I'm familiar enough with the timing. I realize mines a bit odd right now. But there is no kickback on the starter. I don't belive any temp issues are timing related, they are cooling system related. And, it likes the high initial timing (better idle, vacuum etc). I also realize, I should have little more at full advance. but, I'm trying to avoid pinging at the higher rpms (I might have a hard time hearing it). Once, I'm confident that the mech advance and the ingnition in general is good, I'll dial in the max advance.

But...did you guys see the part where I said "BUT, the real problem is........

I don't think it's the timing settings that's the problem. There is a short or miss in the higher RPMS. This is what's killing my power. I guess nobody is familiar with this issue? I think I've finally found the real problem. This is what it feels like when the power loss happens.

 

Correct me if I am wrong....but doesnt the 6AL have a rev limiter in it?

 

yup...I have the 6k module in there. I pulled it today, thinking maybe it was faulty. It didn't help any. I think if you pull the module, then there is basically no limiter.

 

Well Greg, thats shoots that idea down....Awww what next? Hmm..

 

Is your carb opening up....like are the secondaries opening? i dont know your burn out video looked like the secondaries werent opening. I know my chevy did burnouts like that until i adjusted the kickdown cable...i know the c6 is a different animal but i thought id throw some stuff in the air.

 

Isnt your cam a little radical to be having a good idle? maybe in the pursuit of a good idle you are giving too much and its not where it needs to be for the upper revs...I dont know that much about it though.I just think that with a cam that large i would expect to have poor idle.

 

Greg, which stop bushing are you running? Is it possible that after running at high rpm for a short time the advance is finally opening all the way and putting you into detonation, which causes the high end problems you are seeing? The reason I ask is that I am having trouble believing that cross firing is causing your issues when you have new or nearly new components in your ignition system.

-Scouder

 

Possiblle, I guess. But the mechanism seems to move smooth and advance inscreases with RPM as expected, and it is full at 2500rpm as expected wit ha well defined stop. It's just after a second or a few seconds that the timing starts to jump around. This might also explain the really poor mileage...I haven't measured, but I think it's even worse than I expected.

I'll try the next smaller bushing. But, I'm quite sure I'll see the same miss. I think this is the internittent problem I've been fighting for a long time. I think it is intermittent, which explains the one good Dyno! I feel it driving as well.

I emailed the MSD techs last night. We'll see what they have to say. Despite, all of the problems I've had, their tech service has been decent.


Can somebody describe a basic duraspark system...I forgot what it looks like. How many pieces do I need? Can I use the Balster coil (full voltage or less?)

 

"But there is no kickback on the starter".

Starter kickback is more related to cranking compression than timing, base solely on my personal experience. With mild compression and a big cam with lots of duration/overlap, you may not get the starter to kickback. I used to be able to time my vehicles by ear and SOTP with the limit being "kickback". But when I started running a lot of duration, I've found that she won't kick no matter how far I advance the timing.

Just for grins and giggles, I checked it after SOTP tuning and found 55 degrees total. I put the light on it, backed her down to 38 and man whatta difference. Did not pull quite as hard down low, but the top end was dead solid clear to redline (7800+).

Check the latest hotrod, there is an article about Cranes new distributor. The biggest surprise for me was the discussion on vacuum advance. Made me reconsider the fact that I've eliminated this valuable tuning variable. I've been somewhat mistaken as to the purpose of vacuum advance for more years than I'd like to admit.

As far as it missing on the top end, could be a number of things including, lean misfire, timing of course, valve float....yadda yadda yadda.

I'd put a more reasonable timing curve in it like freighttrain and Scouder recommended and then eliminate other possibilities slowly, methodically one at a time.

 

just read this section at the MSD site:

Timing Fluctuations
If your timing seems to be jumping all over the place, check the following items:

What kind of timing light are you using? Many lights have trouble reading the MSD's capacitive discharge multiple sparks. Dial back timing lights are not recommended. Try another non-adjustable light and check the timing again. MSD offers a Timing Light, PN 8990.
Make sure you are not using Solid Core wires.
Inspect the routing of the Magnetic Pickup Harness. It should be routed clear of the coil primary wires and plug wires. It is best to route it along a ground plain such as the firewall, frame or engine block to form a shield around it.
Check the polarity of the magnetic pickup wires of the distributor. Reverse the connectors and check the timing again. The correct polarity is whichever connection gives the most retarded timing.




I'm not using an adjustable timing light (as far as I know:-) I'm going to reroute the magnetic pickup harness...It may be very near some plug wires.

Solid core wires???...I'm running some Taylors! Not sure what core they have?


I'm going to play a little, be back soon with more dissapointment, I'm sure!

 

What RPM does the timing start to jump around at? How far is it moving? Does the RPM remain constant?

Almost sounds like it would be worth another DYNO run with wide band O2 sensor, scope and data logging. The scope will tell you which cylinders are mis-firing and the 02 sensor will tell you where your AF ratios are.

 

Strokster, I was reading about that new Crane Fireball Hi-6 Ignition last night..

It looks like a nice unit? I like that + or- 1/2 degree accuracy!!

almost as good as a trigger set-up...

And greg, I sure hope you find your problem Bud...your long over do..for some at least Hi 13s..maybe quicker??

 

Well, I rerouted the pickup wires, and that may have helped with the miss. The timing does not appear to have that same fluctuation.

But, I've tried the 2 biggest and then the smallest stop bushing, all seem to max out at about 32 BTDC. I have dropped the initial and it's running OK, so I'll leave that around 14-15 BTDC. but, I can't seem to get the full advance...I'll try some lighter spirings. I had one of the big springs in there to make sure it returns...


this SOB is hot to work on...my hands are roasting...:-)

 

here is some pics. The MSD gear looks good to me.

and a pic of the 4 bushings...I'll try to get a pic of the springs....most of the colors are faded..

http://www.thedreyerfamily.com/69f25...leshooting.htm

 

latest update.

I installed the small and medium springs. That seems to give me more total advance. I set the initial to 14. It seems to run OK there. It may be a little cooler. hard to say, it's about 15 degrees cooler outside than I'm used to working in:-) It is a bit easier on the brakes....not trying to take off as much in drive.

I'm not seeing or feeling the miss I had before. I think the rerouting was the fix there. It seems to be pulling hard through 1st and 2nd. I'll have to get to the track to see what hapens in 3rd. I think it's gonna be quicker. There's a lot of rubber out on my local roads! It's a little slow to get back to the idle non-advanced timing. but, appears to get there eventually.


A couple of tests to see wher my torque converter is grabbing.
in 1st gear- things start moving at about 1200 rpm
in 2nd gear- things start happeneing about 1600 prm