alternatives to Mercury "perma gap" plugs?

I have a 77' 85 HP and looking for an alternaive to the permagap champ L76V or NGK BUHX.

It acts like it's running a little lean on idle but I've also heard those permagap plugs are junk so I was gonna try that first.

Re: alternatives to Mercury "perma gap" plugs?

Are you saying you want to go to a plug with a typical ground electrode?

Is there piston clearance for that, I wonder?

Re: alternatives to Mercury "perma gap" plugs?

They are fine, were used for decades and have absolutely nothing to do with ?running lean?. Better to start with a carbs disassembly and cleaning followed by a link & sync and a timing adjustment...

Re: alternatives to Mercury "perma gap" plugs?

I would stick with the permagap plugs. Had a 1965 merc 50 once i couldn't get to idle or run without missing. Tried everything i could think of and couldn't make it run right. On a whim i had the dealer look up the plugs and they were the perma gap type .I was using a standard electrode type plug. I changed to the perma gap plugs and the problem disappeared. Lesson learned i suppose

Re: alternatives to Mercury "perma gap" plugs?

Stick with the permagap NGK. The combustion chamber is designed with that plug in mind. A "regular" plug will not work properly, you will never find the right heat range and your ignition will be erratic .

Re: alternatives to Mercury "perma gap" plugs?

The NGK BUHX is hotter than the BUH8 which is very nearly the same as the NGK B8HS standard electrode plug that I have installed a a great number of 'fishing' motors that see substantial 'idle' time and very little WOT.

If compression is under 120 then I often used the hotter B7HS.

For sustained WOT running, I doubt that you can find a better plug than the surface gaps.

Re: alternatives to Mercury "perma gap" plugs?

outboardnut said:

I have a 77' 85 HP and looking for an alternaive to the permagap champ L76V or NGK BUHX.

It acts like it's running a little lean on idle but I've also heard those permagap plugs are junk so I was gonna try that first.

Click to expand...

Something didn't sound right when I read this.... and I'm a little surprised no one else saw it...

The correct plugs for that engine are BUHW2 (L78V if you must use chumpion), not BUHW (L76V).

I wonder if that could be your problem???

BTW... surface gap plugs are about the best thing ever invented, not, as you so elegantly put it, 'junk'.....

Chris......

Re: alternatives to Mercury "perma gap" plugs?

Yep, achris found your problem. Fix it with the correct plug. The only thing I don't like about surface gap plugs is that they can be hard to read when tuning a engine. They are far less prone to fouling in normal use since there is far more suface area than conventional spark plug.

A convential style plug can and usualy does seem to improve idle in a big motor that was never intended to troll or idle for long periods. In those situations a convential plug does seem to help.

Re: alternatives to Mercury "perma gap" plugs?

I think Chris is wrong here. I double checked in my Champ and NGK book and it calls for the ones I posted.

I also just checked a Seloc specs and it says the L76V.

Compression is 125/125/125/115

I've been a little hesitant to go after the carbs. Word on this motor was a shop just rebuilt them and said they could not make it idle lower without getting into the internals of the motor.

Re: alternatives to Mercury "perma gap" plugs?

achris said:

BTW... surface gap plugs are about the best thing ever invented, not, as you so elegantly put it, 'junk'.....

Chris......

Click to expand...

Chris, I wasn't trying to offend any engineer's here...

An instructor of a school in attended lectured against them. I couldn't find my book to see what he recommended and was wanting to double check him. I found my book and have noted he was recommending. It was the B8HS as stated a few posts above.
The instructors exact words were "Any time I get a motor with those permagap plugs, first think I do with them is take them out and throw them across the shop".

He went on about how much better Mercs would idle with a regular plug.

Re: alternatives to Mercury "perma gap" plugs?

achris said:

Something didn't sound right when I read this.... and I'm a little surprised no one else saw it...

The correct plugs for that engine are BUHW2 (L78V if you must use chumpion), not BUHW (L76V).

I wonder if that could be your problem???

BTW... surface gap plugs are about the best thing ever invented, not, as you so elegantly put it, 'junk'.....

Chris......

Click to expand...

Took your word as gospel but upon questioning in a later post I did a little research and the plug recommended by both Merc and NGK is infact the BUHW plug. Happens to the best of em...

Re: alternatives to Mercury "perma gap" plugs?

outboardnut said:

Chris, I wasn't trying to offend any engineer's here...

An instructor of a school in attended lectured against them. I couldn't find my book to see what he recommended and was wanting to double check him. I found my book and have noted he was recommending. It was the B8HS as stated a few posts above.
The instructors exact words were "Any time I get a motor with those permagap plugs, first think I do with them is take them out and throw them across the shop".

He went on about how much better Mercs would idle with a regular plug.

Click to expand...

Such a blanket statement, especially in the face of most everyone here (probably millions of hour combined experience) speaking against it, ought to tell you something.

My dad used to say, "Them that can, do. Them that can't, teach."

Surface gap plugs are the answer to a lot of questions in an engine that burns oil, either by design or by accident. I'll go with the Merc engineering.

BTW, have you read your plugs? Could you have an errant idle stabilizer, out of spec reeds, uneven compression, uneven carburetion? The bleed system is critical for good idle on these engines.

Sometimes going slightly off spec in tuneup can help a particular engine, for instance setting idle slightly richer and idle timing slight faster, or the opposite combination.

just my 02
John

Re: alternatives to Mercury "perma gap" plugs?

I suspected some would question my post, so here is a scan from the MERCURY (not solec or clymer) service manual.... (I also checked the serial number for 1977 and the starting number for that year is 4590512. That means this is the relevant page)....



