Hi guys, I don't come here much anymore so this topic has probably been beat to death but what spark plugs do you prefer for a Hemi. Mine is an aluminum 528 with Indy Legend heads, pump gas compression, 100% street car with a 1040 cfm APD 4150 carb.
I'd prefer a plug that doesn't come with the washers installed if possible. I tried running w/o the washers lately and the tubes seemed to stay cleaner inside that way.
I've been trying the NGK plugs, R5671A-7 and -9. Still doing some carb tuning but wanted to see if there's something else better for the street.

On my iron headed 528 the R5671A-7 worked well.

Ok thanks, I'm interested to hear more opinions as well.
It seems like the 7's run richer than the 9's in my car but I'm also tuning the carb so I'll keep playing with it.

The only spark plugs I know of that don't came with gaskets are the tapered seat plugs
You don't want to use them in any Hemi motors I know of currently: confused:
As far as heat range I like to run the coldest plug I can that runs clean and doesn't get black at light part throttle driving
On your deal I would try a Champion RN9YC or maybe a Champion race plug. Autolite street plug # 3923 or maybe their 3922. Autolite # 3911 or 3910 on their race plugs.
I'm not current on NGK plug #s

I've always run NGK 4554 plugs (R5671A-8) on pump gas when I run it naturally aspirated. Never bothered to remove the washers.

I run the autolite AR 3911 - been happy with and I have 8 sets in stock in the garage if you want to try them

Some plugs have the washer loose in the box so you have to screw it on yourself, that's what I meant.
Doesn't matter, I'll just use the washers, running without them didn't help anything.

Ok thanks Chip, I'll try those this week.

Thanks Dave, there's only 6 in stock at Summit right now. I'll let you know if I need to buy some from you, I'm gonna try the NGK-4554's first.

[i][/i] I first started with 9's and kept going hotter to until I stopped at 6's and stayed there . The 605 runs it's best on 91 octane and #6 plugs.