Another spark plug question

[further]

So i've researched which plugs to get and picked up the AC MR43LTS. Pulled the plugs today and they're very different from these. The plugs that I pulled from the motor are Champion rv15yc4 and look like they've been there for quite some time. They are substantially different with regard to thread and distance they will sit when installed. I don't want to go with champion per most recommendations on here... So what to do?



Want to be sure I'm putting the correct plug in and obviously if they sit too deep that will cause big problems, i would think.

Did I get the wrong plugs? Should I just get the OEM? These are Champion though and want to stay away.

 

[MikDee]

Re: Another spark plug question

Just get the AC MR43T, The LTS is the long thread plug. Unless your motor requires the long reach plug? If not it could do some damage!

 

[Scott Danforth]

Re: Another spark plug question

the plug on the right is for a vortec head, the plug on the left is for a pre-vortec head

what motor do you have?

 

[gbeltran]

Re: Another spark plug question

What year? 1996 from your signature? I think someone put the wrong plug in there. Is there a sticker on the engine that gives a plug number of any sorts? Else what is the head casting number? I'm not sure when GM changed to the longer plug. I had a 92 that took the short threaded version, my friends 97 takes the longer one. You can probable use a thin wooden dowel or even a screwdriver to "feel" how far the threads extend if you can see it with a flashlight because the manifold is in the way. If they are the wrong ones there is going to be some carbon buildup on the threads in the head. I'd clean that with a tap else the new ones are going to be difficult to tighten properly.

 

[further]

Re: Another spark plug question

the plug on the right is for a vortec head, the plug on the left is for a pre-vortec head

what motor do you have?

Its a 1996. Vortec I presume from the Vortec written on the valve cover. It's a 4.3pnca prod #3868186; ser# 4110129783 if that helps any??

 

[gbeltran]

Re: Another spark plug question

The vortec engines take the longer plug.

 

[Maclin]

Re: Another spark plug question

If the head is supposed to have the longer threaded plug and has been run a long time with an incorrect short threaded plug then there is the possibility of carbon buildup in the threads at the bottom of the spark plug hole and a long thread plug now may start bottoming out too soon, be careful.

 

[Maclin]

Re: Another spark plug question

Just now reread and saw gbeltran's post, did not mean to pile on

 

[further]

Re: Another spark plug question

Thanks for the info on that. What size tap should I use to clean the threads?

 

[Bondo]

Re: Another spark plug question

Its a 1996. Vortec I presume from the Vortec written on the valve cover. It's a 4.3pnca prod #3868186; ser# 4110129783 if that helps any??

Ayuh,.... How many bolts hold the Intake on,..?? 8, or 12,..??

If 8, it's Vortec, 'n needs the long plugs,...

If 12, it's vortec in name only, Not the long plug heads,...

You shouldn't need a tap,...

 

[further]

Re: Another spark plug question

It's 12 Bondo, 6 on each side if I'm counting the right bolts. So wierd. Valve covers both say Vortec and serial numbers match up on all nameplates. Why would there be Vortec valve covers on a non-Vortec motor?? To confuse me I guess. Ughhh.

 

[gbeltran]

Re: Another spark plug question

Take a snapshot of the intake bolts and post it. Actually you might be able to get a shot with your cell phone camera of the plug hole at a slight angle, then you can just count the threads. If I look up plugs for 4.3 PNCA, both the injected and carbed version, on the Volvo Penta site they show a part number for the 24 pack thats the same as the plugs my 2000 5.0 Gi takes, and they are the long version (they dont list an individual number, only 4,6,8 and 24 packs). Do the bolts for the intake go straight up and down or are they at an angle that would match the head if the manfold was off?

(I think 96 was a transition year from the standard head to the vortec style head, I think the valve covers will fit either head, I'm not a GM expert though. If you cant figure it out any other way pull a valve cover and get the casting number from the head)

 

[further]

Re: Another spark plug question

Take a snapshot of the intake bolts and post it. Actually you might be able to get a shot with your cell phone camera of the plug hole at a slight angle, then you can just count the threads. If I look up plugs for 4.3 PNCA, both the injected and carbed version, on the Volvo Penta site they show a part number for the 24 pack thats the same as the plugs my 2000 5.0 Gi takes, and they are the long version (they dont list an individual number, only 4,6,8 and 24 packs). Do the bolts for the intake go straight up and down or are they at an angle that would match the head if the manfold was off?

