spark plug advice?
 

I have a 632 with dart 360 heads, dominator carb with 88"s in the front and a 6.5 pv and 95's in the rear.... i currently have a set of ngk -8 plugs in it but i am afraid that they are too cold. I used to run autolite ar3932 but they are hard to find around here. it has been so humid the the engine is fouling plugs and i think with a couple of jet changed and a hotter plug i should be fine. anybody have any reccomendations? does anyone elese run power valves or do you guys block them off?

seems you have to much separation primary to secodary if you are running 2 power valves, I would block the secondary power valve, leave the front, run about a 6.5, but ck you vacume in gear, divide in half to get the right one, jet the secodary about 8-10 sizes above the primary, as far as plugs are concerned I like accels have been using them for years, easier to get from a speed shop and seem to last forever, Rob

the rear is blocked off. i have a 6.5 in the front. it just fouls plugs when it gets humid. i may try to go down 2 sizes front and rear.

If you are fouling pluds when get humid, it's overlly rich, try going down 4 sizes ft and rear...should get you close, if you are fouling you are way rich anyway...Rob

I think you are on the right track with the reduction in jets. NGK plugs are good, try the -9's.

Aren't 9's colder in NGK's? I understand if he gets his jetting correct, but wouldn't he just be making it worse going to a colder plug? defeating the jetting. I run NGK UR5's (Vgroove) which is a pretty hot plug.

9 are pretty cold, I ran them a few time with a 475 shot,was a dark grey, the 8 did better

is it fouling just at idle?

Woops...them maybe try the -7's. I have run the -7, -8 and -9 and ended up with the -8's.
If you are running the 3-circuit Dominators you are likely going to fight rich in the mid-range forever. If you are, consider selling this carb an get the 1050 or 1150 2-circuit.
I run PV's (PV's are opening late at 5300 RPM+) front and rear with 87 X 88 jets.
Testing with a A/F ratio gauge, we am real close to our A/F ratio targets. I am still messing with the idle circuits so not quite finished with the final jetting.

What engines do you have? I have 500EFI's and was told to use NGK 5YR or NGK 5UR if long idles/no wake zones. Does this advice sound correct?

I have 590HP carb'd 454's. I have about a 25 min idle from the launch to Lake MI and 45 min idle to the Party Cove. I have run the same plugs for 6 years and have never had a problem. JimV told me to run them and he puts them in a lot of engines.

If you are fouling plugs at idle, go up one heat range to a BR7FS. Jetting has nothing to do with fouling plugs at idle. You can try to lean out your idle mixture.


Those are too cold for a 500efi. They are NGK UR5's and are the same heat range as an AC R41T and have a slightly extended tip. The are the same heat range as the NGK 8's he running.
You should be running NGK BR6FS or an AC R43T. You could run the extended tip version AC R43TS as well.

try ngk tr6gp