Spark Plugs for 67 with Original SB?

[Ron N.]

I believe the original plugs used were AC Delco R45 or R43. Can anyone verify. Also what would you recomend for daily driving (5,000 mi/yr).

Ron

[John F.]

Re: Spark Plugs for 67 with Original SB?

Iuse R45-S in my 62 with 250/327.

John

[Chris E.]

Re: Spark Plugs for 67 with Original SB?

Ron, I'm pretty sure I put in R45 in my 67 327/350.

[Larry M.]

Re: Spark Plugs for 67 with Original SB?

Orignial install were AC 44 spark plugs for 1967 small blocks. Most owners found them to cold for the street and installed AC 45.

AC 45 are no longer in production. You can buy on E-bay, or can buy AC R45 or AC R45S from local auto parts stores. They should work fine.

The R45S is an extended tip plug. Many folks like them and others do not. Some have a concern about plug electrode to piston clearance in the 327/350 HP engines.....although not certain there are any solid, documented cases of this problem in this engine.

Larry

[Chris E.]

Re: Spark Plugs for 67 with Original SB?

Disregard my previous post then. I'm away from home and running off of memory.

[Bill I.]

Re: Spark Plugs for 67 with Original SB?

Use the 45 series heat range, best overall. Bill.

[Louis T.]

Re: Spark Plugs for 67 with Original SB?

Hi Ron,

Like Larry mentioned, your car likely came with non-resistor AC 44 plugs, which many found were a bit too cold (i.e., they had a propensity to foul) for average use and switched to AC 45. Current non-resistor equivalents to the discontinued non-resistor AC 45 are the Denso W14-U and NGK B4. These should work well with all small blocks with gasket seat plugs in anything but sustained high speed/racing use where you’d want a colder AC 43 equivalent plug.

Louis

[Ron N.]

Re: Spark Plugs for 67 with Original SB?

I should have checked my owners manual before I posted. It show the spark plug spec - AC R44. The local AC Delco store no longer has R44 or R45 on their pars list. I went with a set of R45S. Eventually I may try to get a set of R44 from ebay or some other source.

Thanks to all for the information.

Ron

[Larry M.]

Re: Spark Plugs for 67 with Original SB?

I should have checked my owners manual before I posted. It show the spark plug spec - AC R44. The local AC Delco store no longer has R44 or R45 on their pars list. I went with a set of R45S. Eventually I may try to get a set of R44 from ebay or some other source.

Thanks to all for the information.

Ron

Ron:

If you have a 1967 small block car, the spark plugs are AC 44 not AC R44. The R plugs did not come along until around 1969.

However, R plugs will still work fine in the 1967 engine.

If you want plugs that will work on the street, get AC 45, AC R45, or AC R45S. If you want totally correct plugs for the 1967 small block engine, get AC 44 with four equal small rings on the insulator.

Larry

[William C.]

Re: Spark Plugs for 67 with Original SB?

I can document the extended tip plugs are NOT the ticket for the pop-up piston engines having caused a set to be forcibly closed by piston contact many years ago. Depends on how close to design tolerances the engine is, the better the engine, the more likely to have a problem using the extended tip plugs at 7000 rpm!

[John D.]

Re: Spark Plugs for 67 with Original SB?

FWIW I have had R45S plugs in my 67 350 HP for many years with no problems.

Has anyone tried the AC rapidfire plug #7 in a SHP small block ?

[William C.]

Re: Spark Plugs for 67 with Original SB?

I'd guess you don't shift the 350hp engine at 7200 like I did my old 365 hp version when I closed the gaps.

[Clem Z.]

Re: Spark Plugs for 67 with Original SB?

I can document the extended tip plugs are NOT the ticket for the pop-up piston engines having caused a set to be forcibly closed by piston contact many years ago. Depends on how close to design tolerances the engine is, the better the engine, the more likely to have a problem using the extended tip plugs at 7000 rpm!

just index the ground electrode to between the 8:00 o'clock and the 4:00 o'clock position and the piston will never hit. i have fixed a few back in the day when the ground electrode was closed by the piston and the corvette developed a "miss" as long as the ground electrode is not at the 6:00 o'clock position no problems

[Stuart F.]

Re: Spark Plugs for 67 with Original SB?

What are you saying Bill? You stretched the rods?

Does any one know off hand if they still make Champion equivalents? That's all I've used for years for driving. Since I went to electronic ignition, I don't change them very often and don't care for the AC's propensity to rust into the heads. I have a great supply of several Champ heat ranges which should hold me for another 10 years or so.

Stu Fox

[Clem Z.]

Re: Spark Plugs for 67 with Original SB?

buy marine spark plugs as all brands have a rust proof plating on the shells