Question Bout Spark plugs
 

Ok...I need some help from you motor guys

I have a motor that runs with the NGK # 7 V groove plugs.
Dart Pro 1 heads.

What ill affects (if any) would running with shorter stem plugs have? AC Delco MR43T

Re: Question Bout Spark plugs
 

all manner of things... none good. if the combustion chambers/head/piston tops are designed for that length plug then you will get lousy flame propagation , misfire at higher revs and maybe even detonation from the open edges of the spark lug hole/threads... can not imagine why you would want to do this.

Re: Question Bout Spark plugs
 

I would never have done this.

these are the plugs that I pulled from my engine after I got my boat back from the mechanic. I now have oil coming out the exhaust from the # 5 cylinder.

Re: Question Bout Spark plugs
 

Are you saying that the shorter plug was installed by accident during service? If so, that sucks :(

Re: Question Bout Spark plugs
 

Spark plugs have two functions. First the obvious one is to fire off the air fuel mixture in the cylinder. Second one that every one forgets or has no idea about is that the plug is also there to remove the heat from the combustion chamber. With the shorter reach plug you have less contact with the head hence less area for the plug to dissipate heat to the head.
Mike

Re: Question Bout Spark plugs
 

Absolutely.....but on the flip side....too long of a reach on the plug and you run the risk of piston contact. Theres also the issue with flame travel now as the flame has to travel around the threads and up instead of just to the sides and down.....

Re: Question Bout Spark plugs
 

If those are the actual plugs. The one on the left is a typical plug for a iron head SBC with the taper seal. One one on the right is from your Dart heads. Cant believe that the delco plug would seal up and if it does it would probable damage some threads. I don't know what other damage could happen, but a compression test and a leak down test will tell the story.

Re: Question Bout Spark plugs
 

Bruce,
The AC R43T is a .460" reach, tapered seat plug
The correct plug is a .750" reach, gasket seat
Do you know where exactly are you passing the oil on #5?
Bob

Re: Question Bout Spark plugs
 

If those were the actual plugs that the mechanic had installed in the engine, I don't think I'd ever take it back there again. :(

Re: Question Bout Spark plugs
 

hey guys ..I appreciate the feedback

yes..these are the plugs the mechanic installed on this engine. I know they are wrong. What he was thinking. I dont have a clue.
I have not pulled the motor apart yet. I just pulled it out of the boat.
Im looking for feedback and some education before I speak with him.

if you look closely, you can see some hardened buildup on the strap of the plug. None of the other plugs have this buildup. Which leads me to believe we detonated the # 5 piston. there is oil coming from the exhaust on the port side only and was smoking a bit when it was running.

Re: Question Bout Spark plugs
 

I spent 3 yr training for GM then 3.5 with bosch now I am here training for Volvo. I still have contacts with bosch If you need any analysis on thoses plug let me know. Here in IL is where bosch does all the product application for there spark plugs.
Mike

Re: Question Bout Spark plugs
 

Thanks Mike

Ill keep you up to date. Once we get the motor apart. I may take you up on that offer.

Re: Question Bout Spark plugs
 

Bruce, Can we get a closer pic of plug electrode?

Re: Question Bout Spark plugs
 

its hard to get that close up without being out of focus. but I'll try

Re: Question Bout Spark plugs
 

Not good. Yank the motor out. Probably nees a set of slugs and a bore.

Re: Question Bout Spark plugs
 

I would suggest doing a leak down test on the engine before pulling it all the way apart. Even cold it will at least give you an idea if the rings are hurt. Sounds like rings though. May have nipped a piston.

Dean Gellner
Gellner Engineering Marine Power

Re: Question Bout Spark plugs
 

Hard to tell but in the pic's there look like there is some Aluminum on the center electrode

Re: Question Bout Spark plugs
 

Did that happen in Camden?

Re: Question Bout Spark plugs
 

yes

Re: Question Bout Spark plugs
 

had to bring this back to the top.....

just an update since last post. detonated piston. aluminum fragments all over the place. needed machining, pistons, rebuild etc etc.......

all because wrong plugs were put in. mechanic aknowledged the error and said he would reimburse me for the rebuild. Obviously, he will not be doing it.

as long as he makes good on the rebuild, I will not mention his name, publically.

motor is just about done.

Re: Question Bout Spark plugs
 

more

Re: Question Bout Spark plugs
 

....

Re: Question Bout Spark plugs
 

Bruce,

That is really bad luck.

I am pleased to hear that the mechanic is owning up to his error, mistakes happen. Also I agree with your not putting his name out here, you can be sure he wont make that error again.

I realize you are still out a lot of time and money and that sucks.

Good Luck.

Re: Question Bout Spark plugs
 

Thanks Mark, while he owned up to his error, I have still not gotten reimbursed. So....stay tuned.

if he pays, his name will not be mentioned. If he stiffs me....

Well you know what happens then :eek:

Re: Question Bout Spark plugs
 

:evilb:

Re: Question Bout Spark plugs
 

Don't know the laws in your area or the dollars involved, but it seems like you would have an excellent case for small claims court. Up to 5k here in Texas.

If he does screw you, try the BBB first and then small claims.

Hopefully it doesn't come to that. It appears that he doesn't have a leg to stand on.