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What heads do you have?

What plugs were you running?

What plugs do you have now?

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you should have the shorter reach plugs in brandon...990's are open chamber

you should have the shorter reach plugs in brandon...990's are open chamber

he was running very short plugs. i bet they werent even sticking out of the hole at all......the AR3933's are the plugs that all the racers use with the 990 heads, what i use on the southwind (990s) and in the race boat (TFS heads). He had a plug that cracked on the porcelain and i had another set of plugs for him to use. the difference in length of plugs made him nervous....but obviously the smile on his face when he got on it was proof they worked better. I think he said he picked up 3k in rpms too. amazing what the difference in a bad plug can make.

he was running very short plugs. i bet they werent even sticking out of the hole at all......the AR3933's are the plugs that all the racers use with the 990 heads, what i use on the southwind (990s) and in the race boat (TFS heads). He had a plug that cracked on the porcelain and i had another set of plugs for him to use. the difference in length of plugs made him nervous....but obviously the smile on his face when he got on it was proof they worked better. I think he said he picked up 3k in rpms too. amazing what the difference in a bad plug can make.

300 RPM's

he was running very short plugs. i bet they werent even sticking out of the hole at all......the AR3933's are the plugs that all the racers use with the 990 heads, what i use on the southwind (990s)

Brad, didn't Terry and Kyle work on your boat last year when it was running like crap at Parker?
When they pulled the plugs, they found the long ones and some of the ground straps were closed (no gap).
You put in a set of short ones and it ran fine after that.
I just ran a long and a short plug into a 990 head we have in the garage. The short one ends right at the end of the casting and the long one threads into the head at least a 1/4".
AR3933's are what I run with the aluminum heads and the closed chambered heads.
Good luck trying to get those out after the threads get burned and carboned up.

The R43 is the plug I just ran into the head that lined up with the inside.
Didn't know they made an extra long.
AR3339's are the ones that stuck into the 990 head too far by at least a 1/4"

i'll just stick with the short reach...i stuck one of the old plugs out of the old motor back into the cyl. head and i like what i saw...i guess if your reaching for a little more and you want to worry about your pistons hitting you can always index your plugs right

How do I find out what kind of heads are on my BBC. There is a casting # on them. Does that have any meaning? I'm currently running the Delco R44T spark plugs and the motor seems to run fine. Of course, if I can get it to run better with longer plugs then I'd be game for swapping them out   

ar 3933 and 35 are for most aluminum heads. most cast iron heads would use ar 12 or ar22. you will run into some early cast iron heads that will require the  long reach .

thanks terry, I was about to call you for clarification.

so brandon. change your plugs  dont throw those 3933's away either.

 A spark plugs heat range is the rate at which it transfers heat from the plug to the head. There are even little water jackets around the plugs. If you've got that much hanging out of the head it cant tranfer heat as well. PLUS all the shrp edges to heat up and turn into a glow plug basicly.

Nordie
Open chamber = short reach plugs
Closed chamber = long reach

Exactly  and
Open chamber alum = long reach