proform secondary guidance
The first thing to fix is that 3.5 power valve. That's where you start.
I realize it's on the primary side but it's opening WAY TOO LATE.
Check your vacuum at CRUISE and set the power valve opening under that. Then tune from there.
Also, don't live and die by that O2 sensor. You can get a lean spot and not hurt anything. I trust plug readings over the O2 for most things, until you are down to the gnats *** for tuning.
Fix that power valve opening.
I agree 100%;plus
I would start with;
-a minimum cooling system temp of 185. I prefer closer to 200
-a 10.5PV,
-and 72/80s
-And with timing at 28* at 2800, going to 34*by no sooner than 3400
-And make sure the primary throttle valves are up the transfers to a little taller than wide. Then set the idle speed with timing and idle-air bypass. If that means the idle timing is down to 12*, so what. With a 2800TC in there, as soon as you whack it, your up to 28* at 2800, and the tires light up.
-Then put the biggest Vcan on there you can find, or mod yours to get at least 20/22*.
-Now; with 4.10s you can cruise at 30mph@2200 in second gear, with about 40/42* cruise-timing, right where she wants to be. Your vacuum will be way up and with the 10.5PV you won't have to floor it to KD, to accelerate briskly; just lay a lil throttle on it and torque away.
You may have to upjet the secondaries on long WOT hauls.But around town you will rarely be at WOT for more than 3 to 5 seconds, so a lil lean is mean.
If you change the thermostat, you may have to rejet just a lil.
Finally, sneak up on the power-timing.
EDIT; FWIW: on a streeter;
With the 10.5PV I
might even try #70s.
I recommend to not tune the primary WOT with the secondaries disabled. You will end up with a PMJ a good size too big, and the secondaries might end up a size too small. The AFR will read right with all 4 bbls open, but the primaries will be fat. I would maintain a front to rear spread in the range of 8 to 10 numbers, for best driveability. I like and agree with what YR says about the PVCR , but it's a one way trip; once it's drilled there's no going back.
You will know when it's right, cuz when you roll into it, she will be eager to go, no matter if the AFR is a tad lean, and when you mash it, with street tires, they will give up instantly. Well they would if you had 160psi cranking pressure.
But if the Scr is still 9.5, the Rs will have to get up a lil higher to pull it off in second gear. Cuz thr pressure might be down around 145 with a 70* Ica.
First gear don't count with 4.10s and a 2800,...... cuz even a 4bbl otherwise-stock smogger-teen can spin that A-body combo,lol.
I ran the 292/292/108 cam for a few months in my 4-speed streeter, but it came out at summer's end. Great power at 5000 plus rpm, put no so good at the rpms where I spent most of my time... With 3.55s, the power didn't come on until 40 mph....in first gear and she was done at 60. Since I was keen on keeping the 3.55s (lots of hiway driving) I got rid of that bruiser. Great cam; lots of power, (dump the clutch and spun to redline around 60 mph), but wrong application for me.
