AMC Eagle Den Forum

The Mighty 258 => The Engine => Topic started by: Obscurity on April 18, 2011, 12:34:45 PM

Title: 4L conversion spark plugs
Post by: Obscurity on April 18, 2011, 12:34:45 PM
Hey, I'm sure there is something on the Nest somewhere, but I haven't found it.
I got the 4L conversion head from Clearwater cylender heads. I know I'm going to need spark plugs for the 4L, does anyone know off the top of their head whether there are differences in the 4L plugs? I can't find the information on my cylender head (I moved, its around somewhere, but it'll probably be a week of digging through paper to find it!).
Also, does anyone know what kind of gap I'll need? The block is bored to .40 (if I recall correctly, I'll have to double check, Comp Cam, 2bbl Webber carb. Thoughts or suggestions? I really want to get the plugs today, and an oil filter if NAPA actually has one in stock (Canadian Tire didn't).
Thanks all!
Title: Re: 4L conversion spark plugs
Post by: eaglefreek on April 18, 2011, 01:19:04 PM
The Eagles 4.2l and the 91-95 Jeep with a 4.0 both use the same plug. Go with your favorite brand Autolite, NGK etc. Regular old copper cores are fine, no need for platinum or iridium. If you experience spark knock you can use a colder plug from an 87-89 Jeep with a 4.0. As far as gap, that depends on your ignition. If stock just go with stock specs. If MSD or HEI you can open it up. I run mine at .045 with a MSD box.
Title: Re: 4L conversion spark plugs
Post by: Obscurity on April 18, 2011, 06:37:04 PM
Whoo hoo, thak you eaglefreek! I picked them up with an oil filter an hour ago. Went with Platinum, less than a dollar more each than the copper. Just that much closer to the first start of the new engine  :hello2: I will be upgrading to a different ignition....eventually.
The parts guy asked what vehicle the parts are for (didn't know for sure what vehicle the head would be for, stock, just gave him the basic info you gave me) then the he tells me to look on the insurance papers and it'll tell me for sure, a Jeep or an Eagle, a '90s model or an '80s....uugh. Wouldn't believe me that I was looking for parts for the same engine. We were both rolling our eyes by the end, both convinced that the other one was a jerk, lol, I should be used to this by now!