Large rpm drop
I had a Hughes HE 2430 AL FTH,(224/
[email protected], 270/276/110+2),
in my LA360, also with KB107s, at zero deck.
but with Edelbrock heads at 10.9 Scr
And the 750DP on an Airgap.
Best dang combo I have ever had.
This combo idled at 650 with 12* initial, and Transfer slots about square, all other air blocked except the PCV.
But I gotta tell ya; my lifter preload was just .020. and my combo had the A833 manual trans, so I did not have the idle-drop into gear. But the combo would pull itself on hard level flat pavement down to 500 rpm with a 3.55x2.66=9.44 starter gear.
Your cam has Looooooooooong acceleration ramps, making it idle like a big cam. Forget trying to tune the idle with an O2 sensor, it will lie,lie,lie and likely finally soot up and quit working altogether. 224/230 is a great sized street cam. But those long ramps make it just a bit tougher to tune the idle.
So like has already been said, get your transfers set right, and the mixture screws about in the center of their working range, the PCV working, and then set the idle speed with Idle-Timing, and maybe a touch of idle-air bypass. Once the transfer slot is ballparked at square,to slightly taller than wide, try not to increase more than ~.020 as per Mattax recommendation.
Just set the idle-speed with timing. I would ballpark 600/650 in gear and up to 100 more in Neutral. I would run the idle-timing between 12 to 16 degrees to get the speed. If it doesn't work down to 12* with the transfer slots as above, and up to 1.25 turns out on the mixture trimmers, THEN, I would suspect a faulty TC but not before.
The transfers are your primary low-speed circuit. The primary job of the mixture screws, is to be idle trimmers. If your transfer exposure is too little, you will find that the trimmers have to be opened to compensate. If the transfer exposure is too much, you will find the trimmers want to be too far closed. Holleys should be 1/2 to 3/4 turn open. Idle timing is your primary idle-speed control; with bypass air your back-up tool.
The more initial timing you run, the smaller will be the transfer slot exposure, and the greater the tendency to stall when you put it into gear. So then the tendency is to increase the idle speed in gear, to increase the idle air, which also increases the transfer exposure, so then you close up the trimmers, until it's happy..... and then you get the high neutral idle. The correct thing to do is to start over with less initial timing NOT more, and to make absolutely sure the timing does not begin to advance until after ~1000 rpm. Sometimes you have no choice but to introduce idle air from an alternate source... but I didn't have to with my 223/
[email protected] Hughes cam.
The more idle-timing you give her the higher will go the rpm. This seems like the thing to do, but it's NOT. Forget thatchit. You can keep going to 30, or maybe even to 40 degrees like that, but it's all wrong, cuz it destroys the transfer slot sync.
Who cares what the timing is below the stall-speed; the engine is never required to do much of anything down there so let the timing be what the engine wants, not what YOU think it should have.
I tell you what; you put a 2-stage timing-curve in there to hit ~25/28* at 2800, and slow it down to hit 34* at 3400 to 3600, and you might be able to burn 87E10 in it. This will give you a 2* window to get the powertiming right.
But if you target 20/25 at 2000, 35* by 3000, you will be buying premium gas for No good reason. Let the engine choose the timing.
I mean if you had a slanty, you might want to run best gas and force the timing on her, cuz you know, they don't have a ton of torque to spare. But a hi-compression 360 already has a preponderance of torque, and there is no good reason IMO, to hunt for it below the stall-speed.
Happy HotRodding
One more thing,for a streeter, install a 10.5 PV in that Holley. Whatever is in there now, if it ain't a 10.5, it's wrong,lol. Mine ran 70/78MJs, to 72/80s at 930 ft elevation, thru TTIs and dual full length 3" pipes. I ran 3.55s