Slight miss in my 69 Z28
 

Check and clean all connections including coil and battery also grounds, everywhere!
Try hot-wiring direct power to the coil also run it in the dark and look for jumping spark.
It may even be the Coil itself, they do goofy things sometimes although usually @ higher revs.
And distrib' shaft play can cause erratic gap too also act differently whether under load or not.
If you're still thinking vacuum leak, even though you've swapped the booster hose it may be best cork it off to test and discount booster itself as leaking too?
Keep trying and good luck!
[img]<<GRAEMLIN_URL>>/beers.gif[/img]
~ Pete

Re: Slight miss in my 69 Z28
 

I THINK I found the problem. I put new condenser and points in and went to start the car. Nothing, no spark at all. I set the gap on the points and kept messing around with the new points. Nothing again. I re-installed the old points still nothing. Saturday the car ran. So I took the ground wire loose from the base plate and moved it around trying to see if there was any damage. Could not see anything so screwed it back to the base plate. Car fired right up. The problem is still there but it was not as bad as before. So I have to assume that when I was removing installing the points I was creating an open situation with base plate ground wire? I assume I have a bad ground?
I also checked the engine vacuum....just now...engine luke warm and perhaps not the best connection to my vacuum gauge. I had a steady gauge reading of 13&quot; of vacuum. I think that is ok for a stock Z28? Will check again when the car is warm and I have the breather off so I can jam my fitting on the base plate of the carb.
Thanks for all the suggestions. Keep you posted on next steps with the distributor.

Re: Slight miss in my 69 Z28
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: paceme</div><div class="ubbcode-body">I would check vacuum level at idle and compare that to power valve #. I've had to change a power valve because it was too low numerically and it was leaking and opening too soon. It idled poorly and loaded up, and stumbled during initial acceleration. Now the car runs perfect. I was convinced it was a distributor vacuum /timing issue and it wasn't.</div></div>

Steve, vacuum level is 13&quot; at idle. Engine was luke warm and perhaps not the best connection on the base plate to the gauge hose. Maybe able to get a few more inches out of the reading. But I believe high enough and not an erratic needle reading. PV in the primary is 6.5 per Eric Jackson, and per the kit I just installed. However, I had to use the original 8.5&quot; secondary per Eric's original build because the kit came with a 10.5&quot;.

Thanks

Re: Slight miss in my 69 Z28
 

Ground wire on base plate,sound like the base plate is worn out,good one. Hope this help's you out.

Re: Slight miss in my 69 Z28
 

Ok guys I need someone a lot smarter than me to help me figure this out. This morning I went and checked the dwell since I had not done that yet. The reading was 85*!!! I could not even believe the car was running. I adjusted down to 30* and during the adjustment I saw a spark on the end of the screwdriver when I was adjusting the dwell. Don't recall ever getting a spark off an allen wrench or screwdriver while adjusting dwell? Anyway set the timing and dwell, car is just purring at 900 rpm with 12* static. I expect something is still wrong with the ground in the distributor but could that &quot;spark&quot; have been a discharged build up of unwanted voltage?

Re: Slight miss in my 69 Z28
 

I can't believe nobody brought up the dwell earlier [img]<<GRAEMLIN_URL>>/grin.gif[/img]. I'm glad to hear you found the problem.


Jason

Re: Slight miss in my 69 Z28
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SuperNovaSS</div><div class="ubbcode-body">I can't believe nobody brought up the dwell earlier [img]<<GRAEMLIN_URL>>/grin.gif[/img]. I'm glad to hear you found the problem.


Jason</div></div>

I should had checked that earlier, but thought nah it isn't the dwell. Still does not really explain the breaker plate ground wire being a possible culprit. I am going to drive it and go from there.

Re: Slight miss in my 69 Z28
 

Still issues. Went for a ride and the engine acts like it is running out of timing at 4K rpm. I am going to put the new points in there so I have a base line.

Re: Slight miss in my 69 Z28
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sixt9rsx33</div><div class="ubbcode-body">Still issues. Went for a ride and the engine acts like it is running out of timing at 4K rpm. I am going to put the new points in there so I have a base line. </div></div>

After that, don't forget to reset the dwell, and make sure the lead is attached to the distributor side (NEG) of the coil.
Then recheck your initial timing. A change of dwell will change that.

Verne

Re: Slight miss in my 69 Z28
 

I have new points, reset the timing, dwell, and put in a new coil. Also put the weakest springs in so the centrifugal timing comes in quick. The problem is still there but now at a higher RPM. The car dies at 4,500 RPM now. Idles great, pulls hard through the power band until 4500 rpm. It acts like the spark just goes away. I am going to check all the wires very close around the distributor. Any ideas let me know.