AUTOLITE 3923

[bbarrett]

I have a update and a question, The stroker has about 700 miles now. I changed the oil to Castrol 10w30 using no additive, The oil that came out was strait 30w Brad Peen breakin oil. The motor has been running very well, It has saw 100+ mph several times. There has been no oil or water consumption. My only problem was when it is pulling a trailer i have some detonation, Very slight but there. I have been running 93 octane with about 12 degrees initial timing. Don't know total i don't have a timing tape and the dial back light wont work on the MSD. (just really haven't had time to figure out marking the balancer) Any how i decided to change to a cooler heat range plug. But the only cooler plug i can find don't have the extended electrode. I wont have a chance to run it till the weekend, So i thought i would ask if anyone has ran these plugs. Pros and Cons.Here is a picture of how the new plug compares to the old.

pictures from iphone 005.jpg

[bbarrett]

3923,s is to cold. I found some 5224 that is a little hotter, Pulled trailer about 80+ miles yesterday, Temp was around 90 degrees, Ran the ac. Had no signs of pinging. This may be the plug to run. Everything seems fine. I haven't pulled one to see if the heat range is where i want it to be, But its bound to be close. I did go back through my old plugs, And under the microscope it shows 5 and 6 cylinders were the worst ones. But that stands to reason as they are the hottest cylinders. I really wish there was a better head that didn't cost 2k as i think this is most of the problem. Now i know why Jeep didnt run much compression from the factory. I also know that this motor will never be a 87 octane motor.

[gradon]

That's good to hear--I haven't tried a cooler range autolite yet, but loved the double plats in the 4.0 pre-stroker. I still have light pinging from 2700-3000 w/ the rc9s(3 ranges colder than the rc12s--it would ping 2k-3k w/ the rc12s) and LT1s @ 25.5#. I just got done trying the single pintle blue top ford 24#ers (27# on the 49psi rail) and it would ping 2300-3000, so the LT1s are back in.

[bbarrett]

That's good to hear--I haven't tried a cooler range autolite yet, but loved the double plats in the 4.0 pre-stroker. I still have light pinging from 2700-3000 w/ the rc9s(3 ranges colder than the rc12s--it would ping 2k-3k w/ the rc12s) and LT1s @ 25.5#. I just got done trying the single pintle blue top ford 24#ers (27# on the 49psi rail) and it would ping 2300-3000, so the LT1s are back in.

According to my books, The 9YCs are the same as the 3923s. These were just to cold for my application. If you do try the Autolites i wouldn't use the platinum, as these can actually cause detonation (or pinging) I build and tune a lot of Blower and nitrous motors and the platinum plugs are a no-no. The reason i don't do Champion is the skinny ground strap, I like a plug with the thickest ground strap i can get. Well good luck to you and i hope you find your cure as i did.

[bbarrett]

Another update, Now i have 1200 miles on the engine and all is well. Still having some mild pinging issues, But still working it out. I took the heat away from the intake yesterday, The 4.2 wouldn't run without heat but the 4.7 seems to like it better. Anyway the next hot day i will load the trailer and try it again. Still getting in the 20s with no trailer and around 18 with, Both running the air.