(I think 96 was a transition year from the standard head to the vortec style head, I think the valve covers will fit either head, I'm not a GM expert though. If you cant figure it out any other way pull a valve cover and get the casting number from the head)

Thanks. Will take some pics in the morning.

 

[further]

Re: Another spark plug question

Well got a shot of the plug hole.



definitely looks like the short threads. I'm counting about 7 which matches the old plugs. So I guess I have a non-Vortec with Vortec covers.

Glad I noticed the difference in plugs and got the feedback from you guys that I did. Would've been bad news if I went and put in the long threaded plugs.
Thanks again as always.

 

[further]

Re: Another spark plug question

So question now. I assume I should venture to source the AC MR43T as mentioned in post #2 but if I can't locate these what would be the equivalent NGK plugs?

 

[MikDee]

Re: Another spark plug question

Yes, That's a short thread plug hole. the AC R45T are a popular marine plug, they should be available just about everywhere, esp. marine centers. It's a great design with a fat center electrode (for strong spark), & it is alloy also, so won't rust out. I didn't realize how good they were till I started using them. I even used them in a slightly worked 355 74' Chevy Nova street engine.

By the way, Vortec, Schmortec,,, lol, Yes, you still have a Vortec V6, Chevy's been using, & improving this engine since it's inception,
even My 95' S-10 pickup has a 4.3 TBI with Vortec embossed on the valve covers.

 

[further]

Re: Another spark plug question

Yes, That's a short thread plug hole. the AC R45T are a popular marine plug, they should be available just about everywhere, esp. marine centers. It's a great design with a fat center electrode (for strong spark), & it is alloy also, so won't rust out. I didn't realize how good they were till I started using them. I even used them in a slightly worked 355 74' Chevy Nova street engine.

By the way, Vortec, Schmortec,,, lol, Yes, you still have a Vortec V6, Chevy's been using, & improving this engine since it's inception,
even My 95' S-10 pickup has a 4.3 TBI with Vortec embossed on the valve covers.

Cool thanks for the info. Btw, just bought a house in Sussex county so we're gonna be practically neighbors lol

 

[gbeltran]

Re: Another spark plug question

I think R45T would be too hot a plug for the marine engine. My opinion of course. On the other hand I think hte R45T has an equivalent heat range of the Champion that was previously installed. How old is that plug, looks like it's running pretty rich. I would look for the MR43T, or R43T. Unless something changed in the last couple of years R45T (or the plain R43T) are not that corrosion resistant alloy. If they did change, great, but the last set of either I bought were just the plain black colored metal.

 

[MikDee]

Re: Another spark plug question

I think R45T would be too hot a plug for the marine engine. My opinion of course. On the other hand I think hte R45T has an equivalent heat range of the Champion that was previously installed. How old is that plug, looks like it's running pretty rich. I would look for the MR43T, or R43T. Unless something changed in the last couple of years R45T (or the plain R43T) are not that corrosion resistant alloy. If they did change, great, but the last set of either I bought were just the plain black colored metal.

The R43T, or (R45T, hotter heat range) are Not marine plugs, and won't hold up!

 

[Bondo]

Re: Another spark plug question

The R43T, or (R45T, hotter heat range) are Not marine plugs, and won't hold up!

Ayuh,.... Other than the alloy of the body, it's the Same plug,....
The R43T might rust, but it's the same plug,...

By the way, Vortec, Schmortec,,, lol, Yes, you still have a Vortec V6, Chevy's been using, & improving this engine since it's inception,
even My 95' S-10 pickup has a 4.3 TBI with Vortec embossed on the valve covers.

Chevy started usin' the name, Vortec a few years before they came out with the Fast Burn heads, which We all now call Vortec heads,...

As I said before, The intake bolt count is the only way to know whether ya got Vortec heads, or the old D chamber heads,...