holley carb help,transition/stage
I ahve only a few things to add, but they may be helpful.
idle restrictor is in lower location, guess is about .032 something between .030 and .035 didn't have something inbetween on front block.
On the idle restrictor, the difference between .031 and .034 is pretty big.
Transition slots are set equal/small square and rear plates are open some to equal out transitions when setting idle speed with screw under plate for secondarys
That's a starting point. It's perfectly OK to adjust slightly.
I've got a note that the idle restrictor in the rear block is .040 but idk if thats correct seems off?
Often they are larger. It depends on how the carb details. I'm assuming this is not set up with 1:1 linkage.
With the rear plates "open some" are ther secondary transition slots exposed?
most is coming through the front transition slot.
I agree unless the secondary t-slots on this carb go low enough to be exposed. That's why I thought it was worth asking.
Perhaps its also worth asking how many turns out the secondary idle mix screws are?
Also car has 7-8" of vac at idle if that helps.
makes it candidate to using 4 corner idle, which you are.
Car free revs nice and responsive,idle is nice at 900-1000 does not load up and is pretty happy,
But this is in neutral. That's a good start.
The real test is with a load on it.
I do not run any power valves in this carb front or rear.
There might be a benefit to running a front PV.
IF there is a situation where the mains are starting to contribute fuel other than wide open throttle, a PV should keep it leaner, cleaner and stronger.
I'll leave that discussion to Mderoy and others
Thats part of my question, If I was to go smaller on the iab what else does that change, anything with the timing of the mains coming in or something anything else except richen this idle/transition circuit, or would increasing the fuel with idle mix screws also add fuel to this "cruise" 2000rpm zone or would it just be taking away from the transition circuit. obviously turning the mix screws would have only a small margin before the idle would but a no go. Does my iab seem off would making a .002 even make a difference
Going smaller on IAB will enrich the idle and transition. Opening the idle mix screws may rob the transition slightly but its not guarenteed to go that way.
The reason is transitions slot itself is a variable air bleed and restriction to the fuel in the idle well that is partially mixed with tiny air bubbles.
So its a question of whether the fuel-air in the well is restricted by the t-slot opening when the throttle plate is near the top. If so, reducing restriction to the idle port will allow slightly more fuel.
IAB changes are less sensitive than IFR changes, but dropping just the primaries by .002 is reasonable. This is fine adjustment, not a radical retune.
Going smaller on the IAB will extend and enrich the idle circuit.
My experience has been a little different on this point.
I've gone smaller on IAB to successfully enricher a lean transition, but did not observe it to carry it higher in the rpms.
For that (extending into higher rpms) it seems a larger IFR is generally what is needed.
Most of the time when I've gone smaller on IAB I have had to retrim the mix screws, and sometimes slightly adjust the thottle position and the mix screws.
