Spark Plugs for 340HP 327
 

G'day my fellow vette nutters :)

Just a quick note if anyone can tell me a good set of plugs to run in my 1963/340hp 327? A set that you may have used and have proven to be reliable please, not just a quess like someone gave me over here LOL! He was wrong DOH!!:willy: NGK is a brand i can get easily but i may be able to track down the AC delco's if i look hard enough. :) All my books are at a freinds so i can't research it myself at the moment.

AC R45, AC R 45S or equivalent in another brand if you have a stock spec engine.

I've never seen any difference in brands, just heat range. You don't need platinum tips or anything fancy. Just the base plug.

I use the AC R45 and have been happy with them.

:iagree:

NGK-B4
Denso-W14-U

AC-44 was the standard plug and AC-45 was (1) one range hotter.

A Champion equivalent is J12YC or J14YC..the 'C' at the end means copper...It wont perform any worse or better than any other plug. You may need a conversion to cross reference different brands to get the proper heat range to match a AC #45 or R45.heat range.....there are no 44`s and do not use a #43 range plug for crusing, that plug is better suited for racing

:iagree:You best for overall daily driving would be the AC 45. Bill.:cheers:

Awesome response guys, thanks for the imput.. I must get my books back off my mate lol!

I run the NGK B4's in my 63 FI car. Same motor as yours, same compression ratio, cam, etc. I like 'em. :)

I have run Autolites in the past and liked them.

NEVER had a problem with Autolite or now the NGK's.

For 40 years, I've had nothing but bad luck with AC 44's and 45's. I've had 'em bad out of the box. I've had them foul within the first 20 miles of driving.


I've never tried the Nippon Denso's.

Chuck

Autolite 86 is the ACR45S crossover....I ran them for a while but I'm back to the ACs just because I had a spare set when it came time to change plugs. Autolite makes fine spark plugs.

:iagree: Autolites have been the spark plug standard for as long as I can remember.

correct spark plugs for 1963 340 hp
 

few years ago, I ordered a replacement set for 340 hp and corvette america sent me a set of 8- 43R. I never used them and would appreciate if OK to do so. Normal cruisiing. regards,, Abe G

The high compression piston of your 327/340 has a .125 dome. If you have the correct 461 heads, the spark plug location is lower than with later 462 heads, later GM heads, or aftermarket heads. The close proximity of the spark plug with the piston dome requires a standard gap plug and not an extended gap plus such as the "S" suffix AC plug.

I've tried the extended gap plugs in my L76 engine (same piston and 461 heads as the '63 327/340) and it worked poorly compared to the standard gap plugs such as the AC R43 or R44, or the Champion J-6 plugs.

:thumbs:

I also use NGK spark plugs on my Corvette and other car except on my Porsche 911.On The 911 i use Bosch spark plugs.The 911 have a tendensy to eat sparkplugs when not driven hard.Had some people doing some work in my driveway and had to move the car and in the end it was changing sparkplugs again.

I think the NGK plugs are working great but every Porsche shop advice against using other than Bosch spark plugs on Porsches here in Norway. Dont know why.

why porsch plugs only?
 

$$$$$$$$$ Regards, Abe G

Any one that fouls out a AC 45 heat range plug has something wrong...Plugs are the only thing that will give you a insight into the engine..by reading the plugs it will help locating the problem...But its not the plugs if your within the proper heat range regardless of the brand. ....they all start out at the same temperture and that's a fact......:cheers:

What i was told by the mecanichs is that the sparkplugs does not hold when just moving the car for some yards a day wich i did this spring having some here doing some work so i had to move my cars.
Never had any problems with any other car when just ,lets say short driving.

What's the difference?
 

What is the difference between the AC R45, and the AC R45S? I just bought a set of AC R45S plugs from NAPA. Thought I'd check before installing in 63 300hp. Thanks!:willy:

AC 45S has an extended tip. For 327-300 Hp either 45 or 45S will work fine.

I use Denso W14-U..... They are a non resistor plug like the original plugs that came in our cars. Same heat range as the AC 45R......I order them from Rock Auto. If you have any kind of transistor/electronic ignition, you might want to stay with resistor type plugs.:thumbs: