Big Blue's Transformation

[Gary Lewis]

Ok, after taking several looks at the plugs and the resistance readings on the wires I have the following thoughts.

Plugs, several of them look borderline too hot or lean (blued electrodes). Since the EFI system is adjusting the mixture on each bank, they shouldn't be too lean. I would say one step colder plugs than what you are running.

Plug wires, the old rule of thumb on resistance wires was 1000 ohms to the inch is the nominal resistance. This means for a 20" wire length, 20K. Less than that is not a problem, more indicates a wire breaking down internally. For your Mopar #7 wire 84K. I would do an after dark check, a slight "halo" around the wires is normal, arcs to valve covers, fuel rails etc are an issue, also Ford recommended that # 7 & 8 not be run side by side, if you remember on the carbureted engine plug wire routing on the left side was 5768 for the 460, the older small Windsors were 7568 on their routing. This is done to prevent cross firing.

Thanks, Bill. I do have the plug wires run close to what you suggested, but don't have #7 between 5 & 6. I'll fix that.

Good idea on the after dark test. I've even in the past used a spray bottle to mist a bit of water on the wires to see if that makes a difference. (I've seen them look like a circus.)

But I have a question, and since you'll probably see this in response to your post I'm tagging Jim: The NGK 2771 UR5 is one step colder than their 6630 UR4, which is stock. But is the UR5 truly equivalent to the Autolite 24, which is said to be one step colder than the Autolite 25 that is stock. IOW, might the NGK UR5 be colder than the Autolite 24's and be just right?

Or are you suggesting that I go with the NGK 7773 UR6, which is two steps colder than the 6630 UR4?

 

[ArdWrknTrk]

Thanks, Bill. I do have the plug wires run close to what you suggested, but don't have #7 between 5 & 6. I'll fix that.

Good idea on the after dark test. I've even in the past used a spray bottle to mist a bit of water on the wires to see if that makes a difference. (I've seen them look like a circus.)

But I have a question, and since you'll probably see this in response to your post I'm tagging Jim: The NGK 2771 UR5 is one step colder than their 6630 UR4, which is stock. But is the UR5 truly equivalent to the Autolite 24, which is said to be one step colder than the Autolite 25 that is stock. IOW, might the NGK UR5 be colder than the Autolite 24's and be just right?

Or are you suggesting that I go with the NGK 7773 UR6, which is two steps colder than the 6630 UR4?

Oh yeah, beware the 7-8 inductive crossfire.

There's this. https://www.ngk.com/heat-range-conversion-chart-2 - which suggests that it is Autolite's numbering convention that is screwy.

So I can't really say that "each number equates to XYZ degrees at the electrode gap"

Sometimes experimentation and testing is required.

[Gary Lewis]

Oh yeah, beware the 7-8 inductive crossfire.

There's this. https://www.ngk.com/heat-range-conversion-chart-2 - which suggests that it is Autolite's numbering convention that is screwy.

So I can't really say that "each number equates to XYZ degrees at the electrode gap"

Sometimes experimentation and testing is required.

Thanks, Jim. I do have 7 & 8 separated.

And yes, NGK takes Autolite to task over there numbering system. And I do understand that it is hard to know how one company's "step" equates to another. So unless Bill has better guidance I think I may go with NGK UR5's.

Bill?

[85lebaront2]

Thanks, Jim. I do have 7 & 8 separated.

And yes, NGK takes Autolite to task over there numbering system. And I do understand that it is hard to know how one company's "step" equates to another. So unless Bill has better guidance I think I may go with NGK UR5's.

Bill?

Guys, before everything went to computers, most companies heat ranges were logical, higher numbers meant hotter plugs. For example F9Y was the champion number for most high performance Fords, F11Y for lower performance and F14Y for the six cylinder engines. The first letter was manufacturer, H was Hudson, F Ford, J for most GM, N for Nash and each generally had a definite difference.

One interesting example, my old Onan gensets take H10 plugs. NGK and I believe a couple of others use inverted numbers, where the higher numbers are colder rather than hotter.

On your truck or Darth, the OEM plug was a Motorcraft ASF42C ASF = 14mm tapered seat 4 = heat range 2 = projected tip and C = copper electrode. P would = platinum electrode. I would, using Motorcraft, go to an ASF32C.

As for platinum plugs, the issue I ran into (and my son Matt also) was Bosch platinum plugs causing erratic misfires in the EFI 302s.

