sparkplug issue

[dgopetactical]

1987 5.7 mercruiser alpha 1

changed plugs end of summer had about 8 hours on them deceided to change them today since there is fogging oil on them and I have a carb issue and had dry black soot on them. My question is I had one plug come out with the center electrode basicly ash fused to the side electrode which is in good shape. any ideas. I have a new carb and will install it in a few weeks when time permits.

that may be why i lost 400rpm at the end of the season which we figured out in other posts last year and was advised that it was a bad carb (also a street carb) please let me know why you think this plug center electrode melted.
thanks,
denny

 

[Haut Medoc]

Re: sparkplug issue

Crud on the plug when you installed it?.....​

 

[dgopetactical]

Re: sparkplug issue

Crud on the plug when you installed it?.....​

its kinda blind when u put them in under the manifolds so it is possible i picked up some junk. I have the manifolds off and its easy now. If it was junk would it melt the center electrode?

also this plug was a tad loose 3/4 in

 

[Don S]

Re: sparkplug issue

Get the right carb, and get it adjusted properly, make sure your base timing and advance timing are where they should be, put a new set of plugs in and give it a run and look at them after a run.
The black on all of them after starting (choke on) and running on the muffs will make them black.
When you recheck, do it after stopping from a good run without a long idle period. Bet they look better then.

 

[dgopetactical]

Re: sparkplug issue

Get the right carb, and get it adjusted properly, make sure your base timing and advance timing are where they should be, put a new set of plugs in and give it a run and look at them after a run.
The black on all of them after starting (choke on) and running on the muffs will make them black.
When you recheck, do it after stopping from a good run without a long idle period. Bet they look better then.

I do have the right carb just gotta get it hooked up. (Had a street carb on from preveious owner so i contacted holley and got the exact match 4160 holley,only it is a marine carb) im sure that will clear the black plugs. I was just realy worried about the melted electrode still confused on how and why that happened.

New plugs are in,putting cap, rotor, and manifolds on now. carb next weekend.
thanks for the help you guys are great.

 

[Don S]

Re: sparkplug issue

Lean will melt a plug, as well as to much timing.
That is why I say put on the right carb (and adjust correctly) and do the same with the timing, both idle and advance timing needs to be checked.

 

[dgopetactical]

Re: sparkplug issue

Lean will melt a plug, as well as to much timing.
That is why I say put on the right carb (and adjust correctly) and do the same with the timing, both idle and advance timing needs to be checked.

will do
thanks again,
denny