Spark Plugs

[zul]

Looking for a spark plug suggestion. Pulled mine, Champion 203 5A. Looks like they come in copper ($2 each) or platinum ($2.50 each). Should I replace with one of these Champion plugs or is there a different plug suggestion out there these days?

Thanks!

 

[alldodge]

Your motor came with one of these 3 type plugs for the 155 and 175 HP

AC-MR43T / Champion RV15YC4 / NGK BR6FS

Or these 3 type plugs if it was 190 or 205 HP

AC - MR43LTS / Champion RS12YC / NGK BPR6EFS

I would use any of the 3 type plugs for the given motor and have them all the same type

 

[achris]

Looking for a spark plug suggestion. Pulled mine, Champion 203 5A. Looks like they come in copper ($2 each) or platinum ($2.50 each). Should I replace with one of these Champion plugs or is there a different plug suggestion out there these days?

Thanks!

Those are the WRONG spark plugs. Sounds like someone just went and put lawn-mower plugs in... :facepalm:

Correct plugs for a 1994 4.3 are NGK BR6FS (or equivalent) for both 2 and 4 bbl carbed engines. (BPR5EFS are for the Gen +/Vortec engines)

Chris..........

 

[zul]

Wrong plugs! Well, they are sitting out of the motor right now. I was going to put them back in to finish trouble-shooting my oil blow-by issues. I've got the AC Delco MR43LTS arriving tomorrow. Sounds like I should toss those old ones and finish troubleshooting with the new AC Delco plugs?? My compression test went really well:

#1 130
#2 129
#3 135
#4 135
#5 135
#6 120

If the previous owner had the wrong plugs in there (and I've had the boat for 2 years), what kind starting and performance change can I expect? This boat has always started well (on the second try) and run well. Lately I've run into a host of issues. It would be nice if new oil, filters and spark plugs took care of a few other problems!

My next plan was to squirt oil into #6 as that was the only suspect result. But then I'd have oil running around my brand new plug...... ??

 

[achris]

... I've got the AC Delco MR43LTS arriving tomorrow. ...

Are also the wrong plug. They are for the Gen + engines. You have a Gen II engine (yes, you also have a gen II drive)....

The correct plug for that engine is AC Delco MR43T.... The MR43LTS are too long....

Chris......

 

[zul]

OK - Going with your original suggestion NGK BR6FS. So helpful.

Now, I plan on doing a wet test on #6. Should I use the old plugs for that?

Thx Chris!!

 

[alldodge]

Do you happen to know your engine serial number?

Chris is the guru, just trying to figure out the differences in the manual

 

[Bondo]

Ayuh,.... MR43T is the plug for Chevy motor up to '96, when the Vortec heads came out,.....

The MR43LTS are for Vortec headed Chevys,....

Bein' a '94, ya want the MR43T plugs,....

 

[achris]

...., just trying to figure out the differences in the manual

Which manual are you looking at?

The original blocks (with no balance shaft) use manual #7. For the 'Gen II' blocks (1993 to mid 1996), with a balance shaft, but not Vortec heads, use manual #18. For later, 'Gen +' (with Vortec heads) blocks, use manual #25.

This is from manual #18... Page 7 in section 1B (maintenance).



Chris.........

 

[achris]

OK - Going with your original suggestion NGK BR6FS. So helpful.

Now, I plan on doing a wet test on #6. Should I use the old plugs for that?

Thx Chris!!

Yes you can use the old plugs to just allow the engine to be spun over to distribute the oil in the cylinder... And don't worry about oiling up the new plugs, it'll burn off fast enough. The other tip.... Don't use normal 4 stroke engine oil... Too much detergent... I use 2 stroke oil... as it's designed to be burnt in a cylinder anyway, and doesn't leave as much residue..

Chris..........

 

[alldodge]

Which manual are you looking at?

The original blocks (with no balance shaft) use manual #7. For the 'Gen II' blocks (1993 to mid 1996), with a balance shaft, but not Vortec heads, use manual #18. For later, 'Gen +' (with Vortec heads) blocks, use manual #25.

This is from manual #18... Page 7 in section 1B (maintenance).



Chris.........

Manual 18 - 1993 to 1997
Your pic is from page 1B-7 and on 1B-8 you see the high hp ratings. At any case I got it, just need to remember 1996, and this is also why I always want a SN

 

[achris]

...., and this is also why I always want a SN

Yep, if everybody just put serial numbers, it'd make our life far less complicated...

Cheers,

And all good.

 

[zul]

My engine serial number has been scratched out. Is it located in multiple locations? Ya' it's bothered me since I bought the boat.

Running the wet test now ...

 

[achris]

My engine serial number has been scratched out. Is it located in multiple locations? ...

http://forums.iboats.com/forum/engi...d-engine-serial-numbers?p=6661415#post6661415

 

[zul]

The first column of numbers is from yesterday's cold and dry ..... second column is from today's Warm and Wet compression test (using 2-stroke oil in #2 and #6) WOW!! Looks like a nice improvement!

#1 130 135
#2 129 145
#3 135 135
#4 135 135
#5 135 140
#6 120 140

Should I have placed oil into all 6 plug holes ?
These numbers are better, does it tell me that my rings and pistons are GOOD>?!
Do those improved numbers tell us anything?

The only strange thing was, while warming the boat -- the port side exhaust manifold was warm and the starboard exhaust manifold was Hot -- not too hot, I could hold my hand on it for 8-10 sec, hot. I had the water on full and idled from 900-1400rpms max. Should this alarm me? Shouldn't they have equal temps?

I think that my next step is to put in new plugs, new oil, oil filters, fuel water separator -- and go to the lake!
Maybe I'm getting ahead of myself?

Thoughts and suggestions?!

THX!!!

 

[JoLin]

The temp difference from side to side is normal. I've had 2 boats with twin 4.3's and all 4 engines acted the same way. Starboard riser runs hotter than port. If you can hold your hand on it you're okay. From what I've seen and heard, all the small block GM V-6's and V-8's act the same.

My .02

 

[achris]

...These numbers are better, does it tell me that my rings and pistons are GOOD>?!...

Quite the opposite. If the pressures improve with oil, then that's an indicator of worn rings/cylinder bores. That said, I don't see any reason to start pulling the engine apart right now. Did we get a 'warm and dry' pressure for #6 and 2?

No improvement would indicate valve problems.

Chris.......

 

[zul]

chris - Yes, warm and dry compression readings are on the left and the wet and warm readings are on the right:

#1 130 135
#2 129 145
#3 135 135
#4 135 135
#5 135 140
#6 120 140

I'm confused, all the research indicates that these numbers are good and rules out worn rings and piston problems ... ??

 

[alldodge]

The numbers are good enough for the motor to run, just not very well. The 130 readings cold shows that it needs heat to expand the rings/piston to get in a decent range.

Te way to find out if its rings or valves is with a leak down test

 

[achris]

The first column of numbers is from yesterday's cold and dry ..... second column is from today's Warm and Wet compression test (using 2-stroke oil in #2 and #6) WOW!! Looks like a nice improvement!

#1 130 135
#2 129 145
#3 135 135
#4 135 135
#5 135 140
#6 120 140

chris - Yes, warm and dry compression readings are on the left and the wet and warm readings are on the right:

#1 130 135
#2 129 145
#3 135 135
#4 135 135
#5 135 140
#6 120 140

I'm confused, all the research indicates that these numbers are good and rules out worn rings and piston problems ... ??

So, is it warm and dry or cold and dry?