What Spark Plugs

[73 Duster_forever 73]

I am struggling to find spark plugs for my 73 duster 225. I am wondering what spark plugs to use

 

[RustyRatRod]

NGK 6578 (BPR4ES) is a good one. Just remember, that head should have drool tubes. If it does, you need to remove the metal gaskets from the spark plugs, as the drool tubes act as the seal.

 

[73 Duster_forever 73]

NGK 6578 (BPR4ES) is a good one. Just remember, that head should have drool tubes. If it does, you need to remove the metal gaskets from the spark plugs, as the drool tubes act as the seal.

i have autolite 985 which is recommended by another member. what are drool tubes?

 

[RustyRatRod]

i have autolite 985 which is recommended by another member. what are drool tubes?

They are thin aluminum tubes that the spark plugs install into in the cylinder head. They seal the crankcase from both ends of the spark plug.

 

[73 Duster_forever 73]

They are thin aluminum tubes that the spark plugs install into in the cylinder head. They seal the crankcase from both ends of the spark plug.

I dont have those on mine, just seems to be a tight fit with the larger diameter plug.

 

[RustyRatRod]

I dont have those on mine, just seems to be a tight fit with the larger diameter plug.

The 73 should have them. Do you have a picture? I JUST tore down a 73 head last night with drool tubes.

 

[73 Duster_forever 73]

They are thin aluminum tubes that the spark plugs install into in the cylinder head. They seal the crankcase from both ends of the spark plug.

 

[RustyRatRod]

Ok, cool. It appears not to have drool tubes.

 

[73 Duster_forever 73]

Ok, cool. It appears not to have drool tubes.

I think they are newer heads, but unsure of what plugs to use!

 

[RustyRatRod]

I think they are newer heads, but unsure of what plugs to use!

The NGK 6630 for the newer head.

 

[slantsixdan]

You have a '75-up head that won't take the gasket-seat spark plugs required for '74-down "drool tube" heads. NGK 4s are too hot a plug; you want 5s or 6s to allow maximum spark advance without ping. Specifically, start with these.