Disconnected Starter Saver, NOPE! Disconnected the Tach, NOPE. Going to the Divisional @ L.V. in Top Sportsman this week, going to re-check all grounds & positives for anything related to the ignition. My Motor RPM graph looks like Charlie Brown's t-shirt.

quote:

Originally posted by Richie:
Thanks Mark, Yes Curly - 02's (I'm stuck on stupid most of the time) I'm experimenting w/ pills now, w/ a reading of around 11.9 @3/4 track, I got my best MPH. I believe the drop in rpm is just the ignition shutting off and coming back on & with no ignition to fire the alky - the 02's drop to 9.0.
I think the major issues on top end was the shorted out coil - hasn't done that yet this year.

this is not right, If the ignition shuts off (or misses) the O2's are going to show lean because of the excess oxygen in the exhaust stream. Are you sure you aren't running into detonation?

Joe

I would not replace any ignition components that have already been replaced. Doing same thing 2X doesn’t resolve problems. It just provides same results at 2X the expense.

At this point I would suggest purchasing a MSD 7730 Grid and plug it into the 7al and let it control the ignition. What this will do, is give you the ability to check the Ignition “In” Pulses against the Ignition “Out” pulses for magnitude and duration. No other MSD ignition offers this feature of Grid.

If Grid data acquisition shows this to be correct, then I’d firmly say your problem is not ignition.

Grid can also provide programmable starting retard that you are presently using with that Starter Saver and a multitude of other features for as little as $400. Money well spent imho.

If you feel it is still electrical after all this I would suggest re-wiring the car. Been there, done it, fixed it.

I think you need to plan on rewiring the car. It appears you may have a ground or wiring problem.

It happens the car vibrates and flexes. It is exposed to heat and you add and remove electrical components through time so some of the wires are compromised. Some may not be getting a good connection all the time. Every connection that has been crimped or wire that flexes or bends is a potential problem. Corrosion can happen on some switches causing intermittent problem.

Chassis dyno time it relatively cheap and can do it rain or shine!

I haven’t read through every page but I chased everything just like you have. I spent 1,800 changing parts and the entire time I kept saying it was the cam I had running the alcohol.only after pulling the motor and putting it on the dyno and putting on gas it went away. Sunset even sent me one of there APD alcohol carbs to try with no help. Finally sent me a different cam and it fixed the miss. Guy I sold the motor to is still running it with no problem. I’m not sure why the head hunters have this issue but they do want a diifrent cam on alcohol. If you put it on gas and it goes away change the cam to something with more ext duration

How about this? When I re-Wired the BAT + & - (10 ga.) for my 7AL2, I twisted the wires together and ran them directly to the battery. Was twisting a bad idea?

Richie,
Twisting is not the best but as long as it was done reasonably well it can work especially when you are trying to find a problem.

I still have both of those Dominators (1050 and 1150) if you want to try it on gas.
I'll be heading up on Thursday afternoon.

I think I even have an electric pump laying around if you need it.

Just let me know, I can bring them with me.

Didn't read all the posts but Just went thru a very perplexing problem on a friends car. Make absolutely sure there are no extra wires near the distributor that aren't supposed to be there. You can read the other post.

Likewise try to shield the other wires that you have carrying the pickup signal to the box.

Just spoke w/ MSD Tech, good info & don't do's. I will try the following: Un-Twist #10 main feed WIRE'S for 7AL2 >going to Battery, remove MSD Acc. ground wires from ground stud on MSD 7AL2, re-wire coil wires (Orange & BLK.), re-wire Rocker Ign. Switch.
Staying determined to find this!

Mine was a loose screw on a toggle switch, the ring connector was hanging there flopping around.
Not your problem but might help someone else. It's a good place to look first.

I re-wired all of the above, problem still there...

quote:

Originally posted by Richie:
I re-wired all of the above, problem still there...

on a brighter side...went 3 rds. in Top Sportsman @ L.V.
NEXT: dropping plug gap to .025 & changing Alky set-up, now = "1" pump w/ 39's & 98 pill changing to 38's & 92 pill for starters. It's allot easier to try these changes -vs- going to Gas or dyno...Wish Me Luck!

This message has been edited. Last edited by: Richie,

This weekend I closed the gap on plugs and changed to 38's & 92 pill, the graph looked allot better, just a few blips, I gained approx. 10* so I first tried to go richer w/ a 86 pill, did not like it & I felt the miss come back so went back to a 92 & went 3 rounds - car is deadly...still backfires after burnout.....Weather & track sucked so no performance diff.

So if I am understanding, less timing and leaner helped?

Changing plug gap and changing fuel pressure helped, fuel amount wise it was a wash...the 38's W/ 92 pill is equal to the original 39's W/ 98 pill. James Monroe hit it dead on.....

So you closed the plug gap some and changed fuel some and it helped but did not eliminate it?

Okay I think I would try a different heat range plug and see what that does. Then maybe plug wires if you have not done that already. Why does it miss? Maybe too lean or too fat or wrong plug? I thought it may be your ignition box earlier but now that it is responding to your changes I think that tells us you are in right area. If your plug is too cold then when it is too fat it could explain much of it. Same with if it was too lean and you had too hot of a plug. I always run about .025 on my plugs with alcohol and with more get random miss and touchy tune up.
Sounds to me like if you made changes and it responded then you are on the right track.

I had a top end miss and car was consistent raced all year like that. Grounding the cylinder heads to the battery was the fix for me . Car picked up almost no ET but MPH went up 2

Curly1, I'm thinking a baby step this weekend, only 1 time shot so I'm going to try a 94 pill to lean it out alittle.
Lately it backfires after tires grab on burnout and 1 out of 3 backfire after I lift on the big end. I would have to believe they are related....

quote:

Originally posted by Richie:
Changing plug gap and changing fuel pressure helped, fuel amount wise it was a wash...the 38's W/ 92 pill is equal to the original 39's W/ 98 pill. James Monroe hit it dead on.....

Yes the volume of fuel was about the same but the droplet size was different (smaller). You may want to continue working this direction if a pill change still doesn't fix it. That said though I'm concerned about this backfire think. Is it through the exhaust or through the throttle body?

Scott