OK, mechanic buddies. Step into my garage, and help me with these plugs.

Those are Autolite Racing plugs aren't they? and they come with the cut back ground, didn't we have a discussion about gaping those, when you bought them? I seem to remember something about them....

 

Yes, we discussed it here. They were a bit odd to gap the first time.

I need to look that thread up. I don't even remember why I went with these in the first place.

 

Because they are cool!!

 

Good enough reason for me!

 

ok.. got it now.

I've tried so many plugs through the years it's not even funny and now I just buy the cheaper ones for hot rodded motors taht run hotter ignitions. Platinums are used on anything else I don't want to monkey around with every 5-10k miles and also need to be avoided for MSD setups as per their rec's.

I also backcut the straps on ALL of them with an air powered cutoff wheel.

If you do put the fresh plugs in right away?.. it would be best to take the car somewhere that you can run it hard and then shut it down right away to read them immediately. Tough to do, especially without getting in trouble along the way, but will allow much more accurate readings than if you drive it at lower rpm's to get back to your garage before taking the readings.

Running hard up hills will also accellerate the process as forces heavier throttles and heats them up more quickly in the process. Then you move on to longer term/lower rpm testing to see how they color. it appears that you have slightly rich mixture combined with a bit of oil consumption looking at the previous pic's.. but only new plugs and further testing will paint a better picture there.

What type of valve stem seals does your motor run? Positive(locked onto the top of the guide).. or stock umbrella's?

 

Fed-Mogul Valve seals MV-1888C NAPA $26

 

good deal.. and that makes stem/guide clearance oiling issues that much less likely.

depending on shortblock mileage(bore/ring wear)?.. what you may end up needing to do here is run 1-2 steps hotter on the plugs combined with slightly tighter gaps(.040-.045).. and then use synthetic oil of slightly higher viscosity to reduce burnoff. That will keep the plugs cleaner for longer periods bwteen changes at the xpense of possible accelerated gap erosion which will warrant a few regaps along the way.

Bout all I got for you bud. At least until you give us more pic's and clues on the matter. Good luck with it all.

 

Engine is a fresh rebuild, with 500-1000 miles on it. Using Motorcraft Semi-Synthetic 10w/30 w/1 qt lucas except for "break-in" of straight 30 for 50 miles, then 30w for the next 100 miles.

I doubt it is worn rings or worn anything else.

I have them all gapped to .045 now, which I bet makes a WORLD of difference compared to .070.

Now, I have to admit that some of those 500-1000 miles were HARD miles, at 6500-7000 rpms...

 

Seem's like you're back on the right track now then. I finally just looked at the "Della" site link and that is awesome work so far. Passion to do something is more than half the battle to getting what you want in life.

depending on how things shake out after the plug change/readings.. you might still consider the slightly hotter plug/thicker oil tips. They all add up to help a bit. Might need to lean out your idle and transition circuits later on too.

 

for years now ive been hearing a lot of good stuff about iridium plugs. we had that autolite representative get involved in a spark plug thread a few years ago and he really touted their iridium plugs. this last week i had a customer come in and they had just replaced their autolite copper plugs that had 6 months of weekend use on them with ngk iridium plugs. he claimed a big seat of the pants gain on how the car felt.
a lot of the people on turbo forums use them.
ill see if maybe i can do a dyno comparison. we have been wanting to dyno tune mo's car. maybe we will so some plug swaps to see the differences and even if their is a tuning change required from the plugs.
also the iridiums are supposed to last over 50,000 miles so the cost gets offset over the longevity.

 

I just recently leaned out the idle, maybe 100 miles ago. It was rich and thick, and burned my eyes. Got it to where it idles way better now, without stinking up the garage and house.

If I swap over to cheap plugs, then it won't hurt so bad to make adjustments up or down in a heat range. Easier to throw away $2 plugs than it is to toss out $6 plugs!

Now that I have GT40 and non-P heads, it only takes 5 minutes to swap plugs, so I have no problem using el-cheapos.

I haven't done much to the car in recent years. Bought a new HUGE house, and a boat, and haven't spent much time on the car. It runs well, and I can use it as a spare if my truck is in the shop (240k miles, so things are wearing out on it!). So there isn't much to add to the Della Website.

Otherwise, I just drive the car around town when the weather is nice, which is SELDOM in SE Texas. And then to the local car show put on by 924 mav once a year. That is about it.

 

there are plenty of sparkplug tests around the internet and things can get confusing when trying to compare baselines between them due to slight variations in design, heat range, and spark kernal exposure.

I run NGK iridiums on my V6 Honda Accord and hotrodded snowmobiles too and they are nice. They are generally longer lived as the metals used for the electrodes/groundstraps are MUCH harder(sometimes even plated) and reduce gap erosion to aid in consistency compared to regular plugs.

Another thing to consider is that not all plugs have the same resistance levels when they're new and that alone can help pass a bit more energy as well regardless of the rest of the design. Get one that pulls low resistance.. has harder metal/electrode.. and more exposed electrode for improving initial spark?.. and you have a winner.

If my MSD setups weren't so picky about running those iridiums?.. I'd be using them exclusively on everything I own.

 

What is the deal with MSD and iridium/platinum plugs?

I guess they do their testing with copper, and cannot guarantee similar performance with other plugs?

 

IIRC, that short block you bought had a problem with one of the cylinders when you got it. By chance, it's not the same cylinder missing on you is it?

I only use platinum plugs in things I don't want to change very often, like my pickup with the 4.6. Went over 100,000 on the last set in it, they still looked fair when they were taken out. I use Autolite copper in everything else, even put a set in the wife's Vette. Some gave me a hard time for it, but hey, I know a good product when I use it. Even put a set of Ford injectors in the Vette to make it run better!

 

No problem, other than the guy who bought it new tried to wire it up as a 302, and it only fired on 6 cylinders, and then sporadically. So when I got it, it had 0 miles on it, and 2 cylinders had never been fired on.

Once I figured out what he was doing wrong, I bought it for $200 and took it home, added all my stuff, new cam, new heads, converted to roller, and been beating the snot out of it ever since.

But that WAS cylinder #7 and #5 that weren't firing, but I think that is just coincidence.