Can I get a read on this plug?

Cab, Autolite AP65s, not really a hot plug is it? Not a real destinct line on the strap. I saw the black dots, not really enough to be detonation in my mind, timing is argueably low infact at this point. One change I made was moving the timing up and ended up with too much total, now plugs are peppered pretty good, no shiny that I saw though.

check your carb.

Here is a picture of the plugs replaced today, this is the same plugs as above but with a jet change from 64s to 67ys briefly and then 65Hs, there is only about 50-60 miles from the earlier picture, it also had way too much total timing during this time period. I took 9 pictures but this is the only one that I thought had a chance of being able to be seen in a post. It is heavy black around the thread base, definitely rich and even black on the porcelain indications of the high timing. This all started because I was getting a slight surge at highway speeds (2700ish RPMs), other than that it ran extremely well with only an occasion minor hot soak start issue and an occasional low idle. I begin to address it like a lean surge starting with the jet change and then began to go through the 6 pack set up as outlined by Tom Quad and Dayclona, at this point the run quality began to deteriorate, mostly the idle quality but it also led to the high timing setting. It would not idle below about 1200 or so I started to return to my base setting (I built the carb and fired it up about 900 miles ago now) during this I could not get my idle back and since it was around 1200 the mechanical advance was coming in so I had to resort to setting total timing at 34, while doing this I realized that the vacuum advance added nothing to the total timing. I found the canister was leaking freely? In taking it apart I found that the spring in the vacuum advance had the plate in a bind and that was the origin (I think) of too much timing at idle. I also found another issue with the distributor as well, so I am replacing it even though it is new. So here is what I think happened, the surge was the first sign on the vacuum advance going bad and as I was adjusting it was getting worse until complete failure, it was doing this while I was making the adjustments so it was really confusing me. The long and the short of it is I plan to replace the distributor and go back to me base settings and see if he surge is gone and everything else returns to normal, the surge was slight so I could live with it if I cant get it out.

One of the reasons for my concern is I am fixin to run it about 3000 or so miles and I don’t wont it running lean.

So does anyone see a reason to be concerned with the condition of the plugs in the first picture, this was where it ran it’s best for 800 miles with the 64s and my settings. I know it’s a long drive but it’s a car that is what it was built for.

Thanks, Kevin

I took 9 frickin picture and this was the best one, I think it is because I took them in the sunlight. I can get better ones tomorrow if it matters, I replaced these plugs. This is what happened with the 67s for a breif time and then 65Hs and way too much timing. It appears heavy black on the base and even some black on the procelean almost like pepper. Definitely running rich so I am going back to the 64s tomorrow.

It appears to me that the original picture shows the mixture good to slightly rich. I am getting a slight surge at highway speeds, 2700ish RPMs. It is a 340 6 barrell that performs well in every other aspect. I started chasing the issue like it was a lean surge but after going through all the set ups as outlined by Tom Quad and Dayclona it began to run poorly at idle(but this was with the 65Hs) essentially not wanting to idle below about 1200. During the process I found a few interesting things with my distributor but I believe they were beginning to occur and the surge was the first sign, it then went down hill while I was doing the set up so I it was giving me bad readings. I am in the process of fixin that and then I can get back to the set up, but frankly I am gonna go back to my settings before I started monkeying with it, it seemed to work well.

So does anyone disagree that the first picture likes acceptable for 800 mile plugs and I have no reason to be concerned about a 3000 mile trip?

Thank you, Kevin

So I wish you lived near me and I would loan you my A/F gauge and sensor. That $130 device took all the guesswork out of my carb tuning and I was able to get a Eddy 750 to function cleanly and without a lean stumble on a 440.

If you are not in too much of a rush, I would consider doing something like that. Amazon sells them for less than $150 and it is an excellent tool for doing exactly what you are doing. I got a local shop to weld a couple of O2 bungs in my exhaust and it cut my carb tuning time and guesswork down to something very manageable.

I don't have the wizard skills to read spark plugs to the level of knowing where the A/F mixture is at Idle, cruise circuit, low-vacuum cruise and WOT.

I am sure there is a wizard here who can look at the photos and tell you what to do since there are some very very smart people on this board like Mr. Cab. BUT, if you have a few days to get in a gauge, around $150 and a local welding shop to install some bungs I can guarantee you will find a solution pretty quickly.

Try putting in one Autolite # 64 in it(in #7 cylinder) and then drive it for a short,5 to 10 miles, part throttle cruise and look at that plug One heat range can make a big difference once you get real close to the best tune If you like the part throttle cruise look, then take it out again and wack it at WOT for 12 to 16 seconds in high gear, if you can safely, and then look at it again as soon as possible, take the tools with you and If it stills has those black or shiny dots on the porcyln look at your fuel supply for WOT

So I live near the ATL Airport. I have Accurate exhaust too, but I have "hidden" the bungs so they are not obvious.

I have heard of people pushing the sensor far up the pipes but you couldn't drive that way of course and would be limited to tests without a load. It may still help and you are welcome to borrow it.

Thank you, I'll do that when I get the distributor back in and my settings back to where I had them.

Innovate Motorsports 3844. They are new on Amazon and Ebay for $140 but there are some used ones that pop up for less money. Right now, there is a used one on Amazon for $143. A few months ago one popped up for around $130 and so I snapped it up.

Well I modified my distributor today and put the 64 jets back in and returned it to my base settings. I regained control of my idle and it performs extremely well again with the exception that the surge it back/still there. I ordered a set of 66s today that I will install tomorrow, it will be too rich I believe but I can at least see if it solves the surge and go from there.

I ran out of time so I haven't changed a plug to the 64s like Mr. Cab suggested but I did buy them and there in the front seat, no difference noticed so far. I will do that after I see what the jets do and will up date as I go with pictures of the a plug before and after.

looks like carbon buildup in that plug, you have a choke on that carb? any black smoke out the exhaust? can you see raw fuel dripping in carb when at idle?

Thank you. Yes a choke, no noticeable black smoke but I little eye burn from rich idle, not bad but you are aware of it in a closed area and I really haven't looked down the throttle of carbs since the Cuda is so frickin wide and only 5'7" or so and I'm not wanting to climb ontnhe fender.

make sure choke is fully open when warmed up, try another carb if you got one.

I am gonna post pictures of 6 different plugs under different driving conditions, all are with 66 jets and 34* total timing. All are Autolies AP64s or AP65s.

64s with about 10 miles of "normal" driving some in town, some open road at cruising speed.

65s 10 miles "normal" driving.

64s 1/4 mile WOT, let off the gas, cut it off and costed into my road, changed the plugs side the road.

65s 1/4 mile WOT, same thing.

64s 50-60 miles of "normal" driving, some in town, some open road cruise speed.

65s 50-60 miles of "normal" driving, some in town, some open road cruise speed.

Let the analysis begin, I have my opinions but will hold them for now.

Mr. Cab, I would really appreciate your thoughts.

Ok I am gonna post 6 different plugs, all of them are Autolites either AP64s or AP65 in different driving scenarios.

64 with about 10 miles of "normal" driving including some town and some open road.

65s 50-60 miles of "normal" driving, some in town, some open road cruise speed.

Let the analysis begin, I have my opinions but will hold them for now.

Mr. Cab, I would really appreciate your thoughts.

Thanks, Kevin