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Finishing up some of the last things to do on the engine and these bored holes suddenly caught my eye and have me scratching my head: ![[Linked Image]](http://www.angelfire.com/on/alvey/block-hole1a.jpg) Those threaded holes are on both sides of the new engine, but are NOT on my original 68 400 engine. Somebody please tell me they are for the infamous 9th and 10th afterburner spark plugs. (After all, this is the infanous M3 428 HO we are dealing with here. Okay, not really. Couldn't help myself.)
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Was a temperature sending unit. They can be plugged up with inverted allen or hex plugs.
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto
1968 Alpine Blue 400 4 speed
1968 Verdoro Green 400 HO 4 speed
2013 1LE 2SS/RS Inferno Orange Camaro.
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That would have been one major coolant leak.
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I am not a happy man at the moment.
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They are like $1-2 plugs...
Need me to ship you a set?
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto
1968 Alpine Blue 400 4 speed
1968 Verdoro Green 400 HO 4 speed
2013 1LE 2SS/RS Inferno Orange Camaro.
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Don't fall for it Tom. He's trying to coax you into sending him some free parts. He did it to me...twice!
I have a set of those plugs, but he 'aint gettn' em!!!
M3 HO my A$$!!!
I'm a hobbyist. Not a professional. Don't be hatin'!
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My engine guy put a couple of petcocks in there. He said all the racers do that so they can drain the block when replacing coolant.
Jerry
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Hardware store. Simple pipe plug, $.27. A little pipe dope on the threads will do it.
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Greg, keep this up and I'll ensure the Easter Bunny does NOT pay you a visit next month.
You've blown my cover (poor lost guy needing free parts!!!)
Thanks for the offer Tom, but I'll hit the hardware stores today and find the plugs.
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You make me wish I could come down there & help you, Nash. I could stop by Dyersburg & see some of my family then. If only I could get this teleporter I got from ebay to work....
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The Transporter probably doesn't work James if he had to MAIL it to you!! 
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Thats where the coolant temp sensor goes on late 70's heads.
Hole looks bigger then on my 6x-4's.
I can check size tonight if you what.
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Had a nice long talk with Banshee Friday night and he squared me away on the right plugs for these "holes". $2.99 each at Lowes.
Tom, Thanks for calling me. Great conversation as usual.
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The Transporter probably doesn't work James if he had to MAIL it to you!! DOH! I should have known when the Captain Kirk was really a cardboard cut-out.
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Now it seems the brand new accel spark plugs that fit into my '68 400 block won't thread into the '74 block? Wazzup wid dat?
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Spark plugs thread into the heads...and later heads use taper seat plugs. Match 'em up.
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Instead of using spark plugs that fit the 13/16" spark plug socket, you will now use the one that fit the 5/8" spark plug socket. The AC R45S seems to be a good guess.
There are other types of R45's that had huge differnce in electrode lenght, causing question as to whether or not the longer electode plugs would be long enough to cause interface problem with the piston. On the other side of the coin, are the short ones too short and the longer ones would give a better spark?
I asked about the differenc in electrode, but no one knows the answer. Without having a head off to see where the plug sits, I went with the R45S to be on the safe side.
Here's something to consider on intake selection. The aftemarket one is lighter; I think by about 35 lbs. The fg f-body is a lousy design, and any weight reduction in the front is a vast improvment to offset this defective design.
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The newer plugs are not R45S, they are R45'T'S. You have it backwards. The original, larger plugs are the S's(R43S). And if you buy the R45TS'X' they will have the correct gap for HEI.
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Nash,
Glad to see your engine build is coming to a close!
Building a 455? Sorry, been out of pocket for quite a while and out of the loop! They expect me to work to earn my salary every now and then....geesh!
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Drew, you've been gone a while here eh....?
Actually, what we are building here is a replica of the infamous M4 496 HO.........
Only two known to exist. I....am building #3.
Didn't I send you a brand new HEI to experiment with four months ago, at no cost to you? Give us all an update on that please.
