need help with correct plugs and wires for my 68 427

[Wayne M.]

Re: need help with correct plugs and wires for my 68 427

So, would these be probably the closest to what it came with that you can buy today? If so I'll order these, thoughts?

I dunno, Brandon. Those don't look like big block plugs (the part that is partially threaded (the snout ?) doesn't look deep enough.

I see GMpartsdirect.com still has the R43XL (no S) # 5613312 at $1.54 ea. [but there's an weasely asterisk saying the part may be replaced by another part #] I have a box of these that I bought in 1994 (made in Mexico, but in AC Delco box).

According to GM tune-up charts, your L36 should be using AC43N's, and the AC R43N's (with resistor) didn't start until 1969MY. Likewise, for those with L89 heads, AC43XL (no S) in 1968, and AC R43XL in '69 and '70. All those fully threaded XL big block plugs will fit in your iron heads 427.

To Jack H. -- thanks for the dated flap tip; couldn't find any code decipherable on the early 43N's, but the 44N box was dated 1973, and my R43XLS was dated 1995 (same year I bought them at an aftermarket parts store).

[Dennis S.]

Re: need help with correct plugs and wires for my 68 427

I have a 69 L36 and it calls for R43N. Went to the local mom & pop auto store nearby a few years ago and asked if they had 'em. Guy came back with a set and charged me $1.58 each.

Looking at the box flap, these "Acniters" (resistor plugs) are dated 1973. I have seen sets on ebay where the box looks different, possibly an older design of box. The guy on ebay was asking over $120 for the set. These plugs that I bought have 4 thin green rings and say "34 AC FLINT MICH MADE IN U S A" and the threads go a little more than halfway up the barrel.

Needless to say, I have been running R43XLS on the street and they work fine. After rebuilding the engine, we are going to try R44XLS.

[Dennis S.]

Re: need help with correct plugs and wires for my 68 427

Oh, and I also bought a set of 1Q 69 dated repro wires from Lectric Limited that cost me $125. The plug boots are grey. They have been working fine for the last 4 years.

[Brandon T.]

Re: need help with correct plugs and wires for my 68 427

Brandon-----


The original plugs were AC 43N. This plug is no longer available from AC-Delco. You can use an AC R-43XL. This is an extended reach plug but it should work OK for you.

You could also use a Champion N5C. This is the Champion equivalent of the original AC 43N.

As far as the wires go, I think that most, if not all, of those in the reproduction market are from the same source and I think that's Lectric Limited. I've heard of problems with these wires.

I bought some AC R-43XL'S today did you just leave the S off or is this a different plug?

I already installed them and all they seem to work fine.

[Joe L.]

Re: need help with correct plugs and wires for my 68 427

I bought some AC R-43XL'S today did you just leave the S off or is this a different plug?

I already installed them and all they seem to work fine.

Brandon-----


The R43XL and R43XLS are different plugs. The "S" suffix indicates an extended tip. However, either should work ok for you. The extended tip should not cause any problems in your application and may burn off combustion deposits better.

[Brandon T.]

Re: need help with correct plugs and wires for my 68 427

Brandon-----


The R43XL and R43XLS are different plugs. The "S" suffix indicates an extended tip. However, either should work ok for you. The extended tip should not cause any problems in your application and may burn off combustion deposits better.

ok thats just what the guy at advance looked up for it.

thanks

[Wayne M.]

Re: need help with correct plugs and wires for my 68 427

Here's comparison pics of the 43XL (on left) vs, the 43XLS. You can see the extended tip on the XLS.

[Brandon T.]

Re: need help with correct plugs and wires for my 68 427

thanks wayne, just as long as either is correct i'm fine with them. but it the xl would have been a better choice I'll just yank them out and go with the xl's not like it's a lot to change them out.

[Brandon T.]

Re: need help with correct plugs and wires for my 68 427

looked at the old plugs I took off of it..they're champion RN12YC.

not sure if thats a correct plug for the car or not but whats on it now is all that matters

[Brandon T.]

Re: need help with correct plugs and wires for my 68 427

Here's comparison pics of the 43XL (on left) vs, the 43XLS. You can see the extended tip on the XLS.

Ah just now saw this picture wayne.

I was thinking the regular 43XL was an extended tip/length plug but apprently I was wrong? so the XLS is but the XL isn't.

[Joe L.]

Re: need help with correct plugs and wires for my 68 427

Ah just now saw this picture wayne.

I was thinking the regular 43XL was an extended tip/length plug but apprently I was wrong? so the XLS is but the XL isn't.

Brandon-----

The plain "XL" plug is EXTENDED REACH (like the old "N" suffix plugs), but NOT extended tip.

[Brandon T.]

Re: need help with correct plugs and wires for my 68 427

Brandon-----

The plain "XL" plug is EXTENDED REACH (like the old "N" suffix plugs), but NOT extended tip.

gotcha, sorry to ask yet another question but what benefit does the extended TIP give you with the XLS series.

little hotter performance?

[Jack H.]

Re: need help with correct plugs and wires for my 68 427

Puts the tip further out into the combusion chamber...

If you have access to a July 2001 issue of Vette Vues magazine, there are two back to back articles on AC spark plugs. One tells you what the model number means and what the alpha prefix and suffix codes mean. The second tells you how to 'autopsy' a used spark plug and interpret what the telltale(s) of its burn discoloration mean regarding the performance of the ignition system and air/fuel mixture the spark plug was working with.

Both are well worth the reading! I'd post the short, 1-page, article on how to interpret the alphameric model designation, BUT that would be a violation of copyright...

[Brandon T.]

Re: need help with correct plugs and wires for my 68 427

Puts the tip further out into the combusion chamber...

If you have access to a July 2001 issue of Vette Vues magazine, there are two back to back articles on AC spark plugs. One tells you what the model number means and what the alpha prefix and suffix codes mean. The second tells you how to 'autopsy' a used spark plug and interpret what the telltale(s) of its burn discoloration mean regarding the performance of the ignition system and air/fuel mixture the spark plug was working with.

Both are well worth the reading! I'd post the short, 1-page, article on how to interpret the alphameric model designation, BUT that would be a violation of copyright...

I understand that but just curious if you they'er taking the XL extended reach plug and putting yet an extended tip on it and calling it the XLS..what advantage will that have over just the extended reach XL plug.

it goes futher in the cylinder but does that give more performance? Looks to me like it would shove the piston into the cylinder a litte better..not sure