Well, after himming and hawing, I put the 3923's in last weekend. First of all, it was easier than I thought it would be thanks to you guys. And second, you all were right. The 3923's are the best for our engines. It runs great. Much smoother idle and better pick-up. I am not sure of the gas mileage yet, because the last tank had some of the old plugs gas mileage, so we will see over the next few fills. Thanks again guys!

 

since i got my egr valve replaced, i actually got to see how the truck would do with a CAI and new plugs. I did go with the 5224 autolites simply do to the fact i don't do alot of hard acceleration, and after all i read, i thought i would try these first. After saying that, i am very pleased with the 5224. THe truck idles better and just seems to run better. now i did put a cai on at the same time so i don't know which to give 100% credit to but i have no complaints with the 5224. 10 times better than what the factory put, i will agree with that!

 

I've always put a little anti-seeze compound on the threads and then put them in "hand tight plus a quarter turn". It's always worked for me.

 

I need to no the correct gap for the autolite 3923 plug installed in a 2006 3.7 .i think its differs from the 4.7. any help would be greatly helpfull thank .mark

 

Here you go: gapSpecs.jpg

 

I was running the 3923's and really liked them, but my in town driving MPG was killing me so I went to the 5224's and my in town MPG went back up and the trucks runs just as good. Beofre I made the change and did have some thing happen that was werid? I was in Presscott, AZ doing my Auto Trader job and it was around 6am and the truck would not start, it turned over just fine but would not fire up. Did it 3 times then ran just like nothing had happened??

 

Tuffone:
The only time I had something like that happen was with my 89 Jeep Wrangler 4 cylinder. It would crank and crank, but not start and then it would start right up and drive fine. It took me a couple of months to figure-out that the dealership had put the wires back in the wrong order after replacing a piston for engine knocking problems (I bought 2 different brands of those car maintenance guides and they had different firing orders so I thought "no way, but what the heck I've tried everything else" and it fixed it.)
It was the wierdest thing since I would have thought a bad firing order should make it run badly all the time (esp on a 4 cyl), but once it started, it ran fine. I assume the engine control module was doing some fancy tricks with the timing to make it run. Pretty amazing that they could do that in 89.

Growlor

 

A follow up question on this 3 year old thread.

I have a 2010 Dakota, 4.7. It is coming up on 30,000 miles. My recollection is that the manual says to change the upper bank of spark plugs at 30,000 miles.

Now my questions for you experts.

Would the Autolite 3923 gapped .040 still be right for my truck?

Should I only change the upper bank of plugs at 30k miles?

Thanks guys.

 

I've been pouring through these posts, web searches, and everything else. I have a 08 Dak, 4.7L Flex, AirAid CAI, AirAid throttle body spacer, Jet Stage 2 performance chip, dual Flowmaster exhaust. I'm coming up on my 30k service as well and the only plugs I've found are Bosch, Denso, or Pulstars. The orginial Bosch are nickle YYTrium plugs, and they have a comparable replacement. The bottom plugs are Iridiums. So, which plug is better? I don't want Denso, Pulstar, Champion, or NGK; so that leaves the rest. Also, if platinum isn't recommended; why are the websites etc. recommending them?

 

You must be losing your memory due to your age. Mercury has never built a straight 8...