I would try a different ignition box if you have or could borrow one. Not saying for sure this is it but you have to replace what hasn’t been done prior.

Did you try disconnecting everything that is attached to the Tach output on the ignition?

Did you try running with the alternator belt off?

Like I said prior, these can be very frustrating to diagnose. Do not replace electrically what has already been changed 1x.

Is the DD relay board Vers 9 or Vers 10? The V10 is listed next to the Ground post on the board.

No I did not. As far as I know the only thing hooked to that is from the Racepak sportsman. I also use the IQ3 display dash. Did not make a run without the alternator belt. Is there any chance the battery could be faulty or the plug gap be to big. .040. I will check what version of the board I have. I bought the DD setup new 3 years ago.

quote:

Originally posted by markemark:
I would try a different ignition box if you have or could borrow one. Not saying for sure this is it but you have to replace what hasn’t been done prior.

Did you try disconnecting everything that is attached to the Tach output on the ignition?

Did you try running with the alternator belt off?

Like I said prior, these can be very frustrating to diagnose. Do not replace electrically what has already been changed 1x.

Here is a pic of how the wires are routed on the cap. I cant imagine the 2 wires that go through are creating an issue

quote:

Originally posted by MorgretNation:
Is there any chance the battery could be faulty or the plug gap be to big. .040.

In a previous post you wrote “Battery Voltage under load is 18.7”. If DA indicates this battery voltage I have to believe the battery is not problem.

I was reading another thread your helping on. It looks like the grid setup has a lot of ways to help troubleshoot ignition issues

Yeah so as I sit & ponder this problem, I would guess that as on a daily driver the battery is really just there to start the car & the alternator is running all the electrics.

quote:

Originally posted by markemark:

quote:

Originally posted by MorgretNation:
Is there any chance the battery could be faulty or the plug gap be to big. .040.

In a previous post you wrote “Battery Voltage under load is 18.7”. If DA indicates this battery voltage I have to believe the battery is not problem.

If you are on alcohol I would drop your plug gap from .040 down to .025. Also I am not a fan of the Taylor wires, I run the Moroso Ultra pro race or what ever they are called.

Yes. Running Ron's terminator. I used to gap them at .035 The 1st set my builder gapped them @ .040 With this new set I put in I did them @ .040. Figured that is where he wanted them, but I agree I will close up the gap. May not do anything but at least I can cross it off the list

quote:

Originally posted by Curly1:
If you are on alcohol I would drop your plug gap from .040 down to .025. Also I am not a fan of the Taylor wires, I run the Moroso Ultra pro race or what ever they are called.

quote:

Originally posted by MorgretNation:
I was reading another thread your helping on. It looks like the grid setup has a lot of ways to help troubleshoot ignition issues

MSD 7730 Grid is the poor racers $400 throw-away programmable control and DA system. For those racers like myself that do not have the perfect race car that can run an analog ignition, it is the perfect Band-Aid.
Go Grid !!!!

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

Had a similar issue at the start of 2018 with a dragster I drove some. Without to much aggravation, ended up being the plug wires had broken down or burned up. We were at Spring Fling and about to change everything electrical except re-wire the car, I just happened to notice this weird spot on a plug wire. The plug wires were 2-3 years old, new set on and problem solved. I dont remember the plug wire brand but I know they werent Moroso.
Now that I see you have a toilet, Im going to choose option B and say you have trash somewhere or the familiar alky build up or possibly bad fuel.

Shane Carr

Check the wires with ohm meter, I had brand new Taylor wires that read open with meter. I changed to MSD wires and they all read good.

I will check the nozzles & filter. I get fuel from Alan & this is a new drum. Never had a issue with his fuel in the past but I will check it out

quote:

Originally posted by Sugar Shane:
Had a similar issue at the start of 2018 with a dragster I drove some. Without to much aggravation, ended up being the plug wires had broken down or burned up. We were at Spring Fling and about to change everything electrical except re-wire the car, I just happened to notice this weird spot on a plug wire. The plug wires were 2-3 years old, new set on and problem solved. I dont remember the plug wire brand but I know they werent Moroso.
Now that I see you have a toilet, Im going to choose option B and say you have trash somewhere or the familiar alky build up or possibly bad fuel.

Shane Carr

I did check the wires. Using the formula from Taylor’s website. These ohm from 236 to 277 per ft. There site says 350 per ft for these wires.

quote:

Originally posted by green1:
Check the wires with ohm meter, I had brand new Taylor wires that read open with meter. I changed to MSD wires and they all read good.

If possible I would try a different ignition box.
At this point that is probably easiest way to narrow it down. I run the 7AL-2 boxes but have had 3 or 4 go bad. I now always have a known good spare with me. The MSD tester says they are good but change the box and problems resolved and shows on my DATA logger.

A dirty nozzle is also a possibility, easy to clean and check. Right after a pass take a wet rag and wipe it across headers near the head or check with IR gun to see if any are cooler than the others.
Your data logger is showing an electrical issue and I am not sure a clogged nozzle would show up like that on your logger so my first guess here would be the ignition box.

Have you had any issues with valve lash changing? Like a possible cam or lifters going away? Still think it is electrical unless you have any other red flags.

As far as valve lash. The heads, cam, lifters are all new this year. They only have 8 runs on it. I am starting to think the plug gap and this is why. Last week on the run the car slowed down I put an old set of plugs from last year that I capped at .030 except for 1 of the new plugs which I had to use. So I had 7 plugs gapped at .030 and 1 plug at .040. Went up and made a test run. The 60ft and 330 came back but the car fell off a hair on the top end. Then this week I put a new set in at .040 and the problem came back. Maybe it is just a simple as plug gap.

quote:

Originally posted by Curly1:
If possible I would try a different ignition box.
At this point that is probably easiest way to narrow it down. I run the 7AL-2 boxes but have had 3 or 4 go bad. I now always have a known good spare with me. The MSD tester says they are good but change the box and problems resolved and shows on my DATA logger.

A dirty nozzle is also a possibility, easy to clean and check. Right after a pass take a wet rag and wipe it across headers near the head or check with IR gun to see if any are cooler than the others.
Your data logger is showing an electrical issue and I am not sure a clogged nozzle would show up like that on your logger so my first guess here would be the ignition box.

Have you had any issues with valve lash changing? Like a possible cam or lifters going away? Still think it is electrical unless you have any other red flags.

If your running alky injection then gap your plugs at 23-25. Timing at 34ish shuold keep it happy.

Many other good suggestions today.

If the wires metered to the correct specs then they are good.

Also check that the cap has the center ball in place that contacts the rotor center tang. The rotor center tang should make contact with the distributor cap the last 3/16 to 1/8” of the cap being seated. You can actually feel this when slowly lowering the cap in place. I’ve seen these centers burn up because of no contact.

You can also try this. For a standard height MSD cap measure 1.875” up from the bottom of the distributor cap and place a 1/4” diameter hole between the plug towers. Place a second hole 180* in the cap. This will better vent the cap with the holes being aligned with the center of the rotor outer surface to help reduce the spark ionization build up.

If that is a crab cap I’d try adding 2 holes as described and align with the center of the rotor outer surface when drilled into cap.

New drum from Interstate basically rules out bad fuel. Somewhat new combo, maybe she just needs a little "tweaking/fine tuning!"

quote:

MSD 7730 Grid is the poor racers $400 throw-away programmable control and DA system. For those racers like myself that do not have the perfect race car that can run an analog ignition, it is the perfect Band-Aid.
Go Grid !!!!

Why is this a throw-away unit?
Can you expand a bit more on the analog/perfect band-aid?