spark plug recommendation

[Schtauffer]

Here's the engine: 331 SBC, double-hump heads, .480" lift/230 @ .050 cam, Performer RPM intake, Holley 4777 carb, 10:1 compression. No ignition box, just an MSD E-curve distributor. Probably makes 325 hp or a little better.

I usually run AC R45TS spark plugs. What do you recommend, and why?

[Tom Slick]

Re: spark plug recommendation

post a very good picture of the ones you took out?

[Tom Slick]

Re: spark plug recommendation

part two, head casting numbers...

Tapered plugs?

[SpiderGearsMan]

Re: spark plug recommendation

R45--AC

[TC]

Re: spark plug recommendation

Run whatever lights your fire. :

After learning that they spun motors over 9000rpm with dual point distributors in the early 70's, I don't think spark is all that it's promoted to be.

[Schtauffer]

Re: spark plug recommendation

post a very good picture of the ones you took out?

Can't, sorry.

Straight plugs.

[SpiderGearsMan]

Re: spark plug recommendation

it is all in the fuel curve
warren was right

[milner351]

Re: spark plug recommendation

anything but champion!

is there a reason you want to change the plug spec? is it detonating? do the porcelain insulators look bad?

I like to keep the factory plug spec as much as possible - then just back off a heat range....

I've had lots of problems with champions fouling out - I won't even use them in small engines anymore.

I've had problems with bosch platinums, accells, etc - I think most "high performance gimmick" plugs are just that....

if you're having detonation issues - I'd just back off a heat range - to the R44 ?
(I'm not too too familiar with the AC # system)

[Schtauffer]

Re: spark plug recommendation

I haven't really had any problems per se; I'm simply looking for any small areas that can be improved.

If I go with a colder plug (R44TS), will that help prevent detonation? ??? Or not really make any difference?

[min301]

Re: spark plug recommendation

Depending on the chamber, piston crowns, timing, cam, yes it could help.
More info is always nice...

[ss427]

Re: spark plug recommendation

For a day at the strip, could go one, or two steps colder, if an R43 fouls(gets wet) idling in the pits, or on the
return road, bump up to R43. No reason to not stick with an ac delco. They work, and are affordable.

[ss427]

Re: spark plug recommendation

Whoops, I meant to say "bump up to an R44"