You can use whatever type sparking plugs you wish, even Lodge. We used to sell Holley plugs, that were made by Hitachi for Holley, just stay away from gimmick plugs.

[Rusty_S85]

Oh yeah, beware the 7-8 inductive crossfire.

There's this. https://www.ngk.com/heat-range-conversion-chart-2 - which suggests that it is Autolite's numbering convention that is screwy.

So I can't really say that "each number equates to XYZ degrees at the electrode gap"

Sometimes experimentation and testing is required.

From what I could tell Motorcraft and Autolite used the same numbering and below is two pages of breaking down the Motorcraft spark plug numbering system.

Heres the Autolite break down, 5 heat range is your normal heat range, 4 is your colder heat range, and 6 is your hotter heat range no different than how Motorcraft does with higher number equate to a hotter heat range. Only thing is I am running a 4 heat range on my 302 build since it is a daily driver and AFR recommended the 4 heat range as a starting point. I may upgrade to the 5 heat range but may stick with the 4 heat range as it will shed heat quicker to the cylinder head keeping the plug cooler.

[Gary Lewis]

Oh yeah, beware the 7-8 inductive crossfire.

There's this. https://www.ngk.com/heat-range-conversion-chart-2 - which suggests that it is Autolite's numbering convention that is screwy.

So I can't really say that "each number equates to XYZ degrees at the electrode gap"

Sometimes experimentation and testing is required.

From what I could tell Motorcraft and Autolite used the same numbering and below is two pages of breaking down the Motorcraft spark plug numbering system.

Heres the Autolite break down, 5 heat range is your normal heat range, 4 is your colder heat range, and 6 is your hotter heat range no different than how Motorcraft does with higher number equate to a hotter heat range. Only thing is I am running a 4 heat range on my 302 build since it is a daily driver and AFR recommended the 4 heat range as a starting point. I may upgrade to the 5 heat range but may stick with the 4 heat range as it will shed heat quicker to the cylinder head keeping the plug cooler.

Guys - Thanks for all the information. But my only question was whether to use NGK 2771 UR5's, which is supposedly equivalent to the Autolite 24's in the pictures, or go with the colder NGK 7773 UR6. And I am going to take Bill's response of "I would, using Motorcraft, go to an ASF32C" as the answer. But since I want to run NGK's I went to their site and found that the ASF32C cross ref's to their 2771 UR5, as shown below.

So unless I have my plug wires crossed I'm going back with essentially the same temp plug as I've been running. And if I have that wrong please tell me soon as I'm going to the part store at 8 AM tomorrow.

 

[ArdWrknTrk]

Guys - Thanks for all the information. But my only question was whether to use NGK 2771 UR5's, which is supposedly equivalent to the Autolite 24's in the pictures, or go with the colder NGK 7773 UR6. And I am going to take Bill's response of "I would, using Motorcraft, go to an ASF32C" as the answer. But since I want to run NGK's I went to their site and found that the ASF32C cross ref's to their 2771 UR5, as shown below.

So unless I have my plug wires crossed I'm going back with essentially the same temp plug as I've been running. And if I have that wrong please tell me soon as I'm going to the part store at 8 AM tomorrow.

Gary, you are on the right track.

I cannot say that one NGK step is exactly equal to one Autolite/Motorcraft number.

So the best we have to go on is the Motorcraft exchange chart.

[Gary Lewis]

Gary, you are on the right track.

I cannot say that one NGK step is exactly equal to one Autolite/Motorcraft number.

So the best we have to go on is the Motorcraft exchange chart.

Thanks, Jim. That helps.

I have a meeting at church at 7:00 and then will swing by Skiatook Auto Parts after they open at 8:00 and see what DeWayne can do for me.

[ArdWrknTrk]

Thanks, Jim. That helps.

I have a meeting at church at 7:00 and then will swing by Skiatook Auto Parts after they open at 8:00 and see what DeWayne can do for me.

Please let him know that he's in the thoughts and prayers of quite a few of us.

I hope that he is doing well.

[Gary Lewis]

Please let him know that he's in the thoughts and prayers of quite a few of us.

I hope that he is doing well.

Thanks, Jim. That almost made me cry.

I was just thinking about him this morning. I'm getting geared up for the show and he's never been able to attend as his boss, David, needed him to work the store on that day. Now that David has passed it is only DeWayne running the store, so there's no chance.

Hopefully there won't be anyone else in when I get there as it gives us a chance to talk.