Spark Plugs

TURNA

Active member
Oct 5, 2018
189
95
28
NY
Anyone have an NGK or equivalent or an XR4 and a XR45.

Would like to see if the are the same plug in appearance/thread size/depth
 

Olds 307 and 403

Active member
Oct 4, 2018
558
196
43
Melville, Saskatchewan
Yes. I do. What plug are you comparing them to?
 

Olds 307 and 403

Active member
Oct 4, 2018
558
196
43
Melville, Saskatchewan
Actually, I have XR45 and XR5. For your 9+ to 1 motor, I would go any hotter than the XR5.
 

TURNA

Active member
Oct 5, 2018
189
95
28
NY
yes I am probably going to run the XR5 but not sure if they will fit the heads.

Did Olds use the same size plug for all there small block heads?
 

Olds 307 and 403

Active member
Oct 4, 2018
558
196
43
Melville, Saskatchewan
Yes, they will fit. Actually they were a AC Delco either 43 or 44, two to three steps colder than the equivalent 46.