Header/Spark Plug Interference

Virg464

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Looking for a little advise/assistance. Trying to install the headers (that came with the car) on my 66 coronet (mildly built 400). Started on the P/S and had to machine (grind) down the edges of the header flanges to clear the studs for the head nuts (minor mod), got the header into place and bolted on. My problem is that the #6 cyl spark plug runs almost directly into one of the header tubes. My first thought was get out the torch and the ball-peen, and make some clearance. My question, is there a set of big block headers for the mid 60's B-bodies out there that doesn't have this issue?

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4speed68rt

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I had to put a fresh motor mount in mine to raise up the motor a few fractions of an inch to gain clearance for the bolts. There may be a header that doesn't require a little mod with the 3' pry bar and ball peen, but it wasnt the ones that I got! haha. There is a few threads on here about this. Good luck.
 

moparedtn

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Looking for a little advise/assistance. Trying to install the headers (that came with the car) on my 66 coronet (mildly built 400). Started on the P/S and had to machine (grind) down the edges of the header flanges to clear the studs for the head nuts (minor mod), got the header into place and bolted on. My problem is that the #6 cyl spark plug runs almost directly into one of the header tubes. My first thought was get out the torch and the ball-peen, and make some clearance. My question, is there a set of big block headers for the mid 60's B-bodies out there that doesn't have this issue?

View attachment 1353729

View attachment 1353730

View attachment 1353731
What heads are you using?
What brand of headers are those?
Facts, man. We need facts! :)
 

pnora

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Looks like your plugs go in at an angle. If thats true most headers esp. older ones will not work.
 

diesel_lv

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I had to use the Accel shorty plugs on my 383 w 440 source heads n TTI headers. I also had to use Taylor Ceramic boots to keep from melting the boots. Ceramic coat, header wrap n plug heat shields wouldn't keep the boots from melting.
 

wagonman

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I had to use the Accel shorty plugs on my 383 w 440 source heads n TTI headers. I also had to use Taylor Ceramic boots to keep from melting the boots. Ceramic coat, header wrap n plug heat shields wouldn't keep the boots from melting.
How long ago did you get those plugs? The newer ones are only about a 1/16 shorter and not the yellow ones. Made by NGK or Nippondenso IIRC. Those Ceramic boots are the **** though.
 

493 Mike

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The Dougs on my 66 Belvedere fit great. 2" primary tubes. 493 cu.in. I have angled plug RPM heads too.
Mike
 
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Virg464

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What heads are you using?
What brand of headers are those?
Facts, man. We need facts! :)
Aluminum Performer Heads (Edelbrock), the headers came with the car and I have no info on them, there's no ID tag or stamped info on them unfortunately.
Looks like your plugs go in at an angle. If thats true most headers esp. older ones will not work.
That is correct, the plugs are set at an angle and the headers are at least 20yrs old. So, do you know of any other options for angled spark plugs? I didn't think about that difference between the OEM heads.
I got them 2 yrs ago. These are the ones I got.
View attachment 1353799
What is the P/N 416S?
 

moparedtn

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There are headers made for those heads. Reckon that's where you start - if you want to do things properly.
 

pnora

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Aluminum Performer Heads (Edelbrock), the headers came with the car and I have no info on them, there's no ID tag or stamped info on them unfortunately.

That is correct, the plugs are set at an angle and the headers are at least 20yrs old. So, do you know of any other options for angled spark plugs? I didn't think about that difference between the OEM heads.

What is the P/N 416S?
If all the rest fits I would cut that tube and modify it to clear the plug. A muffler shop could bend you a simple piece and all you have to do is weld it in.
 

Virg464

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If all the rest fits I would cut that tube and modify it to clear the plug. A muffler shop could bend you a simple piece and all you have to do is weld it in.
I was kindda thinking along those lines because everything else seems to fit just fine. Thanks.
 

diesel_lv

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Aluminum Performer Heads (Edelbrock), the headers came with the car and I have no info on them, there's no ID tag or stamped info on them unfortunately.

That is correct, the plugs are set at an angle and the headers are at least 20yrs old. So, do you know of any other options for angled spark plugs? I didn't think about that difference between the OEM heads.

What is the P/N 416S?
Yes. Accel 416S.
 

pnora

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Another thing you could do is remove the heat wrap. Get that tube hot in two places and try to bend it outward 3/4 of an inch. Then as others suggested the shorter plugs and a small dent in the tube. My experience was always bad with close clearance causing burnt boots and spark jumping so the more the better.
 

493 Mike

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Watch the Engine Masters episode where they beat the hell out of a set of headers and don't lose a single horsepower on the dyno, if that's your concern.
Mike
 

#41

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With dinging the header and short plugs your wire is still going to suffer being that close to the header. You can run heat boots, but they only do so much. I too would cut the header, heat it up and bend it rearward, and add in a 1" section or so. I did this with my cheap Hooker Super Comps to fit them to Indy EZ heads.
 

Virg464

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Watch the Engine Masters episode where they beat the hell out of a set of headers and don't lose a single horsepower on the dyno, if that's your concern.
Mike
I will do that, and that is what my concern was?
 

diesel_lv

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I will do that, and that is what my concern was?
Very common to mark area 1/2" on either side of plug interference area, remove header, oxy/acetylene heat it red glowing, use a socket and hammer and dimple it for clearance. I'd still use Taylor ceramic boots on all wires, and the DEI, or whatever brand you like, wire covers. Just good insurance.
 
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