1972 440 exhaust manifold tabs? Also, what plugs should I run on a 60 over basically stock motor?

[WileERobby]

CHAMPION J-11Y as original OEM...
BOB RENTON

I know that Bob... see post #12... I was doing tune-ups on these cars back in the day, I know the plug specs by heart. I was making a point to the OP.

 

[RemCharger]

Ok but what about the weird Pic of the chevy lookin plug.. is it a motorhome head or is the puc wrong

 

[Nacho-RT74]

I remember have read about RJ11YC being the ones for big blocks on my 71-89 RWD Chrysler Haynes manual. Maybe for non HP engines? Dunno. My manual is 6K miles from me at this momemt to check it out and confirm if my memory is right or not.

 

[Kobrak]

Ok but what about the weird Pic of the chevy lookin plug.. is it a motorhome head or is the puc wrong

I didn't realize it until you mentioned it. The AC Delco plug looks like they were installed due to fouling. Some were the AC Delco 41-985's and the others were Autolite 25's. I guess they were battling oil issues as the mota was wore out.

 

[RemCharger]

What's the cylinder head #? Those are tapered seat plugs, are the heads tapered seat??

 

[Kobrak]

What's the cylinder head #? Those are tapered seat plugs, are the heads tapered seat??

Rem, both heads say 2991. I could read another stamping that looks like 3462346.

 

[RemCharger]

Check the spark plug holes in the head

 

[72RoadrunnerGTX]

Rem, both heads say 2991. I could read another stamping that looks like 3462346.

A cast number of 3462346? Those should not use a tapered seat plug as pictured, should have standard BB gasketed plugs. Both of those pictured tapered seat plugs were in that motor with those heads?

 

[Kobrak]

Check the spark plug holes in the head

Here we go

A cast number of 3462346? Those should not use a tapered seat plug as pictured, should have standard BB gasketed plugs. Both of those pictured tapered seat plugs were in that motor with those heads?

So it looks like they had three different plugs in use. All I can say is it seems that they had no idea what they were doing. I have found numerous things on the car that simply made no sense at all. I really appreciate all the help so far gents!

 

[72RoadrunnerGTX]

Here we go

So it looks like they had three different plugs in use. All I can say is it seems that they had no idea what they were doing. I have found numerous things on the car that simply made no sense at all. I really appreciate all the help so far gents!

View attachment 1738264

View attachment 1738265

If not clear, that is not a tapered seat, use the correct stock style/type plugs.

 

[Kobrak]

If not clear, that is not a tapered seat, use the correct stock style/type plugs.

Got it. I went a head and ordered the NGK XR5's.