Re: Hesitation when you go WOT, anyone not have it?
My 750 DP was the same way until I took off the air horn, made it a 4 corner idle and got rid of the power valve, after that it worked perfect until I stripped out the squirter screw hole, now it's a shelf item. What intakes are you guys running when your having hesitation troubles?
My carb. is also a 750 HP body with the HLY-112-116 aluminum throttle/base plate. I like this base plate because of all the options for a street motor.
I am using a air gap manifold with a 1/2 inch nitrous plate and 1/2 inch phenolic spacer. The problem really surfaces when you try to tune the double pumper for a decent AFR. At 22 degrees advance and no vacuum advance, If I set my double pumper at 11 or 12 to 1 at idle, it only jumps up 1 point AFR during the transition, so, no stumble...., but, if you set a decent AFR at idle, say 14.1 to 1, then, the transition leans out to 15 to 1 plus and you get a lean stumble. If instead, I am able to close the throttle plates a lot more by using more initial timing from the vacuum advance, I don't get a rise in AFR during the transition from idle, instead it gets richer from 14.1 to 1 to 12.5 to 1 -- exactly what I want. That initial opening of the almost closed throttle blades really gets the transition circuit flowing.
BTW, I have a TKO 600 in mine, so, I am mostly in the transition circuit in overdrive on the fwy, so, I need my transition circuit running a great AFR. I also went down on my primary jets, and up on my Power Valve restrictors and I am running a 8.5 power valve with 9 in. hg. of vacuum at idle, and 15 in. hg. best at higher rpm. This lets be lean at cruise, but, instantly richer, when I goose the gas at mid-throttle. I tried a 6.5 power valve, but, my engine got too lean before the power valve kicked in. Try it, it is much better for fuel economy. You need a wideband in your car to play around with this stuff, but, you can get a double pumper to be much more efficient with it.
1970 Chevelle SS396 (408), Fathom Blue,
Original Block & Forged Crank, KB Pistons, Edelbrock 6045 Heads,Comp Cam 292H, March Serpentine, RPM AirGap,750HP,100hp Nitrous
A/F Wideband,Tremec TKO 600, 12 bolt,
30 spline Moser Axles, Richmond 3:73's, Hotchkis control arms, swaybars, springs, Wilwood 12" rotors D/S, 4 piston calipers
Last edited by hjdca; Jun 7th, 19 at 1:18 AM.