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Yeah, there is a difference in the gaps between the ts and tsx. One thing to keep in mind is that there is no such thing as a pre gapped plug. They had “pregapped” plugs when I started driving in 74, but any basic automotive 101 type schooling will point out the fact that there is no such thing as a pregapped plug. If one prefers to listen to what GM claims about its product, GM tells you to “gap to specifications” right on the side of the tsx box, along with any other plug they sell.
If one insists to refer to plugs as pregapped, the ts is pregapped: 7 of them are @ .045 and 1 is @ .043. And the 1 tsx plug I measured is @ .059. Does that mean that the other 7 that I didn’t measure are pregapped @ .060?
In addition to the tsx‘s approximate .060--a gap that has long been considered an incorrect gap for performance--it’s a totally different plug than the ts. The tsx’s overall length is shorter; also, the porcelain surrounding the center electrode is shorter, and the overall electrode protrusion on the tsx is shorter. In other words, the ts sits deeper in the chamber. My guess is that the tsx is a hotter plug. Whether that good or bad is something that’s out of my realm. If you look at the timeline for the ts-tsx applications, however, it seems that the tsx was introduced as one-step-further into emission control.
After researching the difference in the plugs, and applying mechanical aptitude and internal logic to the matter, my hunch was that the ts is the better selection. The hot-cold factor notwithstanding, the electrode is less shrouded than the tsx, and it would seem that the unshrouded electrode would offer a more intense spark in the firing chamber.
I hate to go on hunches or, worse, blind guesses drawn from whatever ill-documented google source, so I always fish for documented, expert sources. Here’s a comment about plug selection from one of the few folks of whom I consider an expert when it comes to Pontiac performance. Seeing that the tsx was dominant on the market when the article was written, you would think that this expert would recommend the tsx over the ts.
Myself, I’ll stay with the ts because it’s a recommendation from one of the kings of Pontiac performance‘s--not my--recommendation.
http://home.comcast.net/%7e69bird3/jhand15.htm
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Ditto here Amervo, every plug set I've ever bought new had to be gapped the old fashioned way, regardless of what the bold print on the box suggested. Cannot rely on mass produced plug gaps. Gap each one yourself, then you know at least THAT part of the project was done right.
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Thanks for the good info.
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Hot plugs have a deeper well around the insulator surrounding the center electrode. Cooler plugs - the well is shallower. The insulator in that area retains heat, so the deeper one retains more heat than the shallower one. If you don't have complete combustion, you probably want the hot one. If you want to minimize hot spots for preignition, you probably want the cold one.
John 
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Yeah, there is a difference in the gaps between the ts and tsx. One thing to keep in mind is that there is no such thing as a pre gapped plug. They had “pregapped” plugs when I started driving in 74, but any basic automotive 101 type schooling will point out the fact that there is no such thing as a pregapped plug. If one prefers to listen to what GM claims about its product, GM tells you to “gap to specifications” right on the side of the tsx box, along with any other plug they sell.
If one insists to refer to plugs as pregapped, the ts is pregapped: 7 of them are @ .045 and 1 is @ .043. And the 1 tsx plug I measured is @ .059. Does that mean that the other 7 that I didn’t measure are pregapped @ .060?
In addition to the tsx‘s approximate .060--a gap that has long been considered an incorrect gap for performance--it’s a totally different plug than the ts. The tsx’s overall length is shorter; also, the porcelain surrounding the center electrode is shorter, and the overall electrode protrusion on the tsx is shorter. In other words, the ts sits deeper in the chamber. My guess is that the tsx is a hotter plug. Whether that good or bad is something that’s out of my realm. If you look at the timeline for the ts-tsx applications, however, it seems that the tsx was introduced as one-step-further into emission control.
After researching the difference in the plugs, and applying mechanical aptitude and internal logic to the matter, my hunch was that the ts is the better selection. The hot-cold factor notwithstanding, the electrode is less shrouded than the tsx, and it would seem that the unshrouded electrode would offer a more intense spark in the firing chamber.
