Spark Plug Query

[FetchMeAPepsi]

Originally Posted by Jmclendon

What I can't make sense of though is why the shorter plug won't fit into the 2 4 6 side of the engine. Is what turbobill suggested the most likely cause? Someone has swapped a head at some point?

The plugs (long and short) are interchangable. The threads are the same. I can't see why they wouldn't fit unless something weird did go on like stripped threads and re-threading or a new head.


Edit: I just re-read your mismatch post. Stripped threads are my guess. Someone either busted out some rusted, frozen plugs or they over torqued them and stripped it. Either way, thank goodness they were shorties or you would have had the entire thing stripped out!

[Jmclendon]

Originally Posted by AZKen

Who bought the plugs? you, the mechanic, already had them in truck?

The mechanic already had the two sizes in the truck.

However, I didn't know that, so I only purchased the 1 size (NGK Bs6) because the conversion chart that I looked at said that would be comparable to the AC C44 that's in the manual.

The longer plug that the mechanic had in the 2 4 6 side was an NGK BP5ES

Side note, for anyone keeping score the plugs the mechanic put in have quite a bit of carbon buildup after only 2-3 weeks of daily driving. Which is part of the reason why I'm replacing them. I had suspected the ones he installed weren't gapped properly (they weren't). So, I'm hoping new plugs with the appropriate gap is going to give me a cleaner burn (and longer lasing plugs).

[AZKen]

Good info from FMAP. As he said, thread problem. However you DID NOT state what won't fit. We assume you mean won't thread into any hole in that bank? Can't imagine all stripped on one head only. I have to think this out. So on one bank you have long thread plugs and the other has short thread plugs ? and the short only fit one bank? and the long fits.......??

The Jolly AC4 under known good parts is 3/4 long thread. I would go with that. I did.

[Jmclendon]

I've bought a set of 6 matching, only to realise that they're not fitting on one side (too short). But the other side fits fine?

That's what I meant when I said they weren't fitting on one side.

To be honest, I haven't checked to see if it's just one hole or all of them on the same side. Once I realized that I had been driving around with 2 different sizes of plugs I called it a night. I'll check when I get home today/tonight.

Either way, from what y'all are saying it sounds like there's no real issues with the (admittedly weird) setup that I've got going on at the moment?

[AZKen]

You are confusing us.
1. It is B6S NOT BS6. The B6S is short 3/8, the BP5ES is long 3/4.
2. BOTH are 14 mm threads!!!! AC4 is 14mm.
3. No reason one fits only one bank.
4. B6S crosses to AC C44 (short) and 14mm thread.
5. You have not mentioned any other plug numbers that I know of.
6. So I don't get what plug fits in what, so called, bad holes? What plug won't fit where? They all have the same bloody thread.

[Jmclendon]

Originally Posted by AZKen

You are confusing us.
1. It is B6S NOT BS6. The B6S is short 3/8, the BP5ES is long 3/4.
2. BOTH are 14 mm threads!!!! AC4 is 14mm.
3. No reason one fits only one bank.
4. You have not mentioned any other plug numbers that I know of.

Sorry, fat fingers on the BS6 vs. B6S.

#3 is pretty much the source of my confusion with this. I don't know why the B6S fits in one side but not the other.

[AZKen]

You missed 5 and 6 on my list. Bottom line, change whiskey brands.

[Jmclendon]

Originally Posted by AZKen

You missed 5 and 6 on my list. Bottom line, change whiskey brands.

Whiskey at work would make the day so much better LOL It might actually make me more sensible as well.

Ooook, here goes. Start to finish.

There are 3 B6S short plugs on the 1, 3, 5 side of the engine.

On the 2 4 6 side there's 3 of the longer BP5ES plugs.

I'm wanting to replace all of them. I've purchased 6 B6S plugs.

For the moment, all I know is that the B6S plug won't thread into the #2 cylinder. It looks like it's just not long enough to catch anything. I haven't tried it in 4 or 6.

Putting the reason aside for the moment (since I'm not sure yet if we're talking 1 stripped plug or a head mismatch at some point in time in the old boy's life) will it cause issues to have the 2,4,6 side of the engine on long plugs and the 1,3,5 side on short ones?

[Jmclendon]

Popped home during lunch.... The short plug won't fit into any of the even numbered cylinders. So, are we thinking mismatched heads?

[kchampagne]

Could you take some pics of the heads? Might help diagnose the issue.
Thanks!