NW_Jim

Mark 4 big block heads. I can't find the old MR-43-TS. The LTS has about a 3/8" longer thread. Can these be used or not. I want the corrosion resistance.

blown formula

I would not use a longer plug. The MR43ts is still available here, but NGK also makes a corrosion resistant plug that is easy to read also. I cannot remember the number but will get it this weekend & post it. Or you could call Dean Nickerson @ 215-781-1370 on monday (he is closed for Easter today) to get the part #.

NW_Jim

Thank's BF

NW_Jim

I called AC Delco and they told me they do not make an MR43TS. They do make the MR43T but I wanted the projected nose plug. The MR43LTS is a projected nose plug. I see Champion makes a stainless plug. That's gonna be expensive. Is the NGK a projected nose plug?

blown formula

No, it is not an extended tip. That is not to say there is not one available by NGK. However, no one at "the lake" (mercury performance) or Dean Nickerson Performance recommends using extended tips. Something about pistons being expensive!!
I have never had the heads off my engine so I have no idea about the clearances involved here. As I have also been advised to stay away from "split or multi-tip plugs also, it is possible that with extended tips that "indexing" of the plugs could become an issue due to the electrode length in relation to the piston.
You & AC are correct! The TS is no longer made. My oversight, I knew that & I used the MR43T instead. I do like the NGK's better though & only slightly more expensive. Not like the Champion racing plugs at all ($$$). Never had a NGK plug foul or "die" in a blown application or from fuel loading due to long idle/no wake zones.

NW_Jim

OK, do you think you use the BR6FS or the R5673-8. The latter has the v on the electrode and NGK says that one is the better plug. Just thought I'd juggle your memory a little. If you don't remember I can wait. Thanks

blown formula

The 5673 sounds about right but mine do not have split electrodes. NGK did change the part # on the plugs last year, but it does show up in the cross reference if your parts guy is good. I just installed a set last weekend, so that part is fresh in my mind. I will confirm for you this weekend or you can call me at or after 8:30 pm cst tonight @ 918-484-2715 (my lake house). I will be there all weekend. just like I am EVERY weekend. It such a burden, but I'll try to hold up under it!

NW_Jim

Do you go by "Blown Formula" or should I ask for someone else?

Tinkerer

Why are you guys running resistor plugs I don't and I dont have any problems and I do run the extended tip for better flame spread. With the strong ignition systems that the marine engines have you don't need the split or multiple ground plugs. The advertisements are all bs. You will gain 10 hp with just about any new plug initially. The only engines that benefit from the split plugs are the foreign engines with their weak ignition systems.