I hate to go on hunches or, worse, blind guesses drawn from whatever ill-documented google source, so I always fish for documented, expert sources. Here’s a comment about plug selection from one of the few folks of whom I consider an expert when it comes to Pontiac performance. Seeing that the tsx was dominant on the market when the article was written, you would think that this expert would recommend the tsx over the ts.
Myself, I’ll stay with the ts because it’s a recommendation from one of the kings of Pontiac performance‘s--not my--recommendation.
http://home.comcast.net/%7e69bird3/jhand15.htm And then you say: my hunch was that the ts is the better selectionI think you are hunching there Merv! Unhunch yourself! To hunch or not to hunch, make up your mind. Why go with your quesses and hunches when you can go with facts. I think I'll use your description to show a fact. MERV QUOTE: The tsx’s overall length is shorter; also, the porcelain surrounding the center electrode is shorter, and the overall electrode protrusion on the tsx is shorter. In other words, the ts sits deeper in the chamber. My guess is that the tsx is a hotter plug. Whether that good or bad is something that’s out of my realm.It is designed specifically for HEI that's why it looks different. To help show another common misconception, I'll use another MERV QUOTE: If one insists to refer to plugs as pregapped, the ts is pregapped: 7 of them are @ .045 and 1 is @ .043. And the 1 tsx plug I measured is @ .059. Does that mean that the other 7 that I didn’t measure are pregapped @ .060? When I say the plugs are pre-gapped at .045 it doesn't mean that they are ready to slap in and all the gaps are perfect. It means that the electrode is made to be gapped at .045. Get it? It's not made to be gapped a .030(or narrower) like the original plugs. So when you gap the TSX the top of the electrode is straight not bent up on an angle to get a gap it wasn't designed for. ALWAYS CHECK YOUR PLUG GAPS. Pregapped doesn't literally mean perfectly gapped and user ready. No plugs are. I like to keep things simple so here's the low down again. TSX have the design made for HEI ignition. AC redesigned their TS specifically for HEI. The redesign was called TSX. Go figure! AC engineers came up with this design in 1980 through research of what type of improvements they could make with their plugs to work with the 'new' high energy style ignitions. They were a few years late. Better late than never. Lucky for us, if correctly informed, we have the better plugs to choose from. If you want the cooler one you get R44TSX. The R45TSX is the most highly recommended and widely applied plug in AC history. Come on out into the post 1980 world and use the technology!
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And I wanted to add that if you still have your original style heads that the R45SX is designed to work with them if you have HEI. The R45TSX is for those that have switched to the newer heads like 6X ect.
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Nash, you certainly did. It has worked great sitting in the box on the shelf until this past Saturday!  I told ya it'd be a while. I believe I also offered to go ahead and pay you for it when you sent it. LOL The HEI itself looks to be a good unit. I changed the springs in it last night and will reset the timing and do more testing tonight. M4 496? Hmmmmm, never heard of it.
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Glad to here it works for you Drew! The deal was always "try it first then pay if you like it."
The M4 thing was just a joke from some other threads you've missed over the past few months.
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Heat range is defined by the number (44, 45, etc.) Even though the porcelain is different, if they have the same number, they have the same heat range.
For emissions, they tried to do .060" gap with HEI for better combustion. But with low compression, once the plug starting getting some carbon buildup on it, sometimes there just wasn't enough energy to jump the gap. This caused misfire, so for this reason many gap to .045" regardless of which type they use.
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I myself do not want to hear any more about these spark plugs. I've got your inputs and I've bought the best ones for my HEI setup, for this particular car.
Now, let us all start fighting about another topic please. Something simple like who is the prettiest Pontiac girl we all know.
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Nash, although your voting panel from the price guessing thread a while back were, well, let's just say "wow", I know who has my vote. It's not one of them. Not only pretty, but smart too!
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Yep, Vikki wins again!
I'll bet she'd love a little competition, but there is none in her league. She is very special, and WE are very lucky to have her here with us.
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Nash, were you involved in a government experiment that made you a mindreader, or was it that obvious? LOL
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