Could it be THIS simple?

[PKRWUD]

You've got the right idea.

I'd like to know your vacuum at idle, in Park. It would be really nice to know what your vacuum is when you feel you're losing your top end power, too. I'm guessing it's between 7" & 8".

Either way, an 8.5 PV will suit your set up better than a 6.5 PV will. May not solve all your problems, but it's a step in the right direction.

Throttle response has nothing to do with vacuum or mechanical secondaries, it's in how the accelerator pump is set up, the idle mixture, and the throttle plates. The reason your car should do better with a 3310 is vehicle weight and an auto tranny. That combo is difficult to tune mechanical secondaries for, whereas vacuum secondaries are tuned by engine demand. You just fine tune them with jets and the secondary spring.

Are you experiencing a bog, or it just feels like the carb runs out of juice way too soon? If it's the later, a 3310, properly set up, should solve it. In the mean time, an 8.5 PV will help.

[~The Jester~]

Don't forget that most people think of the power valve "rating" BACKWARDS!!! If you have a 6.5 PV, it's open BELOW 6.5 hg.

Above that, it's as tight as an ugly 4th grader!

And back to the original question: NO, it can't be that simple. It never is!

[PKRWUD]

Originally Posted by ~The Jester~

Don't forget that most people think of the power valve "rating" BACKWARDS!!! If you have a 6.5 PV, it's open BELOW 6.5 hg.

Above that, it's as tight as an ugly 4th grader!

Correct, which also means as you're getting into your top end, and the vacuum is rising again, a 6.5 PV will close up sooner. That's why I feel pretty confident about suggesting an 8.5 PV.

[82 GT]

Originally Posted by PKRWUD

You've got the right idea.

I'd like to know your vacuum at idle, in Park. It would be really nice to know what your vacuum is when you feel you're losing your top end power, too. I'm guessing it's between 7" & 8".

Either way, an 8.5 PV will suit your set up better than a 6.5 PV will. May not solve all your problems, but it's a step in the right direction.

Throttle response has nothing to do with vacuum or mechanical secondaries, it's in how the accelerator pump is set up, the idle mixture, and the throttle plates. The reason your car should do better with a 3310 is vehicle weight and an auto tranny. That combo is difficult to tune mechanical secondaries for, whereas vacuum secondaries are tuned by engine demand. You just fine tune them with jets and the secondary spring.

Are you experiencing a bog, or it just feels like the carb runs out of juice way too soon? If it's the later, a 3310, properly set up, should solve it. In the mean time, an 8.5 PV will help.

There's no bog at all. It takes off like a freakin rocket! I don't really feel anything.My 15yr. old son once said it looks like my car slows down after the 1/8 mile....I don't know...it's possible I guess. The 12.85 at only 102MPH is what has me baffled. It should be around 105-107mph....despite the excellent 60' times I'm pulling. I'll try the 8.5 valve and see what happens.

[82 GT]

I ordered the new 8.5pv today along with a set of 74 jets for the front. If the 74's are too rich, then it's still ok 'cause I can use them next year when I finally hook up my nitrous. I'll need to jet up for that anyway.
PKRWUD, the 15hg I have at idle IS when it's in park.