Well after 2 years of tinkering and trying to get this carb right ( cause it had issues from day one ) I'm considering going to a different Holley. I have a moderate size cam ( TA288-92H ) and with the idle screws backed out all the way it wants to idle in park at 1200 rpm. Drivability is fine but idle is too much. I'm pretty puzzled at this point. Considering selling it. Maybe it would do better on another motor. It's a Prosystems 1000 HP. Maybe I should go back to a 950 HP again. Car is a street car and runs mid 11s.
1200 isn't high,....what's the concern? Does it do everything else as it should? Agree with Mark,..back the initial off and put more centrifugal advance if you want No vac leaks? Where are the idle speed screws? Both primary and secondary? Your idle should primarily come from the idle mixture and not the idle speed screws An 1/8 of a turn on the rear door screw will equal a good bit of rpm.
Timing is locked out at 34 degs. Idle mix screws are about 1 full turn out. Front & back idle screws are both equal but completely out. Butterflys are completely closed. Can't back them out anymore. It has to be getting air from somewhere else. It pulls hard and drives fine otherwise. I'll start looking for vacuum leaks.
What happens when you turn the idle mix screws all the way in? Does it kill the engine? Does it have any effect?
I have locked out timing of 34*. I have no problem with high idle. My Q-jet and AED100HO both idle at 850-900 RPM in Park, 750 in gear..
Yea if them doors are completely closed its pulling air from somewheres,..get after it with the starting fluid
Keep that carb for now. As Hugger and Larry mentioned, its getting its air from somewhere. Did you have the block deck cut? Reason I ask is that sets the stage for a misaligned, ill fitting, poor sealing intake to head seal unless the intake side of the head was cut ACCURATELY to restore the alignment and seal. I don't know if its advisable as I've never done this, but pull the PCV valve, plug the hose, then spray starting fluid in the PCV hole and see if the engine reacts, if it does, then its sucking air from inside the block from a poor intake to head seal on the bottom edge of the head and intake.
To check for an internal vacuum leak on the intake, inject propane into the PCV hole.. one of those small torches works nice for this, with a hose on it. Back to the leak.. is this a new Utra-HP Holley, with the internal air bypass system? JW
Found the problem. Intake gaskets at 4 & 6, & 3 & 5 both moved down towards the valley. Is this common with the composite intake gaskets ? Block was milled so it's possible I mistakenly got the wrong thickness gaskets.
No way is that common. That is a problem. Unless you somehow misaligned the gaskets upon intake installation, that should not happen. There should be enough crush so that they don't budge. What thickness gasket are you using? Mine are .032, but they come as thin as .015, and as thick as .125. Any misalignment that bad would be apparent in the bolt hole alignment between the intake bolt holes and the threaded holes in the heads. Block/head milling causes the intake to sit higher.
My block has been milled. Have about .008 deck height. I'm thinking I mistakenly bought some intake gaskets that were not thick enough.
Hopefully, the angles aren't off. I'd make sure the intake is fitting. I've never seen that happen. The intake bolts go through the gasket. For the gasket to move, it would need to tear. Be interesting to see what it looks like when you remove the intake.
The thinner the gasket the more chance of that happening are. If you bee the super thin gasket you better secure them to the head with your favorite goop to keep them in place..... I used .060 on my motor for gasket thickness. I loved my pro systems carb minus 2 little things issues.......those red gaskets are messy if you handle them......and on my idle screws they had cheap oring not the sleeves and mine wouldn't stay set till I swapped them out
