452 head spark plug help

[PRHeads]

I have some 452’s here with the bump, but it’s machined out so a normal J series gasketed plug fits no problem.

It would seem that the heads where the bump hasn’t been partially machined away(and have no gasket sealing area) are the ones that use the tapered seat plugs.

If a J series plug won’t fit, use a TS plug.

452 for TS plug-

 

[khryslerkid]

I have some 452’s here with the bump, but it’s machined out so a normal J series gasketed plug fits no problem.

It would seem that the heads where the bump hasn’t been partially machined away(and have no gasket sealing area) are the ones that use the tapered seat plugs.

If a J series plug won’t fit, use a TS plug.

View attachment 1962971

Would the bump also allow more material for the drilled coolant passages. Machining them for the larger plug might not be a good thing. One might think the drilled coolant passages were created for the fact that motor home engines create more heat being stuffed under that dog box.

 

[PRHeads]

Machining them for the larger plug might not be a good thing.

The factory did the heads I have here.

 

[PRHeads]

Looks like the OP had settled on NGK “5” heat range.

The short reach gasketed plug in that heat range is an XR5.

 

[khryslerkid]

Looks like the OP had settled on NGK “5” heat range.

The short reach gasketed plug in that heat range is an XR5.

It's what I'm using in my 452 heads.

 

[Phoenix440]

My 452 heads use regular plugs. I run Champion RJ14YC with gasket in them.

I bought some RJ14yc plugs. The reach is a bit less than what I had in the 906 heads. Just wondering if that looks right( they are listed at 9.5mmm reach). Did you have the heads off and checked the length by any chance?

 

[Phoenix440]

View attachment 1962825you can get them machined.

Thanks for pics, looks like mine have been machined. I ordered some champion RJ14yc plugs but the reach is shorter than what I expected( would have thought 3/8 as those which were in the old 906 heads but they are shorter. What plugs did you use?

 

[Phoenix440]

View attachment 1962963here's the 452 after machining with the plug installed medium tight.

That's exactly what I was hoping to see, thanks for posting this. I was worried the RJ12YC plugs didn't project enough into the chamber. It seems the old heads had a longer reach ( you can see in the pics) , more like 1/2', which confused me.

 

[twinscrew698]

@Pheonix440
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[Phoenix440]

@Pheonix440
A Brief history

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[/URL]
And a AI listing

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Very interesting, thanks.

 

[Dave6T4]

I bought some RJ14yc plugs. The reach is a bit less than what I had in the 906 heads. Just wondering if that looks right( they are listed at 9.5mmm reach). Did you have the heads off and checked the length by any chance?

View attachment 1963739

If you go to your local parts store, and ask for Champion spark plugs for your old Mopar, they is likely what they specify. Or RJ12YC, which I find is a little cold for the type of driving my old Mopars see (mostly cruise nights and car shows).

 

[Geoff 2]

9.5 mm [ 3/8" ] reach plugs were used in Chrys heads. There were also 1/2" reach plugs [ post #26? ] but not aware of them being used in Chrys engines.

 

[Phoenix440]

9.5 mm [ 3/8" ] reach plugs were used in Chrys heads. There were also 1/2" reach plugs [ post #26? ] but not aware of them being used in Chrys engines.

9.5 mm [ 3/8" ] reach plugs were used in Chrys heads. There were also 1/2" reach plugs [ post #26? ] but not aware of them being used in Chrys engines.

Yes the 1/2' plugs were what was in the 906 heads that came off the engine before pulling it down which made me query the shorter reach plugs.