Hi Guys, I have a 870 street avenger that I just replaced the front power valve in.
These carbs come w/ a 4.5 and I installed a 6.5 now I have a 1/2 sec bog when I mash it to the floor, could it be w/ the 6.5 power valve I might have to change my secondary spring to one that is stiffer?
TIA
Jerry

How did it run with the 4.5 power valve? Why did you change it?

It was leaning out w/ the 4.5
already check for vacuum leaks, fuel pressure, float levels etc and guessed it was the power valve was too low

Leaning out with 4.5" of vacuum at WOT? If you have 4.5" of vacuum at WOT you've got way too small of a carb. What's the air/fuel ratio and when does it start to lean out?

it was leaning out under cruise conditions plugs were bone white which scared me to death. My motor
is a .30 over 454 w/ an old magnum 292 cam and 215 heads if anything my carb is a hair big.
maybe a blocked passage? This is driving me nuts

Sounds like you need to increase your jet size, as that's what determines your fuel use at cruise.

The power valve opens up to allow more gas in when the vacuum reaches below the stated value of the valve. If you cruise at 8.5" of vacuum, you would use a 6.5 power valve - when you step on it (hence the name "power valve") the valve opens to let more gas in, but only when you're getting on it - not intended to be open while cruising.

What size jets are you running?

right now I have 78's up front and 82's in the rear. I put on an 850dp that I have yesterday afternoon w/ the same jets and 6.5 power valve and the car ran great, I was hoping to use vaccum secondary instead. The DP is a little over kill for the street.