Mopar73340
Well-Known Member
Another good post above. Make sure timing and PCV valve are correct. Sounds like your on the right path.
The clues are there....
IF the transfer slot position is correct, then idle quality should not change whether the rods are up or down. That is because there is insufficient airflow to activate the main system.
I suspect your pri t/blades are open too far at idle { big[ger] cam? }. Depending on a number of factors, low speed cruise can be off the transfer slots, NOT the main jets...which would explain why changing to smaller jets made no difference.
Another indicator that the blades are open too far is if you screw the mixture screws all the way in & the engine keeps running.
The first step in carb tuning is actually....ign. Get the correct amount of timing at idle that the engine WANTS; it will often be more than the factory amount because the factories had to be conservative. Once dialled in, check t/slot position. Also check that PCV is working. If it vibrates, vacuum is too low for it.
In my opinion, you are over carbed. The 650 would be much more suited for your application.
Between the 650 down on power, and the 800 running like poop, leads me to the question, why did you switch from the Holley ?
I believe you mentioned the idle mixture screws are set at 1-1/4 turns out? That iirc is on the leaner side. I’d richen the idle screws a 1/4 and see if that slight stumble goes away. Then try an 1/8 at a time either way to hone in on it. Ignore the gauge for now, adjust for drivability then If you get near the max range on the screws turned out go up one step lean on the needles or down on the jets. Basically try different combinations on screw settings, and adjust the other stuff step at a time if you get too close to max on the idle screws. Been there done that on a Street Demon 750 (same design) and ignored my gauge at first, focused on drivability and got it licked. Might work for you might not but don’t be set on a certain idle screw setting as being ideal. Gotta search for itBTW , Primary T-blade was set correct. Just barely cracked open .
Still have a slight stumble when I slowly excellerate. I will try a stronger spring . I could see my afr spiking off idle.