked in place" version as we got later in the engine development program. Couldn't keep an "advanceable" distributor from bouncing the timing around. We never, ever, ever had any problems with starting, and as a carry over street car habit both Chet and I stop the engine by turning the key off and letting the clutch out to gently grind it to a halt so no dieseling problems either. You just don't stomp on the gas under load from idle.

[dspillrat]

Ron,
Didn't the 260z come with the larger dizzy base, similar to the 280z? If so, advance auto sells a rebuilt zx dizzy,cap,ignition module for around $165....will fire great even using the stock module.....I ran this a while without problems, til It dawned on me not exactly legal due to larger dizzy base. Comes with a years warranty as well!! Keep a few extra ignition modules in the trailer, they fail every 3-4 races or so.



david

[Ron Earp]

We ran a D.L.Potter recurved distributor (beautiful, but not necessary) for years and eventually moved to the "locked in place" version as we got later in the engine development program. Couldn't keep an "advanceable" distributor from bouncing the timing around. We never, ever, ever had any problems with starting, and as a carry over street car habit both Chet and I stop the engine by turning the key off and letting the clutch out to gently grind it to a halt so no dieseling problems either. You just don't stomp on the gas under load from idle.
[/b]

Ok, I think you've sold me.

I have a locked dizzy we made at the track but we didn't weld it. We made it by taking two steel rivets and putting them in the slots that the weights spin out in. JB Weld was used to fill in some cracks and help hold the rivets in place.

The two "plates" I locked together by drilling a hole through both and placing a bolt and nut there. Loctite was used on the nut, the bolt was long and cut off essentially making the nut captive due to thread deformation.

Do you think this will hold together as a locked dizzy? Or do I need to take it apart and weld it up?

Ron

[I8AV8]

to cure the hard starting with a locked distributor at 34 degrees, i put the ignition on a toggle switch. i get the motor cranking and then hit the switch - never had a problem, much easier on starters. i run a locked distributor and a pertronix pick up. less stuff to break = more chances to finish! good luck.

[Ron Earp]

Damn I am perplexed.

I put the locked dizzy in the car and timed it at 34 degrees BTDC at idle. I verified this with the dial back light (new one). At idle I had to dial the light to 34 degrees on the scale to get the timing pointer to zero. As a side note it started well cold with 34 degrees initial timing.

I then revved the motor up - AND THE TIMING ADVANCED approximately 10 DEGREES!

Now, if you have followed this thread you know that I have used two different dizzys in this motor. Both exhibit the same behavior - the timing advances with RPM more than it should. In this case it shouldn't move at all. But with my recurved dizzy that was verified at 24.5 degrees of advance at 3k I'd get approximately 34 degrees of advance instead of the 24.5 the dizzy man said.

Every 260Z motor that has been in this car (three of them) has done this.

1. The race motor that came with the car had to run at 10 ATDC to advance right for running.
2. The junker motor I put in to finish two races had to be timing this way with the dizzy used for (1).
3. The new race motor using the dizzy in (1), the recurved dizzy from (1), and this locked dizzy exhibits the same problem.

I never discovered this "hidden" 10 degrees of advance until trying this locked dizzy. Previous to the recurved unit I'd just assumed my dizzy was out of whack and it was one of those things I'd get to fixing. And, when I got to trying to fix it there is more to it than I thought.

So, I think it is safe to assume the issue lies in the dizzy timing circuit somewhere, or, each engine has 10 degrees of slop in the timing gear/shaft system?

The MSD is new, it was replaced at CMP on a test day and went in with motor (2).

Can the polarity of the output from the dizzy going into the mag trigger on the MSD have an issue?

Is there something I'm not aware of using a mag trigger on the MSD that can cause this to happen?

Much thinking to do. I will get the connections from my dizzy to the MSD mapped out as to which wire goes to the purple and which goes to the green.

260Z racers, how is your 260 timing circuit setup?

Ron

[Ron Earp]

OK. Problem solved. Easier to solve than to write about it honestly, but writing about it maybe will help someone else.

If you reverse the wires on the mag pickup for the MSD you'll get the off behavior that I just wrote about, a funny 10 degree advance seemingly from nowhere.

I reversed the wires from my original hookup and the locked dizzy does not move timing a bit.

The proper hookup for a stock 260Z dizzy, as far as I can tell, is:

Datsun Green/red to MSD Green
Datsun Green/white MSD Purple

Now the recurved dizzy will probably be just fine.

Lesson I've learned is not to take anything for granted with a race car. Since the car has been working since we bought it I'd never thought to question the MSD wiring, even when I re-wired the car early in the year.

This does not prove that the mis-wire is the cause of my problem, but the results are positive. I revved the motor to 5k and it was rock solid on 0, with 33-34 dialed in on the light. I hope it'll hold as my "dizzy locking" technique is the only thing I'm concerned about.

Ron

[JeffYoung]

I'm dizzy.

[mom'sZ]

alright, way to go Ron. I was stumped. Thanks for posting the solution.

[Ron Earp]

Well, it probably won't help many since there are few 260 racers. And probably fewer that are using the stock dizzy timing electronics. But, those work well and I don't see a need to change. I would bet that your 280Z dizzy is the same though. I'd definitely try it this way before doing it any other way.

So all is good now. The dizzy that I had recurved works great with 9 degrees initial timing with 33-34 advance at speed. The locked one did well too.

I do have a question.

I thought the locked dizzy idled much better at 34 BTDC than the advance dizzy did at 9-10 BTDC. The locked one also started cold with no issue. Push putton, flick on ignition, and bang, ran fine. The 9-10 BTDC also started well when cold.

As far as hot starts (because I have no way to test this before the ECR when Jeff and I drive it) which would be better:

10 degrees BTDC
or
34 degrees BTDC

We have to refuel in the ECR and this car has never been good for hot starting on that old 8 degrees ATDC retarded timing.

Now that we have good timing control which would be better for hot starts, 10 or 34 BTDC?

Ron