One of the real bug-bears with those engines was if they lost the restrictors in the transfer posts, they wouldn't idle very well.

outboardnut said:

...An instructor of a school in attended lectured against them. I couldn't find my book to see what he recommended and was wanting to double check him. I found my book and have noted he was recommending. It was the B8HS as stated a few posts above.
The instructors exact words were "Any time I get a motor with those permagap plugs, first think I do with them is take them out and throw them across the shop".

He went on about how much better Mercs would idle with a regular plug.

Click to expand...

As stated earlier, "Those that can, do. Those that can't, teach". This instructor is an idiot! I've lost count of how many times I've fixed up problems by just doing as the OEM manual says. It still amazes me that some people think they know more than the people who designed and built the engines.

Ok, that's me finished here.... If you really want to put different plugs in, go for it.... I doubt it will fix your problem, but hey, it's your engine to screw with...

Chris.....

Re: alternatives to Mercury "perma gap" plugs?

achris said:

I suspected some would question my post, so here is a scan from the MERCURY (not solec or clymer) service manual.... (I also checked the serial number for 1977 and the starting number for that year is 4590512. That means this is the relevant page)....

One of the real bug-bears with those engines was if they lost the restrictors in the transfer posts, they wouldn't idle very well.

Click to expand...

Yep, I agree my older micro-fitch say's the same thing but Merc Parts Express now shows it as NGK BUHW. Albert Champion (AC-Delco) and Champion are the same thing. It's a marketing thing. The chumps cross to the BUHW or BUHW-2.

Re: alternatives to Mercury "perma gap" plugs?

What's the real world difference between the BUHW's and the BUHW-2's?

I see the Center Electrode gaps are .050" and .071" respectively.

What does that really mean to the performance of the motor?

Re: alternatives to Mercury "perma gap" plugs?

marc c said:

...What does that really mean to the performance of the motor?

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I have seen several examples of the wrong plugs in an engine causing all sorts of running problems. Why is it that manufacturers make so many different spark plugs? It's because different engines need different plugs. Putting the wrong plug in WILL cause run issues...

As far as I'm concerned, and this is 30 years of experience talking, the path to fixing engine problems is to start with all the basics RIGHT. That means the right plugs, gapped correctly, the ignition system working properly, and timed correctly, and the fuel system clean and adjusted to the correct idle speed and mixture. ONLY when all of these things are right will the engine run right. Second guessing the manufacturer and putting different components in and then wondering why it doesn't run properly is a fool's errand.

To answer the question in short terms... spark plugs have a MASSIVE influence on the run quality of any spark ignition engine!

Re: alternatives to Mercury "perma gap" plugs?

Chris, thank you for taking a moment to clarify that.

I had referenced champ spark plug book, ngk spark plug book, and the seloc book.
After reading your second post I flipped through a digital OEM manual I have that covers this, and it says the BUHW-2.

I usually go with what the OEM recommends as a rule of thumb, but have seen cases in machinery where sometimes certain things will work better engineered a little different so I'm a little open minded. However I am also very, very cautious when things get engineered differently. I remember questioning the instructor about changing the plugs and how he knew which ones to do, and he said it was listed as an alternative plug.
Addressing the above post on plug differences,
I think it matters which motor when you are talking real world difference in the two plugs. I have seen the wrong plugs cause a miss. Results will probably vary motor to motor and operating condition's and temperatures. Also I believe the BUHW's are a colder plug and can make a motor harder to start. You are also going to have a little bit of a timing difference.
The motor I am dealing with now calls for the -2's, but runs on the BUHW's. It isnt' running right though.

+1 that OEM recommendations are best, but only most of the time in my book. Engineer's and factories do make errors and they don't always own up to them because of all the havoc of a public "we goofed" statement can make. TSB's are great and I praise the MFG when they release them on known issues.

I trust the OEM book over the trio of champ, ngk, and seloc

Re: alternatives to Mercury "perma gap" plugs?

Whoa Nellie! I wasn't questioning ANYTHING, ANYONE had to say.
I was just curious what the difference in the plugs were and how they would effect a motor.

I should've provided more info.

My motor came with L76V's which cross to a BUHW.
The NGK online catalog now recommends the BUHW-2

achris said:

I have seen several examples of the wrong plugs in an engine causing all sorts of running problems. Why is it that manufacturers make so many different spark plugs? It's because different engines need different plugs. Putting the wrong plug in WILL cause run issues...

As far as I'm concerned, and this is 30 years of experience talking, the path to fixing engine problems is to start with all the basics RIGHT. That means the right plugs, gapped correctly, the ignition system working properly, and timed correctly, and the fuel system clean and adjusted to the correct idle speed and mixture. ONLY when all of these things are right will the engine run right. Second guessing the manufacturer and putting different components in and then wondering why it doesn't run properly is a fool's errand.

To answer the question in short terms... spark plugs have a MASSIVE influence on the run quality of any spark ignition engine!

Click to expand...

Re: alternatives to Mercury "perma gap" plugs?

I posted wrong, my books says L78V not BUHW-2.

BUHW-2 vs BUHW = possible misfire

Re: alternatives to Mercury "perma gap" plugs?

outboardnut said:

I posted wrong, my books says L78V not BUHW-2.

Click to expand...

BUHW-2 is the NGK equivalent of chump L78V.
BUHW is the NGK equivalent of chump L76V.

outboardnut said:

BUHW-2 vs BUHW = possible misfire

Click to expand...

Definitely possible.

I [size=+1] NEVER [/size] use chumpion plugs... Too many DOA out of the box.

marc c said:

My motor came with L76V's which cross to a BUHW.
The NGK online catalog now recommends the BUHW-2

Click to expand...

Someone put the wrong plugs in... Gee, I've never heard of that happening.

1982 Merc 50.... correct plug is BUHW-2.... (also from the MERCURY manual)

Chris.........